solutions

worldwide

No. 19

Food Safety

3-MCPD and
Glycidol
PFAS Analysis
Thermal Desorption
Ethylene Oxide (EO)
LabWorks Platform
Olfactory Data

www.gerstel.com

Prepared for further growthrequirements. Our key areas of
These are memorable times.
technology continue to be therChange around us is leading tomal desorption and automatedchange inside every organization.
sample preparation for GC-MS
Over the past two years, we haveand LC-MS. You can count on
prepared GERSTEL, restructuring
GERSTEL to deliver uniqueand readying the company andsolutions supported by technicalour processes for new opportuniand application know-how, whichties and challenges.
are second to none based on 50
Steps have also been taken that
GERSTEL Management, from left to right: Peter
years of accrued experience inare important for a family operWiersdörfer, Holger Gerstel and Ralf Bremer
the market. This is your guaranated business. A lot is at stake,tee that the requirements you arenothing less than retaining andfaced with can be met and expectations exceeded. To
expanding know-how and passing it on to the next
give you an impression, we cordially invite you to takegeneration. To continue to be a reliable, competent,
a closer look at solutions for various applications thatand responsive partner for you, our customers, weare presented in the following pages of this 19th issue
continually strive to fully understand and support yourof the GERSTEL Solutions Worldwide magazine. Will
needs and your applications. Further we constantly
you also profit directly using a product or a solution tofollow developments in how lab operations can be
make your operation even more efficient? Let’s have
optimized to meet the relentless demands for producthe conversation. Maybe you can visit us at one of thetivity growth and higher performance. Our company
many conferences we attend – or just contact us towide processes have been scrutinized, and structuresfind out how GERSTEL technology can benefit you.
and communication tools optimized to make the entire
organization more responsive and more flexible. Thishas been done with a view to making new product deWe look forward to meeting you.
velopments available faster, and to be able to respond
GERSTEL Management
more quickly to requests and to changes in laboratory

CONTENTSGERSTEL COMPANY NEWS / Introducing the GERSTEL Management Board .......................... 3
DRINKING WATER ANALYSIS / PFAS analysis miniaturized and automated ............................. 6

INNOVATION / GERSTEL LabWorks Platform – The basis of your analytical success ............... 10
FOOD SAFETY / Focusing on 3-MCPD and Glycidol ................................................................ 12
FOOD SAFETY MONITORING / Ethylene oxide in the sights of inspectors ........................... 20

NEWS ..................................................................................................................................... 16, 24
IMPRESSUM .................................................................................................................................. 2
IMPRINT
Published by
GERSTEL GmbH & Co. KG
Eberhard-Gerstel-Platz 1 · 45473 Mülheim an der Ruhr
Germany
Edited by
Guido Deussing · www.pressetextkom.de
Reader service
info@gerstel.de
ISSN 1619-0076 · 04/2022

2

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
LayoutPaura Design · www.paura.de

Front cover © Copyright: istock /kzenon© Copyright GERSTEL / Heike Wippermann (pp. 2-5)

THERMAL DESORPTION / Comprehensive and flexible analysis ............................................. 17

Introducing the GERSTEL Management Board
For 55 years, GERSTEL has been developing and producing technology that is highly regarded inlaboratories worldwide. During that time, our products and solutions have provided added value toanalysts working in research and development, quality control, food safety, environmental and forensic analysis, and product development.
Our actions, characterized by mutual respect, are aimed at building, and maintaining long-term relationships with our customers and our partners. Our goal is to make it an inspirational experience towork with our company and with our products and services. It is a great honor for us to be entrustedwith the implementation of technical and application innovation. Our committed, skilled employees
ensure that we live up to the trust placed in us.
To address the welcome challenges of a steadily growing company, we have expanded the company‘s management team. The aim is to improve cooperation between all areas of the company tofurther increase productivity, efficiency, product quality and delivery reliability.
The key to mutual success is people - our customers, our business partners, and our employees. As a
responsible employer, we attach great importance to actively developing and supporting our team.
Holger Gerstel
Holger Gerstel (Owner and Managing Director) joined the company, which was founded by his father Eberhard Gerstel Sr. (19272004), 35 years ago. He has held key responsibilities as Owner andGeneral Manager since 1998, establishing GERSTEL GmbH & Co.
KG and developing it into a worldwide leading technology provider, specializing in thermal desorption GC and automated GC/
LC sample preparation and sample introduction. During this time,
the company has expanded both nationally and internationally andhas established subsidiaries in the USA, Japan, China, Singapore,and Switzerland. GERSTEL is present in more than 70 countries. Now, as the sole owner, Holger
Gerstel is working to shape the future of the entire GERSTEL Group. He is guided by a quoteby the German poet and thinker Johann Wolfgang von Goethe: “It isn’t enough to know – youmust apply your knowledge. It isn’t enough to want to do something – you must act”.

”It isn’t enough toknow – you must apply
your knowledge.
It isn’t enough to want
to do something– you must act.”
Holger Gerstel
Owner and Managing Director

Ralf Bremer
Once Eberhard Gerstel Senior’s right-hand man, Ralf Bremer took
over responsibility for the further development and expansion of
the GERSTEL product portfolio as Managing Director in 1998 after
the company founder‘s retirement. Since then, he has been driven
by the idea of developing analytical solutions that make the daily
work of laboratory personnel easier and that contribute to greater
sustainability with low environmental impact. Ralf Bremer‘s activities span decades with worldwide reach. His countless mutually
beneficial cooperation projects with customers and business partners have expanded and sharpened his sense of the achievable analytical solutions, innovations, and markets. Ralf Bremer‘s competence and experience have greatly contributed to ourbusiness success. Transferring his knowledge to the next generation of employees is a matterof particular importance to him.

”Make the daily workof users in the laboratory easier for greater
sustainability andenvironmental
protection.”
Ralf Bremer
Managing Director

3

GERSTEL Management Board
Peter Wiersdörfer
”Those who say it
can‘t be done should
get out of the wayof those doing it.”Peter Wiersdörfer
Chief Financial Officer

For 35 years, Peter Wiersdörfer worked in various banks, mostrecently as a director and divisional manager at a leading
independent regional bank. The appeal was great to use theexperience he had gained to help grow a medium-sized company. For more than two years now, Peter Wiersdörfer has beenpart of GERSTEL‘s upper management. True to the motto „Whodares wins“, he understands and conveys change as an opportunity. His responsibilities include business finance, but also theestablishment and development of internal structures and processes that generate added value for the company as well as for GERSTEL‘s customers
and business partners. One of his overriding goals is to expand the company‘s leading
market position and to guide its transition to the family’s third generation.

Dr. Sascha Giegold”My job is to brighten
the stars and to makeus all shine.”
Sascha Giegold, Ph.D.
Director Global Sales
and Marketing

As a former application and sales specialist, product manager, and branch manager of a leading global player in theanalytical industry, the Ph.D. chemist Dr. Sascha Giegold
knows what matters in laboratories - and he has a proven performance record. As Director of Global Sales and Marketing,his stated goal is to optimize and focus the organization using
the latest communication and process tools for best-in-classefficiency and responsiveness. Leading through motivationand curiosity is his mantra, making sure that the team effort is
supported by all to reach our market leadership goals. “My job is to brighten the stars
and to make us all shine”, says Dr. Giegold.

Dr. Eike Kleine-Benne„Key to GERSTEL’s
success has been
listening to our customers and working
closely with them todevelop solutions
that meet their critical challenges.”
Eike Kleine-Benne, Ph.D.
Director Innovation
and Technology

4

Dr. Eike Kleine-Benne, involved in research and developmentfrom the start of his career at GERSTEL in 2000, initially focused on cooperation with external partners. In recent years,
his focus has increasingly been on technical product management. In joint leadership with Dirk Bremer, Dr. Kleine-Benne
has taken on the task of further developing the company‘s
products and services, leveraging the existing knowledge
base, and pursuing new opportunities. “Key to GERSTEL’s success has been listening to our customers and working closelywith them to develop solutions that meet their critical challenges”, says the Ph.D.
chemist, who plans to continue this tradition and to further expand GERSTEL’s expertise in providing innovative products.

Walter Mertzen
GERSTEL is a leading technology supplier and a responsible business partner. This includes comprehensive, end-to-end service
and support. Walter Mertzen knows how important service andsupport is, based on his experience over 27 years at GERSTEL,
building both the local and worldwide support organizations. The
chemical engineer has deep knowledge of GERSTEL technology
and experience in designing and conducting customer training courses, as well as in overcoming technical and application
challenges. In his view, two ingredients are essential for success:Enthusiasm and balance. Those attributes are Walter Mertzen‘s guiding principles in his
dealings with customers and in the management of his team. He draws on a wealth of experience gained through work for GERSTEL both nationally and worldwide.

“Two ingredients are
essential for success:Enthusiasm andbalance.”
Walter Mertzen
Director Service and Support

Dirk Bremer
Based on his many successful years at GERSTEL, Dirk Bremer is
one of the most experienced employees in the company. During
his 30-year career, he has worked in all technical areas of thecompany. For the past 20 years, as R&D Manager he has also
been responsible for custom-made products and solutions thathave successfully been implemented in laboratories throughout
the world. There is hardly a device or system in GERSTEL‘s product portfolio that Dirk Bremer has not been involved in developing. His extensive knowledge of GERSTEL technology, especiallyin the field of thermal desorption and automated sample preparation and sample introduction, makes Dirk Bremer an excellent counterpart to Dr. Eike Kleine-Benne, with whom
he is jointly responsible for the Innovation and Technology Division.

„Those who want toachieve somethingfind a way; those
who don’t find areason.”Dirk Bremer
Director Innovation
and Technology

Marcel Müchen
A company whose core business is the development, production, and supply of sought-after high technology solutions isconstantly faced with challenges that can be described in justa few words: Productivity, efficiency, product quality and ontime delivery. What is easy to put down on paper requires skill,
experience, depth of knowledge, and assertiveness in businesspractice. Marcel Müchen took the reins two years ago as Headof Production and Quality Assurance and has made it his task
to harmonize existing processes company wide, making themmore efficient through process oriented management and control. Marcel Müchen is also
responsible for purchasing, logistics, order planning, quality management and production, which enables an even more targeted and sustainable approach throughout theentire internal process chain. In this respect, Marcel Müchen builds on experience gained
as a production manager and project manager in previous jobs. The results of his efforts
are added value for both GERSTEL and the company‘s customers.

“Productivity,
efficiency, productquality and on timedelivery require skill,
experience, depthof knowledge andassertiveness.”
Marcel Müchen
Director Business Operation

5

PFAS —
dissemination via
water and soil

GLOBAL AIR AND
OCEAN CURRENTS

THE ARCTIC

Emission pathways known to date.
Emission quantities are not quantified.

DEPOSITIONFROM THE AIR

EXHAUST AIR

IRRIGATION WATER

SEWAGE SLUDGEFLUOROPOLYMER PRODUCERS,USE OF PFAS CONTAINING
MATERIALSCONTAMINATED COMPOSTILLEGAL DEPOSITSAGRICULTURE

PRODUCTSAIR

AIR

HOUSEHOLDSWASTEWATERTREATMENT PLANT

FOOD CHAIN

HUMANSMUNICIPAL
SEWAGE SLUDGEFRUITS AND
VEGETABLESWASTEWATER
FIRE-FIGHTINGLIVESTOCKFOAM

SURFACE WATERSOTTERSDRINKING WATERFOUNTAINFISH

TREATED

SOIL

SOIL

WASTEWATERGROUNDWATERGROUNDWATER

SEDIMENTPFAS — Pathways from waste disposal
RECYCLINGPOSSIBLE CARRY-OVER
IN ARTICLES / PRODUCTS

PFAS analysis miniaturized and automated
WASTE

ENERGYRECOVERY(WASTE INCINERATION)

DESTRUCTION OF PFAS BY
HIGH-TEMPERATURE
TREATMENTLANDFILLSLANDFILL GAS(COMBUSTION IN
ENGINE OR TORCH)NEGLIGIBLE
RELEASE INTO THE
ENVIRONMENTThe EU Drinking Water Directive (EU 2020/2184) includes limits for total PFAS of 0.5 µg/L and26(SINK FUNCTION)

LEACHATE(COSTLY REMEDIATION)

27

sets a limit of 0.1 µg/L for the sum of 20 per- and polyfluoroalkyl substances (PFAS) of mostconcern. The Directive entered into force in January 2021. EU Member States have a 2-year
transitional period to develop national laws. The listed perfluorinated carbonic and sulfonic acids can be determined by an automated method based on miniaturized solid phase extraction
with weak anion exchange sorbent combined with LC-MS/MS. Surface adsorbed analytes areincluded using rinse cycles and effluent recovery, at the same time minimizing sample-to-sample carry-over. Based on just 1 mL sample volume, as opposed to the normally used 250 mL,
the required quantification limit of 1.5 ng/L is reached for all listed analytes with good method
accuracy.

It occasionally takes a while, before we as consumers
realize that synthetic chemicals, which make our lives
easier and more convenient, are harmful in addition
to being useful. The category of synthetic chemical
troublemakers includes Persistent Organic Pollutants(POPs). Once released, the members of the so-called
dirty dozen can hardly be recovered and neutralized
since mother nature has no effective mechanism to
do so. Per- and polyfluoroalkyl substances (PFAS)
should now be added to that list. Their resistance tophotolytic, hydrolytic, oxidative, and reductive breakdown mechanisms are the exact properties designed

6

into these compounds to make them fulfill their purpose. PFAS belongs to a family of highly fluorinatedanthropogenic organic chemicals with special physical chemical properties. Adding PFAS to the surface
makes a material oil and water repellant in addition
to heat resistant. These are useful properties in many
household and industry applications. They are usedin commercial products like cooking utensils, foodpackaging, clothing, carpets, cleaning products, andin firefighting foams. And there is more to PFAS thanjust thermal and chemical stability.

© Copyright Umweltbundesamt (p. 6),© Copyright GERSTEL (pp. 7-9)

By Thomas Brandsch, Ph.D.

Peeking into the molecular cosmos
The PFAS carbon atom chain is hydrophobic, whereas
the head of many PFAS molecules is hydrophilic. The
resulting amphiphilic character is what makes a compound useful as surfactant. As opposed to classicalsurfactants, the hydrocarbon chain of the PFAS is also
oil repellent, which is why PFAS is used as water, oil,fat, and dirt repellant. At the same time, PFAS are sufficiently water soluble to access and accumulate in thefood chain, ground water, rivers, and surface waters,
which means in our main drinking water reservoirs.

Clear and present danger
An estimated 4700 chemical compounds are classified
as PFAS. 20 of these have been targeted in the EU
Drinking Water Directive 2020/2184 due to their toxicity [1]. They are strongly suspected of causing liver

damage, thyroid disease, adiposity, fertility disorders,and cancer [2] leading to their inclusion in the EU
Directive: To minimize the risk of adverse effects through potentially contaminated drinking water, the EU Drinking
Water Directive 2020/2184 establishes a limit of 0.5µg/L for the sum of all PFAS.
 The Directive also sets a limit of 0.1 µg/L for the sumof the 20 per- and polyfluoroalkyl substances (PFAS)
of most concern.
 The lower limits of quantitation (LOQ) subsequently
required are: 30 ng/L for the sum of the 20 PFAS and
1.5 ng/L for the compounds individually.

To minimize the overall environmental impact and tolimit adverse effects on humans, livestock, and wildlife,
not only drinking water will need to be monitored forcontamination with the relevant PFAS compounds, butalso ground-, surface-, and wastewater. Unlike drinking water, the latter types can be expected to containup to significant amounts of particulate matter andsolid matrix, which will impact the analysis. Extracting
adsorbed PFAS from solid matrix material and subsequently eliminating the solids from the extract will
become key objectives of the sample preparation.

Solid Phase Extraction
The separation technique of choice specified inGerman standard procedures for the analysis of waste
water and sludge (DIN 38407-42) [2] is solid phaseextraction (SPE). Due to the anionic properties of theanalytes the extraction is performed using weak anion
exchange (WAX) resins. The matrix is purged from theSPE cartridge, and retained analytes are subsequently
eluted using a methanolic ammonia solution. How efficiently the SPE and thereby the analysis is performed
depends to a large extent on the SPE technique used.

Chemistry of PFAS

The importance of rinsing and recovering the rinse effluent can beseen in the above comparison of chromatograms obtained throughdirect injection of 1 mL of PFAS standard solutions into the onlineSPE-LC-MS/MS system. The uppermost chromatogram resulted
from subsequently rinsing the vial, syringe and injection loop andadding the rinse effluent to the SPE cartridge before the analysis.
For the middle chromatogram, only the syringe and injection loop
were rinsed, and the effluent recovered. Finally for the bottom
chromatogram, no rinsing was performed resulting in significantly
decreased recovery of relevant analytes.

Per- and Polyfluoroalkyl compounds are purely synthetical man-made chemicals. They are formed by chemical
reactions substituting hydrogen atoms with fluorine atoms
in carbonic and sulfonic acids with a chain length from C4 to
C18. Two categories of PFAS are especially relevant for environmental and food analysis: Perfluorinated alkyl sulfonates(PFAS) with perfluorooctanoic sulfonate (PFOS) as the mostwidely known representative, and perfluorinated carbonicacids (PFCA), for which perfluorooctanoic acid (PFOA) isthe most widely known. Among the estimated 4700 PFAS
compounds, are alkaline, neutral, and poly- rather thanperfluorinated compounds.

7

As opposed to standard dimension SPE cartridges, as
described in the DIN 38407-42 method, the OnlineSPE (GERSTEL SPEXOS) relies on smaller cartridges
from which the eluate is transferred directly and quantitatively to the HPLC mobile phase for 100 % analyte
recovery and significantly lower limits of detection andof quantification. In other words, the required limits
can be reached even with substantially smaller sample
amounts.

Online SPE the method of choice
The combination of the GERSTEL SPEXOS and the MultiPurpose Sampler (MPS) robotic makes PFAS analysis
both efficient and simple to perform. SPEXOS automates all steps normally associated with standard SPE.
These include conditioning, loading, rinsing, eluting
into the HPLC mobile phase, and finally exchanging
the cartridge. The MPS, on the other hand, injects
the sample into the SPE system and then rinses thevial, syringe, and injection volume to recover surface
adsorbed PFAS. The rinse effluent is transferred to
the SPE cartridge for inclusion in the analysis leading
to improved analyte recovery and reduced sample tosample carry over. Following analyte elution, SPEXOS
removes the cartridge from the HPLC mobile phaseflow path and prepares the system for the next analysis in parallel to the ongoing HPLC-MS/MS analysis.

Parallel sample preparation and analysis (PrepAhead)
ensures maximum efficiency and throughput.

SPExos method details
During the development project, the method was extensively tested and validated, resulting in a rugged
and robust miniaturized method for determinationof the PFAS listed in the EU Drinking Water Directive
2020/2184:
 An Agilent Technologies HPLC-MS/MS system was used
(1260 Infinity II LC and ULTIVO LC/TQ MS) combinedwith a GERSTEL MPS robotic and SPEXOS, which performed all sample preparation and introduction, including SPE cartridge exchange (SPEXOS Polymer WAX,
25-35 µm) in parallel to the ongoing analysis.
 Analyte elution was performed using a 0.25 % solutionof ammonia in Methanol. HPLC separation (duration 15min) was performed using a Poroshell 120 EC-C18 column, 3.0 x 100 mm, 2.7 µm (Agilent Technologies) witha gradient of 0.1 % formic acid in water and 0.05 % formic acid in a 0.25 % solution of ammonia in methanol ata flow rate of 0.6 mL/min.
 Analyte detection was performed in dynamic Multiple
Reaction Monitoring Mode (dMRM). For every target
compound and every isotopically labelled internal standard (ISTD), two MRM transitions were selected, one
Quantifier and one Qualifier, with the exception of PFBA
and PFPeA, for which only one transition was available.

Calibration was performed using
water spiked with a standard
solution containing the 20 relevant
PFAS (carbonic- and sulfonicacids ranging from C4 to C13) inthe range from 1–1000 ng/L. To
each reference solution and eachsample, a standard mixture of isotopically labelled compounds wasadded. All calibration curves werelinear in this range with correlation
coefficients R2 > 0.998. Calibration
curves for the first and last eluting
compounds (PFBA and PFTrDS) are
shown in the figure.

8

SamplePreparation

Loading

Eluting

Analysis

The MPS-Online-SPE
system automates liquidsample preparation as well
as SPE with automatedcartridge exchange

Successful implementation
The combined MPS-SPEXOS -HPLC-MS/MS system
was successfully validated for the target compounds
listed in EU Drinking Water Directive 2020/2184. To
prove its usefulness for standard laboratory analysis
work and the accuracy and trueness of the results,
drinking water (tap water) samples as well as surface
water samples from the river Ruhr were spiked at twoconcentration levels (5 and 100 ng/L) and analyzed.
The fivefold analyses showed only minimal concentrations of some short chain PFAS (below 10 ng/L).
These results were confirmed by determining low
concentrations spiked into the samples. Trueness wasdetermined at between 90 and 110 %, except PFPeA
for which trueness was at 70 %. The higher-level
spiked samples were analyzed resulting in truenessfor all compounds between 70 and 130 %, as well
as relative standard deviations with a median of 2.6% and an upper range of 8.6 %, demonstrating thegood performance of the method.

For more details on the analysis, please consult GERSTEL AppNote 237: Determination of PFAS in Water
according to EU 2020/2184 and DIN 38407-42 using
online-SPE-LC-MS/MS. Download AppNote 237:
https://gerstel.com/en/Determination-of-PFAS-in-Water

Limits of Determination (LODs) and Limits of Quantitation (LOQs) determinedby sixfold injection of 1 mL zero blind water sample into the Online-SPE xos -LCMS/MS-System according to DIN 32645.

Compound

LOD LOQ[ng/L] [ng/L]

Acronym

Formula

Perfluorobutyric acidPFBA

C4HO2F7

0.4

1.2

Perfluoropentanoic acidPFPeA

C5HO2F9

0.1

0.3

Perfluorohexanoic acidPFHxA

C6HO2F11

0.3

0.8

Perfluoroheptanoic acid

PFHpA

C7HO2F13

0.2

0.5

Summary

Perfluoroctanoic acidPFOA

C8HO2F15

0.4

1.2

The presented online SPE-LC-MS/MS-System enables
the fully automated determination of the 20 target PFAS compounds listed in EU Drinking Water
Directive 2020/2184 at low ng/L concentrations while
meeting the requirements of DIN 38407-42. The added value of the dedicated analysis system includes
vastly simplified handling, dramatically reduced
solvent consumption for improved laboratory sustainability, as well as excellent accuracy and reproducibility. In addition, water samples need not be filtered.
By rinsing the sample vials with methanol, PFAS
compounds adsorbed on the glass surface as well as
fine particulate matter are recovered and transferredto the SPE cartridge where particle adsorbed PFAS
compounds can equally be desorbed and included in
the analysis for a true picture of the PFAS load in theentire water sample.

Perfluorononanoic acidPFNA

C9HO2F17

0.2

0.5

Perfluorodecanoic acidPFDA

C10HO2F19

0.2

0.5

Perfluoroundecanoic acid

PFUnDA

C11HO2F21

0.3

0.8

Perfluorododecanoic acid

PFDoDAC12HO2F23

0.3

0.9

Perfluorotridecanoic acid

PFTrDA

C13HO2F25

0.4

1.1

0.2

0.5

Perfluorobutanesulfonic acid

PFBS

C4HO3F9S

Perfluoropentanesulfonic acidPFPeS

C5HO3F11S

0.1

0.4

Perfluorohexanesulfonic acidPFHxS

C6HO3F13S

0.2

0.5

Perfluoroheptanesulfonic acid

PFHpS

C7HO3F15S

0.1

0.3

Perfluorooctanesulfonic acidPFOS

C8HO3F17S

0.2

0.5

Perfluorononanesulfonic acidPFNS

C9HO3F19S

0.2

0.5

Perfluorodecanesulfonic acidPFDS

C10HO3F21S

0.4

1.3

Perfluoroundecanesulfonic acidPFUnS

C11HO3F23S

0.3

1.0

Perfluorododecanesulfonic acidPFDoS

C12HO3F25S

0.5

1.4

Perfluorotridecanesulfonic acidPFTrS

C13HO3F27S

0.3

0.9

9

GERSTEL LabWorks Platform

The basis of your analytical successWith this system in your lab, youare prepared for whatever comes
your way: The GERSTEL LabWorks
Platform is the only truly universal
system for GC-MS sample introduction. LabWorks incorporates highly
efficient automation with modular
flexibility that enables the GC-MS lab
Sascha Giegold, Ph.D.
to meet critical challenges at short
Director, Global Sales
and Marketing
notice. LabWorks Basic enhances
the potential of GC labs by incorporating 10 fully automated sample
introduction techniques that are intuitively selected,
set up and controlled using MAESTRO software. No
programming skills are needed, the setup is integrated with the Agilent software for easy and error-freesystem operation. Whether a liquid, solid, or gas
phase sample, LabWorks can handle it. Analytes
are extracted and introduced to the GC-MS in an
accurate, reliable, and precise manner for best
possible results. A single LabWorks GC-MS system handles a wide range of samples ensuring agood return on investment and giving you peaceof mind. Even complex application workflows areeasily automated, while further techniques can be
added as needed without the need for additional lab
bench space.
The LabWorks platform relies on True TrapTM technology for analyte trapping without loss or discrimination. The system is based on the liner-in-liner technology without valves or transfer lines in the analyte
flow path. This means that active surfaces and deadvolumes are reduced to an absolute minimum
for best possible analyte recovery and accurate
results – even for unknown compounds (non-target analysis). The True TrapTM technology can beused with Headspace, Thermal
Desorption, SPME, SPME Arrow,
SBSE, and TF-SPME for highly
efficient analyte enrichment
and unsurpassed limits of

10detection and quantification. The LabWorks platform further includes a range of sample preparation
capabilities such as adding internal standard to yoursample, diluting, derivatizing, as well as generating
calibration curves and updating the method with the
new calibration. And LabWorks is easily expanded toinclude more than 20 sample preparation and introduction techniques that can be accessed as needed.
For laboratories that need to respond quickly andflexibly to meet critical challenges, the LabWorks
platform offers the most comprehensive and flexible
solution available today.

Techniques included in the
GERSTEL LabWorks platform

Important features of the
LabWorks platform Liquid injection

 10 sample introduction techniques includedin LabWorks Basic Large volume injection (LVI) Headspace Thermal desorption (True TD) with TDU
and True TrapTM Technology
 True headspace enrichment
 Twister TF-SPME (Thin Film SPME) Direct thermal extraction
 Thermal desorption of tubes packed
with sorbent
 Thermal extraction of liquids in µ-vials
 Derivatization
 Adding internal Standards
 Generating calibration standards
 Generating dilution series True TrapTM technology requires only one
cryogenic trap for all applications
 Cryogen free focusing of target analytes True enrichment for HS, SPME, TD, Twister,
TF-SPME and DHS techniques No valves or transfer lines – best possible
system for nontarget analysis (unknowns)
 Simple modular expansion path for more than
20 additional sample introduction techniques
 Very simple addition of advanced analysis
techniques (ODP, 1D/2D etc.)
 No need to reconfigure the GC inlet whenchanging between techniques
 Space saving system, no further lab bench
space required in addition to the GC-MS.
 MAESTRO integration into the Agilent
Technologies Software platform

LabWorks platform
hardware components
 MPS robotic: Automates the sample
preparation and all sample preparation
techniques Thermal Desorption Unit (TDU 2): Enables theanalysis of all sample matrices
 Cooled Injection System (CIS): PTV type GC
inlet, highly suitable as universal cold trap forthermal desorption.

11

Source: istock / Kuzihar

Focusing on 3-MCPD
and Glycidol
When fat containing foods are processed and heated, fatty acid esters of 3- and 2-monochloropropanediol (3-MCPD and 2-MCPD), and of glycidol can be formed, all of which
are unwanted process contaminants. To ensure a safe food supply, the presence of thesecompounds in food must be monitored. Given the abundance of food and food products,
monitoring should be efficient and therefore automated. GERSTEL offers a wide spectrumof validated, proven automated analysis solutions.
By Oliver Lerch, Ph.D. and Jasmin Zboron

3-Monochloropropanediol (3-MCPD), 2-Monochloropropanediol (2-MCPD) and glycidol - as well as theirfatty acid esters - are unwanted substances in food
due to their health effects. These compounds can
all be generated during food processing – especiallywhen heating is involved. The compounds have beenfound in fatty bakery products, baby food, soy sauce,
as well as edible fats and oils [1]. Free 3-MCPD and
2-MCPD can be formed when fat and salt containing
food is exposed to high temperatures in the production process. The ester bound form of 2-MCPD,
3-MCPD as well as Glycidol are formed duringrefining of oil types that are not edible in the native
form. Refining, and especially deodorization involves
heating the oil or fat to temperatures between 200
and 300 °C to remove off-flavors and contaminant
residues.

12

Dangerous process contaminants
The International Agency for Cancer Research (IACR)
has designated 3-MCPD a potential carcinogen [2].
During food production and processing, it is nearly
impossible to completely avoid the formation of
3-MCPD, and therefore the European Food Safety
Agency (EFSA) aims to limit the exposure, having
defined a tolerable daily intake (TDI) of 0.8 µg of
3-MCPD per kg body weight [3]. For 2-MCPD and its
fatty acid esters, an assessment of the health risks iscurrently not possible due to a lack of toxicological
data [1]. The IACR categorizes glycidol as a probable
carcinogen and as genotoxic.
The contaminant levels in food must be reduced tominimize consumer health impact – especially for
infants who are not breastfed and are instead givenfood produced in an industrial process. Reachingsuch ambitious goals requires use of highly sensitive
laboratory instruments for chemical analysis.

sample preparation step is required: Extractionof the fat contained in the product. The 3-MCPD,
2-MCPD, and glycidol levels are then determined in
the extract.

Maximum Levels in certain foods:
The European Union (EU) Commission has defined
maximum levels in Directive 2020/1322 [4]:3-MCPD Plant based oils and fats (palm-, sunflower-,
rape-, and olive oil etc.): 1250 μg/kg
 Other plant- and animal-based oils / fats:2000 μg/kg
 Baby food/infant formula and ingredients used:
15 to 750 μg/kg

Glycidol Plant based oils and fats, fish oil, oil from marineorganisms etc.: 1000 μg/kg
 Baby food/infant formula and ingredients used:
6 to 500 μg/kg

Choosing the right method
In collaboration with food producers and contract
laboratories, GERSTEL has developed fully automated analysis solutions that meet the requirementsof key international methods for determination of
3-MCPD, 2-MCPD and Glycidol present in their fatty
acid ester form. The solutions are being used successfully in the laboratories of leading international
companies and of reputable contract laboratories
and public institutes.
All methods listed and presented in this article arebased on the same chemistry through hydrolysis.
Further, glycidol is transformed to 3-MCPD or 3-MBPD(brominated form) respectively. After derivatization
with phenylboronic acid (PBA), the analytes are finallydetermined directly or indirectly by GC-MS or GCMS/MS. Differences between the listed methods aremainly found in the reaction control, the internal standards added, and the data handling and calculations
performed. Incidentally, if the sample is a complex
food type, such as a bakery product, a nougat creamthat contains nuts, a chocolate bar, or similar, a further

Differential method
The “original” 3-MCPD solution, described in
GERSTEL Application Note No. 191 (2017) [5] performs fully automated determination of
3-MCPD and glycidol fatty acid esters
AOCS Cd 29c-13
in plant-based oil following the official
DIN EN ISO
AOCS* method Cd 29c-13 [6], the DIN
18363-1:2015
DGF C-VI 18 (10)EN ISO 18363-1 method [7], and the
DGF** Unified method C-VI 18 (10).
*The American Oil
Chemists‘ Society
The system is available from GERSTEL**Deutsche
as customer specific solution based on
Gesellschaft für Fettwissenschaften
the GERSTEL MultiPurpose Sampler(MPS). Two sample or extract aliquots
are saponified and the reaction stopped in thepresence of an acidic chloride- or bromide solution
respectively. This step influences the conversionof the ester-bound analytes in their free form andenables the determination of the original levels of
3-MCPD and glycidol in the sample. This method,referred to as the differential method, enables thefast and efficient determination of the analytes. It
is the most frequently used method and is implemented worldwide in incoming raw material quality
control (QC) as well as quality QC of the final product in oil mills, in the food industry, and in contract
laboratories.

DGF C-VI 18 (10)Reaction (Chromatogramm)
Assay A (3-MCPD + Glycidol)
Assay B (3-MBPD)

By adding NaBr in Assay B, glycidol reacts
to form 3-MBPD

13

AOCS Cd 29a-13 · ISO 18363-3:2017 Unilever

Zwagerman / Overman method
Unilever method
AOCS Method Cd 29a-13, respectively the DIN EN
ISO 18363-3:2017 method also known as the Unilever
Method. In collaboration with a customer laboratory,
GERSTEL application scientists developed an automated application solution for the Unilever method,
described in AppNote 217 [8]. The main difference
from the differential method lies in the sample preparation. Just one analysis run per sample is required
and the analytes in question are released gradually insteps: Glycidyl esters react with acidiAOCS Cd 29a-13
fied sodium bromide solution to their
DIN EN ISO
corresponding 3-Monobromopropane18363-3:2017diol-fatty acid esters (3-MBPD). The fatty
acid esters are extracted with hexane the extract isthen subjected to evaporative concentration, and theresidue is taken up in tetrahydrofuran (THF). Subsequently, 3-MBPD-, 2-MCPD- and 3-MCPD fatty acid
esters are hydrolyzed to their free form in acidic media
at 40 °C for 16 h. Following derivatization with PBA
in an ultrasonic bath, the analytes are extracted withhexane. The extract is again evaporated, and the residue taken up in another solvent and finally separated
and determined using GC-MS. The automated sample
preparation meets the requirements of the standard
method and greatly simplifies the analysis thanks tothe significant degree of automation.

Kuhlmann or SGS 3-in-1 method
Known as the “Volvo” among the 3-MCPD andglycidol fatty acid ester methods, the DIN EN ISO
18363-2:2018, respectively AOCS Cd 29b-13 method, are collectively referred to as the
AOCS Cd 29b-13
Kuhlmann- or SGS 3-in-1 method [11],DIN EN ISO
a rugged method that delivers good
18363-2:2018
results reliably. It is a relatively slow, buthighly precise method that requires sample coolingto between -22 °C and -25 °C. The method including
sample preparation and analysis can be fully automated using an integrated GERSTEL system complete with GC-MS.

14

ISO 18363-4:2021 [9] is the most recent standard
method for the determination of 3-MCPD, 2-MCPD
and glycidol fatty acid esters in edible oils. The method was devised by two Dutch scientists, Zwagerman
and Overman [10]. Several internal standards are used
to compensate for even minor deviations in chemical
reactions and in sample preparation. This concerns,
among other things, an overestimation of glycidol thathas been observed in the presence of large amountsof 3-MCPD. The use of a triple quadrupole GC-MS/MS
is required, analytes are determined in MRM Mode.
The standard method including all sample preparation steps specified therein have successfully beentransferred to a GC-MS/MS system directly coupled toa GERSTEL MPS leading to a fully automated workflow
described in GERSTEL AppNote 239 [12]. Important:
A high power mixing module is required for efficientvortex-like mixing during extraction, a cooled vial tray
for accurate temperature control during transesterification and a fast wash station, all ofwhich are integrated in the autoDIN EN ISO
18363-4:2021
mated system.
The only manual step that remains
is to weigh the sample in an autosampler vial andtransfer it to the MPS tray. To keep the system clean
and reduce memory effects to a minimum, a backflush system prevents high-boiling matrix residue andreagent from reaching the analytical column and the
MS/MS system.
The method was successfully validated and implemented for the analysis of plant- and animal-basedoils and fats. Successful participation in round robins
has demonstrated the high quality of the automatedsample preparation process and the analysis systems.
Relative Standard Deviations were between 0.1 and
10 % for all analytes in different matrices, with only a
few values above 5 %. The Limit of Determination of
0.1 mg/kg required in the ISO method was reached.
Lower LOQs are possible if a Multi-Position Evaporation module (mVAP) is installed on the MPS. The chromatograms are simple, “clean “, and easy to interpretdue to the high selectivity of the triple quadrupole
GC-MS/MS that largely eliminates nontarget signal.
Automation enables 24/7 operation and priority samples can easily be inserted into the running sequence
as needed, adapting to urgent changes.

m

The GERSTEL VAP
enables automatedevaporative concentration of extracts as
specified in standard
methods. Up to 6 extracts
can be concentrated
in one batch.

L I T ER AT U R E R EFER EN C E S
1. Bundesinstitut für Risikobewertung (BfR),
Possible health risks due to high concentrations of
3-MCPD and glycidyl fatty acid esters in certain foods
BfR Opinion No 020/2020 issued 20 April 2020 https://www.bfr.bund.de/cm/349/possible-health-risks-due-tohigh-concentrations-of-3-MCPD-and-glycidyl-fatty-acidesters-in-certain-foods.pdf
2. Y. Grosse, R. Baan, B. Secretan-Lauby et al., Carcinogenicity of chemicals in industrial and consumer products,
food contaminants and flavourings, and water chlorination
byproducts, The Lancet Oncology 12 (2011) 328-329,
https://doi.org/10.1016/S1470-2045(11)70088-2

AOCS Cd 29c-13 · ISO 18363-1
Differential method

Selecting a method
Compared with DIN EN ISO 18363-1, the 18363-4(Zwagerman/Overman) method is somewhat faster(one assay per sample and calibration is required) and
it is much faster than the DIN EN ISO 18363-2 and -3
methods. The DIN EN ISO 18363-4 method relies on
multiple expensive internal standards but it delivers
highly accurate and precise results with good trueness,for example, compared with DIN EN ISO 18363-1.
The methods DIN EN ISO 18363-1 and -4 are mostoften used where results are needed quickly in a
production laboratory or for incoming or outgoing
quality control, accepting or releasing a shipment; theISO 18363- 1 (differential method) is used more widely
than the ISO 18363-4 (Zwagerman/Overman method),
mainly because DIN EN ISO 18363-1 was accepted asa standard method much earlier. Many operations are
reluctant to change from a well-known method thatdelivers good results in a reliable manner – even whena new method offers advantages. The transition to theZwagerman/Overman method is therefore typically adrawn-out process – unless the analytical requirements
involved are changed and updated. This means thatlaboratories are well advised to prepare and broaden
their offering to meet ever changing market demands.
If you are interested in learning more about updating your lab to perform automated 3-MCPD analysis,
please contact GERSTEL to discuss which solution will
best meet the requirements of your organization andhow to best approach the analysis of your particularsamples.

3. EFSA, Process contaminants in vegetable oils and foods
https://www.efsa.europa.eu/en/press/news/process-contaminants-vegetable-oils-and-foods
4. COMMISSION REGULATION (EU) 2020/1322 of 23.9.2020
amending Regulation (EC) No 1881/2006 as regards
maximum levels of 3-monochloropropanediol (3-MCPD),
3-MCPD fatty acid esters and glycidyl fatty acid esters incertain foods, https://eur-lex.europa.eu/legal-content/
EN/TXT/PDF/?uri=CELEX:32020R1322&from=PL
5. D. Lucas, A. Hoffmann, C. Gil, Automated Determinationof 3-MCPD and Glycidol in Edible Oils by GC/MS Basedon the Commonly Used Methods ISO 18363-1, AOCS
Cd 29c-13, and DGF C-VI 18 (10). GERSTEL AppNote 191
https://gerstel.com/en/3-MCPD-Glycidol-in-oils-fatsAOCS-Cd-29c-13-ISO-18363-1
6. https://www.aocs.org/attain-lab-services/methods/
methods/search-results?method=118272
7. https://www.beuth.de/en/standard/iso-183631/241591453
8. C. Choo, M. Sabri, S. Goh, Fully Automated Determination of 3-MCPD & Glycidol based on the AOCS Cd 29a-13
Method, AppNote 217 https://gerstel.com/en/3-MCPDGlycidol-in-oils-fats-AOCS-Cd-29a-13-ISO-18363-3
9. ISO 18363-4:2021, Animal and vegetable fats and oils Determination of fatty-acid-bound chloropropanediols(MCPDs) and glycidol by GC/MS - Part 4: Method using
fast alkaline transesterification and measurement for
2-MCPD, 3-MCPD and glycidol by GC-MS/MS
10. R. Zwagerman, P. Overman, A novel method for the automatic sample preparation and analysis of
3-MCPD-, 2-MCPD-, and glycidylesters in edible oils andfats, European Journal of Lipid Science and Technology,
118 (2016) 997-1006
11. J. Kuhlmann, Collaborative Study for the Quantificationof Total Contents of 2- and 3-MCPD and Glycidol in Food
Emulsifiers by GC-MS, Authorea, 29. Juni 2021, https://doi.org/10.22541/au.162499187.75255939/v1
12. O. Lerch, J. Zboron and M. Wolff, Fully Automated Determination of 3-MCPD, 2-MCPD and Glycidol in Edible Oils
and Fats based on ISO 18363-4 - Zwagerman/Overman
Method. GERSTEL AppNote 239.
https://gerstel.com/en/3-MCPD-Glycidol-in-oils-fatsISO-18363-4

15

DYNAMIC HEADSPACE DHS 3.5
The DHS 3.5 is based on ¼” x 3.5”
tubes with up to four times moresorbent than standard DHS tubes
leading to improved recovery ofvolatile organic compounds (VOCs).
GERSTEL Plus 3.5” tubes, for example, hold up to 240 mg Tenax TA.
Improved recovery leads to higher
precision and lower limits of determination, including for very volatile organic compounds (VVOCs). During
the dynamic headspace extraction
and concentration step, the sorbent

tube is held at a user defined temperature between 10
and 70 °C to optimize analyte trapping. Following the
DHS step, a user activated dry purge can be included asneeded. The GERSTEL MultiPurpose Sampler (MPS) roboticPRO automatically transfers the sorbent tube to the
Thermal Desorber (TD 3.5+) for analyte desorption and
GC-MS determination. The standard size MPS processes
up to 120 samples in one efficient analytical sequence.
For larger batches, larger MPS versions can be chosen.
The DHS 3.5 system processes samples in 10 mL or 20
mL vials. The DHS large module can be added for processing of samples in 250, 500 and 1000 mL vessels.

MPS PYRO – Automated Pyrolysis System
The GERSTEL MPS PYRO performs automated pyrolysis of up to 40, 80, or 120 samples at temperatures ashigh as 1000 °C in standard pulsed (instant) mode, or in
multiple steps (fractionated) for separate determinationof VOCs, SVOCs, and pyrolysates. Smart Ramp Pyrolysis(SRP) enables analysis of unknown samples and polymer
mixtures without method development and without
interference from compounds that are formed in secondary reactions when a single “compromise” pyrolysis
temperature is used. In Evolved Gas Analysis (EGA),
gases formed as the sample is heated are determined.
The valve-free liner-in-liner flow path provides excellent recovery, as well as minimized contamination andsample-to-sample carry-over. Temperature verificationand calibration in the sample
position is performed by theuser, ensuring accurate and reproducible results from
instrument to instrument
and from laboratory tolaboratory, and liquid injections can be
performed for
GC-MS performance tests
or for trouble
shooting.

MPS TD – DEDICATED TO THERMAL DESORPTIONThe GERSTEL MultiPurpose Sampler (MPS) is
characterized by its automation performance, highdegree of flexibility, and adaptability to a wide
application range. When a high level of flexibility
is not needed, a dedicated automation platformthat requires a more limited investment is called
for. With this in mind, the new MPS TD was developed specifically for automated thermal
desorption (TD), thermal extraction (TE), anddynamic headspace (DHS).
The MPS TD is equipped witha GERSTEL gripper that can

16transport either Thermal Desorption Unit (TDU
2) or Thermal Desorber 3.5+ (TD 3.5+) tubes. The
system can process up to 240 TD samples when
fitted with two tray holders. System control is
intuitive and highly efficient using MAESTRO
software which is integrated with the Agilent
GC-MS method and sequence table. If required,
the MPS TD can also be reconfigured to perform
liquid standard injections.

Liquid Injection

Thermal Extraction ofliquids and solids

Sorbent Tube

SPME
Headspace Techniques

Pyrolysis

SBSE / Twister®

Kurt Thaxton
International ProductManager
Thermal Desorption and
Pyrolysis

Solutions for Thermal Desorption

Comprehensive and flexible analysis
For many types of analyses, a key objective is to determine both known (target) and unknown (nontarget) analytes, for example, to help safeguard product quality and acceptance or to monitor material emissions. For volatile and semivolatile organic compounds(VOCs and SVOCs) the analysis is ideally performed without using potentially toxic solvents and without analyte loss or degradation. In many such cases, thermal desorption is
the technique of choice.
Whether a nontarget analysis is successful largely
depends on the sample handling and analysis technique used, but it also requires choosing a suitable
analytical instrument for the task. Ideally, it should
be flexible enough to allow fast adaptation to new
and unexpected challenges, for example, whenevera critical product quality issue emerges that must be

resolved quickly. Flexibility is best achieved in systems
that are modular and offer a wide range of techniques.
Whenever nontarget (unknown) compounds must be
identified, the ability to cover a wide range of chemicalcompounds without discrimination or loss is criticallyimportant. As an example, off-odors are frequently
caused by compounds with extremely low odor thresh-17

olds. These compounds are easily
detected by the human nose but
require extreme analyte concentration either by preextraction or by the
analytical instrument/technique used for the analysis
to be definitively identified by a mass spectrometer.
To top off the wish list, the analytical system must be
automated, reliable and rugged, and its operation user
friendly. When it comes to the determination of VOCs,
thermal desorption (TD) in combination with GC-MS
has emerged as the technique of choice – and for obvious reasons: No need for potentially toxic solvents that
dilute the sample and are expensive to both purchaseand to dispose of. GERSTEL has provided instruments
and systems for solvent free, highly sensitive andenvironmentally friendly thermal desorption analysis formore than 30 years and is a recognized global leader inthis field.

A deeper look at TD technology
and instrumentation
Thermal desorption instruments generally consist offour core elements: An autosampler, a thermal desorber, a flow path, and a focusing trap - not necessarily inthat order.

The trap
The heart of every GERSTEL thermal desorber has
always been the Cooled Injection System (CIS), a PTV
type GC inlet used to concentrate and transfer analytes
efficiently and without discrimination or loss. The CIS
was originally developed for GC analysis to perform
discrimination-free liquid injection at low temperature
followed by programmed temperature vaporization(PTV). This approach was also widely used forlarge volume injection (LVI) for improved
detection limits. In thermal desorption
systems, the CIS is used as a cold trap,
concentrating analytes before transferring
them to the GC column in a sharp band for
optimal separation and compound detection. Ideally, analyte focusing is performed at
low temperatures without having to rely on sorbents.
Sorbent traps can cause chemical reactions and analytedegradation of more labile compounds and should be
avoided when an application requires the identificationof nontargeted (unknown) compounds.

18

True TrapTM
GERSTEL’s True TrapTM technology is applied when the
CIS is cooled with liquid nitrogen to -180 °C and only
inert glass beads are used to enhance compound trapping. This is the ideal way to trap even the most volatilecompounds and obtain a “true” profile of the analytes
in a sample. This single trap configuration can be used
for all applications and does not require the CIS to bereconfigured as the sample type changes. Since thetechnology does not rely on sorbent material, it eliminates the challenge of selecting the “right” sorbent
which requires the use of standards and a cumbersome
trial and error approach to ensure the compounds ofinterest are being trapped without significant loss ordegradation. There are other features that contributeto making the CIS the ideal cold trap. The slender
design and short analyte flow path free of valves andactive surfaces minimizes the risk ofanalyte loss and sample-to-sample carry-over. The user defined
temperature and programmed
temperature vaporization during
analyte release enable thesimplest possible operation. In
some cases, the use of True TrapTM
technology may not be necessary. For example, if the compounds to be determined are known(target analysis) or the compound type and boilingpoint range is well defined, other cooling options canbe used. Cooling with carbon dioxide provides trap
temperatures to -70 °C, the cryogen-free Cryostatic
Cooling Device (CCD) provides trap temperatures as
low as -40 °C and Peltier Cooling goes to +10 °C. These
options provide trapping temperatures that allow theTD system to be optimally configured for any application or laboratory requirement.

Flow path
When selecting your TD instrument, always consider
the analyte flow path between the thermal desorber,
the trap and the GC column. It should have low deadvolume while being inert, rugged, and leak free. As
always “the best transfer line is no transfer line”, since
void volumes and active surfaces are eliminated forbest possible analyte recovery and quality of GC
separation. These requirements were developed toperfection in the TDU and TD 3.5+ by connecting themodules directly using the“liner in liner” approach andhaving the GC column inserted directly into the CIS trap
liner. Connecting the elementsof a thermal desorption system insuch a compact manner eliminates multiple elementsfrom the analyte flow path: No o-rings; no valves; nopolymer stator or rotor/slider; no connecting tubing;no protective PTFE filters used to protect the valves.
Protect the valves? Yes, valves must be protected fromsorbent particles using PTFE filters in the analyte flow
path to avoid surface scratching and leaks. Such instruments may be specified to a maximum desorption
temperature of 400 °C, but the PTFE filters will melteven at temperatures well below that level, so best not
to try it. The compact liner-in-liner flow path eliminatescomplexity and provides the inertness required forgood recovery across the volatility range even for morelabile compounds.
Liquid samples or standards can be injected directly
into the TDU and TD 3.5+ or introduced using µ-vials
placed in the TD tube. The CIS can also be used for
liquid injection, for example during GC-MS method
development, when validating GC-MS performanceusing a liquid standard, or when performing trouble
shooting. Further, the Tube Spiking System (TSS)
module enables the MultiPurpose Sampler (MPS) used
for the TDU 2 and TD 3.5+ to spike sorbent tubes withliquid standards as required in various air monitoring
methods.

Choice of thermal desorber
The CIS can be combined with any of the three different GERSTEL TD systems: Thermal Desorption Unit
(TDU 2), Thermal Desorber 3.5+ (TD 3.5+), and Thermal Desorption System (TDS 3). Sample introduction
is performed by inserting an TD tube best suited forthe sample type (gas, liquid or solid) or preliminary
extraction technique (GERSTEL Twister® or Thin Film
SPME). During primary (tube) desorption, a high carriergas flow and programmed temperature desorption
should be used to reduce the riskof analyte overheating anddecomposition. The GERSTEL TD systems, uniquely, use this approach. To
meet all requirements,

GERSTEL TD systems support use of three of the mostwidely used tube dimensions worldwide: 2.4” (60 mm),3.5” (89 mm) and 7” (179 mm) long. The most suitable
instrument is simply selected based on the analysis
requirements. As to choosing the tube size, we offer
the following recommendations: 2.4” TDU tubes areespecially well suited for thermal desorption of the
GERSTEL Twister® and for Thin Film SPME devices. The
3.5” (1/4“OD) tubes used in the TD 3.5+ enable the useof significantly more sorbent providing larger sample
capacity resulting in improved recovery during whole
air sampling or, for example, when performing Dynamic
Headspace sampling (DHS) of very volatile species.

Autosampler
All GERSTEL TD systems can be operated with highly
efficient autosamplers. For the TDU 2 and TD 3.5+,
the dedicated MultiPurpose Sampler MPS TD version
can be used, or the MPS robotic Smart
series is available if a fully flexible
configuration is required. Further,
the LabWorks basic system offers
10 techniques including TD, andthe LabWorks advanced system isscalable to more than 30 techniques,in one system. These range from liquid
injection through headspace and dynamic
headspace, SPME and TF-SPME as well as Stir Bar Sorptive Extraction using the GERSTEL Twister®.

Conclusion
Users that need to perform nontarget analysis as well
as determination of labile or adsorptive compounds aspart of their daily tasks are well equipped to meet theirchallenges with a GERSTEL TD solution. Our powerful
TD platforms further help to maximize the use andperformance of powerful mass spectrometers suchas TOF-MS. The simplicity and ruggedness of the TD
systems enable routine quantitative determination ofa wide range of VOCs and SVOCs. Whether you arelooking for a few compounds in a packaging sample,
a wide range of analytes in air, a full aroma profile ofa beverage, or a critical off-odor in your product, the
GERSTEL TD technology will quickly provide the results
you need.

19

Ethylene oxide in the sights
of food safety inspectors
In large numbers of sesame seed shipments, especially from India, EU food inspectors have found residues of the highly toxic compound ethylene oxide, leading tofood product recalls with associated public information campaigns. Many years ago,the fumigant was widely used as a disinfectant for foodstuffs, but its use for foodand feed has been strictly prohibited in the EU since 1991. To safeguard the foodsupply, fast, safe, and reliable analysis methods are clearly needed.
By Tatiana Cucu, RIC Technologies

Ethylene oxide (EO) is a sweetish smelling, colorless, highly flammable gas, which in many countries
outside the European Union EU is still in use as abiocide to eliminate insects, bacteria, and fungi fromthe food supply. The fumigant is especially used for
dry foodstuffs, such as herbs, spices, nuts, or oily
seeds. In the EU, the use of EO to treat food has
been prohibited since 1991
due to its carcinogenic and
2-CE, also known as ethylene
chlorohydrin, counts among
genotoxic properties. Nevthe most toxic halogenatedertheless, the EU commisorganic compounds. Incision’s Rapid Alert Systemdentally, 2-CE seems to be
for Food and Feed (RASFF)
the dominating compoundhas received a large andin foods treated with EO.
This is widely attributed toincreasing number ofthe extreme reactivity andnotifications relating to EO
volatility of EO.
contaminated foodstuffs
found at EU entry points
since 2020, initially mainly regarding sesame seedshipments from India. The determined EO amounts
exceeded maximum residue level (MRL) of 0.05 mg/kg,
specified in EU Commission Regulation 2015/868 [1], bya wide margin leading to further increased monitoring and, in turn, a significant number of productrecalls in various EU member states. Incidentally,recalls were issued both for conventional and organic
food products and the list of afflicted food products

20

and of countries of origin has grown with the numberof samples taken. The US Food and Drug Administration and Canadian authorities specify tolerance limitsof 7 ppm for Ethylene oxide and 940 ppm for 2-CE
for a range of spices, dried herbs, and vegetables.

The active ingredient and its metabolite
To safeguard a healthy food supply, industry andfood safety inspectors need a proper toolkit of highly
sensitive analysis methods. They must be able toreliably determine ethylene oxide (EO) and its main
metabolite 2-chloroethanol (2-CE), at concentrationlevels well below the specified MRLs (see above).
Literature searches reveal different methods used todetermine EO or, in some cases, the sum of EO and2-CE. Some methods, such as the official German
method (§ 64 LFGB, L53.00-1) rely on converting
2-CE to EO under alkaline conditions and then converting the formed EO to 2-Iodoethanol (2-IE), whichis in turn determined by GC-ECD or, more frequently
nowadays, by GC-MS. Other methods
rely on converting EO
to 2-CE underacidic conditions followedby extraction of
the resulting 2-CE

with ethyl acetate and GC-MS determination. In December 2020, the EU Community Reference Laboratory for Single Residue
Methods in Stuttgart, Germany (https://
pesticides.cvuas.de/) proposed a combination of a QuEChERS sample preparation
method and GC-MS/MS determination [2].

Meeting the challenge
When analyzing food products for EO and
2-CE, there are challenges to overcome.
The very volatile EO, for example, requires
a special GC column to avoid co-elution
with acetaldehyde, frequently found in fatty foods. To sharpen the challenge, acetaldehyde and EO not only have similar retention indices, but also similar mass spectra.
GC-MS traces of curcuma extracts analyzed in scan mode without backflush
At the other end of the molecular size
(upper trace) and in MS/MS mode with backflush (lower trace). Source:
spectrum, even after QuEChERS cleanup,Tatiana Cucu / RIC Technologies
food extracts contain large amounts of
nonvolatile matrix material. Such matrix
the analytical column was protected by integrating
residue accumulates in the GC inlet liner
a pre-column backflush option, which improved
impacting analyte recovery and thereby method
ruggedness and reduced instrument downtime for
accuracy and ruggedness. When nonvolatile material
maintenance.
is then transferred to the GC column, it accumulates
and impacts separation performance before eventually contaminating the MS ion source.
At the RIC Technologies laboratories, we took up thechallenge of developing and validating an automated method for the determination of EO and 2-CE
in matrix laden QuEChERS extracts while reducing
or eliminating instrument downtime for cleaning
and maintenance. The analysis method upon which
our solution is based on was developed by the EU
Community Reference Laboratory for Single Residue
Methods at CVUA Stuttgart, Germany (https://pesticides.cvuas.de/). The method performs quantitative
determination of EO and its main metabolite 2-CE infoodstuffs, specifically in sesame seeds and curcuma.
It was found that to obtain sufficient method ruggedness, residue from the sample matrix must not be allowed to accumulate in the GC inlet liner, GC column
or reach the MS ion source. The automated system
we used consisted of an Agilent 8890 GC, Agilent
7010 Triple Quadrupol MS and a GERSTEL MultiPurpose Sampler (MPS) fitted with the Automated Liner
Exchange (ALEX) option. ALEX removes and replaces dirty liners at user defined intervals. In addition,

A look at the analysis details
Method development was performed using EO and2-CE standard solutions, the method validation was
performed based on real samples that had beenmechanically homogenized and spiked with deuterated standards. Quantification was performed using
deuterated EO and 2-CE as internal standards. The
QuEChERS extraction was performed manuallyaccording to DIN EN 15662.
To demonstrate chromatographic stability, extracts ofsesame seeds and curcuma werespiked with EO and 2-CE resulting
in concentrations of 10, 40, and
100 ng/mL. These were repeatedly
injected from the same vial to thesame GC inlet liner. A moderate
reduction was observed in the EO
peak areas for the sesame extract
injections, slightly more for the curcuma extract
injections. This was explained by evaporative lossof EO from the sample, which was kept at ambient21

temperature over a period during
which multiple septum punctures
were performed to aspirate thesamples. Nevertheless, repeatability was a respectable 5-6 %, indicating that the loss was adequately
compensated for using internal standards in thecalculation. Unexpectedly, the less volatile 2-CE
also exhibited some loss over the period. The 40 %reduction in absolute 2-CE peak area seen between
the first and fifth injection was clearly caused byincreasing activity in the GC inlet liner. Further, peak
distortion was observed after injection of samples
with particularly high matrix loads, for example in thecase of curcuma extracts. The injection of relatively“dirty” QuEChERS extracts influenced the recoveryof 2-CE prompting the decision to use AutomatedLiner Exchange (ALEX) in the EO and 2-CE analysis
system. Using the ALEX option, clean liners wereinserted after 20 injections (user defined) to ensurethat extracted nonvolatile matrix material couldn’t
accumulate to a degree that would influence 2-CE
recovery and compromise the quality of the analysis
results. Further, installing a pre-column backflush
option clearly prevented a large amount of highboiling material from reaching the GC column and byextension the MS ionization source. When the backflush option was activated, MS source contamination
was negligible. If pre-column backflush was activatedshortly after the target analytes had reached theanalytical column, the sample would have no or almost no impact on the analytical column, extending
column life and protecting the MS ion source fromcontamination that would otherwise impact systemstability and require down time for cleaning.

Succesful ethylene oxide determination
The described method for determination of ethyleneoxide and 2-chloroethanol was validated by performing recovery experiments in triplicate at threedifferent concentrations (0.05, 0.2, and 0.5 mg/kg)
in actual samples. Recoveries ranged from 84.5 to100.6 % for EO and from 88.8 to 106.2 % for 2-CE
in sesame seed and curcuma samples. To demonstrate the practicalusefulness of the method, representative food samples that had beenpurchased in a local food store
were analyzed.

22

22

Result: None of the samples tested positive for EO,
but all tested positive for 2-CE, some even exceeding the MRL levels. The precision of the developed
method was tested using sesame seed reference
samples kindly provided by a partner laboratory
and the established value was close to the reported
average of 4660 μg/kg (27.3 % CV). Recovery was
between 85 and 106 %, with good repeatability forboth EO and 2-CE. Concerning the sensitivity, thedeveloped method achieves LOQs for sesame andcurcuma (representativefor food category spices)
below the currently valid
MRLs. Results were stable
both for sesame and for
curcuma samples, RSDs
for triplicate combined
extractions and analyses for the recovery
experiments were
well below 20 %. The
sample preparation and the optimized
GC-MS/MS method reliably delivered results andperformance that would indicate the usefulness ofthe method for the quantitative determination of EO
and 2-CE down to well below the regulated concentrations for sesame and spice samples. The processdelivers high sensitivity, selectivity, precision, andespecially high sample throughput with minimal
downtime for cleaning and maintenance of the inlet
system, replacement of GC columns, and MS ion
source cleaning.

REFERENCES:[1] Regulation (EU) 2015/868 of 26 May 2015 amending

Annexes II, III and V to Regulation (EC) No 396/2005 of
the European Parliament and of the Council as regards
maximum residue levels for 2,4,5-T, barban, binapacryl,
bromophos-ethyl, camphechlor (toxaphene), chlorbufam, chloroxuron, chlozolinate, DNOC, di-allate,dinoseb, dinoterb, dioxathion, ethylene oxide, fentin
acetate, fentin hydroxide, flucycloxuron, flucythrinate,
formothion, mecarbam, methacrifos, monolinuron, phenothrin, propham, pyrazophos, quinalphos, resmethrin,
tecnazene and vinclozolin in or on certain products. Off.
J. Eur. Union L 145/1 – 71 (2015).
[2] EURL-SRM-Analytical Observation Report: Analysis of
Ethylene Oxide and its metabolite 2-Chloroethanol by
the QuOil or the QuEChERS method and GC-MS/MS.
Dezember 2020. Link: https://www.eurl-pesticides.eu/
library/docs/srm/EurlSrm_Observation_EO_V1.pdf

22

Olfactory Data Interpreter (ODI)
The novel Olfactory Data Interpreter (ODI) software brings a new level of ease to data
handling and interpretation of Olfactory data obtained in combination with GC/MS.
ODI is part of GERSTEL Enterprise Edition powered by OpenChrom.

The GERSTEL Olfactory Data Interpreter (ODI) enables
fast and reliable evaluation of olfactory information
including identification of unknown odor-active compounds. Chromatography data is typically acquired
using a mass spectrometer / mass selective detector(MSD), a Flame Ionization Detector (FID) or a Sulfur
Chemiluminescence Dectector (SCD) or a combination
thereof. The chromatogram is loaded into the ODI
software, which automatically recognizes the chromatogram data format before importing the data. In
parallel, an olfactogram is imported with information
provided by the user as he or she assessed odors eluting from the GC column in parallel with the detection
process during the GC run. The olfactogram combines
spoken comments from the sensory analyst and theregistered intensities along a time axis. The „Olfactory
Intensity Device“ (OID) conveniently enables the user
to indicate the intensity of the olfactory impression as
it transpires. Text comments are added using voicerecognition software to translate spoken descriptors.
The combined information is presented in the
ODI Software in a clear and concise overview including a chromatogram, an olfactogram and a table.
In addition, the detailed report of the signals registered during olfactory detection at the sniff port
includes important parameters such as retention time(RT) and retention index (RI) as well as NIST library
search results for compound identification. The audio
file with descriptors is stored for later evaluation, as
needed. If changes to the initial impression have beenrealized, the text comments can be edited. Regarding
the MS data, results from database searched can bealigned with Retention indices (RIs) calculated by the
ODI Software. To evaluate olfactory information anddetermine the identity of a critical or key odor active
compound or compounds that result in an olfactory
impression, the Olfactory Data Interpreter (ODI) provides the analyst with several helpful software featuresand functions.

Figure: Chromatogram with peak annotations and overlay olfactogram

Cumulative Olfactogram presentation
When a sample is evaluated in multiple dilutions using
Olfactory GC (GC-O), the resulting olfactograms areconveniently combined and presented in cumulated
form: The ODI software adds the respective odor
intensities and displays the cumulative value. Substances that are still above the odor threshold in thehighest dilution will be represented with the highest
values in the cumulative olfactogram. The cumulative
olfactogram function is a simple yet efficient tool that
instantly provides the odor analyst with reliable information as to which compounds belong to the groupof more potent odor active compounds that influence
the flavor or odor impression even at very low concentrations.

Aroma Extract Dilution Analysis (AEDA)
The ODI Software enables efficient evaluation ofclassical Aroma Extract Dilution Analysis (AEDA) withdefined dilution factor (Flavor Dilution, FD). The ODI
software performs all calculations and determines theFD value, which is a measure of the intensity of an odor
active compound within a mixture. The software transfers the established value to a ready to print report.
The AEDA report provides the sensory analyst a tool
for simpler and more efficient evaluation of panel data.

23

Sensory Panel Analysis
If a sample undergoes olfactory evaluation by a sensory
panel, the resulting data
will show how many panel
members perceive a given
impression or compound.
This information can be very
helpful as a supplement to
GC-O data or to correct
GC-O data, as well as forfurther analysis and aroma
identification. Manually
generated reporting can
be both cumbersome andlabor intensive, requiring a lotof time. The Olfactory Data Interpreter helps to perform the panel analysis evaluation by mouse-click anddelivers the detection frequency of each compound
without delay.

MS Library Search
The ODI Software integrates numerous functions
relating to extraction, cleanup, and interpretation ofmass spectra. Spectral recognition is performed using
existing libraries; various data formats can be used.
The GERSTEL Application Laboratories recommend
the NIST AMDIS software, which is coupled directly
to the ODI Software enabling efficient and convenientcompound identification and spectral deconvolution ofco-eluting compounds.
In summary, the GERSTEL ODI software simplifies andsupports fast determination and elucidation of unknown flavor active compounds and mixtures, determined by GC/MS-Olfactory (GC/MS-O) analysis or panel analysis. When it comes to handling and processing
Olfactory Data, the ODI software offers the necessary
combination of incisiveness and flexibility, required toreach the right answer when confronted with inherently
fuzzy olfactory data. The ODI is a novel highly useful
tool for the flavor chemist.

ODP 4 and Olfactory Data Interpreter (ODI) Software
The GERSTEL Olfactory Detection Port (ODP 4) enables
simultaneous detection of compounds with the humannose and a mass spectrometer. The ODP 4 has auniformly heated highly inert transfer line connected toa heated mixing chamber, resulting in good recovery
and sensitive olfactory detection even for high-boilingand polar compounds. Makeup gas and humidification
can be added to the GC column effluent as required.
The ODP is mounted on a multi-jointed arm with acentrally placed fixation knob for optimized ergonomics
and easy positioning. Nasal positioning guideposts
are available for each user to ensure consistent results
through reproducible nasal positioning. For improved

safety and hygiene, each analyst can use his or her own
PTFE outer cover, positioning guideposts and glass
funnel; these can be exchanged in a few seconds. The
ODP can be operated with or without a glass cone,and sorbent tubes can be inserted to trap and concentrate interesting fractions for further analysis. The
ODP 4 is supplied with Olfactory Data Interpreter (ODI)
software enabling time-aligned sensory evaluation ofcompounds determined by the GC-MS, complete withintensity levels and qualifiers displayed in a combined
olfactogram. For more information on the ODI software, please see the previous article.

GERSTEL GmbH & Co. KG,
Germany

GERSTEL GmbH & Co. KG
Eberhard-Gerstel-Platz 145473 Mülheim an der Ruhr
Germany

GERSTEL, Inc., USA

GERSTEL K.K., JapanGERSTEL AG, Switzerland

GERSTEL Shanghai Co. Ltd

GERSTEL LLP, Singapore

CER

M
IED Q -SYS
T
TIF
EM

Follow us:

CE

86

5

O
1
9001:20FIC
00
AT E N O .

IS

TI

D

ISO 9001
R

www.gerstel.com
GERSTEL®, GRAPHPACK®, TWISTER® and TWICESTER® are registered trademarks of GERSTEL GmbH & Co. KG. · Subject to change.
Agilent® is a registered Trademark of Agilent Technologies, Inc. · LinkedIn, the LinkedIn logo, the IN logo and InMail are registered trademarks or trademarks of
LinkedIn Corporation and its affiliates in the United States and/or other countries · YouTube is a trademark of Google LLC · Copyright by GERSTEL GmbH & Co. KG

24