News from GERSTEL GmbH & Co. KG · Eberhard-Gerstel-Platz 1 · 45473 Mülheim an der Ruhr · Germany · Phone + 49 (0) 208 - 76503-0 · gerstel@gerstel.com
No. 18

Green
AnalysisStir Bar Sorptive Extraction (SBSE)

Stirred, not shaken
Powerful water analysis based on the EU-WFD
Metabolomics

Forensic Dating Services

Food Safety Analysis

Presenting the Lab

Watereddown taste

Gunshot Residue
DatingRefined Risk
The DOW Ecology Lab
3-MCPD & glycidol in Stade, Germany

18
CONTENT
Cooling options
To maximize performance, a cooling systemthat matches the application is needed. The
available cooling options and where they
best fit are described below.

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3 Mülheim ander Ruhr· Germany· PhoneStir Bar
Sorptive
Extraction(SBSE)

StirredMetabolo

Powerful watermics

Watereddown tasteForensic

Dating, not sh+ 49 (0)208 - 7650

Food Safety Analysis
Food Sa
fet
Analysis y

Presenting
theLab
The DOW
in Stade Ecology Lab, Germany

Forensic Dating Services

Watered down taste

Gunshot Residue Dating

Extreme weather with alternating periods ofdrought and heavy rainfall can negatively
affect yield and quality of agricultural crops.

To determine if and when a handgun has
been fired, forensic scientists are searchingfor and analyzing Gunshot Residue (GSR)
deposits. An extraction technique basedon Headspace Sorptive Extraction (HSSE)
has now been shown to extract additional
information from spent cartridges.

page

4

Herbal warfare
Plant based food and feed can contain toxic
pyrrolizidine alkaloids (PAs) due to coharvesting of weeds that contain PAs alongwith the main crop. Experts recommend
testing crops known to co-exist with PA
containing weeds before use.

Metabolomics studies generally require efficient, fully automated sample preparationand the right autosampler.

Presenting the Lab

Always one step ahead
GERSTEL Solutions Worldwide magazine
visited the Ecology Services Laboratories of
DowDuPont at the Chemistry Park Stade inGermany. The lab is responsible for waterand environmental analysis at the site andwe had a look around.

page

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analysis
based onthe EU-W
FD

Service
Gunshot Residue
DatingMetabolomics

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AnalysisAnalytical mass movementpage

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Food Safety© istock / amphotora / PauraDesign

GERSTEL
Gmb

Metabolomics

Chilled out

2News from
No. 18

page

13

Food Safety Analysis

page

7

Water analysis

Stirred, not shaken
A highly sensitive method for quantitative
determination of around 100 contaminantsin surface waters with and without sedimenthas been developed. SBSE is the method of
choice for analyte concentration, providing
simple, yet powerful, water analysis basedon the EU Water Framework Directive.

page

16

Environmental analysis

Refined Risk

Lingering Poison

An automated GC/MS-method enables
highly efficient determination of 2-MCPD,
3-MCPD, glycidol and their fatty acid esters
based on standard methods.

Sampling procedures and sample handlingare key factors in generating valid analyticalresults as illustrated in the characterizationof concentration profiles of DDT-related
compounds in marine pore water.

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25

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GERSTEL Solutions worldwide – No. 18

Cooling options

Chilled out
The GERSTEL Cooled Injection System (CIS) is a PTV-type GC inlet that is also used as cold trap in
GERSTEL GC sample introduction solutions such as thermal desorption. To maximize performance,
a cooling system that matches the application is needed. The available cooling options and where
they best fit are described below.

The GERSTEL product range includes cooling options
to meet every application need. To find out which
cooling option is best for you, contact GERSTEL todiscuss with our experts.

Liquid Nitrogen (LN2)When using the CIS strictly as a PTVtype GC inlet for liquid injections theelectrically powered Universal Peltier cooling module (UPC Plus) can be used. The
UPC plus is based on Peltier Cooling andit continuously circulates coolant to remove heat. UPC Plus requires very little
maintenance and operates quietly in the
background. Temperatures as low as 10 °C
can be reached reliably and the UPC Plus
doesn’t require additional bench space, it ismounted on the GC. The UPC Plus is also
used to cool all GERSTEL modules where
cooling aids in decreasing analysis cycle
time such as the TDS, TDU, TD 3.5+, and
DHS. It can also be used when cooling isneeded for sample trays and agitators.

Carbon Dioxide (CO2)

Cryostatic Cooling Device (CCD 2)

When you know that your compounds of interest are ina higher volatility range, but you still do not want touse adsorbents for trapping, liquid CO2 can be used toreach temperatures as low as -70 °C. Liquid CO2 has
the advantage of being stored conveniently in a gas cylinder at ambient temperature. However, compared to
LN2, LCO2 has less cooling
capacity; the number ofanalysis cycles that can be
performed using a single
cylinder is significantly
smaller when comparedto LN2.

When performing targeted analysis where the use of adsorbent traps is acceptable or non-target analysis of, forexample, SVOCs, the GERSTEL Cryostatic Cooling
Device (CCD 2) is a perfect replacement for cryogenic
cooling. It provides continuous, reliable cooling of the
CIS to as low as -40 °C. The CCD 2 provides two separate cooling channels with independent temperature
control so it can also be used to cool a TDS, TDU, or a
TD 3.5+.

© istock / axily; Text: Guido Deussing

Illustration: GERSTEL / Dr. Malte Reimold

LN2 based cooling provides the widest
range of trapping temperatures, and greatly
simplifies method development. Thanks tobeing able to cool the CIS to as low as -180
°C, you can always be sure you are trapping
even the most volatile compounds. Physicsbased cryogenic trapping with LN2 ensuresthat all unknown analytes are trapped without chemical transformation and are consequently transferred to the GC column discrimination free. The use of LN2 eliminates
the need to use chemical sorbents that havespecific trapping characteristics and aredesigned to trap a range of compounds ora specific compound type (i.e. sulfur compounds). Solving critical problems requiresthat you see all compounds in your sample,
but with chemical trapping you can never besure that you have selected the right adsorbent/adsorbents. They should never be used
unless performing target analysis where you
validate trap performance through the use of standards

GERSTEL Solutions worldwide – No. 18

Universal Peltier Cooling(UPC Plus)

3

Metabolomics

Watered down taste
Extreme weather with alternating periods of drought and heavy rainfall can negatively affect yield andquality of agricultural crops. Recent research into the impact of climate variations on the quality of tea
have shown how dramatic the influence can be.
By Guido DeussingS© istock / nevarpp

econd only to water, tea is by far the most widely consumed beverage in the world. Apart from actual or
imagined physiological effects, the main and most important aspects for a tea drinker are thought to be flavor
and enjoyment. There may be regularly recurring trends
towards consuming only the healthiest beverages, but
generally, consumers’ main concern is that their drinks
taste good. However, sensory characteristics such as taste
and aroma are exactly the qualities affected by weather, as
Professor Albert (Al) Robbat, Director of the Tufts University Sensory and Science Center in Medford, Massachusetts explains to GERSTEL Solutions worldwide. As
it turns out, this is especially the case when the harvest
literally falls into the water.

Tea – an ideal model plantfor climate effect studies
In cooperation with an interdisciplinary team of colleagues, Al Robbat investigated tea samples from Yúnnán province in Southwestern China,
an area renowned for excel-

lent tea. The aim was to determine why tea leaves picked
during the rainy monsoon season are less aromatic andfrequently have off flavor issues compared with tea leaves
picked during the dryer spring season. This was found tobe the case even when comparing leaves picked from thesame plant. The chromatography expert explains that not
only do tea drinkers suffer when exposed to inferior quality brews; tea farmers incur significant losses since they
are forced to sell crops grown during the monsoon season
at much lower prices compared with the spring crop.
There is an urgent need for more insight into causes
and effects since the Yúnnán region is increasingly facedwith extreme weather conditions that can affect quality and yield and in extreme cases lead to total loss of
harvest. As Al Robbat explains, there has already been a
noticeable shift in the start of the summer monsoon andits duration, which means that periods with ideal harvest
conditions are becoming shorter. The scientists set out todetermine the root causes for changes in quality and flavor of Yúnnán tea as a function of rainfall, temperature,and elevation. Their findings are reported in Journal of
Chromatography A [1].

Preliminary investigations
showed the way
Initial investigations of tea harvested in themountains of Yúnnán from spring until the onset of the monsoon period brought the following results: With
increasing

4

GERSTEL Solutions worldwide – No. 18

A closer look at plant metabolism
Taste and aroma of tea are a result of complex interactions
between hundreds of chemical compounds. Al Robbat:“Extending our knowledge of potentially sensory relevant
metabolites and monitoring them over a period of time is
key if we want to develop an understanding of how environmental and climate factors influence tea quality.” Weknow that seemingly unimportant compounds can significantly influence the organoleptic quality. Most studies
listed in literature have focused on seasonal changes of
non-volatile compounds, but we now know that volatileorganic compounds (VOCs) with low odor thresholds
contribute significantly to the total sensory impression,
Al Robbat points out. This realization had led the group
towards using GC/MS as the technique of choice formonitoring metabolites.

Tea harvester in a Chinese
highland region.
Flavor research needs GC/MS analysis, and GC/MS
methods are widely used in metabolomics research (seepage 9). In the case of tea plants, the sample matrix ishighly complex and a huge number of potentially relevant
GERSTEL Solutions worldwide – No. 18© iStock / lzf

amounts of rainfall, the catechin compound concentrations dropped by more than 50 percent. Among these are:catechin, catechingallate, epicatechin-3-gallate, epigallocatechin, epigallocatechin-3-gallate, gallic acid, gallocatechin and gallocatechin-3-gallate. The same effect was
found for methylxanthines (caffeine, theobromine andtheophylline) Al Robbat reports [2]. Although catechinsand methylxanthines, astringent bitter compounds characteristic of poor quality teas decreased in concentration,other polyphenolic compounds (also astringent and bitter) increased in concentration. “Initially, we assumed thatthe loss of quality was related to a kind of dilution effect, in other words that the plant growth would outpace
the production of secondary metabolites to which theflavor compounds belong”, the scientist explains. However, when they determined that the total concentration
and activity of antioxidants in teas harvested in spring
was lower than in comparable teas harvested during themonsoon period, Al Robbat and his colleagues concluded
that the plant chemistry, i.e. metabolism and physiology
had changed completely and had adapted to the change
in precipitation. This had resulted in changes in metabolism and, therefore, in the associated flavor determining
metabolites. The idea was obvious, Prof. Robbat explains,
to not just focus on significant flavor compounds in tea,
but rather look at the bigger picture, including determining the entire group of flavor relevant compounds and to
generate a profile of as many metabolites as possible inorder to understand how environmental conditions influenced tea plant chemistry.

flavor compounds are involved. Literature sources countaround 600, according to Prof. Robbat. This is the reason
that a sequential, multidimensional GC-GC/MS method
was used in order to comprehensively determine all detectable volatile metabolites in spring- and monsoon teas.
The acquired data were used to build a metabolite database that relies on a deconvolution software to solve highly complex analysis tasks very quickly using a standard
GC-MSD system. This is even possible when multiple
compounds co-elute and also have overlapping signals.
The deconvolution technology developed by Professor Robbat and his colleagues offers added value in comparison with conventional approaches. This includes thepossibility to obtain and store retention times and spectraof neat metabolites that aren’t skewed by matrix influence.
It is also possible to identify perfectly co-eluting compounds. Professor Robbat and his group routinely measure the relative concentration of more than 400 compounds from infused tea leaves.

Technology that enables
successful analysis
Initially the aim had been to use the spring harvested tea
samples to find as many metabolites as possible and build
a solid reference database. Al Robbat: “In order to build
a comparative database, we instead analyzed tea samples
consisting of buds and leaves that had been collected overthree day periods in both spring and summer”. In otherwords, the periods spanned both the dry season (spring)and the rainy season (monsoon). Collected tea samples
were briefly microwaved in the field to stop enzymatic
activity and subsequently sent to the laboratory in sealed
plastic bags. In the laboratory, they were vacuum sealed,wrapped in aluminum and stored in a deep freezer awaiting analysis. GC-GC/MS analysis was performed on5© istock / langdu© GERSTEL / Wolfram Schroll

extracts of the tea
samples. The previously used classicalextraction procedure was simultaneous distillation andextraction (SDE) using the LikensNickerson process on a tea infusion
prepared using deionized water and concentrated under a nitrogen atmosphere
over anhydrous sodium sulfate. For thework described here, the GERSTEL Twister® was used since it provides a simple, clean
method to extract organic chemical compounds
from the tea infusion requiring no or almost no use oforganic solvent. The Twister is a glass coated magnetic
stir bar fitted with a PDMS sorbent phase. While stirring
the sample, the Twister efficiently extracts organic compounds. The Twister was also used to collect organics inthe field by placing it directly under the leaf and holding
it in place with a magnet [3]. For the tandem GC-GC/
MS analysis Al Robbat and his colleagues used two 6890
GCs from Agilent Technologies. The first system was fitted with an FID; analyte separation was performed using
a column with polar stationary phase. Sample introduction to the Cooled Injection System (CIS) PTV-type inlet was automated using the GERSTEL MultiPurpose
Sampler (MPS). The second GC system was configured
with a non-polar capillary column and a Cryo-Trapping
System (CTS) in order to enable heart-cutting and cryofocusing of fractions separated on the first column and todeliver these to the second column as a narrow band forbest possible quality of separation as well as MS
determination (Agilent Technologies MSD 5973).
The second system employs a GC 6890 and two
Low Thermal Mass (LTM) units with individual
GC columns (Agilent Technologies), to performthe GC-GC/MS experiments.
Professor Robbat’s group analyzed spring andsummer, high and low elevation samples from6both Yunnan and Fujian Provinces, temperatures during sampling varied by up to 10 °C. The samples weretaken to study locational differences over a 3-year period(2014-2016)[4]. The data analysis software developed by
Dr. Robbat and sold through GERSTEL provided themeans to analyze these samples by GC/MS and trackcompositional changes in tea under stress conditions [5].

Analysis results confirm
sensory impression
Al Robbat: “Our analysis results confirm what tea farmers tell you: The spring tea is of much higher quality andhas a sweet floral flavor compared with the monsoon tea,
which is described as green or earthy. Using tandem GCGC/MS analysis we succeeded in identifying hundredsof metabolites in the spring and monsoon teas”. Professor
Robbat’s group found 169 metabolites that were common to both tea types and more than 100 compounds
that were unique seasonal compounds. A further 163
compounds were detected, but could not be identified. In
future, we will increasingly have to contend with extreme
weather conditions. This means that plant research must
develop tools that can monitor the influence not only onplant growth and yield, but also on taste, flavor and nutritional value of crops. “Our work has delivered a set oftools to monitor seasonal variations in the metabolism oftea plants”, says Al Robbat, “and I’m certain these tools
can be used for similar metabolomics studies of crops andhuman systems”.
Using a comparable MPS-GC/MS system, Professor
Al Robbat performed the analysis of tea plant extracts
and determined secondary metabolites as described inthis article.

Reference[1] A. Kowalsick, N. Kfoury, A. Robbat Jr., S. Ahmed, C. Orians, T. Griffin, S. B. Cash, J. R. Stepp, Metabolite profiling of Camellia sinensis
by automated sequential, multidimensional gas chromatography/
mass spectrometry reveals strong monsoon effects on tea constituents, Journal of Chromatography A, 1370 (2014) 230–239[2] S. Ahmed, J. R. Stepp, C. Orians, T. Griffin, C. Matyas, A. Robbat, S.
Cash, X. Dayuan, L. Chunlin, U. Unachukwu, S. Buckley, D. Small,
E. Kennelly, Effects of extreme climate events on tea (Camelliasinensis) functional quality validate indigenous farmer knowledge
and sensory preferences in tropical china, PLoS ONE 9 (2014)
e109126.
[3] N. Kfoury, E. Scott, C. Orians, A. Robbat, Jr., Direct Contact Sorptive
Extraction: A Robust Method for Sampling Plant Volatiles in the
Field, J. Agric. Food Chem. 2017, 65, 8501−8509. DOI: 10.1021/
acs.jafc.7b02847[4] N. Kfoury, J. Morimoto, A. Kern, E. R. Scott, C. M. Orians, S. Ahmed,
T. Griffin, S. B. Cash, J. R. Stepp, D. Xue, C.Long, A. Robbat Jr, Striking changes in tea metabolites due to elevational effects, Food
Chemistry 264 (2018) 334–341, https://doi.org/10.1016/j.foodchem.2018.05.040[5] A. Robbat Jr., N. Kfourya, E. Baydakovb, Y. Gankinb, Optimizing
targeted/untargeted metabolomics by automating gaschromatography/mass spectrometry workflows, Journal of Chromatography A, 1505 (2017) 96–105, http://dx.doi.org/10.1016/j.
chroma.2017.05.017

GERSTEL Solutions worldwide – No. 18

Forensic Dating Services

Gunshot Residue Dating
To determine if and when a handgun has been fired, forensic scientists are searching for and analyzing
Gunshot Residue (GSR) deposits. GSR can be found directly on firearms, spent cartridges, or on persons,clothing or materials that were near the firearm at the time it was discharged. One highly interesting
aspect of GSR is the presence of volatile organic chemical residues, which can offer clues as to when aweapon was fired. An innovative extraction technique based on Headspace Sorptive Extraction (HSSE)
has now been shown to extract additional information from spent cartridges.
By Guido Deussing

W© iStock / shawn_hempel

hen investigating a crime that was carried out using a firearm, it is often of critical importance todetermine whether gunshot residue (GSR) can be foundat the crime scene or on weapons potentially used. Sucha finding can enable detectives to identify - or rule out a firearm as the weapon used and potentially link it to asuspect. Further, given the right technique, chemical analysis can shed light on the time elapsed since a weapon
was last fired.
Widely used analysis methods based on gas chromatography with mass spectrometry detection (GC/MS)and Solid Phase Micro-Extraction (SPME) have been
GERSTEL Solutions worldwide – No. 18

7evaluated by collaborating scientists at the Universityof Lausanne, Switzerland; the Sapienza University in
Rome, Italy; and King’s College in London, England. In
addition, a novel method using Headspace Sorptive Extraction (HSSE) followed by thermal desorption-GC/
MS (TD-GC/MS) was compared with the SPME based
method. The scientists were pleased with the results. [1].

The Content of Gunshot Residue© GERSTEL

Every firearm emits gunshot residue when discharged.
The compounds involved are released at explosive speed
and deposited or adsorbed on the hand, body and clothing of the shooter. Depending on the distance to the firearm, residue can also be found on the victim and, obviously, on the weapon used and on spent cartridges thatwere ejected.
Sources of GSR are the ignition- and propellant
charge powders in the cartridge. In addition, metallic
powder is formed by abrasion from the bullet and car-

To perform Headspace Sorptive Extraction (HSSE), a GERSTEL Twister is suspended
inside a sealed vial placed in the headspace above the sample. In the case shown
here, a spent handgun cartridge (left) is being analyzed. During extraction, volatileand semi-volatile organic compounds (VOCs and SVOCs) are concentrated in thesorption phase of the Twister. The Twister shown here is the Polydimethylsiloxane(PDMS) version. Following the extraction period, the Twister is removed, placed ina glass liner, and analyzed by thermal desorption-GC/MS. The GERSTEL Thermal
Desorption Unit combined with a GC/MS-System (Agilent Technologies) was usedin the work reported here.

tridge and added to the mix. GSR consists of various
inorganic and organic chemicals. Due to aging processes
and volatilization, changes in the concentrations andamounts of organic chemicals as well as certain compound to compound ratios of amounts can be helpful indetermining the time of discharge of a weapon according
to Gallidabino et al. as reported in their paper in Analytical Chemistry [1].
The compounds identified as GSR from literaturereferences are, among others, nitroglycerine, diphenylamine, ethylcentralite, dibutylphthalate and 3-Ethyl1-Hexanol as well as organic reaction byproducts, espe-

8cially derivatives of benzene, and polycyclic aromatichydrocarbons (PAHs). To determine these, the SPME
technique has been widely used in combination with
GC/MS. To perform GSR-based dating, Gallidabino
et al. performed repeat extractions of analytes from theinterior of a firearm and/or spent ammunition withthe aim of establishing an aging profile, which can becompared with reference profiles. Naphthalene and decomposition products of nitrocellulose were proposed
as target reference compounds.

The problem with handguns – and thesolution
SPME is an established technique for time estimatesconcerning discharge of ammunition from rifles andother larger firearms. However, its usefulness for forensic dating of firing of smaller handguns is more limited.
The repeatability is insufficient, as reported by the scientists, and degradation curves for the target analytes
quickly fall below their limits of detection with SPME,
as Gallidabino et al. [1] report. For these reasons,
SPME is not the ideal technique for the investigationof GSR in combination with handguns.
In their search for an alternative extraction andanalysis method with significantly higher sensitivity for the target analytes, the scientists’ attention wascaught by Headspace Sorptive Extraction (HSSE).
HSSE is based on the GERSTEL Twister, a glass
coated magnetic stir bar with a PDMS sorption phase.
The Twister is most often used for Stir Bar Sorptive
Extraction (SBSE) of aqueous samples. In HSSE,
the Twister is suspended in the Headspace above thesample inside a sealed 20 mL headspace vial. HSSE
is thus very similar in principle to Headspace Solid
Phase Micro-Extraction (HS-SPME). The main difference is that the Twister offers a much larger sorption phase volume than SPME fibers which consistof a thin sorption phase coating on a metal or glass
fiber contained within a syringe needle. Consequently,
SBSE provides better recovery, better repeatability, andlower limits of detection. After the extraction step,
analytes are released from the Twister by thermal desorption in the GERSTEL Thermal Desorption Unit
(TDU 2) immediately followed by GC/MS determination of the analytes. These steps are fully automatedusing the GERSTEL MultiPurpose Sampler (MPS)
under MAESTRO software control. “The Twistercan provide up to 1000 times higher sensitivity than
SPME, depending on the application”, says Oliver Lerch, Ph.D., Application Scientist from GERSTEL.
SBSE can be performed with different Twisters tocover a wide range of analytes from non-polar to polar.
Desorption can be performed by thermal desorption– as is most often the case - or by liquid desorption
combined with either GC/MS or LC/MS.
GERSTEL Solutions worldwide – No. 18

Preparing the GSR analysis

GSR target analytes from discharged cartridges. HSSE
proved to be significantly more sensitive while delivering
better reproducibility than SPME. Among the 4 compounds not found were thermally labile compounds suchas nitroglycerine that are decomposed during thermal desorption. Further studies are to be performed to optimize
the analysis method parameters with the aim of increasing the number of target analytes that can be determined.
As part of their project, Gallidabino et al. generated
aging curves in order to develop a method for determining the approximate time of discharge including determining whether the firearm was discharged at all. TheseTo determine whether HSSE is a suitable extraction technique for the analysis of GSR, different types of cartridges were inserted into a semi-automatic pistol, discharged,
and the spent cartridges placed in sealed HS vials with
GERSTEL Twisters suspended in the headspace above
the sample. The cartridges contained propellant charges
based on either nitrocellulose or a combination of nitrocellulose and nitroglycerine. The results from the HSSETD-GC/MS analysis were compared with results fromthe analysis of a reference mixture based on 55 selected
substances, identified as GSR compounds. This is how Gallidabino etal. approached the analysis: In theheadspace above the spent cartridge
to be analyzed, a perforated glass
insert containing a conditioned
Twister was positioned and theheadspace vial was sealed. Different Twister techniques enable different sampling approaches alongwith the use of different phases tocollect a wider range of analytes.
In this case, the analytes were extracted at 80 °C for 72 hours. The
Twisters were removed from thevial and placed in individual sealed
Ion Chromatogramm (EIC) of the standard solution containing 55 substances injected by Gallidabino et al.
glass tubes ready for Thermal De- Extracted
Using HSSE-GC/MS, the researchers were able to determine 51 of the 55 compounds in GSR. The “missing comsorption-GC/MS analysis. The pounds” were thermally labile substances including nitroglycerine and N-nitrosophenylamine.
glass tubes were fitted with individual transport adaptors, which seal
the tubes and enable the MultiPurpose Sampler (MPS) aging curves are based on GSR compound concentragripper to transfer them to the Thermal Desorption Unit tions on spent cartridges from handguns and their degra(TDU) for temperature programmed desorption. The re- dation curves. The scientists report that based on the useleased analytes are focused in the GERSTEL Cooled In- of HSSE on aged samples, several GSR compounds havejection System (CIS) PTV type GC inlet at -80 °C. The shown significant aging profiles. In addition, compoundCIS is then heated using a temperature program and the to-compound ratios can be used to extend the time peanalytes transferred to the GC column in splitless mode riods that can be covered. This approach also contributes
using a helium carrier gas flow of 1.3 mL/min for highly to making the determination more rugged and to reducsensitive GC/MS determination. The CIS was installed ing variability, making the method more useful for thein a gas chromatograph (Agilent GC 7890A) connected forensic scientist entrusted with the case.
to an Agilent 5975 Mass Selective Detector (MSD). The Gallidabino and his colleagues concluded
column used was an Agilent HP-5MS (30 m x 0.25 mm that their results were very encouraging
x 0.25 μm). The GC oven initial temperature was 40 °C, for the development of a new and comthe program progressing to a final temperature of 280 °C. plete forensic dating technique based
The GC run including cool-down and equilibration last- on GSR.
ed 46 minutes. Mass Selective Detection (Agilent 5975C
MSD) was performed in EI mode in full scan modeacross a range of m/z 40 to 500.

HSSE delivers
The results of their study clearly showed that by using
HSSE, the scientists were able to determine and track theconcentration degradation curves of 51 of the selected 55
GERSTEL Solutions worldwide – No. 18© iStock / VladimirFLoyd

Reference[1] M. Gallidabino, F. S. Romolo, K. Bylenga and
C. Weyermann, Development of a Novel
Headspace Sorptive Extraction Method to
Study the Aging of Volatile Compounds
in Spent Handgun Cartridges, Analytical
Chemistry 86 (2014) 4471-4478

9© istock / 49pauly

Food Safety

Herbal warfare
Plant based food and feed can contain toxic pyrrolizidine alkaloids (PAs) due to co-harvesting of weedsthat contain PAs. Experts therefore recommend testing crops known to co-exist with PA containing weeds
before use in food or feed. The method of choice for direct determination is solid phase extraction(SPE) cleanup followed by LC-MS/MS analysis.
By Guido DeussingGreen and lush pastures and fields present a wonderfulsight. A closer look, however, can reveal more thanjust healthy greens and harmless edible plants. Among thecrops we grow for use as food and feed, wild herbs crop up
that are a thorn in the flesh of farmers and horse breeders.
In temperate zones in Europe, ragwort is a ubiquitous, particularly toxic wildflower, which looks similar to plants of
the arugula family. Unlike arugula, however, it is anything
but wholesome. Ragwort and related species contain toxic
pyrrolizidine alkaloids (PAs), presumably synthesized by
the plants as a defense against herbivorous enemies. PAs
are natural toxins whose toxicity is not limited to insects:
Many are toxic both to humans and to the herbivores werely on for meat and dairy products. Some PAs cause liver
damage and are both genotoxic and carcinogenic. Regularintake of even small amounts can lead to a creeping process of progressive damage to internal organs, as can beobserved in horses and cattle. PA poisoning can lead toserious illness and even death.

10

How big is the threat?
The challenge facing producers and consumers is significant: A total of more than 6,000 plant species produce
PAs, equal to about 3 % of the total number of flowering
plants world-wide as calculated by BLL, the German Federation for Food Law and Food Science. BLL is the mainindustry association of the German food sector.
More than 600 PAs and their N-oxides have beenfound and characterized in more than 350 different plant
species Worldwide, according to the Federal German Institute for Risk Assessment and Consumer Safety (BfR)
in Berlin. PA toxicity has long been established; a recent
scientific publication by US FDA scientists also established the toxicity of a number of PA N-oxides, recorded
to induce Hepatic Sinusoidal Obsctruction Syndrome(HSOS) in humans, and further confirming PA N-oxideinduced hepatotoxicity on mice with hepatotoxicity similar
to, but potency much lower than, the corresponding PAs.
GERSTEL Solutions worldwide – No. 18

Consumer protection
The widespread occurrence of PA-synthesizing plants
worldwide means that we as consumers should accept thefact that the risk of having PAs in food and feed cannot be
totally eliminated. This may be part of the reason that until
now, no country has introduced legally binding maximum
concentration levels, relying instead on recommendations.
In 2001, the United States Food and Drug Administration(FDA) issued a ban of comfrey based products marketed
for internal use, and a warning label for those intended
for external use. In an opinion published by the BfR, foodproducing companies have an obligation to take steps toensure that PA levels in food are reduced. In preparation
for such action, and based on a request from the European Commission, the European Food Safety Authorities(EFSA) in 2016 published a scientific report entitled: Dietary exposure assessment to pyrrolizidine alkaloids in theEuropean population [3]. A further extensive publicationin the form of a “Statement” was published by the EFSA
in 2017, entitled: Risks for human health related to thepresence of pyrrolizidine alkaloids in honey, tea, herbal infusions and food supplements [4]. In summary, the EFSA
recommends gathering more toxicological data, expanding
the proposed list of 17 PAs to be monitored, and developing more sensitive analysis methods. EFSA currently
sees no possibility of establishing a tolerable daily intake(TDI) value. In Germany, the BfR therefore recommends
a zero-tolerance approach. While this is commendable, it
is highly unlikely to be implemented in practice. According to the BfR, the aim of following this approach is simply to keep PA levels in food and feed as low as possible
and to support this effort by monitoring, which requires
efficient and highly sensitive chemical analysis including
sample preparation.

Analysis methods
Monitoring PAs in agricultural products, such as food andfeed, is not exactly easy: PAs are structurally diverse, they
are present in a wide range of products and the analysis
poses a real challenge. Over the past years, scientists at the
BfR have developed accurate and reliable methods for thedetermination of PAs. These methods have been validated
GERSTEL Solutions worldwide – No. 18

in round-robin tests. The methods could be implemented in food and feed monitoring performed by individual
German states, but currently only a limited number of
PA standards are commercially available. This has led the
BfR to develop additional analysis methods that can beused to estimate the total amount of PAs in a sample. To
determine PAs in plant material, the BfR recommends
analyte concentration using solid phase extraction (SPE)followed by LC-MS/MS determination: The PAs are
extracted from plant material in an ultrasonic bath using
diluted sulfuric acid. The material is extracted twice andthe extracts combined and centrifuged. An aliquot of thesupernatant is taken for solid phase extraction (SPE) using
a C18-phase. Following elution with methanol, the eluate is evaporated to dryness and the residue taken up in amethanol-water mixture. Finally, the sample is injected forchromatographic separation and MS/MS detection [1].

Automation provides added value
A contract laboratory that specializes in the analysis offood and feed requires efficient sample processing in order
to be competitive. That also applies to PA, of course. “Thisis where I see a deficit of the BfR methods”, says Franziska
Chmelka, Food Technologist at TeLA GmbH, “the sample preparation is quite labor intensive”. TeLA is an accredited contract laboratory for food and environmental
analysis in Northern Germany. In order to improve theproductivity of the BfR analysis method, TeLA automatedit, including sample preparation. Franziska Chmelka andher colleagues used the GERSTEL MultiPurpose Sam-© TeLA GmbHThe FDA scientists conclude that the levels of both PAs
and PA N-oxides in herbs and foods should be regulated
and controlled [2]. As an example, PAs have been found inherbs used for herbal infusions - also referred to as herbal
teas. Examples are fennel-, chamomile-, herbal-, peppermint-, nettle-, and garden balm (Melissa) tea. In 2013, theBfR assessed the situation and concluded that PA levels
in some foods (herbal tea, rooibos tea, black and green tea
as well as honey) can pose a threat to children and adults
alike when these foods are consumed on a regular (chronic) basis and that effort should be made “to minimize the
PA contents in herbal teas and teas in order to minimize
the putative higher cancer risk of frequent consumers andin particular of children” [1].

Instrument setup used for the automated determination of pyrrolizidine alkaloids:
GERSTEL MultiPurpose Sampler (MPS) configured for automated SPE in combination with an LC-MS/MS system from Agilent Technologies (1290 HPLC and 6495
Triple Quadrupole LC/MS).

pler (MPS) to automate the required sample preparation
steps for the PA determination. A key component of thesystem is automated SPE in combination with LC-MS/
MS (Agilent Technologies 1290 HPLC and 6495 Triple
Quadropol LC/MS).
Separation of the analytes was performed using aStandard-RP-Phase column (Nucleodur C18 HTec 250 x
2 mm x 5 μm, Macherey-Nagel) and gradient elution with
5 mM formic acid (Eluent A) and methanol (Eluent B): 0
min (5 % B) – 3 min (5 % B) – 7 min (20 % B) – 13 min

11

Analysis of a standard mixture of 17 pyrrolizidine alkaloids resulted in a clean chromatogram with wellresolved peaks. Good separation of the individual PA compounds is extremely important. Many exhibit very
similar mass transitions and can only be distinguished and identified unequivocally when peaks are fully
resolved. (Source: TeLA GmbH)(20 % B) – 16 min (65 % B) – 17 min (95 % B) – 20,1 min(5 % B). The flow rate was 0.25 mL/min and the column
temperature 28 °C. A 5 µL aliquot of the eluate was injected. Target analytes were detected in Multiple Reaction
Monitoring (MRM) mode, ESI positive.
For method development, an aqueous standard solution was used, containing 17 different PAs: Monocrotaline,
erucifoline, intermedine, jacobine, lycopsamin, monocrotaline N-oxide, erucifoline N-oxide, intermedine N-oxide,
retrorsine, jacobine N-oxide, senecivernine, senecionine,
retrorsine N-oxide, senecivernine N-oxide, senecionin Noxide, lasiocarpine and lasiocarpine N-oxide.

© TeLA

Automated SPE to the rescue“Our focus when developing the method was on automating the most labor intensive step in the process, which iswithout a doubt the solid phase extraction (SPE)“, saidFranziska Chmelka. After completing their initial experiments, the application experts from TeLA decided
to use a C18-RP sorbent(Macherey-Nagel C18 ec 3
mL/500 mg).
All SPE steps were successfully automated: Conditioning the sorbent with 5
mL of methanol and 5 mLof water; injecting 5 mL
sample onto the sorbent; as
Chopped Chamomile (left), spiked with 0.1 % ragwort (right). well as eluting the analytes
with 5 mL methanol. “Wealso succeeded”, says Norbert Helle, Ph.D., President andOwner of TeLA GmbH and established LC/MS expert,“in automating the remainder of the process: Evaporating
the eluate to dryness, taking up the residue in 1 mL of a 10
% methanol solution, and injecting 5 µL of the resulting
extract into the LC-MS/MS-System”.
Analysis of the standard mixture resulted in a cleanchromatogram with well resolved peaks. Franziska Chmelka explains the focus: “Good separation of individual peaks

12

is essential. Many of the compounds have similar masstransitions and we must be able to differentiate between
the different analytes. That is only possible if we have retention time differences.” The application experts from
TeLA then put both the method and the instrument setup
to the test by running real samples, in this case, ragwort
leaves. “All statistically relevant parameters confirmed that
our automated SPE-LC-MS/MS method is delivering
accurate results”, says Franziska Chmelka. Good linearity
was achieved across a wide concentration range, going as
low as 1 ng/mL, and recoveries ranged from 85 to 98 percent for all analytes. The overall method reproducibility,
including sample preparation, was in the range from 1.3
to 4.8 percent for all analytes. Franziska Chmelka: “It was
especially important to us to achieve good retention timestability as this is a key indicator of method ruggedness.
Using our method, retention times for the analytes only
varied between 0.063 and 0.35 percent over a period ofseveral days. Finally, the limits of determination we canreach are between 0.05 and 0.5 μg/kg”.
In a further step, the TeLA team tested how many PAs
are actually transferred to the herbal infusions we brew
and drink and how much PA is transferred in total: Dry
Chamomile material was spiked with different levels of
Ragwort; the amounts added were 10.1 and 0.1 percent
w/w relative to the chamomile. As Franziska Chmelka
reports: “Just adding 0.1 percent ragwort resulted in ourfinding a significant amount of PAs in the brewed herbal
infusion”.

Conclusion
The automated SPE-LC-MS/MS analysis method was
successfully used to determine PAs in various food andfeed samples. In all cases, the method worked well andprovided good results. Looking forward, the methodneeds to be extended. A larger number of PAs will need
to be monitored and the sensitivity of the method must
be improved. In its curSuggested bedside reading (292 pages):rent form, however, theUS
Food and Drug Administration, FDA.
method provides highly
Bad
Bug Book, Foodborne Pathogenic
satisfactory results, as
Microorganisms and Natural Toxins.
Franziska Chmelka reSecond Edition.
ports.
https://www.fda.gov/downloads/
Food/FoodborneIllnessContaminants/
UCM297627.pdf

References[1] www.bfr.bund.de/cm/349/pyrrolizidine-alkaloids-in-herbal-teasand-teas.pdf (2018/01/19)[2] Yang, M., Ruan, J., Gao, H. et al. Arch Toxicol (2017) 91: 3913.
https://doi.org/10.1007/s00204-017-2013-y[3] EFSA (European Food Safety Authority), 2016. Dietary exposure
assessment to pyrrolizidine alkaloids in the European population. EFSA Journal 2016;14(8):4572, 50 pp. doi:10.2903/j.
efsa.2016.4572[4] EFSA CONTAM Panel (EFSA Panel on Contaminants in the Food
Chain), Knutsen HK, Alexander J, Barregård L, Bignami M, Brüschweiler B et al., 2017, Statement. Risks for human health related tothe presence of pyrrolizidine alkaloids in honey, tea, herbal infusions and food supplements. EFSA Journal 2017;15(7):4908, 34
pp. https://doi.org/10.2903/j.efsa.2017.4908
GERSTEL Solutions worldwide – No. 18

© istock / SusanneB

Metabolomics

Analytical Mass Movement
When epidemiological studies require analysis of large sets of blood, plasma, or urine samples underuniform conditions, with good accuracy, and within a limited time frame, manual sample preparation
may not be the best approach. Metabolomics studies generally require efficient, fully automated sample
preparation.
By Guido DeussingAccording to experts, cardio vascular disease, obesity,
Type 2 diabetes, and various types of cancer are often linked to a lack of exercise and to an unhealthy diet.
Especially certain fatty foods can have a lasting influence
on your health and well-being, but individual humans
respond differently and are affected to different degrees.
That, at least, is one way to explain why a fast food dominated diet causes some people to become overweight andincreases their risk of developing diseases while others
seem unaffected. The reason could be differences in genetic make-up with respect to metabolic processing of,and energy recovery from, nutrition in the organism.
In order to determine the effects of nutrition on health,as well as determining the role and influence of the genepool, large epidemiological studies are undertaken that examine the resulting metabolites. The entirety of metabo-

GERSTEL Solutions worldwide – No. 18

lites is referred to as the metabolome, the study and quantification of metabolites is referred to as metabolomics.

Profiling thousands ofindividual compounds
When searching for knowledge, in the form of correlations between health, genetics and nutrition, researchers
use metabolite profiling hoping to find biomarkers thatcan provide information on metabolic processes in theorganism. The tools they typically use are high level analytical instruments such as mass spectrometers, combinedwith gas chromatography (GC) or Ultra-High performance Liquid Chromatography (UHPLC), the combined
instruments are typically referred to as GC/MS or LC/
MS systems. In the case reported here, fatty acid methyl

13

For quality control purposes, QC samples with a defined concentration of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were included and analyzed
in every sequence. The table shows the median values in %. N is the number ofsequences processed, SD the standard deviation, and % CV is the coefficient ofvariation in percent. The numbers demonstrate the excellent long term stability andreproducibility of the systems. [1]Month
1 (n = 36)
2 (n = 36)
3 (n = 38)
4 (n = 38)
5 (n = 37)
6 (n = 38)
7 (n = 38)
8 (n = 38)
9 (n = 38)
10 (n = 38)
Comparison of mean values

Mean
2.14
2.14
2.13
2.15
2.16
2.15
2.16
2.15
2.15
2.17

DHA
SD
0.06
0.06
0.06
0.08
0.06
0.05
0.04
0.07
0.06
0.05
P = 0.062

% CV
2.60
2.66
3.02
3.58
2.66
2.47
1.78
3.23
2.71
2.55

Mean
0.46
0.46
0.47
0.47
0.47
0.48
0.47
0.47
0.46
0.46

EPA
SD
0.02
0.01
0.03
0.04
0.03
0.04
0.03
0.02
0.03
0.03
P = 0.064

% CV
4.22
2.22
7.28
9.16
7.13
8.46
6.54
5.30
6.90
6.31

esters were quantitatively determined using a GC withflame ionization detector (GC/FID), due to the larger
linear and dynamic range of the FID.

© GERSTEL / Wolfram Schroll

Metabolomics calls for automation
In order to obtain scientific evidence of possible healtheffects, you need large, comprehensive, and reliable data
sets. It is not unusual for metabolomics studies to involvethe determination of hundreds or even thousands of individual compounds. Just processing the large number ofsamples required within a reasonable time frame represents a challenge. In addition, it must be ensured that theresults generated are extremely accurate in order to be able
to draw any meaningful conclusions. To achieve all this,metabolomics experts agree, you cannot rely on manual
sample preparation, you need as much automation as possible. As an example, Laura Yun Wang and her colleagues
from the Elsie Widdowson Laboratories and the Institute of Metabolic Science in Cambridge, England, havereported on their work developing and validating a fully
automated method for the determination of phospholipid-bound fatty acids in human blood plasma. The goal
was to help perform metabolic phenotyping as part of alarge epidemiologic study involving a sample set of morethan 25,000. Their work was published in Genome Medicine [1,2] (Open Access). In it, the scientists haveclearly documented where they see the challengesof the classical and in many cases manually performed or just partially automated process in-

The GERSTEL MultiPurpose Sampler (MPS) is available in a single headversion as well as a dual head version, which provides similar performance to the dual rail versions used by Laura Wang et al. for automateddetermination of phospholipid fatty acids from human blood plasma.

14

volved. They also report on how they have fully automatedand validated the process steps needed.

The Sample Preparation Challenge
The use of nutrition related biomarkers in large-scale
epidemiological studies is only possible, “if the analysis issufficiently fast, relatively cheap, robust and precise”, according to Wang et al. It was decided to develop an automated method for fatty acid profiling of the phospholipid
fraction in human plasma. A number of steps would haveto be automated: The lipids would have to be extracted in
total from the plasma using solid phase extraction (SPE)and converted into free fatty acids and then volatile fatty
acid methyl esters (FAMEs), which can be determinedusing a GC with a flame ionization detector (FID). Using this method, stereo-isomers (cis- and trans fatty acidisomers) can be determined by GC in an acceptable timeframe, according to the scientists.
When performed by hand, the large number of complex steps requires an inordinate amount of time and theprocess is prone to human error, as pointed out by Wanget al. As they found in their literature searches, multiple
research groups had previously reported automated GC/
FID analysis methods for fatty acid profiling in humanplasma running a large number of samples. However, none
had previously managed to automate the entire analysis,
including extraction of the phospholipid fraction and hydrolysis and derivatization of the free fatty acids for a large
set of samples as needed for epidemiological studies.

All Steps Completely AutomatedUsing a combination of three automated systems, thescientists succeeded in achieving the required highthroughput combined with sufficient long-term stability and accuracy for the determination of phospholipid
fatty acid fractions of human plasma samples. This wasdone as part of epidemiologic studies designed to correlate genetic and nutrition related factors with thedevelopment of type 2 diabetes. Each of the three automated systems consisted of two independently operating MultiPurpose Sampler (MPS) systems. One MPS
was equipped with automated SPE option and an integrated centrifuge to perform automated extraction andcleanup of the lipid fraction. The second MPS
in each system was integrated with the GC/
FID and was used to perform sample preparation, i.e. the steps required for hydrolysis
and derivatization to form fatty acid methyl
esters (FAMEs) as well as introduction to theintegrated GC 7890 N (Agilent Technologies, Little Falls, DE, U.S.A.). When choosing
the second autosampler, Wang et al. focused onfunctionality. The MPS in the dual head or dual
rail versions features two independently operating andfreely moving towers that can simultaneously operate
different tools, or syringes of different sizes. For example, a dual head system can simultaneously handle large
GERSTEL Solutions worldwide – No. 18

volume sample preparation and µL scale introduction to
the GC analysis system. In order to achieve the required
accuracy and reproducibility, reliable and accurate timing is necessary, especially when analyte derivatization is
performed and the reaction product may not be stable.
In such a case, the time period that elapses between analyte derivatization and introduction to the GC/FID system must be exactly the same for each sample in orderto ensure accurate and reproducible results. In practicethis means that samples are best prepared immediately
prior to sample introduction. The MAESTRO software,
which is used to operate the MPS systems by mouseclick automatically optimizes the process timing andensures that every step is performed on time without
having to be watched over by laboratory staff.

(A)
2
3

4

1

5

6

7

8

(B)
2

4

1

3

Final Words
Laura Yun Wang and her colleagues were confronted
with a huge set of samples as part of the EPIC InterAct
Project (See box below) for metabolic phenotyping of
human plasma samples. Even with efficient automation,
the analysis work took several months to complete. The
three combined sample preparation and analysis setups
used by the team performed extremely well over this extended period, delivering highly reproducible, reliable
and stable results, including good instrument to instrument performance.
In direct comparison with the manual method, automation based on the MultiPurpose Sampler (MPS)came out ahead in many respects including improved
standard deviation, as reported by Wang et al.; anotheraspect is the processing time per sample and the achieved
throughput: Using the manual process, a team of two
people could analyze 350 samples per month, or 4200
samples per year. Automating the process with three
MPS systems operating in parallel enabled a team offour to process up to 90 samples plus standards and QC
samples per day. On a monthly basis, 1,200 samples wereanalyzed, doubling the number of samples processed perperson. Over a two-year period, 860 sequences were processed analyzing more than 25,000 samples in total [1].
The systems were described by the authors as both rugged and user-friendly, suitable for the determination of
fatty acids in plasma phospholipids for both epidemiological research and routine analysis purposes. In addition, the method can easily be adapted to the analysis ofother matrices such as cell extracts, tissue homogenatesand food samples.
The work reported on in this article was part of alarge case-cohort study of diabetes incidence nested
within an even larger investigation into cancer andnutrition that includes 350,000 participants from 10
European countries. EPIC (European Prospective Investigation into Cancer & Nutrition) was designed toinvestigate the relationships between diet, nutritional
status, lifestyle and environmental factors and the incidence of cancer and other chronic diseases.

GERSTEL Solutions worldwide – No. 18

5

6

7

8

9

10

MultiPurpose Sampler (MPS) Systems for automated sample preparation, derivatization of fatty acids from human plasma phospholipid fractions as well as sample
introduction to GC/FID.
(A) MPS Single Rail for extraction of the phospholipid fraction, configured with:
1.) Solid phase extraction (SPE) unit; 2.) Syringe holder; 3.) Salt solution reservoir;
4.) Solvent reservoirs; 5.) Three tray holders; 6.) SPE cartridge tray; 7.) SPE / Evaporation; 8.) Vortexer / centrifuge.
(B) MPS DualRail/DualHead for hydrolysis, derivatization and injection of phospholipids 1.) Derivatization unit; 2.) Derivatization syringe holder; 3.) Injection unit;
4.) Injection syringe holder; 5.) Heated Zone; 6.) Wash bottles; 7.) SPE / Evaporation; 8.) Solvent reservoirs; 9.) Four tray holders; 10.) Agitator. [1]InterAct
Investigating how our genes and lifestyle interact to leadto diabetes. The InterAct project started in 2006 and is an
EU funded large scale collaboration between nine European
Countries and India, designed to:• discover how genetic and lifestyle behavioral factors, particularly diet and physical activity, interact in their influenceon the risk of developing type 2 diabetes• investigate how these discoveries may help to prevent thedevelopment of diabetes
More information: www.inter-act.eu

References[1] Laura Yun Wang, Keith Summerhill, Carmen Rodriguez-Canas,
Ian Mather, Pinal Patel, Michael Eiden, Stephen Young, Nita G.
Forouhi, and Albert Koulman, Development and validation of arobust automated analysis of plasma phospholipid fatty acids formetabolic phenotyping of large epidemiological studies, Genome
Medicine 5 (2013) 39, doi: 10.1186/gm443[2] N. G. Forouhi, F. Imamura S. J. Sharp, A. Koulman, M. B. Schulze, J.
Zheng, Z. Ye, I. Sluijs, M. Guevara, J. M. Huerta, J.Kröger, L. Y. Wang,
K. Summerhill, J. L. Griffin, E. J. Feskens, A. Affret, P. Amiano, H.
Boeing, C. Dow, G. Fagherazzi, P. W. Franks, C. Gonzalez, R. Kaaks,
T. J. Key, K. T. Khaw, T. Kühn, L. M. Mortensen, P. M. Nilsson, K.
Overvad, V. Pala, D. Palli, S. Panico, J. R. Quirós, M. Rodriguez-Barranco, O. Rolandsson, C. Sacerdote, A. Scalbert, N. Slimani, A. M.
Spijkerman, A. Tjonneland, M. J. Tormo, R. Tumino, D. L. van derA, Y. T. van der Schouw, C. Langenberg, E. Riboli, N. J. Wareham,
Association of Plasma Phospholipid n-3 and n-6 Polyunsaturated
Fatty Acids with Type 2 Diabetes: The EPICInterAct Case-Cohort
Study, Genome Medicine 13 (2016)e1002094; doi: 10.1371/
journal.pmed.1002094

15© istock / amphotora

green
analytic

Water analysis

Stirred, not shaken
A highly sensitive method for quantitative determination of around 100 contaminants in surface waters
with and without sediment has been developed. The key element of this GC-MS/MS-based method
is Stir Bar Sorptive Extraction (SBSE) using the GERSTEL Twister. The SBSE technique is the method of
choice for analyte concentration, providing simple, yet powerful, water analysis based on the EU Water
Framework Directive (EU-WFD) (2013/39/EU).
By Oliver Lerch, Ph.D. and Jasmin Zboron, B.Sc.

I

n 2000, the EU Parliament and the Council released
Directive (2000/60/EC) [1] that focuses on the protection and improvement of the quality of surface waters andground water. The directive in its own words “lays downa strategy against the pollution of water. That strategy involves the identification of priority substances that posea significant risk to, or via, the aquatic environment at(European, Ed.) Union level”. The directive was extended
and amended in 2008 (2008/105/EC) [2] and in 2013(2013/39/EU) [3]. In essence, the Water Framework
Directive (WFD) of the European Union (EU) makes
it mandatory for all member states to take measures tocontinually monitor and improve the condition and qual-

16

ity of water bodies in their territory: Various parametersmust be monitored, including a range of identified key
chemical pollutants. In the EU WFD, priority substances
are listed.
EU Environmental quality standards (EQS) specify
maximum allowable concentration (MAC) levels for pollutants in surface waters that must be adhered to, at least
within a foreseeable future. As the directive is worded:“with the aim of achieving good surface water chemical
status in relation to those substances by 22 December 2021
by means of programs of measures included in the 2015
river basin management plans…”. In the Environmental
Quality Standards that apply to surface waters, there is
GERSTEL Solutions worldwide – No. 18

© GERSTEL

differentiation between annual average
concentration (AA-EQS) and Maximum
Allowable Concentration (MAC-EQS)
levels specified for “inland surface waters”,
such as rivers and lakes, or on the other
hand for “other surface waters”, listed astransitional, coastal and territorial waters.

A closer look at the requirements© GERSTEL

Relative Abundance (%)

Commission Directive 2009/90/EC pro- GERSTEL MPS-SBSE-TDU-GC-MS/MS system used for the determination of around 100 contaminants including priority pollutants
as specified in the EU Water Framework Directive (EU WFD).
vides technical details for the chemical
analysis and monitoring specified in the
EU WFD. Minimum performance criteria for analyti235.0 -> 165.2 , 237.0 -> 165.2 , 212.0 -> 176.1
cal methods are specified, such as limits of quantificax10 2 Ratio = 62.2 (94.3 %)Ratio = 9.7 (100.8 %)tion (LOQs). Compound LOQs lower than 30 % of the1
respective Annual Average EQS (AA-EQS) values are
0.8
required, for some compounds in the low- to sub-nano0.6
gram range per liter. For example, the required LOQ for
0.4
benzo[a]pyrene is 0.051 ng/L. Reaching such levels re0.2
quires a highly efficient analyte concentration technique,0such as Stir Bar Sorptive Extraction (SBSE), combined
26.1
26.15
26.2
26.25
26.3
26.35
26.4
with a highly sensitive analysis technique. In addition, theAcquisition Time (min)standard deviation (SD) must be lower than 50 % (k=2) of
Chromatogram of p,p´-DDT at a concentration of 0.068 ng/L spiked in river water.
the specified EQS concentration value.
If these criteria cannot be met, due to a lack of suitable analysis methods, the EU-WFD offers some freedom: Monitoring should then be performed using thebest available method that doesn’t lead to excessive cost.

Stir Bar Sorptive Extraction (SBSE) with the patented
GERSTEL Twister® has long been used for environmental water analysis and has performed well in roundrobin tests. In 2009, the Environmental protection agencyof the State of Bavaria, Germany demonstrated SBSE
performance in full compliance with the requirements of
the German Federal drinking water regulation (TrinkwV
2001). Furthermore, SBSE was previously successfully
used for the determination of priority pollutants in surface waters following the EU WFD 2000/60/EU.
As a result of a significant investment of time and resources, the SBSE method has recently been optimized
for highly sensitive determination of the GC compatible
priority pollutants listed in EU Directive 2013/39/EU –including particle adsorbed pollutants - using one comprehensive method.

GERSTEL Solutions worldwide – No. 18© GERSTEL

Proven water analysis technique

Chromatogram of dichlorvos at a concentration of 0.12 ng/L, spiked in river water.

A detailed look at SBSE
The extraction medium used in SBSE is the patented
GERSTEL Twister®. It is a glass coated magnetic stir
bar mounted with a substantial sorbent layer. The sorbents used are either polydimethylsiloxane (PDMS) or an
ethyleneglycol-silicone polymer (EG-Silicone Twister).
The extraction principle of SBSE, like that of liquid–
liquid extraction (LLE), relies on partitioning, reaching17

Table 1: Limits of quantitation, determined according to DIN 32645, reflecting the results for precision and accuracy. In case the water samples were free from - or had
only very little - contamination with individual analytes, the limits of quantitation were determined in the matrix surface water.

AnalyteLimit of
Quantitation [ng/L]

Acenaphthene
Acenaphthylene
Aclonifen
Alachlor
AldrinAmetryn
AnthraceneAtrazineBenz[a]anthracene
Benzo[a]pyrene
Benzo[b]fluoranthene
Benzo[g,h,i]perylene
Benzo[k]fluoranthene
BifenoxBiphenylBis(2-ethylhexyl)phthalate (DEHP)
Chlordane, cis
Chlordane, trans
Chlorfenvinphos
Chlorpyrifos-Ethyl
Chrysene
Cybutryn (Irgarol 1051)
Cypermethrin (Isomerenmix)
p,p´-DDDp,p´-DDEo,p´-DDTp,p´-DDT
Dibenz[a,h]anthracene
Dichlobenil
Dichlorvos
Dicofol
Dieldrin
Diflufenican
2,6-Di-tert.-butyl-4-methylphenol

1.00
0.10
0.56
0.42
0.066
0.069
0.061
0.18
0.076
0.033
0.078
0.049
0.081
0.47
9.00
134
0.052
0.026
0.084
0.024
0.027
0.030
0.12
0.020
0.017
0.052
0.067
0.073
2.10
0.073
0.15
0.034
0.16
5.90

Analytealpha-Endosulfan
beta-Endosulfan
Endosulfan sulfate
EndrinEndrin ketone
Ethofumesat
Fenitrothion
Fenpropimorph
Fluoranthene
Fluorene
Heptachlor
Heptachlorepoxide
Hexachlorobenzene
Hexachlorobutadienealpha-Hexachlorocyclohexane
beta-Hexachlorocyclohexane
gamma-Hexachlorocyclohexane
delta-Hexachlorocyclohexane
Indeno[1,2,3-cd]pyrene
Isodrin
Methoxychlor
Metolachlor
Naphthalene
Nonylphenol
Octylphenol
Oxadiazon
PBDE 28
PBDE 47PBDE 99
PBDE 100PBDE 153
PBDE 154
PBDE 183
PCB 77equilibrium between the aqueous sample and the sorbent
phase. In the work described here, PDMS Twisters wereused. Analyte extraction and concentration takes place
while the Twister stirs the sample. Subsequently, theTwister is removed from the sample, quickly dried, placedin a glass liner for thermal desorption, and the liner placedin a sealed sample tray position on the MultiPurpose
Sampler (MPS). The MPS performs fully automatedprocessing of large sample batches in combination with athermal desorber. Following thermal desorption, analytes
are focused in a GC inlet (GERSTEL CIS 4) and subsequently transferred to the GC column in split or splitless mode using programmable heating. This approachensures that extracted analytes can be transferred up to
100 % to the column for extreme sensitivity. The PDMS
Twister is well suited for non-polar to medium polarity
compounds while the EG-Silicone Twister is mainly used
for polar compounds that form hydrogen bonds as proton
donor, for example phenols, alcohols and organic acids.

Simple and efficient water analysis
In this work, SBSE, using the GERSTEL Twister, was
our method of choice for the GC compatible compounds

18

Limit of
Quantitation [ng/L]
0.070
0.059
0.052
0.043
0.052
0.073
0.024
0.13
1.00
0.45
0.052
0.052
0.10
0.043
0.052
0.13
0.052
0.052
0.044
0.16
0.083
0.064
5.00
8.80
0.46
0.082
0.018
0.015
0.050
0.011
0.032
0.020
0.13
0.041

AnalyteLimit of
Quantitation [ng/L]

PCB 81
0.039
PCB 105
0.043
PCB 114
0.036
PCB 118
0.012
PCB 123
0.037
PCB 126
0.050
PCB 156
0.046
PCB 157
0.047
PCB 167
0.044
PCB 169
0.054
PCB 1890.054
Pendimethalin
0.094
Pentachlorobenzene
0.075
Pentachlorophenol
3.00
Phenanthrene
2.50
Picolinafen
0.26
Prometon
0.18
Prometryn
0.13
Propazine
0.057
Propiconazol
0.14
Propyzamide
0.35
Pyrene0.45
Quinoxyfen
0.087
Simazine
1.90
Terbutryn
0.10
Triallate
0.084
Tributyl phosphate
9.70
1,2,3-Trichlorobenzene
0.95
1,2,4-Trichlorobenzene
1.20
1,3,5-Trichlorobenzene
0.18
Triclosan
1.40
Trifluralin
0.19
Tris(2-chloroisopropyl)-phosphate (TCPP) 29.00

listed in the EU Water Framework Directive (WFD). In
addition to reaching the prescribed LOQs, we also wanted to perform quantitative determination of compounds
adsorbed on particulate matter, as demanded by the EU
WFD, including polyaromatic hydrocarbons (PAHs). The
overall analysis requires a special approach: At first, we
performed classical SBSE on individual 100 mL samples,
which is a large enough volume to generate meaningful
results. After adding an internal standard, we let a Twister stir the sample for five hours to extract free organic
compounds. The Twister was then removed, an organic
modifier was added to the sample along with a second
Twister, and the sample extracted at elevated temperature
overnight. Using this approach, compounds adsorbed onparticulate matter were successfully released and extracted.
The two Twisters were transferred to a TDU glass linerand simultaneously desorbed in the Thermal Desorption
Unit (TDU) using a temperature program (90 – 300 °C).
The analytes were focused in the Cooled Injection System(CIS 4) at – 40 °C. The CIS is a PTV type Universal GC
inlet, which can be heated very rapidly in order to releaseanalytes to the GC column, in our case a HP 5ms Ultra
Inert (30 m x 0.25 mm x 0.25 μm) from Agilent Technologies. Following separation, the analytes were deterGERSTEL Solutions worldwide – No. 18

using SBSE, we reached 0.033 ng/L. For pentachlorobenzene: LOQ of 2.1 ng/L; with SBSE, we lowered it
to 0.075 ng/L (see table 1). Comparable results wereachieved for around 100 other contaminants relevant forsurface water analysis.
Relative standard deviations (RSDs) near the respective limits of quantitation were between two and ten percent for the vast majority of compounds with a median of
6.9 percent. Trueness was between 90 and 110 percent inmost cases. The extractability and quantifiability of particle adsorbed analytes was tested and confirmed using
a certified reference sediment (WEPAL SETOC 745).
Certified analysis results were available for PAHs and a
few chlorinated compounds.

© GERSTEL / Wolfram Schroll

Assessing SBSE

Analytes are extracted and concentrated in the sorbent phase while the Twister stirs
the sample. The stir bar is then removed, dabbed dry, and placed in a TDU liner,
which is placed in an individually sealed tray position in the GERSTEL MPS. Thermal
Desorption of the concentrated analytes is performed in the Thermal Desorption
Unit (TDU), the process is fully automated using the MPS. After being focused in the
GERSTEL Cooled Injection System (CIS), analytes are transferred to the GC column
where they are separated and finally determined using a mass spectrometer.

mined using a Triple Quadrupol MS (Agilent Technologies 7010) in Multi-Reaction Monitoring (MRM) Mode.

Successful determination ofwater contaminants
The newly developed SBSE-GC-MS/MS method presented here is both efficient and highly sensitive. We wereable to determine the GC compatible compounds listed
in the EU WFD at the levels specified – or even well
below - with three exceptions: Cypermethrin, heptachlor,and heptachlorepoxide. Those three are also notoriously
hard to determine at the required levels down to subpg/L using conventional techniques.
In the following, we list a few examples of required
limits of quantitation for surface water following the EU
guidelines. For dichlorvos: 0.18 ng/L; using SBSE, wereached 0.073 ng/L. For benzo(a)pyrene: 0.051 ng/L;
GERSTEL Solutions worldwide – No. 18

SBSE using the GERSTEL Twister is simple to perform and highly efficient, resulting in high sensitivity, notonly in the case described here, in which we successfully
determined priority pollutants listed in the EU WFD.
The high sensitivity is mainly due to the large volume of
Twister sorbent phase, in our case 63 µL, which guarantees a high concentration factor when doing trace analysis. When the Twister is thermally desorbed, the analytes
extracted from the sample are transferred quantitatively
to the GC, whereas when performing liquid extraction
and injection, only a small aliquot is injected. SBSE performed on a 100 mL water sample coupled with thermal
desorption and a highly sensitive triple quadrupole mass
spectrometer provides extremely low limits of detection,
reaching the sub-ng/L range. A further bonus when using Twister technology: The entire method requires only
a very small amount of solvent. And since many solvents
are toxic, hazardous and harmful to the environment, a
reduction in the amount used would seem particularly
meaningful and fitting in order to reach environmentally
sustainable solutions for chemical analysis.

References[1] DIRECTIVE 2000/60/EC OF THE EUROPEAN PARLIAMENT AND
OF THE COUNCIL of 23 October 2000 establishing a framework
for Community action in the field of water policy[2] Directive 2008/105/EC of the European Parliament and of theCouncil of 16 December 2008 on environmental quality standards
in the field of water policy, amending and subsequently repealing Council Directives 82/176/EEC, 83/513/EEC, 84/156/EEC,
84/491/EEC, 86/280/EEC and amending Directive 2000/60/EC
of the European Parliament and of the Council[3] DIRECTIVE 2013/39/EU OF THE EUROPEAN PARLIAMENTAND OF THE COUNCILof 12 August 2013 amending Directives
2000/60/EC and 2008/105/EC as regards priority substances in
the field of water policy.

19

Presenting the Lab: The Ecology Lab at DOW in Stade, Germany

Always one step ahead
Chemical production and reaction processes, as well as storage and transportation of the resulting
products, represent a risk potential. Leaks into the environment, or unwanted exposure of workers tocontaminants, must immediately be rectified. The law provides minimum requirements on how toproceed in such a case. A key role is played by instrumental chemical analysis, which is used by Public
Health authorities and industry alike for monitoring air, soil, and water for potential contamination.
GERSTEL Solutions Worldwide magazine visited the Ecology Services Laboratories of DowDuPont at
the Chemistry Park Stade in Germany. The lab is responsible for water and environmental analysis at
the site and we had a look around.
By Guido Deussing

Alittle less than one hour by car west of Hamburg,
Germany, on the Southern banks of the lower Elberiver, lies the old Hanseatic town Stade, population
46,000. Stade is a county seat in the state of Lower Saxony. Right next door is the “old country” area, which is
known for its many orchards and abundant supply of fruit
and also serves as recreational area for the people of theregion – as well as a flood area when the Elbe rises much
above normal levels.
The Schwinge, anElbe tributary, runs
through Stade. The
meadows along theDow combines the power of science andupper
Schwingetechnology to passionately innovate what isand those in Stadeessential to human progress. The Company isalong the rivulet are
driving innovations that extract value from maprotected nature reterial, polymer, chemical and biological science
serves due to bothto help address many of the world‘s most chaltheir biodiversity andlenging problems, such as the need for fresh
their serene beauty.
food, safer and more sustainable transportaHere you find plentytion, clean water, energy efficiency, more duof agricultural land
rable infrastructure, and increasing agriculturaland picturesque vilproductivity. Dow‘s integrated, market-driven
lages with quaintportfolio delivers a broad range of technologynames that reinforce
based products and solutions in high-growth
the impression of
sectors such as packaging, infrastructure, transvisiting
unspoiledportation, consumer care, electronics, and agricountryside. The imculture. The Dow Chemical Company („Dow“)
pression is accurate,
is a subsidiary of DowDuPont (NYSE:DWDP).
but there is more to
DowDuPont was formed by Dow and DuPont
the story. Stade may
to create three strong, independent, publicly
be in the countryside,
listed companies in the areas of Agriculture,but it is an industrial
Material Science and Specialty Products.
hub, home to global
players. Airbus has
produced airplanes
here since 1959. The 2,500 Airbus employees in Stade
are specialized in the production and development of carbon fiber reinforced materials for aircraft and space craft.

20

Among other things, they produce the vertical stabilizers (fins) for all Airbus aircraft. Around Airbus, a reliablesupply chain of industries has developed.
The Dow Chemical Company also established a presence here. Since 1972, the largest chemical producer by revenue in the world
has been producing in Stade at the address Bützflether Sand, which to Germans sounds like the name of
the local beach on the river. Over time, Dow transformed
its huge premises to an industry park and opened it tooutside companies. The conversion was part of a quest toachieve higher efficiency: Share resources, develop and use
synergies, and reduce cost by spreading the burden of expenses on multiple shoulders. The concept seems to work.
Multiple companies are acting in synergy and coexistingat Bützflether Sand: Trinseo is operating a Polycarbonate facility; Olin is producing epoxides and chlorinatedorganic compounds; Air Liquide produces and supplies
process-relevant technical gases; Air Products supplies
hydrogen; Evides handles water treatment; Talke Carriers
handles the central stock facilities; and the nearby ElbePort serves as their gate to the world. Well connected to
the freight depot train station and the container terminal,
an almost perfect scheduling can be achieved for just intime transport of important goods, raw products and final
products. These are shipped in all directions by rail, which
unlike the express freeways in the area are generally unclogged. The industrial infrastructure here has been developed and perfected over decades, including freight forwarders that are specialized in the handling of hazardous
goods. These and many other aspects make the Chemical
Park Stade stand out as extremely well connected, even inglobal comparisons, though it is embedded in the countryside. The Ecology Lab in Stade is also in a good place:This environmental laboratory receives a lot of attention
globally within the Dow organization because it, among
other things, has developed outstanding methodology formonitoring volatile organic compounds (VOCs) using
Thermal Desorption (TD).
GERSTEL Solutions worldwide – No. 18

© Guido Deussing

The Ecology Lab at Dow in Stade rely on the Thermal Desorption System (TDS) from GERSTEL for
their TD analysis work. And for many other applications
that are performed in the lab, GERSTEL instruments
and systems play a key role. Reason enough for me tovisit and to look behind the scenes. I made the appointment with Michael Gröger, GERSTEL Sales Manager
for Germany, Austria and Switzerland and account manager for Dow. Michael has known and looked after the
Dow colleagues since… forever and he is here for a meeting with my hosts Sandra Hirsch and Andreas Köhler,
who are established experts in matters environmental andwater analysis at the Ecology Lab. They are considering
investing in a GERSTEL MultiPurpose Sampler (MPS)WorkStation to be used for automated generation ofanalysis standards. At this point, some questions remain
open and my scheduled visit to the Ecology Lab offers
Michael Gröger a good chance to join and provide someanswers. We are meeting shortly after ten on a Wednesday
morning in January in light snowfall. Sandra Hirsch will
pick us up in her car at the visitor parking area. We cannot
access the Chemistry Part Stade premises in our own vehicle. As outside visitors, a pre-arranged permit is needed
even though Michael Gröger has paid regular visits formore than 16 years. Everything follows set rules. We need
the permit and that requires time and patience. First time
visitors – and those who haven’t been back within the past
year – must acquaint themselves with the safety rules by
watching a video while the person at the reception fills in
the paperwork and secures personal information from thevisitor’s ID card. After being registered in the Dow system, it is time for the test: Three questions about security
procedures in the Chemistry Park must be answered correctly. The computer delivers the result on a small pieceof paper that I hand to the receptionist who checks it
and hands me a permit. So far, so good. We meet Sandra
Hirsch in the visitor parking lot, she greets us with a big
smile and a cheerful „Moin, Moin“, a sure sign that weare now in Northern Germany and the gut feeling says
we’re in good hands. Ms. Hirsch drives an American car,
Dodge Charger, with ample room for all. Do you have todrive a US-made car even in Germany when you work
for a US company? “I also like Jim Beam”, she responds,
she clearly likes the car, it’s that simple. The gatekeeper
checks all permits and then opens. The Dodge surrounds
us with a deep growl and begins moving. We are met witha surprisingly green landscape, the Elbe flows nearby at
the Northern edge of the Chemistry Park and I can see
the endless meadows at the river bank powdered withfresh snow. “We even have deer and wild boar here”, says
Sandra Hirsch. I don’t see any, but I’ll take her word forit. But where do the 1,200 Dow employees work? And
Andreas Kohler (left) and his colleague Sandra Hirsch assess a water sample extract.
Before entering the Ecology Lab, clear and clearly visible signs alert you to workplacesafety rules that must be followed at all times. Work safety is the highest priority at
Dow, and not only in the laboratory, but throughout all production areas and theentire Chemistry Park Stade.

GERSTEL Solutions worldwide – No. 18

21© Guido Deussing
The GC Lab, part of the Ecology Laboratory within the Chemistry Park Stade, relies on GERSTEL solutions for much of its automation

where do they produce the three million tons of Dowanol,
Methocel or MDI?
Where is the huge plant process equipment so typical for larger industrial chemistry sites where they produce and process allylchloride, chloroform and methylene
chloride, sodium hydroxide and hydrochloric acid, propylene and… ? The stacks and huge cylinders that requiremassive amounts of power, steam and compressed air?
Where hydrogen, oxygen and nitrogen are produced or
added to the chemical processes? Where are the pipes
through which countless cubic meters of process andcooling water are pumped in and waste water discharged?
No sign of Trinseo, Air Liquide or Evides, companies thatgenerate added value here. “The area covers 550 hectares
or almost 1400 acres” , says Sandra Hirsch, “things are lessvisible in these wide-open spaces.“
The Ecology Lab, where Sandra Hirsch, Andreas
Köhler and Ute Schomacker work is located in the
ground floor of a two story building at the edge of the
Chemistry Park Stade, a few minutes by car from ourmeeting point. Since its inauguration in 1975, the lab
has regularly been expanded and updated. The laboratory deals with environmental and water analysis in theChemistry Park Stade, including monitoring workplace
air, and ensuring compliance both with maximum allowable concentrations, as per German Occupational Safety& Health rules for workplace air, and with regulations forhazardous materials.
The lab monitors water to ensure compliance withlegal requirements for water quality including adherence
to maximum allowable concentrations laid down in theregulations issued by the Lower Saxony State Office for
Water Economy, Coastal and Environmental Protection.
Every year, the Ecology Lab team analyzes around 6,000
samples, making sure that maximum allowable concentrations of various chemicals are not exceeded. 60 % of
the samples are water, mainly waste water. Air samples

22

that are required to be drawn regularly as part of routine monitoring protocols, or whenever a leak or too highworkplace concentrations are suspected in the production
area, make up 30 % of the samples. Soil samples are taken
and analyzed, for example, whenever a new building isbeing planned or if doubts about earlier contaminationneed to be alleviated. Soil samples make up approximately
10 % of the annual sample load. “Added to all this, we getabout 10 samples per month that are sent to us by the environmental protection agencies for comparative analysis.
This is done in order to check the accuracy of our analysis
results. The agencies can call anytime and draw samples
anywhere in the entire Chemistry Park in order to perform their legally required controls”, Sandra Hirsch explains. Laboratory routines are well established here, but
it never gets boring for the three persons who run the lab.
Occasionally there are even tasks outside the plantarea, for example, when the Company Fire Brigade arecleaning up after a spill and need to know its chemical
make-up. Or maybe the Fire Brigade from the town of
Stade is handling an emergency or potential emergency,
involving a road truck or a freight ship on the river transporting hazardous materials. “If they need chemical analysis, we are here to support them”, says Andreas Köhler.
Occasionally, we have even had the Police Crime
unit request an assessment from us as to the nature of
substances found at the scene of a suspected suicide. The
Ecology Laboratory takes on such tasks as technical support. Good to know: Technical analytical expertise can befound when needed. It is time for a tour of the laboratories. Sandra Hirsch and Andreas Köhler lead the way. The
first stop for our small procession is the Thermal Desorption Laboratory.
The lab is remarkably orderly, it almost seems as if
it had been cleaned up and made extra neat for our visit,
but apparently that is the way they always work. Sandra
Hirsch explains: “Searching takes a lot of time, right?”
GERSTEL Solutions worldwide – No. 18

On the lab bench across the aisle, two Tube Conditioners (TC 2), used to condition sorbent tubes, are standing
ready within their yellow line frame. Right next to them
are two Tube Standard Preparation Systems (GERSTEL
TSPS), used to load sorbent tubes with standard mixtures.
“For quite a while, we experimented with different sorbent materials, and today, using just one method, we areable to determine more than 50 analytes in the range from
C10 to C40 with limits of determination in the single
ppb range”, Andreas Köhler says. “And we are far below
the required limits of determination specified by the authorities”, Sandra Köhler adds. The two colleagues clearlytake great pride in their work and in reaching ambitious
goals. To be ahead of regulations, and always stay aheadin the analytical race, drives them to great performance.
This is also wise as a precaution: “We know from expe-© Guido Deussing

I answer: “Right!“. “And we don’t have time”, says Andreas Köhler. “And we don’t need to either”, adds Sandra
Hirsch, “Because we know where everything is located”.
The method by which everything is organized originallycame from Japan. It is termed the 5S or 5A method. The
method specifies that everything must be in its place,must be clean, and must be ready for use. A clear sign thatthe 5A method is in use is the clear markings on the labbenches around important tools or instruments: Yellow
lines marking areas on the lab benches, on the floor, on
drawers, and on cabinet doors make it easy to locate theright tool or instrument and to handle it correctly. It reminds me of the areas designated for smokers in Railway
Stations. An optically clearly distinguishable element candiscipline people operating in the area, even though there
are of course lots of yellow lines and signs in the lab.

The Thermal Desorption laboratory of Dow in Stade. Sandra Hirsch: „Colleagues from other sites are sending us their samples for analysis”.

Another color that dominates is GERSTEL magenta. Even a lay person would recognize that the lab has ahigh affinity towards GERSTEL products. On the labbenches along the windows, there are three complete GC/
MS systems, each equipped with a GERSTEL Thermal
Desorption System (TDS) with Autosampler (TDS A)
mounted above a Cooled Injection System (CIS). “Apartfrom ensuring that the lab is well organized and neat, automation is the other way to improve efficiency”, Sandra
Hirsch remarks, “and this is especially important when
you are not free to hire more people”, as is the case in mostlabs. Compounds are detected using MSD and FID, connected to the GC column via a column effluent splitter.
GERSTEL Solutions worldwide – No. 18

rience”, says Sandra Hirsch, “that rules and regulations
change at short notice”. Instead of waiting and reacting,the two experts are proactively meeting future challenges
with steadily lower required limits of determination in order to be ready if these are enforced. “That approach has
always served us well”, says Andreas Köhler, “wheneverstricter guidelines were enforced, we were prepared andready”. As to the method, he adds: “From volatile organic
compounds (VOCs) with boiling points around -20 °C
to semi-volatile compounds (SVOCs) with boiling pointsof 180 °C, we can generally determine them all using justone method“. And the word is out within the worldwide Dow organization about the results the team has

23© Guido Deussing

24

GERSTEL Solutions worldwide – No. 18© Guido Deussing

achieved. The Ecology Lab in Stadeis the center of excellence for thermal
desorption analysis world-wide. Sandra Hirsch: “Colleagues from othersites are sending us their samples foranalysis, that is quite a recognition”.
But not just Occupational Safety andHygiene samples are received fromother Dow sites. Highly labor intensive AOX analyses, the results of Standing side by side as they have for many years, from right to left: Andreas Köhler and Sandra Hirsch from the
Ecology Laboratory with GERSTEL Sales Manager Michael Gröger
which must be reported to authorities, are performed by the lab, which
receives samples from sites in various countries. This Köhler reports that in the field water analysis, the Ecolis the work area of Ute Schomacker who has extensive ogy Lab has equally been faced with steadily tightenedknowledge in the field. By the way, Andreas Köhler dis- requirements, which they have been able to meet. Waste
covered Thermal Desorption for his work before the water with its high salt content and the various polar
year 2000. Sandra Hirsch, who today shares his enthusi- compounds that need to be determined had posed quiteasm, later joined the team. a challenge to the analysis experts. Many compounds
When their “homemade” can be determined with standard headspace GC analysis
TD had reached its capac- resulting in perfectly adequate results in terms of senity limits, they decided to sitivity and accuracy. Other compounds are less simple
purchase a commercially to determine, especially higher boiling compounds ormade system: “We needed those that are more water soluble. “The solution camea system that enables ac- in the form of GERSTEL’s HIT technology”, says Ancurate determination of dreas Köhler. The acronym HIT signifies Hot Injection
the many compounds we and Trapping. “The method ensures that higher boilingmust to report with low compounds are kept in the gas phase during sample inlimits of detection and troduction”, Andreas Köhler explains, “they don’t conwithout sample to sample dense on the syringe needle and, more importantly, arecarry-over” says Sandra not removed and lost from the inlet when the needle isHirsch. Apart from that, retracted following the injection”.
In addition, analytes from multiple injections can be
Dow needed the potential
to reach even much lower trapped and transferred together to the GC column for
limits of determination as a single GC run. HIT has provided the Ecology Lab
Structure promotes efficiency – also when it comes to operegulations grow stricter, with a way to achieve better sensitivity, allowing themrating the GERSTEL TC 2. The team in the Dow Ecology Lab
coupled with efficient au- to stay ahead of the game for a long period of time. In
keeps the lab orderly following the Japanese 5S method. The
areas framed by clearly visible yellow lines are designatedthe never-ending race for lower limits of determination,
tomation.
exclusively for one instrument. No other instrument or unrelaEarly on, Andreas clearly, the team in the Ecology Lab takes great pleasure
ted tool is allowed to be stored within this area.
Köhler was interested in in being a step, or more exactly several steps, ahead of
the GERSTEL TDS and in 2001 he contacted Mi- the authorities in meeting regulatory requirements. Sanchael Gröger, beginning what has today developed into dra Hirsch: “one of our goals was to lower the limit ofa friendly professional partnership. The cooperation is determination to 1 μg/L even though the requirements
not limited to the determination of VOCs in air. GER- are 2 μg/L. We actually reached 0.2 μg/L“. And while
STEL is also supplier of solutions for the analysis of wa- others are struggling with standard headspace or liquid/
ter samples that make up the bulk of the samples in the liquid extraction techniques, the Ecology Lab staff has
Ecology Lab. In the GC lab, I count at least six GC sys- automated their analysis quite efficiently. This means
tems with individual GERSTEL MultiPurpose Sam- more time is available for data handling, data interpretaplers (MPSs) mounted on top. Just like in the TD lab tion and reporting – or for method development. “Or
we just toured, the 5S yellow markings and GERSTEL to ponder how much work an MPS WorkStation needs
Magenta stripes here accentuate the beige colored GC to perform in the lab”, says Sandra Hirsch, a friendlylab, which somehow exudes quality work. And as to reminder that the tour through the lab is coming to an
the underlying quality of the analysis systems, Andreas end and urgent work is waiting – I hear you.

© istock / AlexPro9500

Food Safety Analysis

Refined Risk
In the refining process for edible oils conditions must be carefully controlled to avoid the formation of
toxic process contaminants, such as 2-MCPD, 3-MCPD, glycidol and their fatty acid esters. An automated
GC/MS-method now enables highly efficient determination of these compounds based on standard
methods such as ISO 18363-1, AOCS Cd 29c-13, and DGF C-VI 18 (10).
By Guido DeussingT

he European Food Safety Authority (EFSA) has recently updated their risk assessment for 3-monochloropropanediol (3-MCPD), 2-MCPD, fatty acid estersof these compounds, as well as glycidyl fatty acid esters(GE) in food [1]. The result is based on data submitted by
23 member states: “Glycerol-based process contaminants
found in palm oil, but also in other vegetable oils, marGERSTEL Solutions worldwide – No. 18

garines and some processed foods, raise potential healthconcerns for average consumers of these foods in all young
age groups, and for high consumers in all age groups.”[2]. According to the press release: “The highest levelsof glycidyl esters, as well as 3-MCPD and 2-MCPD(including esters) were found in palm oils and palm fats,
followed by other oils and fats. For consumers aged three25

3-MCPD
2-MCPDand above, margarines and ‘pastries and cakes’ were themain sources of exposure to all substances.” Incidentally,
the FDA refers to GE as glycidol fatty acid esters.

Glycerol as building block
All fats and edible oils contain glycerol in the form of
fatty acid esters (triglycerides). Not all oils are ready for
consumption in their native form; processing is generally required to remove off-odors and to ensure sufficient
shelf life. For deodorization, as part of the refining process, steam is used to gradually heat the oil under vacuum
to around 200-230 °C to ensure that unwanted flavor andtaste-intensive compounds are removed along with otherunwanted VOCs and even pesticides. When chloride ispresent, heat treatment accelerates the substitution of
fatty acids in triglycerides with chlorine atoms, leading
to the formation of 2-MCPD and 3-MCPD fatty acid
esters. Under these conditions, diglycerides also react toform the glycidyl fatty acid esters.

SIM chromatogram m/z 198 : Top: Virgin olive oil used as blank oil. Middle: Edibleoil sample assay B (3-MCPD). Bottom: Edible oil sample assay A (3-MCPD +glycidol).

© GERSTEL / Wolfram Schroll

Assessing the risk
The EFSA risk assessment of the above-mentioned glycerol derivatives is based on findings from animal experiments: In rats that had been fed 3-MCPD, cell changes
were found, especially in the kidney area. Higher dosages
led to benign tumors, as reported by the BfR in Berlin.
According to the EFSA, the tolerable daily intake (TDI)
value is 0.8 µg per kg body weight for 3-MCPD; due toa lack of adequate toxicological information, no assured
TDI value for 2-MCPD can be given.
The risk assessment of glycidyl fatty acid esters isbased on the assumption that these are fully transformed
to free glycidol in the body. Since the free compound is
known to be both genotoxic and carcinogenic, the experts from the panel on contaminants in the food chain(CONTAM)[3] organized by EFSA could not provide
any guidance on a safe level of glycidyl fatty acid esters.
When a safe level doesn’t appear to exist, there is all themore need for action toward minimizing the level ofthese contaminants in order to minimize any health risk
to consumers, and especially to infants who are
not breast fed and therefore given industriallyprocessed baby foods. Monitoring of these crucial levels requires adequate methods of chemical
analysis.

GERSTEL MPS used for automated sample preparation of edible oils
for GC/MS determination of 2-MCPD, 3-MCPD, glycidol and fatty acid
esters of these.

26

Linearity study for 3-MCPD assay B (top) and glycidyl assay A (bottom),
0.12-1.9 mg/kg each.

Refining process for production of edible oils.

A challenge for the analytical chemist
For the determination of 2-MCPD and 3-MCPD fatty
acid esters, as well as glycidyl fatty acid esters, internationally, the ISO 18363-1 [4] and the AOCS Cd
29c-13 [5] methods are widely accepted. In Germany,
the German Society for Fat Sciences (DGF) recommends a unified method, DGF C-VI 18 (10) [6]. The
mentioned methods are all based on the use of gas
chromatography with mass spectrometric detection(GC/MS). The DGF unified method C-VI 18 (10)is almost identical to the AOCS Cd 29c-13 method:
The 3-MCPD content of the 3-MCPD fatty acid esters
present is determined following alkaline hydrolysis andderivatization with phenylboronic acid (assay B). Thesemethods also enable determination of glycidyl esters (asGERSTEL Solutions worldwide – No. 18

MANUAL

bound glycidol) by indirect calculation after hydrolysis
and conversion to 3-MCPD. Glycidol is determined as
the difference between the total amount of 3-MCPD
present including converted glycidol (assay A) and theamount of 3-MCPD determined in assay B. This in
short highlights the added value of the unified DGF
C-VI 18 (10) and the AOCS Cd 29c-13 methods. Thesemethods enable the determination of the amount of glycidol in the sample and reading through them provides
a fair impression of the effort required to transform thecompounds such that they can be determined by gas
chromatography, in this case relying on a manual sample
preparation process that includes hydrolysis, extraction
and derivatization. In addition, duplicate analysis of eachsample prepared in two different ways is needed in orderto determine both 3-MCPD and glycidol.

l Weigh a 100 mg sample into a viall Fill a second vial with sodium sulfate
as drying agent (drying vial) – optionall Add MTBE to the sample
l Add ISTD solution and mix,
or melt and mix (solids)
l Add MeOH/NaOH mixturel Agitate and incubatel Add acidic NaCl solution (Assay A)l Add acidic NaBr solution (Assay B)

Higher efficiency and better
sensitivity through automation
GERSTEL experts have developed a fully automatedsample preparation solution, integrated with the GC/MS
system, that replicates the AOCS Cd 29c-13/ DGF C-VI
18 (10) methods step by step on a robotic sampler. “Theautomated sample preparation is performed on a MultiPurpose Sampler (MPS roboticpro) Dual Head version
with two independently moving towers fitted with different syringe sizes. This means that larger amounts ofliquid can be handled for sample preparation with one
syringe while another smaller syringe handles smaller
volumes, for example, used for injection into the GC/
MS”, says Dominik Lucas, formerly Application Specialist, now member of the German sales organization within
GERSTEL.
In addition, method steps such as liquid-liquid extraction, solvent evaporation, solvent exchange to a GCcompatible solvent and analyte derivatization, are fully
automated and very efficiently integrated in the overall
method (see listing on the right hand side). Finally, the
MPS introduces the prepared sample to the GC/MS
system. Dominik Lucas adds: “The analysis results wegenerated using the described automated method showed
good correlation with reference analysis results obtained
from independent laboratories. Relative standard deviations for repeat analyses were at 5 percent for 3-MCPD
and 6.4 percent for glycidol for the complete process”. As
to using the described sample preparation and system solution for determination of 2-MCPD, 3-MCPD, glycidol
and their fatty acid esters: “The evaporation step in themethod means that users can reach the required sensitivity and stability even when using a single quadropole mass
spectrometer”, Dominik Lucas states. The evaporation
step ensures better sensitivity by concentrating analytes.
In addition, it provides improved overall system stability
by removing excess derivatization reagent before it canenter and destabilize the MS ion source.
GERSTEL Solutions worldwide – No. 18

GERSTEL MPS

l Add n-hexane for matrix extractionl Agitate and incubatel Discard hexane phasel Repeat extraction with n-hexane twicel Perform multiple analyte extractions
using MTBE/Ethylacetate 3:2 (v/v),transfer the organic phases to thedrying viall Add phenylboronic acid solutionl Evaporate to dryness and derivatize inthe mVAP at 50 °C and subambientpressurel Take up the derivatives in isooctanel Introduction to GC/MS(/MS) if
integrated with sampler

Listing of the required manual sample preparation steps, which were transferred to
the GERSTEL MPS and automated. The MPS automates the AOCS Cd 29c-13 and
DGF C-VI 18 (10) methods for the determination of 2-MCPD, 3-MCPD, glycidol andfatty acid esters of these. Depending on the instrument configuration, the preparedextracts can be introduced directly to the GC/MS system for analysis.

References[1] www.efsa.europa.eu/en/efsajournal/pub/4426[2] www.efsa.europa.eu/en/press/news/160503a[3] www.efsa.europa.eu/en/panels/contam[4] ISO 18363-1:2015 Animal and vegetable fats and oils -- Determination of fatty-acid-bound chloropropanediols (MCPDs) andglycidol by GC/MS -- Part 1: Method using fast alkaline transesterification and measurement for 3-MCPD and differential measurement for glycidol[5] AOCS Official Method Cd 29b-13, Revised 2017: 2- and 3-MCPD
Fatty Acid Esters and Glycidol Fatty Acid Esters in Edible Oils andFats by GC/MS (Difference Method)[6] DGF Unified Method C-VI 18 (10) (Available only in German language).

27

Environmental analysis

Lingering Poison
Sampling procedures and sample handling are key factors ingenerating valid analysis results. When it comes to sample
manipulation, less is more, as illustrated in this case of characterizing
concentration profiles of DDT-related compounds in marine porewater almost 50 years after the latest spills.
© iStock / robas

By Guido DeussingW

hen bodies of water are found to contain pollutants,
it may not necessarily be a result of ongoing or recent contamination. It could be related to past spills that
occurred during a time when “dilution” was considered an
acceptable means of disposing chemical waste. Unfortunately, these persistent organic pollutants (POPs) can beadsorbed on sediment particles and then can slowly andsteadily return to the marine ecosystem over a long periodof time. If you want to assess the degree of contaminationin any part of the ocean floor in order to appraise the riskof contamination of aquatic ecosystems, the bioavailability of contaminants in the sediment must be determined.
U.S. scientists Robert P. Eganhouse and Erica L. DiFilippo successfully developed a new method for determination of ten DDT-related compounds in marine pore water
based on extraction with disposable PDMS-coated fusedsilica fibers. After extraction, the analytes on the fibers
were determined using automated Thermal Desorption
GC/MS (TD-GC/MS). As they report in their journal
paper, the method is simple, and “improves the ability tomeet quality objectives at a significantly lower cost” [1].

Characteristics of sampling procedures
As part of a multi-disciplinary investigation of the factors
controlling the fate of DDT in sediments of the Palos
Verdes Shelf in the Pacific Ocean near Los Angeles, it
was the task of Eganhouse and DiFilippo to assess thewhereabouts and fate of the insecticide dichlorodiphenyltrichloroethane (DDT), which was prohibited in the
US in 1972. The project was called into life following
public discussion of the need for highly cost intensive
clean-up [2]. Between 1947 and 1971, the Montrose
Chemical Corporation released waste water containing hundreds of tons of DDT from their plant into the28

county sewer system from where it was released into theocean. Eganhouse and DiFilippo set about determining
the concentrations of ten DDT-related compounds inmarine sediment pore water. As a first step, they identified a suitable sampling procedure and analysis method,which would give accurate results while not being too labor intensive or time consuming and preferably keeping
cost and environmental impact to a minimum. Samples
were taken slightly above the ocean floor and from ocean
floor sediment. Sampling was conducted at three different locations on the Palos Verdes Shelf off the coastof Los Angeles, the scientists took sediment cores at awater depth of 60 meters using specially designed coringboxes. Subcores were subsequently taken using core tubes
with sealed ports along their lengths for later insertion ofanalyte sampling devices. The cores were finally sealed atboth ends and overlying seawater was expelled througha vent hole. The whole process was performed without
compacting the core or altering its composition or structure, as Eganhouse and DiFilippo report. The cores were
kept cool at the original sediment temperature (11 °C)
and transported to the Laboratories of the United States
Geological Survey (USGS) Water Science Center in San
Diego, where they were stored in vertical position at atemperature of 11 °C until they could be sampled.

Extraction with disposable fibers
Eganhouse and DiFilippo succeeded in preserving theoriginal sample structure and in avoiding changes to thenatural distribution of contaminants between pore waterand sediment in the sample. The scientists then focused
their attention on determining the DDT related compound concentrations in the pore water. The next step was
to extract and concentrate the analytes on a suitable carriGERSTEL Solutions worldwide – No. 18

er material for later analysis by TD-GC/MS. The extraction technique of choice was solid phase microextraction(SPME) and after several test runs, they decided to use 10
cm long pieces of fused silica fiber coated with a thin layerof polydimethylsiloxane (PDMS) (Fiberguide, Dr. M. T.
O. Jonker). An important criterion was that the extractive
capacity of the fibers should not disturb the system bysignificantly depleting the sample of contaminants. The
fibers were inserted into the core through holes on theside, which were resealed, and were left for up to 79 daysin order to allow equilibrium to be established between
the fiber, pore water and sediment. Fibers were recovered
after different extraction periods and prepared for TDGC/MS analysis: They were rinsed, dried and cut in 2
cm long pieces that were placed in micro-vials and storedcontamination free at -20 °C until they could be analyzed.

Intuitive Software Control
Open micro-vials, each containing three pieces of a single
SPME fiber, were transferred to individually sealed glass
thermal desorption tubes. The TDU tubes were fittedwith transport adapters for automated processing using
the GERSTEL MultiPurpose Sampler (MPS). Thermal
desorption of the SPME fibers was performed using a
GERSTEL Thermal Desorption Unit (TDU) connected
to a Cooled Injection System (CIS), which was used for
cryofocusing and subsequent transfer to the GC column
for highly sensitive GC/MS determination. The intuitive
MAESTRO software control enabled Eganhouse and
DiFilippo to quickly set up and automate processing of
the samples as well as automating spiking of the TDU
tubes with liquid calibration standards or adding internal standard. The CIS was used to transfer analytes to
the GC column inside the 6890 GC plus (Agilent Technologies) using programmed temperature vaporization(PTV). Separation was performed on a 30 m DB 5 capillary column, 0.25 mm ID and 0.25 μm film thickness,
which was connected to the mass selective detector (5973
MSD from Agilent Technologies) through a heated interface kept at 275 °C. The quadropole was kept at 150 °C
and the ion source at 230 °C.
Data acquisition was performed in full scan mode(FS) ranging from 50 to 500 amu at 1.68 scans per second. Setup and control of the MPS-TDU-GC/MS system as well as data acquisition and processing was performed using the MAESTRO software integrated with
Agilent® Technologies ChemStation.
Verification of individual compound identities was
based on MS and retention time data as well as comparisons with mass spectra in the NIST MS library database,
Eganhouse and DiFilippo report.

Reaching the set goals
Following extended method development, during which
Eganhouse and DiFilippo worked out the best extraction
medium for the analysis and optimized desorption and
GERSTEL Solutions worldwide – No. 18

analysis conditions, the scientists succeeded in determining ten DDT-related compounds in marine pore waterusing their TDU-GC/MS system. Among the analytes
were: 4,4‘-DDNS, 4,4‘-DDNU, 4,4‘-DDMU, 2,4‘-DDE,
4,4‘-DDMS, 4,4‘-DDE, 2,4‘-DDD, 4,4‘-DDD, 2,4‘DDT, and 4,4‘-DDT.
Method Detection Limits (MDLs) for all DDTrelated compounds in the fiber coating were in therange between 0.177 ng/μL (4,4‘-DDNS) and 1.66 ng/
μL (4,4‘-DDT) in FS and between 1.90 pg/μL (4,4‘DDNS) and 4.98 pg/μL (4,4‘-DDT) in single ion monitoring mode (SIM). These units are per µL fiber coating,which translates to MDLs in seawater of 0.05–2.4 ng/L
and 0.67–16 pg/L for FS and SIM respectively, calculated
based on compound-specific PDMS-water partition coefficients at 11 °C. It should be noted that the GC/MS
system used was an older model; current models will provide at least an order of magnitude better sensitivity andthus should generate significantly better MDLs.
In addition to the DDT-related compounds, otherhydrophobic organic contaminants (HOCs) can be determined at sub-parts per trillion levels and monitored
over extended time periods using the presented method.
In their work analyzing marine pore water, Eganhouseand DiFilippo found the dominant contaminants to be4,4‘-DDNU, 4,4‘-DDMU, 4,4‘-DDE and 2,4‘-DDE.
Furthermore, a range of other compounds, both of natural and anthropogenic origins, were identified, among
which were fatty acids, steroids, tensides, gasoline additives, antioxidants, plasticizers, and polychlorinated biphenyls (PCBs).
Performance data on the final method confirmed thehigh quality of the overall SPME-TD-GC/MS method
used. The authors concluded that the method is relatively simple, cost effective, efficient, accurate and precise.
Method recovery can be adjusted quite easily by adjusting
the length of fiber inserted for analyte extraction and, asa precaution, multiple fibers can be inserted in each section in order to have a back-up sample in case of loss or
breakage. Finally, the following statement from the authors should speak for itself: “Moreover, the TDU-CIS
system appears to be effectively inert; we detected little
or no evidence of degradation of these thermally sensitive
compounds”.

References[1] Robert P. Eganhouse, Erica L. DiFilippo,
Determination of 1-chloro-4-[2,2,2trichloro-1-(4-chlorophenyl)ethyl]
benzene and related compounds inmarine pore water by automated thermal desorption gas chromatography/
mass spectrometry using disposable
optical fiber, Journal of Chromatography
A, 1415 (2015) 38–47[2] www.scientificamerican.com/article/the-mystery-of-the-vanishing-ddt-in-the-ocean-near-los-angeles29

TD 3.5+: Steely and 20 percent more capacity
The Thermal Desorber TD 3.5 + is a key component of automated thermal desorption andextraction solutions. The TD 3.5+ fits on top of any modern GC without the need for additional
bench space and is perfectly suited for the analysis of material emissions and air. The TD
3.5+ handles 3.5” tubes, as prescribed in standard methods, and GERSTEL plus tubes withup to 20 % more sorbent for enhanced break-through volume and improved recovery
and limits of detection.

T© GERSTEL / Wolfram Schroll

he TD 3.5+ incorporates the latest advances in thermal desorption technology. Intelligently designed
and based on a “Liner-in-Liner” concept it has no valves or transfer lines.
The TD 3.5+ is connected directly to
the GERSTEL Cooled Injection System (CIS), which serves both as a cryofocusing trap and as a temperature programmable GC inlet. Active sites are
eliminated, reducing the risk of analyteloss, discrimination and memory effects
to an absolute minimum.
The TD 3.5+ can be operated in single split, dual split
or true splitless mode enabling it to cover the widest rangeof concentrations, to protect the column from water andcontamination, and to reach the lowest possible limits ofdetection. For extreme sensitivity, multi-desorption modeis simply selected in the method.
The MAESTRO software combined with Agilent
Technologies MassHunter or ChemStation controls
the complete process from DHS to thermal desorption to GC/MS analysis with one integrated method
and one sequence table ensuring efficient and error-

free operation. Samples can be analyzed using one ormore methods and priority samples inserted as needed.
Techniques supported by TD 3.5+:• Thermal desorption of adsorbent tubes used for air
sampling• Dynamic Headspace (DHS 3.5+) based on standard
headspace vials• DHS 3.5+ Large based on sample containers up to 1 L
in volume• Thermal extraction of solid samples placed in fritted
TD tubes• Twister desorption following stir bar sorptive extraction (SBSE)The TD 3.5+ can be removed in seconds to enabledirect liquid sample introduction into the GERSTEL
Cooled Injection System (CIS), a PTV-type universal
GC inlet.
When configured with the GERSTEL MultiPurpose
Sampler (MPS robotic), up to 40 samples are stored per
TD 3.5+ tray in individually sealed sample positions. The
system can easily be scaled up by using up to three TD
3.5+ trays per tray holder. The number of tray holders depends on size and configuration of the MPS robotic.

Hot in the vial:
Pyrolysis for HPLC and more

DHS large 3,5+: Automatedmicro-scale chamber

The GERSTEL PyroVial enables pyrolysis procedures in a
dedicated sample vial up to 800 °C. Volatile pyrolysis products can be sampled directly from the headspace for GC/
MS determination. Less volatile pyrolysis products can betaken up in a suitable solvent for subsequent GC/MS- or
LC/MS determination – or for analysis using other techniques. The pyrolysis process is fully automated based on
the GERSTEL MultiPurpose Sampler (MPS). Placing thesample into the reaction chamber is very simple and the
PyroVial can be used as a micro-scale reaction chamber.
The gas phase in the vial canbe replaced by an inert gas ora reactant as needed. Foodpreparation processes, suchas the Maillard reaction can be
simulated in small scale. The
addition of reagents or catalysts
before pyrolysis even enables
the simulation of complex industrial processes.

The DHS large 3.5 allows samples to be placed in individual
inert chambers up to 1 liter involume with precise temperature and purge gas flow control.
Analytes are automatically collected at user-defined intervals
followed by thermal desorption
in the TD 3.5+ and GC/MS determination. Emission profiles
can be established automaticallyand automated spiking of standards onto sorbent tubes canbe performed
for calibrationand qualification purposes
using
the
TSS option for
the MPS robotic .

30

GERSTEL Solutions worldwide – No. 18Sequence by barcode: Type it all
in? No, just load up the samples
In addition to sample
logging, new automation
efficiency
and QC options havebeen integrated into
the MAESTRO software based on the
GERSTEL Sample ID (SID) Barcode reader:• Automated analysis by predefined methods• Automated generation of sequence tables• Single sample mode or Batch Analysis Mode (BAM)
selected by mouse-click• Trigger vials introduced at user defined intervals, activating solvent injection(s) followed by one or more checkstandard runs as part of the QC routine operation.

Quick Mix: Shake it up
QuickMix is now available for the

GERSTEL MPS robotic series.
QuickMix enables extremely fastand efficient mixing and extraction of samples as part of theautomated sample preparation
process. The mixing power iscomparable to that of vortex mixing. QuickMix can be used with 2
mL, 4 mL, 10 mL, and 20 mL
vials. If needed, QuickMix can be
configured with a heated tray.
All sample preparation steps
are set up by mouse-click in the
MAESTRO software in stand-alone operation, fully integrated with Agilent Technologies MassHunter or ChemStation, or coupled with software from SCIEX or Thermo Fisher Scientific.

• Trigger function requires only one vial position enablinghigh overall analysis throughput• Multiple options for sample verification and handling ofdeviations• Password restricted access, no unauthorized changes• Sample ID transfer to the data file
• Sample ID incorporation into the data file name• Data import and export functions enable LIMS or
Data Base synchronization.

SPE 2: Rugged automation
The new GERSTEL SPE 2 isavailable for the MultiPurpose
Sampler (MPS robotic Pro).
All SPE steps are performed
automatically using the MAESTRO PrepAhead function
for maximum efficiency andthroughput. SPE can be followed by sample introduction to a dedicated GC/MSor LC/MS system resulting in
the exact same treatment of
all samples. Or SPE can be
performed off-line for independent analysis using one ormore techniques. Liquid volumes are dispensed highly accurately; eluates are transferredusing individual syringe needles and collection vials, minimizing sample-to-sample carry-over. Samples are processed using
individual standard dimension 1, 3, and 6 mL SPE cartridges
for easy transfer of established SPE methods to the automatedsystem. Set up by mouse-click includes added sample prep
steps such as evaporation, dilution, and mixing, as well as adding standards and reagents or introducing the clean eluate to
the analysis system.
The Solvent Filling Station (SFS 3) holds up to four 1 L
solvent bottles; up to two SFS 3 modules can be mounted on
the MPS robotic pro. Solvent waste can be collected in separate receptacles for optimized waste disposal.

GERSTEL Solutions worldwide – No. 18

Benchtop Mixture Maker for Flavorists
The Mixture Maker from GERSTEL is a bench-top blending station withdedicated software, designed for highly accurate automated generationof flavor and fragrance blends from large numbers of ingredients.
More than 900 raw materials (essential oils, extracts...) can be stored
protected from light in 3 cooled stacks with 3 drawers each.
The Mixture Maker generates blends in the µL range, resulting insignificant savings on the costly ingredients often required in flavor andfragrance product development.
Weighing is performed automatically and is used for individual
ingredient delivery calibration or for general liquid additions when highest
possible accuracy is needed. The Mixture Maker software includes
detailed ingredient information, with individual correction factors, recipe
checks and ingredient stock monitoring. All steps in the process anddeviations in weight are logged, allowing the flavorist to take corrective
action. The Mixture Maker is designed for uninterrupted 24/7 operationand highest productivity.
• Miniaturization, blending in µL range• Raw material savings up to 90 %, excellent ROI• Easy automated generation of series of flavors• Automation level for common flavors > 75%• Automation level up to 100% for test or calibration mixtures• Recipes can be generated in LIMS and imported• Recipe administration• Weighing of liquid additions for highest accuracy• Ingredient Status check before mixing is started• Full protocol of all steps, deviations, and ingredients/recipes used
• 24/7 availability

Mixture Maker currently
in 24/7 operation at acustomer site

31

Preview – coming up in the next issue

www.gerstel.com

Caution: E-cigarettes
E-cigarettes and e-liquids have one thingin common with classical tobacco products: They must be closely monitored toensure that they do not expose consumers
to health risks. The analysis of e-liquids is
not at all trivial, however. It requires both
the right strategy and the right technology.

Efficient Anti-Doping
analysis

GERSTEL online: Information on products,
applications, events and downloads, as wellas e-Newsletter subscription and general information about GERSTEL and our customer
focused solutions: www.gerstel.com
US and Canada: www.gerstelus.com

The Center for Preventive Doping Researchat the German Sport University in Cologne,
Germany is racing to stay ahead of doping
offenders by upgrading the laboratories
with fully automated Dried Blood SpotLC-MS/MS Systems.

Link toGERSTEL
videosWellness in the woods
Even a short stay in the woods supposedly
brings about healing - or is it all in yourhead? Apparently not: Japanese researchers have found that Natural Volatile Organic
Compounds (NVOCs) emitted from trees
have healing properties and they are looking at setting up customized natural wellness areas.

Additives on the fly
They are volatile, and they pose healthrisks: Phthalates are used in many industrial
processes and must be monitored in theenvironment. Based on extensive literaturesearch, scientists have been working todetermine, which air monitoring methods
deliver the best results.

Published by
GERSTEL GmbH & Co. KG
Eberhard-Gerstel-Platz 145473 Mülheim an der Ruhr, Germany
Edited by
Guido Deussing, Neuss, Germany
guido.deussing@pressetextkom.de
www.pressetextkom.de
Scientific advisory board
Eike Kleine-Benne, Ph.D.
eike_kleine-benne@gerstel.de
Oliver Lerch, Ph.D.
oliver_lerch@gerstel.de
Malte Reimold, Ph.D.
malte_reimold@gerstel.de
Translation and editing
Kaj Petersen
kaj_petersen@gerstel.com
DesignPaura Design, Hagen, Germany
www.paura.de

ISSN 1619-0076

Imprint

G L O B A L

GERSTEL, Inc., USA+1 410 - 247 5885
sales@gerstelus.com
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gerstel_brasil@gerstel.com

A N A L Y T I C A L

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Germany+49 208 - 7 65 03-0
gerstel@gerstel.com
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Subject to change. GERSTEL®, GRAPHPACK®, TWISTER® and TWICESTER® are registered trademarks of
GERSTEL GmbH & Co. KG. Copyright by GERSTEL GmbH & Co. KG

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china@gerstel.com

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sea@gerstel.com

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