bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Oral Fluid and Urine for Detection of Cocaine Abuse Using Liquid Chromatography with Tandem Mass Spectrometry
Authors: Melanson Stacy E F , Petrides Athena K , Khaliq Tahira , Griggs David A , Flood James G
Published: February 2020

Background

Requests for urine (UR) and oral fluid (OF) drug testing at our institutions are increasing. However, few studies have assessed the accuracy of each matrix using paired specimens and LC-MS/MS. We compared OF and UR for detection of cocaine (COC) abuse in addiction medicine-psychiatry (AMP) clinics.

Methods

We measured COC and benzoylecgonine (BZE) in OF (limit of detection (LOD) 2.0 µg/L) and BZE in UR (LOD 5 µg/L) by LC-MS/MS in 258 paired samples, and compared the two matrices when higher UR cutoffs of 25, 50, and 150 µg/L were employed.

Results

UR detected more COC abuse than OF at the LOD (5 µg/L). BZE was detected in 63 UR specimens and COC and/or BZE in 40 OF specimens (29 OF+UR+, 11 OF+UR-, 34 OF-UR+). UR creatinine was lower in OF+UR- specimens. COC and BZE were detected in 88% (35/40) and 75% (30/40) of OF specimens, respectively. OF was equivalent to UR at detecting COC abuse using a 25 µg/L cutoff, and detected more COC abuse than UR using 50 and 150 µg/L cutoffs. The ratio of OF COC/BZE increased with decreasing UR BZE concentrations.

Conclusions

We demonstrate that OF detects more COC abuse in an AMP setting when UR BZE cutoffs ≥ 50 µg/L are utilized, and that UR creatinine concentrations are significantly lower in specimens positive for COC and/or BZE in OF and negative for BZE in UR. The presence of only COC in OF and low concentrations of UR BZE likely indicates remote use of COC.
Stability of Domoic Acid in Saline Dosing Solutions
Authors: Johannessen Jan N
Published: February 2020

Studies designed to assess the effects of repeated low doses of domoic acid require an assessment of its stability in solution under the conditions used for in vivo studies. The stability of 1 mg/mL solutions of domoic acid in saline, with or without ascorbic acid, was determined for 15 weeks. Solutions were refrigerated, but warmed to room temperature for several hours each working day to simulate conditions of actual use. The solutions of domoic acid showed no evidence of decomposition as evidenced by stability of UV absorbance spectrum, concentration of domoic acid as determined by a liquid chromatographic method, and the chromatographic elution pattern. The addition of ascorbate to the domoic acid/saline solution did not alter the stability, but was deemed unnecessary because of the firm stability of the domoic acid/saline solution.
Evaluation of a Hypercrosslinked Polystyrene, MN-200, as a Sorbent for the Preconcentration of Volatile Organic Compounds in Air
Authors: Baya Maria P , Siskos Panayotis A , Davankov Vadim A
Published: February 2020

Breakthrough volumes, average percentage recoveries, and storage stabilities were obtained for vapors of 8 volatile organic compounds (pentane, octane, undecane, isooctane, cyclohexane, toluene, methanol, and dichloromethane) on a new adsorbent material, Hypersol-Macronet, MN-200. Breakthrough volumes were estimated as half of the gas chromatographic specific retention volumes at 20°C for the compounds. Recoveries of the adsorbates were determined by both solvent extraction and thermal desorption methods. The results obtained compare favorably with those for Tenax GR (values reported in the published literature and others obtained in our laboratory). Results of storage stability studies on MN-200 meet the criterion for acceptability (<10% loss). High adsorption capacity for very volatile and polar compounds, combined with ease of desorption of less volatile compounds, render MN-200 a highly promising adsorbent for sampling volatile organic compounds in indoor and outdoor air.
Determination of Total Taurine in Pet Foods by Liquid Chromatography of the Dansyl Derivative: Collaborative Study
Authors: McCarthy Kieran , Hischenhuber Claudia , Joyce Neil ,   Collaborators:, Cherix G , Hischenhuber C , Joyce N , Kuhr S , McDonald J , McKnight S , McNamee P , Mevissen L , Müller B , Revitt S
Published: February 2020

A liquid chromatographic (LC) method for the determination of total taurine in pet foods was evaluated in a collaborative study. Ten laboratories assayed 6 blind duplicate pairs of wet and dry pet foods. The taurine in the 6 sample pairs ranged from low (170 mg/kg) to high (2250 mg/kg) concentrations as is. Collaborators also assayed a sample of known taurine concentration for familiarization purposes. Samples were hydrolyzed to release bound taurine, which was subsequently converted to the dansyl derivative and quantitated by gradient-elution LC with fluorescence detection. Repeatability relative standard deviations, RSDr, ranged from 3.2 to 10.0%; reproducibility relative standard deviations, RSDR, ranged from 6.1 to 16.1%. The method has been adopted Official First Action status by AOAC INTERNATIONAL.
Determination of Parthenolide in Selected Feverfew Products by Liquid Chromatography
Authors: Abourashed Ehab A , Khan Ikhlas A
Published: February 2020

The migraine prophylactic herb feverfew (Tanacetum parthenium L.) is marketed in the United States in a variety of forms and compositions. Although its therapeutic efficacy is still uncertain, the sesquiterpene lactone parthenolide is the constituent recommended to be measured for quality control of feverfew preparations. A validated liquid chromatographic method was developed and used to estimate parthenolide in a number of U.S. feverfew market products formulated as capsules, tablets, or crude powder. The method uses a Lichrosphere 5 C18 column, a mobile phase consisting of 50mM NaH2PO4 in H2O (solvent A), and CH3CN–MeOH (90 + 10, v/v; solvent B). Elution was run at a flow rate of 1.0 mL/min with a linear gradient of 50–15% A in B over 20 min and UV detection at 210 nm. The correlation coefficient for the calibration curve was 0.9999 over the range of 0.00–0.400 mg/mL. Overall recovery of parthenolide was 103.1%.
Determination of Tilmicosin Residues In Chicken, Cattle, Swine, and Sheep Tissues by Liquid Chromatography
Authors: Stobba-Wiley Carolyn M , Chang Jen P , Elsbury David T , Moran John W , Turner James M , Readnour Robin S
Published: February 2020

A method was developed and validated for determination and quantitation of tilmicosin residues in swine, cattle, and sheep edible tissues, as well as chicken fat, skin, and muscle over a concentration range of 0.025 μg/g–20 μg/g. For chicken kidney and liver, the method was validated over a range of 0.060 μg/g–20 μg/g. The tissue sample was extracted with methanol and a C18 cartridge was used for solid-phase extraction cleanup. A reversed phase gradient liquid chromatographic method with detection at 280 nm was used to separate the tilmicosin from matrix components in 30 min run time. The limit of quantitation (LOQ) of the method was 0.025 μg/g for all tested tissues except chicken kidney and liver, for which the LOQ was 0.06 μg/g. Average recoveries for tissue samples ranged from 73 to 98%. Relative standard deviation values ranged from 0.6 to 14.7%.
Analysis of Botanicals and Dietary Supplements for Antioxidant Capacity: A Review
Authors: Prior Ronald L , Cao Guohua
Published: February 2020

Free radicals and other reactive species are considered to be important causative factors in the development of diseases of aging such as cancer and cardiovascular diseases. This relationship has led to considerable interest in assessing the antioxidant capacity of foods and botanicals and other nutritional antioxidant supplements. The use of the oxygen radical absorbance capacity (ORAC) assay as a tool for antioxidant assessment is described and proposed as a method for comparing botanical sources and for standardizing nutritional supplements. The free radical or oxidant source is important and direct comparisons cannot be made between procedures that use different sources. The ORAC procedure uses 2,2′-azobis(2-amidinopropane) dihydrochloride as a peroxyl radical source, which is relevant to biological systems because the peroxyl radical is the most abundant free radical. Other oxidant sources (hydroxyl radical and Cu++) can also be used to characterize antioxidants in botanicals. Phenolics or polyphenolics are responsible for most of the antioxidant capacity in fruits, vegetables, and most botanical antioxidant supplements. Although little is known about the absorption and metabolism of these components, improvement in the in vivo antioxidant status has been observed in human subjects following consumption of antioxidant botanicals. The ORAC method provides a basis from which to establish appropriate dietary intakes that might impact health outcomes.
Determination of Resistant Starch in Selected Grain-Based Foods
Authors: Gelroth Janette A , Ranhotra Gur S
Published: February 2020

Resistant starch was determined in 70 grain-based foods by modification of the method commonly used to measure total dietary fiber in North America. The modification involved solubilizing resistant starch in dimethyl sulfoxide. Total dietary fiber in these products ranged from 0.9 to 18.6%, with resistant starch representing 0 to 88% of the total fiber values. Many bread products and breakfast cereals contained over one-third of the total fiber as resistant starch.
Minimum Detectable Level of Salmonellae Using a Binomial-Based Bacterial Ice Nucleation Detection Assay (BIND®)
Authors: Irwin Peter , Gehring Andrew , Tu Shu-I , Brewster Jeffrey , Fanelli Joseph , Ehrenfeld Elizabeth
Published: February 2020

A modified bacterial ice nucleation detection (BIND®) assay was used for rapid and sensitive detection of several Salmonella species. For the BIND assay, Salmonella cells are infected with bacteriophage genetically modified to contain DNA encoding an ice nucleation protein (INP). After infection, de novo protein synthesis occurs and INPs are incorporated into the outer membrane of the organism. After supercooling (−9.3°C), only buffer solutions containing transfected salmonellae freeze, causing a phase-sensitive dye to change color. This technique, and a probability-based protocol modification, provided quantitative detection with a minimum detectable level (MDL) of 2.0 ± 0.3 S. enteritidis cells/mL in buffer (about 3 h). The MDLs for S. typhimurium DT104 and S. abaetetuba were 4.2 ± 0.2 and 11.1 ± 0.4 cells/mL, respectively. Using salmonellae-specific immunomagnetic bead separation technology in conjunction with the modified BIND protocol, we achieved an MDL of about 4.5 S. enteritidis cells/mL with an apparent capture efficiency of 56%.
Determination of Biotin and Folate in Infant Formula and Milk by Optical Biosensor-Based Immunoassay
Authors: Indyk Harvey E , Evans Eileen A , Caselunghe Malin C Bostrom , Persson Bjorn S , Finglas Paul M , Woollard David C , Filonzi Enrico L
Published: February 2020

Biomolecular interaction analysis was evaluated for the automated analysis of biotin- and folate-supplemented infant formulas and milk powders. The technique was configured as a biosensor-based, nonlabeled inhibition immunoassay using monoclonal antibodies raised against analyte-conjugate. Sample extraction conditions were optimized and antibodies were evaluated for cross-reactivity. Performance parameters included a quantitation range of 2–70 ng/mL, recoveries of 86–102%, agreement against assigned reference values for National Institute of Standards and Technology Standard Reference Material 1846, between-laboratory reproducibility relative standard deviation of 9.1% for biotin and 8.1% for folate, respectively, and equivalence against reference microbiological assay methods for both analytes.
Determination of Oxalate in Urine, Using an Amperometric Biosensor with Oxalate Oxidase Immobilized on the Surface of a Chromium Hexacyanoferrate-Modified Graphite Electrode
Authors: Milardović Stjepan , Grabarić Zorana , Tkalčec Mihael , Rumenjak Vlatko
Published: February 2020

A novel enzymatic amperometric method is described for the determination of oxalic acid in urine. An amperometric biosensor was made by immobilizing oxalate oxidase on the surface of a chromium(III) hexacyanoferrate-modified graphite electrode by using a bovine serum albumin and glutaraldehyde cross-linking procedure. The enzyme biocatalyzes oxalate decomposition in the presence of oxygen into carbon dioxide and hydrogen peroxide. The oxalate concentration, which is proportional to the amount of hydrogen peroxide, was determined amperometrically by measuring the current resulting in the reduction of hydrogen peroxide at a very low working potential (0.05 V versus the Hg | Hg2Cl2 | 3M KCl electrode), which minimized the influence of the possible interferences present in human urine. All experiments were performed with succinic buffer, pH 3.8, containing 0.1M KCl and 5.4mM ethylenediaminetetraacetic acid. In an aqueous solution of pure oxalic acid, the biosensor showed good linearity in a concentration range of 2.5–100μM without the use of a dialysis membrane. For untreated urine samples, a high correlation (R2 = 0.9949) was obtained between oxalate concentrations added to urine samples and oxalate recoveries calculated for determinations with the described oxalate biosensor.
Voltammetric Behavior and Analytical Applications of Lomefloxacin, an Antibacterial Fluorquinolone
Authors: Álvarez-Lueje Alejandro , López Camilo , Núñez-Vergara Luis J , Squella Juan A
Published: February 2020

Lomefloxacin was reduced on a dropping mercury electrode, producing one or more peaks, depending on the pH of the aqueous medium. Coulometric measurements gave an experimental value of 1 electron for the main peak. Electrolysis was followed by UV spectrophotometry and liquid chromatography (LC), showing that a new band at 413 nm appeared for the electrolysis product in an acidic medium. Furthermore, by using UV spectrophotometry, an apparent pKa value of 6.75 ± 0.05 was obtained for lomefloxacin corresponding to the carboxyl moiety in the 3-position. For analytical studies, the differential pulse polarographic mode in 0.1N HCl was selected. The repeatability and reproducibility of the method were adequate (coefficient of variation [CV], 0.51%). The calibration curve method was used for the lomefloxacin concentration range of 7.0 × 10−6 to 7.0 × 10−5M. The detection and quantitation limits were 1.0 × 10−6 and 6.9 × 10−6M, respectively. For purposes of comparison, both UV spectrophotometric and LC (with UV and fluorimetric detection) methods were developed. The polarographic method showed good selectivity with respect to both excipients and degradation products. The recovery study showed a CV of <2% and an average recovery of 99.5% and it was not necessary to treat the sample before analysis. The method was applied to the determination of the uniformity content of lomefloxacin commercial tablets. The polarographic method was also successfully applied to the quantitation of lomefloxacin in urine, and the renal excretion profile was also determined.
Application of Liquid Chromatography to the Simultaneous Determination of Acetylsalicylic Acid, Caffeine, Codeine, Paracetamol, Pyridoxine, and Thiamine in Pharmaceutical Preparations
Authors: Ramos-Martos Natividad , Aguirre-Gómez Francisco , Molina-Díaz Antonio , Capitán-Vallvey Luis F
Published: February 2020

This paper describes a rapid reversed-phase liquid chromatographic method, with UV detection, for the simultaneous determination of acetylsalicylic acid, caffeine, codeine, paracetamol, pyridoxine, and thiamine in pharmaceutical preparations. A reversed-phase C18 Nucleosil column is used. The mobile phase consists of 2 successive eluants: water (5 min) and acetonitrile–water (75 + 25, v/v; 9 min), both adjusted to pH 2.1 with phosphoric acid. Before determination acetylsalicylic acid is completely converted to salicylic acid by alkaline hydrolysis. Salicylic acid, caffeine, paracetamol, pyridoxine, and thiamine are all detected at 285 nm, whereas codeine is detected at 240 nm. Calibration curves were linear for salicylic acid, caffeine, paracetamol, and pyridoxine in the range of 50–500 mg/L, and for codeine and thiamine in the range of 50–1000 mg/L. The method was applied to the analysis of 13 fortified commercial pharmaceutical preparations. Recoveries ranged from 92.6 to 105.5%, with relative standard deviations of 1.1–5.8%.
Extension of AOAC Official Method 996.01 to the Analysis of Standard Reference Material (SRM) 1846 and Infant Formulas
Authors: Satchithanandam Subramaniam , Fritsche Jan , Rader Jeanne I
Published: February 2020

There is currently no official method for the analysis of fatty acids (including trans fatty acids) in infant formulas. AOAC Official Method 996.01 for Fat Analysis in Cereal Products was extended to the analysis of milk-based infant formula Standard Reference Material (SRM)1846 to determine its applicability for use with infant formulas. Following the analysis of SRM 1846, 2 infant formulas, one milk-based liquid and one soy-based powdered infant formula, were analyzed for total fatty acid composition. Fatty acid methyl esters were prepared and analyzed by gas chromatography. The results of the analysis of SRM 1846 show that the mean analyzed values were highly reproducible as indicated by low coefficients of variation (CV). The CVs were <5% for the major fatty acids. Mean analyzed values for individual fatty acids in SRM 1846 were within ± 1 standard deviation of the certificate values. The analyzed value for total fat as triglycerides (26.27 ± 0.25%) agreed well with the certificate value (27.1 ± 0.59%). Analyses of infant formulas showed that the concentrations of linoleic acid and fat meet the requirements for such formulas.
Determination of Glyphosate and Aminomethylphosphonic Acid in Crops by Capillary Gas Chromatography with Mass-Selective Detection: Collaborative Study
Authors: Alferness Philip L , Wiebe Lawrence A ,   Collaborators:, Anderson L , Bennett O , Bosch M , Clark D , Claussen F , Colin T , Cook C , Davis H , Ely V , Graham D , Grazzini R , Hickes H , Holland P , Hom W , Ingram R , Ling Y , Markley B , Peoples G , Pitz G , Robert G , Robinson C , Sen L , Sensue A , South N , Steginsky C , Summer S , Trower T , Wieczorek P , Zheng S
Published: February 2020

A collaborative study was conducted to validate a method for the determination of glyphosate and aminomethylphosphonic acid (AMPA) in crops. The analytes are extracted from crops with water, and the crude extracts are then subjected to a cation exchange cleanup. The analytes are derivatized by the direct addition of the aqueous extract into a mixture of heptafluorobutanol and trifluoroacetic anhydride. The derivatized analytes are quantitated by capillary gas chromatography with mass-selective detection (MSD). The collaborative study involved 13 laboratories located in 5 countries 12 laboratories returned valid data sets. The crops tested were field corn grain, soya forage, and walnut nutmeat at concentrations of 0.050, 0.40, and 2.0 mg/kg. The study used a split-level pair replication scheme with blindly coded laboratory samples. Twelve materials were analyzed, including 1 control and 3 split-level pairs for each matrix, 1 pair at each nominal concentration. For glyphosate, the mean recovery was 91%, the average intralaboratory variance, the repeatability relative standard deviation (RSDr), was 11%, and the interlaboratory variance, the reproducibility relative standard deviation (RSDR), was 16%. For AMPA, the mean recovery was 87%, the RSDr was 16%, and the RSDR was 25% at mg/kg levels.
Furanocoumarins in Celery and Parsnips: Method and Multiyear Canadian Survey
Authors: Lombaert Gary A , Siemens Karin H , Pellaers Peter , Mankotia Mohan , Ng Winnie
Published: February 2020

The natural occurrence of biologically active furanocoumarins in common vegetables is an area of increasing interest with respect to human health. In this study, an efficient, rugged, and sensitive liquid chromatographic method with ultraviolet photodiode array detection was developed for the estimation of 5 biologically active furanocoumarins (psoralen, bergapten, xanthotoxin, trioxsalen, and angelicin) in celery and parsnips. When authentic samples were spiked with a mixture of furanocoumarins at individual levels of 2 to 10 μg/g, the method produced overall recoveries of 77 and 75%of all furanocoumarins from celery and parsnips, respectively. The method was applied in 2 laboratories to a multiyear survey of more than 200 samples. Of 110 parsnips samples, 109 (99%) contained quantitatable levels of furanocoumarins. The mean level of total furanocoumarins in the positive parsnip samples was 15.1 μg/g; the maximum level detected was 145 μg/g. Of 114 celery samples, 88 (77%) contained quantitatable levels of furanocoumarins. The mean level of total furanocoumarins in the positive celery samples was 1.9 μg/g; the maximum level detected was 15.2 μg/g. Xanthotoxin and bergapten were the most commonly detected furanocoumarins in both celery (68 and 63%) and parsnips (97 and 96%). Xanthotoxin had the highest mean level of positives in both celery (1.3 μg/g) and parsnips (8.5 μg/g). Little year-to-year variation in either total furanocoumarin levels or incidence was noted.
Recent Advances in Thin-Layer Chromatography of Pesticides
Authors: Sherma Joseph
Published: February 2020

Advances in the applications of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1998–2000. Analyses are covered for a variety of samples, such as food, biological, and environmental, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References on formulation analysis, hydrophobicity studies, and the use of TLC and thin-layer radiochromatography (TLRC) for studies of pesticide metabolism, degradation, uptake, and related studies are also included.
Pesticide Residue Analysis (1999–2000): A Review
Authors: Sherma Joseph
Published: February 2020

The literature of pesticide residue analysis is reviewed selectively for the period 1999–2000. Analyses of a wide range of pesticide classes and sample types, as well as some related organic pollutants, are covered. Studies of exposure and monitoring as well as pesticide degradation, persistance, leaching, mobility, and metabolism studies are included.
Determination and Confirmation of the Amnesic Shellfish Poisoning Toxin, Domoic Acid, in Shellfish from Scotland by Liquid Chromatography and Mass Spectrometry
Authors: Hess Philipp , Gallacher Susan , Bates Lesley A , Brown Nigel , Quilliam Michael A
Published: February 2020

During 1998 and early 1999, shellfish samples from sites in Scotland were found to contain the amnesic shellfish poisoning toxin, domoic acid (DA). Two different techniques, liquid chromatography (LC) with UV diode-array detection and LC with mass spectrometric (MS) detection, were used to detect and confirm DA in shellfish extracts. The LC/UV method was validated for routine monitoring by recovery experiments on spiked mussel and scallop tissues with a certified mussel tissue used as reference material. Crude extracts of selected samples as well as extracts cleaned with strong anion exchange (SAX) were analyzed by both LC/UV and LC/MS. Good correlation (linear regression r2 = 0.996, slope = 0.93) between the 2 methods was found for cleaned extracts. Analyses of crude extracts by LC/UV produced false-positive results in 2 crab samples, whereas LC/MS analyses gave accurate results. It was concluded that LC/UV is a valid approach for routine monitoring of DA in shellfish when cleanup is performed with a SAX cartridge to prevent false positives. A variety of shellfish species were surveyed for DA content, including Pecten maximus (king scallops), Chlamys opercularis (queen scallop), Mytilus edulis (blue mussels), Cancer pugaris (crab), and Ensis ensis (razor fish). The highest concentration of DA was 105 μg/g in Pecten maximus.
Development of Reference Materials for Paralytic Shellfish Poisoning Toxins
Authors: Egmond Hans P van , Mouriño Antonio , Burdaspal Pedro A , Boenke Achim ,   Collaborators:, Alvito P , Arevalo F , Botana-López L M , Bustos J , Dietrich R , Donald M , Franco Soler J M , Gago Martinez A , Hald B , Helle N , Hummert C , Ledoux M , Legarda T , Luckas B , Mesego A , Paulsch W E , Rodriguez-Vieytes M , Salgado C , Stockemer J , Usleber E , van den Top H J , Walther L , Walther M , Winkler F
Published: February 2020

A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained <0.07 mg saxitoxin·2HCl/kg and 1.59 ± 0.20 mg decarbamoyl-saxitoxin·2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained <0.07 mg saxitoxin·2HCl/kg and <0.04 mg decarbamoyl-saxitoxin·2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 ± 1.2 μg/g.
Determination of Gliclazide in Pharmaceutical Preparations by Capillary Gas Chromatography with Cool On-Column Injection and Elimination of the Matrix Effect
Authors: Krzek Jan , Czekaj Janusz , Moniczewska Maria , Rzeszutko Włodzimierz
Published: February 2020

Conditions were established for the identification and quantitation of gliclazide in pharmaceutical preparations by capillary gas chromatography with flame ionization detection and cool on-column injection. Gliclazide was extracted with methanol and, after filtration, assayed on a (25 m × 0.25 mm id, 0.2 μm film thickness) CP-WAX 58 (FFAP)–CB WCOT fused silica column. Because the available preparations were of various origins and, therefore, could differ in auxiliary substances and their qualitative parameters, the influence of the matrix constituents on the analytical results was taken into account. Good separation conditions were established for the developed method. The retention time of gliclazide is about 36 min and differs from the retention times of the internal standard (approximately 29 min) and additional peaks present in chromatograms (20–26 min), which were assigned to matrix constituents. The recoveries of gliclozide were high and reached 96.5%. The developed method is characterized by selectivity and precision (relative standard deviation 0.38–1.26%), a wide range of linearity (0.1–10.0 mg/mL), and a limit of detection of 30 ng. In addition, the results of chromatographic analyses calculated in 3 ways were compared with those obtained by UV spectrophotometry. The suggested technique of cool on-column injection, in contrast with split-splitless injection (used in preliminary investigations), reduces to a minimum the possibility of thermal decomposition of gliclazide.
Liquid Chromatographic Determination of Simple Phenolic Compounds in Waste Waters from Olive Oil Production Plants
Authors: Ceccon Luciano , Saccù Debora , Procida Giuseppe , Cardinali Stefano
Published: February 2020

A method was developed for the determination of simple phenolic compounds (PCs) in waste waters from olive oil production plants by liquid chromatography (LC). The sample under examination was acidified to pH 2 to precipitate proteins, acetone was added to eliminate the colloidal fraction, and hexane was used for extraction to eliminate lipidic substances. The solution obtained was filtered and injected into the LC system; the wavelength selected for the spectrophotometric detection was specific for PCs, so that carbohydrates, organic acids, and short-chain free fatty acids did not interfere. Recoveries of 9 PCs spiked to a real sample were 90–100% for concentrations ranging from 20 to 2000 mg/L for each analyte.
Analysis of Agricultural Commodities and Foods for Alternaria Mycotoxins
Authors: Scott Peter M
Published: February 2020

Fungi of the genus Alternaria are parasitic on plants and other organic materials. A. alternata is a frequently occurring species of particular interest because it produces a number of mycotoxins, including alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT), altertoxins I, II, and III (ATX-I, -II, and -III), and L-tenuazonic acid (TeA). Cleanup procedures of analytical methods for foods and foodstuffs include solvent partition, generally used for TeA, and solid-phase extraction columns for AOH, AME, and ATX-I. These Alternaria mycotoxins have been determined by TLC, GC, and more usually LC, mainly with ultraviolet detection, although fluorescence and electrochemical detection have also been used for Alternaria toxins other than TeA. A Zn2+ salt is usually added to the LC mobile phase for TeA. Recently, atmospheric pressure chemical ionization and electrospray LC/MS and LC–MS/MS have been applied to the determination and confirmation of AOH and AME in apple juice and other fruit beverages at sub ng/mL levels. Natural occurrences of AOH, AME, and in some cases other Alternaria toxins have been reported in various fruits, including tomatoes, olives, mandarins, melons, peppers, apples, and raspberries. They have been found also in processed fruit products such as apple juice, other fruit beverages and tomato products, wheat and other grains, sunflower seeds, oilseed rape meal, and pecans.
Determination of Ochratoxin A in Wine and Beer by Immunoaffinity Column Cleanup and Liquid Chromatographic Analysis with Fluorometric Detection: Collaborative Study
Authors: Visconti Angelo , Pascale Michelangelo , Centonze Gianluca ,   Collaborators, Anklam E , Betbeder A M , Brereton P , Burns G , Cagnina A , Chiappetta G , Creppy E E , Di Stefano R , Eklund E , Hald B , Herve I , Kakouri E , Larcher R , Majerus P , Medina B , Melotti F , Möller T , Moruno E G , Nuotio K , Pavanello F , Pietri A , Tricard C , van den Top H J , Versini G , Werner J , Wilson P
Published: February 2020

The accuracy, repeatability, and reproducibility characteristics of a liquid chromatographic method for the determination of ochratoxin A (OTA) in white wine, red wine, and beer were established in a collaborative study involving 18 laboratories in 10 countries. Blind duplicates of blank, spiked, and naturally contaminated materials at levels ranging from ≤0.01 to 3.00 ng/mL were analyzed. Wine and beer samples were diluted with a solution containing polyethylene glycol and sodium hydrogen carbonate, and the diluted samples were filtered and cleaned up on an immunoaffinity column. OTA was eluted with methanol and quantified by reversed-phase liquid chromatography with fluorometric detection. Average recoveries from white wine, red wine, and beer ranged from 88.2 to 105.4% (at spiking levels ranging from 0.1 to 2.0 ng/mL), from 84.3 to 93.1% (at spiking levels ranging from 0.2 to 3.0 ng/mL), and from 87.0 to 95.0% (at spiking levels ranging from 0.2 to 1.5 ng/mL), respectively. Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 6.6 to 10.8% for white wine, from 6.5 to 10.8% for red wine, and from 4.7 to 16.5% for beer. Relative standard deviations for between-laboratories reproducibility (RSDR) ranged from 13.1 to 15.9% for white wine, from 11.9 to 13.6% for red wine, and from 15.2 to 26.1% for beer. HORRAT values were ≤0.4 for the 3 matrixes.
Determination of Cry9C Protein in Corn-Based Foods by Enzyme-Linked Immunosorbent Assay: Interlaboratory Study
Authors: Trucksess Mary W ,   Collaborators:, Artis T , Diaz C , Fernandez C , Harkin K , Layton D , Shillito R , Thomas F , Williams K , Yeung J
Published: February 2020

The performance of a commercially available enzyme-linked immunosorbent assay kit (Enviro-Logix) was assessed for the determination of Cry9C protein, which is produced by the genetically modified corn StarLink, in 8 types of corn-based foods (starch, refined oil, soft tortillas, tortilla chips, corn flakes, corn puffs, corn muffins, and corn bread) in an interlaboratory study involving 7 laboratories in the United States. The assay kit is a double antibody sandwich and is based on the specific interaction between antibody and antigen. The Cry9C protein analyte is sandwiched between 2 antibodies, one to capture the analyte and the other is conjugated to the enzyme, horseradish peroxidase. The enzyme uses tetramethylbenzidine/peroxide for color development. A strong acid stopping reagent is then used to change the color from blue to a stable yellow. The intensity of the color is proportional to the concentration of the Cry9C protein. In this study blind duplicates of control samples (blank material prepared from non- StarLink corn), spiked samples (blank material with the addition of Cry9C protein), and samples containing incurred analyte (products prepared with StarLink corn) were analyzed. Cry9C protein from 2 different sources was used to spike the food products. Cry9C protein produced and purified from a bacterial host was used to prepare spiked test samples at 2.72 and 6.8 ng/g. Cry9C protein from StarLink corn flour was used to prepare spiked samples at 1.97 ng/g. Average recoveries for samples spiked with corn flour Cry9C protein at 1.97 ng/g ranged from 73 to 122%, within-laboratory relative standard deviations (RSDr) ranged from 6 to 22%, and between-laboratories relative standard deviations (RSDR) ranged from 16 to 56%. Average recoveries for samples spiked with bacterial Cry9C protein at 2.72 and 6.8 ng/g ranged from 27 to 96% and from 32 to 113%, respectively; RSDr values ranged from 10 to 35%and from 7 to 38%, respectively; and the RSDR ranged from 28 to 84%and 15 to 75%, respectively. The incurred test samples were found to contain Cry9C protein at levels ranging from 0.8 to 3187 ng/g depending on the product, RSDr values ranged from 5 to 16% and RSDR values ranged from 11 to 71%. Results of the statistical analysis indicate that this method is applicable to the determination of Cry9C protein in the 8 types of collaboratively studied corn-based products containing Cry9C protein (from StarLink ) at levels of ≥2 ng/g.
Determination of Iodine in Seafood by Inductively Coupled Plasma/Mass Spectrometry
Authors: Julshamn Kaare , Dahl Lisbeth , Eckhoff Karen
Published: February 2020

A method was developed for determination of total iodine content in different standard reference materials (SRMs) and seafood products by inductively coupled plasma/mass spectrometry (ICP/MS). If iodine is present as iodide and nitric acid is used in the wet digestion system, the observed signal is not stable when iodine is measured by ICP/MS at m/z 127. To stabilize the iodine signal, 3% ammonia solution (1 + 1, v/v) was added to the digest. The limit of quantitation of the method, defined as 6 times the standard deviation in the blank solution (n = 20) was estimated to be 15 mg/kg (using 0.2 g dry mass and a dilution factor of 50). The precision, expressed as repeatability of the iodine concentration, varied between 3.2 and 12% in SRMs, with concentrations of 4.70–0.17 mg/kg dry matter. The described method was compared with a method using tetramethylammonium hydroxide extraction. Both methods showed good precision and trueness by analyses of SRMs. The 2 methods were used to determine iodine in seafood from the Barents Sea, the Norwegian Sea, and the North Sea. The results showed great variation between different fish species as well as between individuals within a species. The lowest values of iodine were recorded in muscle of ling (Molva molva) with a mean of 0.07 mg/kg fresh weight and a variation between 0.03 and 0.11 mg/kg fresh weight. The highest values were found in cod (Gadus morhua) from the Barents Sea, with a mean of 2.5 mg/kg and a variation between 0.7 and 12.7 mg/kg fresh weight.
Determination of Polycyclic Aromatic Hydrocarbons from Buzzards (Buteo buteo) and Tawny Owl (Strix aluco) by Liquid Chromatography with Fluorescence Detection
Authors: Amigo Susana González , Yusty Maria Asunción Lage , Lozano Jesús Simal
Published: February 2020

Supercritical fluid extraction was applied to the determination of naturally contaminated polycyclic aromatic hydrocarbons (PAHs) in bird tissue by liquid chromatography with fluorescence detection (LC-FL). Recoveries (>90%) and relative standard deviations (≤7.7%) were satisfactory. The levels of 10 PAHs were analyzed in 6 classes of tissues (heart, liver, intestine, muscle, lung, and kidney) of 10 buzzards and 2 tawny owls, predatory birds from the Galicia (northwest Spain). The PAHs found most abundantly were pyrene, fluoranthene, benzo[a]anthracene, and anthracene. Chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene were not detected. Intestine, kidney, and lung were more polluted than other tissues.
Simultaneous Liquid Chromatographic Determination of 39 Polycyclic Aromatic Hydrocarbons in Indoor and Outdoor Air and Application to a Survey on Indoor Air Pollution in Fuji, Japan
Authors: Ohura Takeshi , Sugiyama Tomohiko , Amagai Takashi , Fusaya Masahiro , Matsushita Hidetsuru
Published: February 2020

An analytical method was established for the simultaneous determination of 39 polycyclic aromatic hydrocarbons (PAHs) in air. The method was applied to a survey of gaseous and particulate PAHs in household indoor air. The survey was performed in 21 houses in the summer of 1999 and in 20 houses in the winter of 1999–2000 in Fuji, Japan. Thirty-eight PAHs were determined in indoor and outdoor air in the summer, and 39 PAHs were determined in indoor and outdoor air in the winter. The concentrations of gaseous PAHs in indoor air tended to be higher than those in outdoor air in the summer and winter. The concentrations of particulate PAHs in indoor air were the same as or lower than those in outdoor air in the summer and winter. PAH profiles, correlations between PAH concentrations, and multiple regression analysis were used to determine the factors affecting the indoor PAH concentrations. These results showed that gaseous PAHs in indoor air were primarily from indoor emission sources, especially during the summer, and that indoor particulate PAH concentrations were significantly influenced by outdoor air pollution.
Determination of Total Fumonisins in Corn by Competitive Direct Enzyme-Linked Immunosorbent Assay: Collaborative Study
Authors: Bird Chuck B , Malone Bruce , Rice Larry G , Ross P Frank , Eppley Robert , Abouzied Mohamed M ,   Collaborators:, Ashman P , Carpenter N , Drouches M , Fairchild A , Hartman R , Herald S , Holloway S , Horrisberger G , Jackson H , Jones K , Landis K , Leichtweis H , Peden J
Published: February 2020

Fumonisins—mycotoxins produced by some Fusarium species—have been shown to be the causative agent of diseases in horses and other domesticated animals as well as possible carcinogens in humans. A collaborative study was conducted to evaluate the effectiveness of a competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for the determination of total fumonisins (B1, B2, and B3) in corn. The test portion was extracted with methanol–water (7 + 3), filtered, diluted, and tested on the CD-ELISA. Naturally and artificially contaminated corn test portions were sent to 13 collaborators in the United States. Naturally contaminated field test portions were prepared at 3 different levels. Artificially contaminated test portions were spiked at 1.0, 3.0, and 5.0 mg/kg total fumonisins (B1, B2, and B3). Average recoveries of total fumonisins were 120, 100, and 90%, respectively. The relative standard deviations for repeatability ranged from 13.3 to 23.3% and the relative standard deviations for reproducibility ranged from 15.8 to 30.3% across all levels tested. HORRAT values, calculated for each individual sample, ranged from 1.24 to 1.94. This method demonstrated acceptable intra- and interlaboratory precision at the levels tested.
Determination of Vitamins A (Retinol) and E (alpha-Tocopherol) in Foods by Liquid Chromatography: Collaborative Study
Authors: DeVries Jonathan W , Silvera Karlene R ,   Collaborators:, Al-Hasani S , Alfiere J , Berge C , Boerner C , Cardozo S , Chettiar M , Dupont K , Gustafson K , Hanson E , Kazeminy A , Krueger D , Mazal R , Meland P , Mioc B , Oehrl L , Vinski E , Willis D , Wittrig B
Published: February 2020

A collaborative study was conducted for the determination of vitamins A and E. Existing AOAC liquid chromatographic (LC) methods are suited for specific vitamins A and E analytical applications. This method differs from existing methods in that it can be used to assay samples in all 9 sectors of the food matrix. Standards and test samples are saponified in basic ethanol–water solution, neutralized, and diluted, converting fats to fatty acids and retinol esters and tocopherol esters to retinol and tocopherol, respectively. Retinol and alpha-tocopherol are quantitated on separate LC systems, using UV detection at 313 or 328 nm for retinol, and fluorescence detection (excitation 290 nm, emission 330 nm) for alpha-tocopherol. Vitamin concentrations are calculated by comparison of the peak heights or peak areas of vitamins in test samples with those of standards.
Method Extension Study to Validate Applicability of AOAC Official Method 997.03 Visual Immunoprecipitate Assay (VIP®) for Listeria monocytogenes and Related Listeria spp. from Environmental Surfaces: Collaborative Study
Authors: Feldsine Philip T , Lienau Andrew H , Leung Stephanie C , Mui Linda A ,   Collaborators:, Aguilar G , Aharchi J , Aldridge I , Arling V , Bitner B , Bullard C , Carlson P , Cox C , Deiss K , Dillon J , Dombroski P , Ellingson J , Fitzgerald S , Forgey R , Gailbreath K , Gallagher D , Geftman V , Herbst K , Hillis P , Johnson M , Koch S , Lewis D , Luepke J , Martensen D , McDonagh S , McGovern B , Moon B , Moreland L , Murray L , Richter D , Robertson M , Rogers P , Rucker C , Sacca J , Siu M-C , Smith C , Smith J , Stoltzfus E , Summers C , Taylor B , Toth J , Vess R , White S , Witt J-L , Young S
Published: February 2020

Test portions from 3 environmental surface types, representative of typical surfaces found in a food production facility, were analyzed by the Visual Immunoprecipitate assay (VIP®) and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) culture method for Listeria monocytogenes and related Listeria species. In all cases, naturally contaminated environmental test samples were collected from an actual food production facility by sponge or swab. Test samples from concrete surfaces were collected by both swab and sponge; sponge test samples were collected from rubber surfaces, and swabs were used to sample steel surfaces. Test portions from each surface type were simultaneously analyzed by both methods. A total of 27 laboratories, representing government agencies as well as private industry in both the United States and Canada, participated in the study. During this study, a total of 615 test portions and controls was analyzed and confirmed, of which 227 were positive and 378 were negative by both methods. Nine test portions were positive by culture, but negative by the VIP. Five test portions were negative by culture, but positive by the VIP. Four test portions were negative by VIP and by culture, but confirmed positive when VIP enrichment broths were subcultured to selective agars. The data reported here indicate that the VIP method and the USDA/FSIS culture method are statistically equivalent for detection of L. monocytogenes and related Listeria species from environmental surfaces taken by sponges or swabs.
Cleanup Procedure for Determination of Aflatoxins in Major Agricultural Commodities by Liquid Chromatography
Authors: Sobolev Victor S , Dorner Joe W
Published: February 2020

A simple, fast, reliable, and inexpensive chemical cleanup procedure was developed for quantitation of aflatoxins in major important agricultural commodities by liquid chromatography (LC). Aflatoxins were extracted from a ground sample with methanol–water (80 + 20, v/v), and after a single cleanup step on a minicolumn packed with basic aluminum oxide, they were quantitated by LC equipped with a C18 column, photochemical reactor, and fluorescence detector. Water–methanol–1-butanol (1400 + 720 + 25, v/v/v) served as the mobile phase. Recoveries of aflatoxins B1, B2, G1, and G2 from peanuts spiked at 5.0, 2.5, 7.5, and 2.5 μg/kg were 87.2 ± 2.3, 82.0 ± 0.8, 80.0 ± 1.8, and 80.4 ± 2.8%, respectively. Similar recoveries, precision, and accuracy were achieved for corn, cottonseed, almonds, Brazil nuts, pistachios, and walnuts. The quantitation limit for aflatoxin B1 was 1 μg/kg. The minimal cost of the minicolumn allows for substantial savings compared with available commercial aflatoxin cleanup devices.
Quantitative LC/MS-MS Determination of Sulfonamides and Some Other Antibiotics in Honey
Authors: Kaufmann Anton , Roth Sven , Ryser Bianca , Widmer Mirjam , Guggisberg Dominik
Published: February 2020

A simple and rapid method was developed for the determination of 20 antibiotics (sulfonamides, tetracyclines, and flumequine) in honey by liquid chromatography tandem mass spectrometry. The proposed method is sensitive (limit of detection 0.5 to 10 ppb for the various antibiotics) and selective. A hydrolysis step ensures the liberation of sugar-bound sulfonamides. The approach has been used to analyze some 300 honey samples. A number of them were found to have exceeded the Swiss limit of 50 ppb.