bluuebunny/crossref_metadata_2025 huggingface dataset:
Accumulated Pesticide and Industrial Chemical Findings from a Ten-Year Study of Ready-to-Eat Foods
Authors: Office Kan-Do , Team Pesticides
Published: February 2020

This report lists the pesticide and industrial chemicals found in the ready-to-eat foods tested repetitively for 10 years through the U.S. Food and Drug Administrations’s Revised Market Basket Study. The study operated from 1982 to 1991. During that time 37 market baskets, each containing 234 food items that represented about 5000 food types in American diets covering all age groups, including infants and children, were collected. Each food item was individually prepared for eating; that is, it was opened, unwrapped, washed, peeled, sliced, formulated by recipe, or cooked. Each item was then composited and analytically screened for about 300 different chemicals, including chlorphenoxy acids, ethylenethiourea, methyl carbamates, organochlorines, organophosphates, organosulfurs, phenylureas, and pyrethroids. Overall, less than 1% of the potential of 2.5 million findings occurred for the 10-year study period. In total, 138 different chemical residues accounted for 17 050 accumulated findings. Most findings were less than 1 μg/g, which is considered a low-level finding. Each food item averaged about 2 low-level findings per analysis.
Electrochemical Behavior and Polarographic Assay of Nitroxynil
Authors: Alvarez-Lueje Alejandro F , Bastías Marcos , Bollo Soledad , Núñez-Vergara Luis J , Squella Juan A
Published: February 2020

Nitroxynil is an anthelmintic veterinary drug used in prophylaxis and treatment of hepatic distomatosis. A simple method for its identification and determination in pharmaceutical parenteral solutions is described. The method is based on electrochemical reduction of the nitro group at the dropping mercury electrode. The ac and dc polarographic and cyclic voltammetric responses of the drug are reported. Accuracy and precision of the method are good, and sample preparation is easy.
Determination of Carbohydrates in Soluble Coffee by Anion-Exchange Chromatography with Pulsed Amperometric Detection: Interlaboratory Study
Authors: Prodolleet Jacques , Bugner Emmanuel , Feevberg Max
Published: February 2020

A collaborative study was conducted to validate a liquid chromatographic (LC) method to determine the free and total (after acid hydrolysis) carbohydrate profile of soluble coffee. Carbohydrates were separated on a pellicular anion-exchange column using pure water as mobile phase, and were detected by pulsed amperometry. Eleven collaborators were sent 6 test samples of commercial soluble coffee for duplicate analysis. They were also sent a practice sample with known levels of free and total carbohydrates and material for preparation of all standard solutions. The reproducibility relative standard deviations (RSDR) were 9.9–59.5% for mannitol, 35.6–72.6% for fucose, 4.9–21.1% for arabinose, 4.1–13.0% for galactose, 6.1–24.3% for glucose, 10.0–41.6% for sucrose, 20.2–37.7% for xylose, 10.6–40.0% for mannose, 15.5–71.7% for fructose, and 17.8–97.9% for ribose. Precision in the determination of free and total carbohydrates was very similar. The average repeatability RSDr and RSDR values were 4.5 and 14.3%, respectively, for carbohydrate levels above 0.3%. The precision of the technique was considered good, regardless of the usual peak integration problems always encountered in LC, the low levels of free carbohydrates, the hydrolysis step, and the relative lack of experience of most participating laboratories. The method allows good and reproducible separation of all major carbohydrates found in soluble coffee and is, therefore, suitable for routine analysis.
Determination of trans Unsaturation by Infrared spectrophotometry and Determination of Fatty Acid Composition of Partially Hydrogenated Vegetable Oils and Animal Fats by Gas Chromatography/Infrared Spectrophotometry: Collaborative Study
Authors: Ratnayake Wakisundera M N
Published: February 2020

An infrared spectrophotometric (IR) method for the determination of total trans unsaturated fatty acid (trans) content and a combined gas–liquid chromatographic/infrared spectrophotometric (GC/IR) method for determination of fatty acid composition of partially hydrogenated vegetable oils (PHVO) were studied collaboratively in 12 laboratories using 7 PHVO samples, including 1 pair of blind duplicates. The test samples were methylated and analyzed for total trans content by IR and for fatty acid composition by GC/IR using a capillary column coated with SP-2560 or another suitable cyanoalkylsiloxane stationary phase. From the measured IR absorption, the isolated trans content was calculated using a calibration curve of absorption versus trans content developed with 2-component calibration standard mixtures of methyl elaidate and oleate. The GC provided the levels of mono-trans-octadecadienoates (18:2t), di-trans-octadecadienoates (18:2tt) and mono-trans-octadecatrienoates (18:3t). The trans-octadecenoate (18:1t) content was calculated with the formula: 18:1t = IR trans−0.84 × (18:2t + 18:3t − 1.74 × 18:2tt. The cisoctadecenoate (18:1c) content was obtained as the difference between total octadecenoates (18:1) and 18:1t. Reproducibility relative standard deviations (RSDR) for 15 to 35% trans content determined by IR were in the range of 8.8–11.7%, whereas RSDR for the test sample with 5% trans content was 34.6%. RSDR values for 18:1t by the GC/IR followed the same pattern as that of IR trans values: 36.4% for the test sample with 4.9% 18:1t versus 7.8–12.5% for test samples with 14.9 to 32.6% 18:1t. The content of 18:1 c in the test samples varied from 24.7 to 34.5% and their RSDR values ranged from 3.8 to 10.5%. The mean values for 18:1t and 18:1c compared favorably with the absolute levels determined by a silver nitrate-thin layer chromatography/GC procedure. The IR and GC/IR methods are recommended for determination of trans content and fatty acid composition, respectively, of partially hydrogenated fats derived from vegetable oils, terrestrial animal fats or such oils and fats isolated from food products containing >5% trans fatty acids. For samples containing ≤5% trans fatty acids, a direct GC method (American Oil Chemists' Society Official Method Ce 1c-89) is available for determination of both trans content and fatty acid composition, because at lower trans levels, overlap of 18:1 cis and trans isomers on GC with very polar capillary columns is negligible. The IR method for determination of isolated trans unsaturated fatty acid content in partially hydrogenated fats and the capillary GC/IR method for determination of total cis- and trans-octadecenoic isomers and general fatty acid composition in hydrogenated vegetable oils and animal fats have been adopted first action by AOAC INTERNATIONAL.
Rapid Determination of Methyl Parathion and Methyl Paraoxon in Milk by Gas Chromatography with Solid-Phase Extraction and Flame Photometric Detection
Authors: Baynes Ronald E , Bowen John M
Published: February 2020

Methyl parathion (MPT; O,O-dimethyl-O-4-nitro-phenyl phosphorothioate) and its active metabolite, methyl paraoxon (MPO; O, O-dimethyl-O-4-nitro-phenyl phosphate), were isolated from raw milk by solid-phase extraction (SPE) and determined by gas chromatography with flame photometric detection. The SPE method was compared with a traditional liquid-liquid extraction (LLE) procedure to determine whether SPE had suitable sensitivity and better efficiency in extracting MPT and MPO from milk of cows and goats. Method detection limits were higher for SPE, but the differences were not significant (t-test). Recoveries of MPT and MPO from raw milk samples spiked at 0.05, 0.5, and 5.0 pg/mL ranged from 80.0 to 118%, and the coefficients of variation were usually less than 10% for both methods. LLE required more organic solvents and was more time consuming compared with SPE.
Development of a Method of Analysis for 46 Pesticides in Fruits and Vegetables by Supercritical Fluid Extraction and Gas Chromatography/Ion TVap Mass Spectrometry
Authors: Lehotay Steven J , Eller Konstantin I
Published: February 2020

A multiresidue method using supercritical fluid ex-traction (SFE) and gas chromatography/ion trap mass spectrometry (GC/1TMS) was developed for analysis of 46 pesticides in fruits and vegetables. The SFE procedure used 2 commercial instruments that trapped the extracts on solid-phase material. Silica gel chemically bound to octadecylsi-lane (ODS) collected the extracted pesticides efficiently, and elution of the trap with acetonitrile gave high recoveries. Extracts thus obtained were sufficiently clean for subsequent GC/ITMS analysis. The SFE conditions were 320 atm and 60°C (0.85 g/mL CO2 density) and 1.6 mL/min CO2 flow rate for 6 extraction vessel volumes. Trapping on 1 mL ODS occurred at 10°C, and a 0.4 mL/min flow rate of acetonitrile at 40°–50°C was used to elute the pesticides. Quantitative and qualitative analyses of the 46 pesticides were performed simultaneously by GC/ITMS. Studies of fortified samples gave >80% recoveries for 39 pesticides, and recoveries of >50% for the other pesticides, except methamidophos and omethoate. Grapes, carrots, potatoes, and broccoli were used as samples during method development, and a blind experiment involving incurred and fortified samples was used to test the approach. Results of the blind study compared satisfactorily with results from 7 laboratories using traditional GC detectors and solvent-based extractions.
Development of a Sample Preparation Technique for Supercritical Fluid Extraction for Multiresidue Analysis of Pesticides in Produce
Authors: Lehotay Steven J , Aharonson Nadav , Pfeil Emy , Ibrahim Medina A
Published: February 2020

Supercritical fluid extraction (SFE) of fruits and vegetables poses unique sample preparation considerations because the sample size is small (1–3 g) and the analyte is distributed in a moist solid matrix. The goal of this research was to develop practical sample preparation procedures for SFE of pesticide residues in produce so that acceptable accuracy and precision are maintained. In this study, 130 extractions of potato, fortified with up to 40 pesticides, were performed with 2 commercial SFE instruments. Extracts were analyzed by gas chromatography with ion trap mass spectrometry or electron capture detection. Four sample preparation procedures were tested and Hydromatrix was used to control the amount of water in the sample. The highest recoveries and lowest standard deviations were obtained when 20–50 g samples were blended with an equal amount of Hydromatrix and dry ice was added to keep the samples frozen. The dry ice helped produce a homogeneous flowable powder and greatly reduced the degradation or vaporization of several pesticides. Recoveries of most pesticides from subsamples of <4 g with this procedure were 90–105%, with relative standard deviations of 1–6%. Only diphenylamine and disulfo-ton gave reduced recoveries with this procedure. When samples were extracted sequentially with an autosampler, certain pesticides were degraded in the extraction vessels over a period of several hours. To avoid losses of these pesticides, the sample in the extraction vessel was either purged with CO2 to remove oxygen or kept frozen until extracted. Peach and orange check samples were analyzed with the method, and results were comparable with those from traditional analyses.
Analysis of Total Free and Glucose-Conjugated Pyrethroid Acid Metabolites in Tea Infusions as Hexafluoroisopropyl Esters by Gas Chromatography with Electron Capture Detection
Authors: Mortimer Richard D , Weber Dorcas F , Sun Wing F
Published: February 2020

A gas chromatographic method with electron capture detection (GC–ECD) has been developed to quantitate the sum of free acids of pyrethroid metabolites, their glucosides, and their other base-cleav-able conjugates that are extracted from tea leaves when a tea infusion is prepared. Four representative glucoside conjugates were synthesized; hydrolytic conditions were established; and extraction, derivatization and GC conditions were developed for analysis of these pyrethroid acid metabolites at ≥0.01 ppm on dry tea. GC/mass spectrometry was used to confirm assignment of residues found in some tea samples.
Liquid Chromatographic Determination of trans-10-Hydroxy-2-Decenoic Acid Content of Commercial Products Containing Royal Jelly
Authors: Bloodworth Bosco C , Harn Chan Sheot , Hock Chua Teck , Boon Yio Oon
Published: February 2020

Thirty-nine samples of commercial products containing royal jelly were analyzed by liquid chromatography for their trans-10-hydroxy-2-decenoic acid (10-HDA) content. Most of the samples contained 10-HDA. Samples claimed to be pure royal jelly contained 1.98 to 6.37% 10-HDA (w/w). The 10-HDA content of samples claimed to contain royal jelly as an ingredient ranged from nondetectable to 1.28% (w/w).
Total Dietary Fiber Determined as Neutral Sugar Residues, Uronic Acid Residues, and Klason Lignin (The Uppsala Method): Collaborative Study
Authors: Theander Olof , Åman Per , Westerlund Eric , Andersson Roger , Pettersson Dan
Published: February 2020

A joint AOAC/American Association of Cereal Chemists (AACC) collaborative study was conducted to determine by the Uppsala method the dietary fiber content and its composition in various foods. The method includes preparation of a residue by treatment with thermostable α-amylase and amyloglucosidase and then ethanol precipitation of solubilized dietary fiber components while leaving low-molecular weight carbohydrates in solution. After acid hydrolysis of residue, neutral polysaccharide residues are determined as alditol acetates by gas-liquid chromatography, uronic acid residues are determined by colorimetry, and ash-free acid-insoluble residue (Klason lignin) is determined gravimetrically. Total dietary fiber, including enzyme-resistant starch, is calculated as the sum of nonstarch polysaccharide residues and Klason lignin. Nine laboratories completed the study, analyzing in duplicate 8 unknown dried products that included 4 cereal products, green peas, potato fiber, carrots, and apples. Total dietary fiber contents of products tested ranged from 4.6 to 84.3%, with an average RSDR value of 8.4% (range, 4.8–11.1%). Total neutral polysaccharide residues ranged from 3.8 to 64.1%, with an average RSDR value of 7.5% (range, 5.4–10.5%). Individual neutral sugars (rhamnose, arabinose, xylose, mannose, galactose, and glucose) and uronic acid residues present at more than 1% generally had good RSDR values (3.3– 22.8%), whereas, as expected for Klason lignin, only the wheat bran sample with a high content (16%) had an excellent RSDR value (5.0%). The gas chromatographic-colorimetric-gravimetric method (Uppsala method) for determination of total dietary fiber (as neutral sugar residues, uronic acid residues, and Klason lignin) has been adopted first action by AOAC INTERNATIONAL.
Simultaneous Determination of Arsenic, Selenium, and Antimony in Environmental Samples by Hydride Generation for Inductively Coupled Plasma Atomic Emission Spectrometry
Authors: Anderson Kim A , Isaacs Brandon
Published: February 2020

Total arsenic, selenium, and antimony are determined simultaneously by inductively coupled plasma atomic emission spectrometry (ICP AES) with hydride vapor generation. A1 g wet, 0.25 g dry, or 10 mL water sample is digested by 1 of 2 methods in a 10 mL volumetric culture tube on a programmed heating block by heating with nitric acid and then boiling in a mixture of sulfuric and perchloric acids. For soils, a 0.25 g sample is digested in a 10 mL volumetric culture tube with hydrochloric acid. After digestion, the sample is treated with additional hydrochloric acid. Arsenic, selenium, and antimony are reduced to their hydrides by sodium borohydride in a simplified continuous- flow manifold. A standard pneumatic nebulizer separates the gaseous hydrides (AsH3, SeH2, and SbH3), which are then quantitated by ICP AES at 193.696,196.026, and 231.147 nm, respectively. The detection limits for As, Se, and Sb are 0.55,1.0, and 0.41 μg/L, respectively. Recoveries from 10 matrixes are 65 to 109%; recovery ranges for As, Se, and Sb are 81–109,87–108, and 65–123%, respectively. The method demonstrates good accuracy and precision for environmental samples and is especially suited for analysis of small samples. It requires no additional apparatus for hydride generation or sample introduction.
Multivessel Supercritical Fluid Extraction of Food Items in Total Diet Study
Authors: Hopper Marvin L , King Jerry W , Johnson James H , Serino Alberta A , Butler Robert J
Published: February 2020

An off-line, large capacity, multivessel supercritical fluid extractor (SFE) was designed and constructed for extraction of large samples. The extractor can simultaneously process 1–6 samples (15–25 g) by using supercritical carbon dioxide (SC–CO2), which is relatively nontoxic and nonflammable, as the solvent extraction medium. Lipid recoveries for the SFE system were comparable to those obtained by blending or Soxhlet extraction procedures. Extractions at 10 000 psi, 80°C, expanded gaseous CO2 flow rates of 4–5 L/min (35°C), and 1–3 h extraction times gave reproducible lipid recoveries for pork sausage (relative standard deviation [RSD], 1.32%), corn chips (RSD, 0.46%), Cheddar cheese (RSD, 1.14%), and peanut butter (RSD, 0.44%). In addition, this SFE system gave reproducible recoveries (>93%) for butter fortified with c/s-chlordane and malathion at the 100 ppm and 0.1 ppm levels. Six portions each of Cheddar cheese, saltine crackers, sandwich cookies, and ground hamburger also were simultaneously extracted with SC-CO2 and analyzed for incurred pesticide residues. Results obtained with this SFE system were reproducible and comparable with results from organic-solvent extraction procedures currently used in the Total Diet Study; therefore, use and disposal of large quantities of organic solvents can be eliminated.
Determination of Sulfonylurea Herbicides in Grains by Capillary Electrophoresis
Authors: Krynitsky Alexander J , Swtneford Douglas M
Published: February 2020

A capillary electrophoresis (CE) method was developed to separate and determine residues of 5 sulfonylurea herbicides in grains (wheat, barley, and corn). This work demonstrated the practicality of using CE for residue analysis of sulfonylureas. The method yielded good recoveries and adequate sensitivities at tolerance levels (0.05–0.1 ppm). The compounds investigated were metsulfuron methyl (Ally), thifensulfuron methyl (Harmony), chlorsulfuron (Glean), rimsulfuron (DPX-E9636), and tribenuron methyl (Express). Acetonitrile extracts of grain samples were partitioned with hexane and then cleaned up with cation exchange solid-phase extraction cartridges. Quantitation was performed by micellar electrokinetic capillary chromatography using a high-sensitivity optical cell. Average recoveries at the 0.05 ppm level ranged from 72.9 to 118.5%. The lower limit of detection was approximately 0.02 ppm, except for rimsulfuron and tribenuron methyl, for which the lower limit of detection was 0.035 ppm. The method was less complicated and showed better sensitivity than current single-analyte liquid chromatographic enforcement methods.
Estimation of 1992–1993 Dietary Intake of Organochlorine and Organophosphorus Pesticides in Fukuoka, Japan
Authors: Nakagawa Reiko , Herakawa Hironori , Hori Tsuguhide
Published: February 2020

To estimate Japanese daily intakes of organochlorine pesticides such as hexachlorocyclohexanes (HCHs), 1,1,1 -trichloro-2,2-bis-(4-chlorophenyl)-ethane (DDTs), dieldrin (aldrin), heptachlor-epoxide (heptachlor), and hexachlorobenzenes (HCBs) from foods, fish, fish products, meat, eggs, milk, and milk products were analyzed as major sources of these pesticides in the diet. Estimated daily intakes (EDIs) per person were 0.56 μg for total HCH, 0.20 μg for γ-HCH, 0.09 μg for dieldrin, 1.42 μg for total DDT, and 0.15 μg for HCB. Similarly, daily intakes of organophosphorus pesticides such as malathion and chlorpyrifosmethyl were estimated by analyzing wheat and wheat products as major contributing foods. EDIs of malathion and chlorpyrifos-methyl were 0.22 and 0.24 μg, respectively. Daily intakes of total HCH, dieldrin, and total DDT in fiscal year 1992–1993 decreased 29,44, and 40%, respectively, but γ-HCH intake increased 167%, in comparison with results of total diet studies for fiscal years 1980–1984. It was also shown that increase in γ-HCH intake was due to recent increase in consumption of imported meat and meat products. Malathion intake did not change significantly. This method, which estimates EDIs based on concentrations of pollutants in main foods and statistical data of food consumption from the Japanese National Nutrition Survey, is considered to be sufficiently accurate for use as a simplified total diet study.
Determination of Ephedrine, Pseudoephedrine, and Norephedrine in Mixtures (Bulk and Dosage Forms) by Proton Nuclear Magnetic Resonance Spectroscopy
Authors: Hanna George M
Published: February 2020

A simple, specific, and accurate 1H nuclear magnetic resonance (NMR) spectroscopic method has been developed for quantitative determination of the Ephedra alkaloids (−)-ephedrine, (+)-pseudoephedrine, and (±)-norephedrine, either singly or in mixtures with each other. Determination of individual alkaloids was carried out in D2O solution, with acetamide as internal standard. Although calculations were based on integrals for the C–CH3 protons, those for the N–CH3 and –CH–O– protons may also be useful, depending on the compound. Determination of diastereomeric cross-contamination of ephedrine and pseudoephedrine—or of the concentrations of these alkaloids in the presence or absence of (±)-norephedrine—was feasible by using the integrals for the –CH–O– protons after addition of a trace of DCI. Mean recoveries for ephedrine and pseudoephedrine from their respective synthetic mixtures with the internal standard (acet- amide) were ≥99.9 ± 0.6% (n = 10) and 99.6 ± 0.8% (n = 10) of the amount added. Recovery for pseudoephedrine from diastereomeric mixtures with ephedrine was >99.4 ± 0.7% (n = 10) of the amount added, with as little as 1.92% still being measurable. Mean recovery of (±)-norephedrine from mixtures with ephedrine and pseudoephedrine was >99.7 ± 2.5% (n = 4) of the amount added, with about 1% still being measurable. Application of the proposed NMR spectroscopic method to commercial dosage forms, including ephedrine sulfate injections and pseudoephedrine hydrochloride tablets, yielded assay results ranging from 97.8 to 100.2% (mean, 99.2%) and from 98.7 to 100.5% (mean, 99.7%) of declared, respectively.
Proton Nuclear Magnetic Resonance Spectroscopic Detection and Determination of Ethylene Glycol Dimethacrylate as a Contaminant of Methyl Methacrylate Raw Material
Authors: Hanna George M , Lau-Cam Cesar A
Published: February 2020

A simple, specific, and accurate proton nuclear magnetic resonance (1H NMR) spectroscopic method is presented for detection and assay of ethylene glycol dimethacrylate dimer as a contaminant of methyl methacrylate monomer. In addition to minimizing exposure of the analyst to the irritant and toxic methacrylic acid esters, the proposed method requires no sample preparation. Quantitations are based on integrals for signals of methylene protons of ethylene glycol dimethacrylate at 4.37 ppm and methyl protons of methyl methacrylate at 3.70 ppm. Analysis of 10 synthetic mixtures of the monomer with 1–11% of dimer yielded a dimer recovery of 100.5 ± 2.05% (mean ± standard deviation). Correspondence (correlation coefficient, r=0.9999) between the amount of dimer added and the amount found was excellent. The proposed method measures as little as 1% of dimer.
Comparative and Multilaboratory Studies of Two Immunodiffusion Method Enrichment Protocols and the AOAC/Bacteriological Analytical Manual Culture Method for Detection of Salmonella in All Foods
Authors: Feldsine Philip T , Falbo-Nelson Maria T , Hustead David L , Flowers Russell S , Flowers Mary J
Published: February 2020

The single enrichment immunodiffusion (1-step), the preenrichment and selective enrichment immunodiffusion (2-step), and the AOAC/Bacteriological Analytical Manual culture methods for Salmonella were evaluated for equivalence in 2 separate studies, a comparative evaluation and a multilaboratory dilution study. In the comparative study, all 3 methods were performed on 10 food types. For 550 samples, analyses resulted in 99.3 and 99.6% agreement between the culture method and the 1-step and 2-step methods, respectively. False negative rates were 0.9 and 0.3% for 1-step and culture, and 0.0% and 0.6% for the 2-step and culture, respectively. Subsequently, 6 food types were included in a multilaboratory dilution-to-extinction study. A sequential dilution series of Salmonella in foods was analyzed by the 3 methods to determine their lower limits of detection for Salmonella. A total of 1185 samples analyzed resulted in 98.9% agreement between 1-step and culture, and 99.7% agreement between 2-step and culture. False negative rates were 1.8 and 0.1% for 1-step and culture, and 0.4 and 0.1% for 2-step and culture, respectively. During these evaluations, 1735 samples and controls representing 10 different naturally contaminated and inoculated foods were tested. The data indicate statistical equivalence of all 3 methods when analyzing all food types.
Determination of Magnesium in Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Studies of Some Spectral and Interelement Effects at Different Wavelengths
Authors: Matilainen Rose , Tummavuori Jouni
Published: February 2020

Four analytical wavelengths of magnesium were tested for determination of Mg from fertilizers by inductively coupled plasma atomic emission spectroscopy (ICP-AES): 202.528, 285.213, and 383.826 nm (Mg I) and 279.553 (Mg II). The effects of fertilizer matrix elements on Mg determination were examined by adding matrix elements to fertilizer solutions. Multiple linear regression calculations proved a valuable technique for evaluating the effects of matrix elements on Mg determination. The observed interferences at Mg wavelengths may be both spectral and interelement. Interelement effects were typically caused by Na, K, and Ca, and spectral effects, by P, Fe, and S. The best wavelength for determination of Mg in fertilizers by ICP-AES was 383.826 (Mg I).
Comparison of Four Commercially Available Rapid Test Kits with Liquid Chromatography for Detecting Penicillin G Residues in Bovine Plasma
Authors: Boison Joe O , Korsrud Gary O , Papich Mark G , Macneil James D
Published: February 2020

Four commercially available rapid tests (Brilliant Black reduction test, LacTek test, Charm Farm test, and Charm Test II receptor assay) were compared with a liquid chromatographic (LC) method (lowest quantitatable level of 5 ng/mL) in their efficiency, reliability, and sensitivity to detect penicillin G in bovine plasma. Samples were obtained from 16 steers treated with procaine penicillin G alone or in combination with its long-acting form, benzathine penicillin G. The steers were injected intramuscularly with penicillin G doses ranging from label dose to about 9 times label dose. When results of the Brilliant Black reduction, LacTek, Charm Test II, and Charm Farm tests for penicillin G in plasma (with detection sensitivities of 5,10,20, and 30 ng/mL, respectively) were compared with results of LC, none of the rapid tests gave false-positive results. Each rapid test elicited a positive response when used to test bovine plasma containing penicillin G residues at concentrations above the test’s detection sensitivity. The simplicity, selectivity, and sensitivity of the rapid tests, coupled with rapidity with which results are obtained, make them suitable for use in large-volume preslaughter screening of penicillin-treated cattle.
Fully Automated Solid-Phase Extraction Cleanup and On-Line Liquid Chromatographic Determination of Benzimidazole Fungicides in Fruit and Vegetables
Authors: Hiemstra Maurice , Joosten Jeannette A , de Kok Andre
Published: February 2020

A liquid chromatographic (LC) method using fully automated solid-phase extraction (SPE) sample cleanup and on-line LC analysis was developed for determination of the benzimidazole fungicides car-bendazim and thiabendazole in various crops. Preparation of food samples involved extraction with acetone followed by solvent partitioning with dichloromethane–petroleum ether to draw the analytes into the organic phase. The laborious liquid–liquid partitioning cleanup procedure described in the literature was replaced with a fast SPE cleanup using diol-bonded silica cartridges. Automation of the total procedure was achieved by using a commercially available SPE cleanup apparatus (ASPEC). The cleaned-up extract was injected on-line into an LC system with UV and fluorescence detection in tandem. Chromatographic separations were performed with a methanol–phosphate buffer mobile phase (pH = 7) and different polymeric stationary phases. The polymer-based columns performed better than silica-based columns in separating benzimidazole fungicides, and different columns were compared. Results of validation studies with fortified lettuce and citrus fruit are presented. Shewhart control charts of analytical results of control samples demonstrated good performance of the complete system. Sample throughput (extraction, automated SPE, and on-line LC analysis) was about 50 samples per 24 h. Residues of carbendazim and thiabendazole found during our pesticide residue monitoring program in 1992–1994 are reported.
Total, Free, and Glucose-Conjugated Acid Metabolites from Permethrin and Cypermethrin in Foods by Gas Chromatography-Electron Capture Detection
Authors: Mortimer Richard D , Shields J Brian
Published: February 2020

A method was developed to determine the combined amount of residual free pyrethroid metabolite acids and their glucosides on fruit and vegetables after application of permethrin or cypermethrin insecticides. Samples were spiked with glucose-conjugated acid metabolites, extracted, derivatized, and cleaned up for gas chromatography (GC) with electron capture detection. Limits of detection in the various matrixes were approximately 0.01 ppm, expressed as free acids. In addition, 2 field-grown crops were analyzed over 21 days after spraying with permethrin. Three commercial food samples known to contain parent pyrethroid were also analyzed. In general, the amounts of acid metabolites found were small; commercial samples of grapes, lettuce, and spinach analyzed by GC/mass spectrometry contained 0.005–0.02 ppm.
Comparison of Liquid Chromatography–Atmospheric Pressure Chemical Ionization/Mass Spectrometry and Liquid Chromatography–Postcolumn Fluorometry for Determination of Carbamates in Food
Authors: Newsome W Harvey , Lau Benjamin P-Y , Ducharme Dean , Lewis David
Published: February 2020

Two detection methods, postcolumn derivatization with fluorescent detection and atmospheric pressure chemical ionization/mass spectrometry (MS) were compared for determination of N-methyl carbamates in food by liquid chromatography. Five commodities were spiked with 11 carbamates at levels from 10 to 100 ppb, extracted, and cleaned up by using a method based on the AOAC official method. With each detection method, sample blanks showed false-positive responses, indicating that neither method alone provides definitive identification. Except for aldicarb sulfoxide determined by MS, recoveries were linear between 10 and 100 ppb. Agreement between the 2 methods was good for determination of recoveries at 25 ppb. Coefficients of variation were 11–33% for fluorescence detection and 9–26% for MS.
Rapid Ultratrace Analysis of Tributyltin in Aqueous Matrixes by Purge-and-Trap Gas Chromatography with Flame Photometric Detection
Authors: Sharron Daniel , Swami Kamal , Jansing Robert L
Published: February 2020

A simplified purge-and-trap technique for detecting subnanogram amounts of the biocide tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in aqueous environmental samples is described. Butyltin chlorides present in the sample were derivatized to volatile butyltin hydrides with NaBH4 and simultaneously purged by drawing ambient air through the purge vessel. Butyltin hydrides were trapped on a Porapak-N cartridge, eluted with dichloromethane, and analyzed by gas chromatography with flame photometric detection. Recoveries of the butyltin species ranged from 46 to 101%. Method detection limits for MBT, DBT, and TBT were 1.28, 0.39, and 0.24 ng/L, respectively. The major advantages of this technique are sensitivity, reduced analysis time, and a significant reduction in the amount of dichloromethane used. Results from the analysis of various surface water samples collected in New York are presented.
Practical Application of Thin-Layer Chromatography for Detection of Polyphosphates in Seafood
Authors: Krzynowek Judith , Panunzio Laurie J
Published: February 2020

The practical application of previously published thin-layer chromatographic (TLC) methods to polyphosphate detection in seafood was determined. Exogenous polyphosphates are distinguishable from naturally occurring phosphates by using TLC; their detection can be enhanced by sampling techniques. Polyphosphates will eventually hydrolyze to monophosphates and make detection virtually impossible. Hydrolysis and therefore, nondetection, is accelerated by certain commercial practices. Results indicate that TLC detection of added phosphates can be used as an inspection tool for fresh products and for frozen products stored about 1 year.
Bacillus Stearothermophilus Disc Assay: A Review
Authors: Katz Stanley E , Siewierski Marie
Published: February 2020

The literature on the Bacillus stearothermophilus disc assay was reviewed and evaluated. The history of the assay development; data on applicability, sensitivity, interferences, and cowside screening; potential for the future; and limitations are presented and discussed.
On-line Steam Distillation/Purge and Trap Analysis of Halogenated, Nonpolar, Volatile Contaminants in Foods
Authors: Page B Denis , Lacroix Gladys M
Published: February 2020

An on-line, steam distillation/purge and trap gas chromatographic procedure is described for determination of halogenated analytes in foods and beverages. Recoveries were generally >80% (versus aqueous standards) from vegetable oil, flour, root beer, cream (10% butter fat), and milk spiked at 1 - 3 μg/kg for each of the 32 analytes studied. Analytes ranged in volatility from vinyl chloride to 1,2,3,4-tetrachlorobenzene. Repeatabilities from aqueous standards were <10% for most analytes. For a 1 g food sample, method detection limits ranged from 0.02 to 0.2 μg/kg for the 32 analytes. Reduced recoveries for less volatile analytes, however, occurred when steam-distillable, nonpolar food components were carried to the sparger. This effect was observed for citrus beverages containing steam-volatile limonene, roasted and ground coffees, and some salad dressings. The method was applied to a variety of foods.
Determination of Extractable, Apparent Total N-Nitroso Compounds in Cured-Meat Products
Authors: Fiddler Walter , Pensabene John W , Doerr Robert C , Gates Robert A
Published: February 2020

The modification of a newly developed method for determination of apparent total N-nitroso compounds by chemical denitrosation and chemiluminescence detection of nitric oxide (thermal energy analysis) is described. The minimum level of reliable measurement was 0.1 ppm, and the repeatability of the method was 0.2 ppm, based on the response of N-nitrosoproline (NPro). Seventy-three samples of cured-meat products, including frankfurters, bacon, and ham, were examined; 50 samples contained less than 1 ppm. The largest amounts, up to 24.8 ppm, were detected in canned corned beef. This method has several advantages over other methods.
Determination of Total Dietary Fiber in Foods and Food Products by Using a Single-Enzyme, Enzymatic-Gravimetric Method: Interlaboratory Study
Authors: Li Betty W
Published: February 2020

A simplified enzymatic-gravimetric method for total dietary fiber (TDF) determination has been published and used in the Food Composition Laboratory of the U.S. Department of Agriculture since 1988. This method gives comparable results to AOAC Official Methods 985.29 and 991.43 but the AOAC methods use 100°C (water bath) to gelatinize the sample and a combination of α-amylase and an amyloglucosidase to hydrolyze starches, whereas the simplified method incorporates an autoclaving step (121°C) for gelatinization followed by incubation with only amyloglucosidase. The simplified method omits protease hydrolysis and does not require any pH adjustment. Overall, the simplified method cuts cost and is less labor intensive. An interlaboratory study was conducted to validate this method. Blind duplicates of six sample (baked beans, corn bran, roasted peanuts, cooked potatoes, white bread with reduced calories, and cooked white rice) were sent to 11 laboratories. The reproducibility relative standard deviations of the TDF values (without outliers) ranged from 3.46 to 27.6%. The repeatability standard deviations ranged from 0.91 to 14.6%.
Importance of Cooking Temperature and Pancreatic Amylase in Determination of Dietary Fiber in Dried Legumes
Authors: Mongeau Roger , Brassard René
Published: February 2020

Total dietary fiber (TDF) was measured in large lima, roman, black turtle, light red kidney, white navy, pinto, black-eyed, and soya beans and in chick peas by the Mongeau rapid method (A), the Prosky method (B), and the Lee method (C). When the samples were soaked and cooked according to package instructions (gentle boiling, 95°C), TDF values by method A were all within 19.7-22.1%, except for black-eyed beans (9.9%) and chick peas (11.3%) (g/100 g, cooked dry matter). For large lima beans (20.0-21.3%) and soya beans (19.2-19.7%), TDF values by methods A, B, and C were in agreement. For 7 samples, however, TDF values were up to 81% higher by method B (17.4-34.7%) and up to 122% higher by method C (21.1-39.8%) than those by method A (P ≤ 0.01). For 6 legumes, TDF values by method C were 15-28% higher (P ≤ 0.013) than by method B. White navy beans were analyzed also after different cooking conditions, varying from no cooking to autoclaving for 15 min at 120°C. TDF values by method A were independent from cooking conditions and remained between 20.2 and 22.4%. For navy beans cooked at 95°C, TDF values by method B (up to 34.7 ± 1.4%) and C (up to 39.8 ± 0.3%) were unpredictable, but autoclaving at 120°C reduced them to about 22%. Incorporation of a pan-creatic amylase in methods B and C consistently decreased the aforementioned analytical discrepancies, as did the absence of cooking. Only autoclaving (for at least 15 min at 120°C) fully restored agreement among methods A-C.
Multiresidue Liquid Chromatographic Method for Simultaneous Determination of Pyrethroid Insecticides in Fruits and Vegetables
Authors: Pang Guo-Fang , Chao Yan-Zhong , Liu Xie-Shan , Fan Chun-Lin
Published: February 2020

A simple and rapid liquid chromatographic (LC) method has been developed for simultaneous determination of 9 pyrethroid insecticides (biphenthrin, cypermethrin, fenpropathrin, fenvalerate, flucythrinate, methothrin, permethrin, py-115, and tetramethrin) in fruits and vegetables. Residues are extracted from crops with methanol and partitioned with toluene. Extracts are cleaned up by Florisil–charcoal column chromatography. LC separation is performed on a μBondapak C18 stainless steel column with acetonitrile–deionized water as mobile phase. The insecticides are detected at 206 nm with 0.03 absorbance unit full scale. Recoveries of 9 pyrethroid insecticides from 6 crops (cucumbers, tomatoes, cabbages, apples, pears, and peaches) fortified at 0.5–5.0 mg/kg were 62.7–129.2%. Detection limits were about 0.05 mg/kg, except for py-115, for which detection limit was 0.10 mg/kg.
Multiresidue Method for Determination of Organophosphorus Insecticide Residues in Fatty Processed Foods by Gel Permeation Chromatography
Authors: Sannino Anna , Mambriani Paola , Bandini Mirella , Bolzoni Luciana
Published: February 2020

A multiresidue method for quantitative determination of 39 organophosphorus compounds (parent pesticides and their major metabolites) in 7 fatty processed foods is described. Samples are extracted with methylene chloride and cleaned up by automated gel permeation chromatography with a Biobeads SX3 column and a methylene–chloridecyclohexane (15 + 85) eluant. Organophosphorus compounds are quantitated by capillary gas-liquid chromatography with flame photometric detection using OV-1701 and DB-5 columns. Average recoveries from samples fortified at 0.025–1 mg/kg ranged from 50.6% for dichlorvos to 185% for malaoxon. Determination limits were between 0.005 and 0.040 μg/mL. Results were confirmed by gas chromatography/mass spectrometry with selected-ion monitoring.
Alternative Catalyst to Mercury for Kjeldahl Determination of Nitrogen in Water and Wastewater Samples
Authors: Anderson Kim A , Möller Gregory
Published: February 2020

A non-polluting alternative catalyst was used in a U.S. Environmental Protection Agency (EPA) Kjeldahl digestion procedure for water and wastewater samples. The colorimetric semiautomated block digestion method (EPA Method 351.2) was essentially unchanged except that 1 mL of a saturated solution of titanium dioxide was added to the digestant mixture, instead of 2 g mercuric oxide. Titanium dioxide is a nontoxic compound, which makes an excellent replacement in total Kjeldahl nitrogen (TKN) determination. Samples were digested and then placed on a flow injection autoanalyzer for ammonia determination. All other digestion and analysis procedures were the same as in the original method. Detection limit for TKN was 0.1 mg/L. Recovery of glutamic acid averaged 96.2%. Recoveries of standard reference water samples over a 9 month period averaged >95%.
Effect of Extraction Systems on Clomazone Recovery from Aged Soil Samples
Authors: Kirksey K Bruce , Mueller Thomas C
Published: February 2020

Seven extraction methods were examined to determine which one provided a simple, efficient clomazone extraction from aged soil. The method selected involved adding 80 mL acetonitrile to moist soil and shaking for 16 h. The extract was filtered, and an additional 80 mL acetonitrile was added, equilibrated for 1 h, and filtered. Filtrates were combined and concentrated with a rotary evaporator. Clomazone concentrations were then determined by reversed-phase liquid chromatography with UV detection at 220 nm. Recovery with this method was equal to a 16 h + 1 h extraction with methanol, but acetonitrile was selected as extraction solvent because of its ease of removal with a rotary evaporator. The recovery from fortified soil samples was >80%, and a conservative lower limit of detection was 40 ng/g soil.
Detection of Salmonella spp. in Eggs: DNA Analyses, Culture Techniques, and Serology
Authors: Burkhalter Paul W , Müller Christoph , Lüthy Jürg , Candrian Urs
Published: February 2020

A polymerase chain reaction (PCR) method for direct detection of Salmonella spp. in whole-shell eggs is described. The method does not require isolating strains. Preenrichment, rapid DNA isolation, and a nested PCR system targeting the invA gene enabled detection of the genus Salmonella. The specific nested PCR product of 283 base pairs was formed from all 21 serovars, including 43 Salmonella strains tested. No PCR product was formed from 56 non-Salmonella enterobacteriacea and other bacterial strains tested. Experiments with artificially contaminated eggs showed a detection limit of about 103–104 colony-forming units (cfu)/egg before and about 1–10 cfu/egg after preenrichment. In analysis of 180 single eggs from 4 flocks and 36 pools of 5 eggs each from another 4 flocks from the same producer, Salmonella spp. were detected in 5 of 90 eggs from 2 different flocks. Determination of anti-Salmonella antibodies in eggs yielded positive results for 2 additional and the 2 PCR-positive flocks. In contrast, classical selective culture detected Salmonella spp. in only 1 of 100 eggs in one flock when 100 eggs from each flock were analyzed.
Performance-Based Field Methods for Analyses of Substituted Phenols by Thermal Desorption Gas Chromatography/Mass Spectrometry
Authors: Jiao Kaisheng , Robbat Albert
Published: February 2020

Performance-based field methods that provide qualitative and screening level data for phenol and its substituted (chloro, methyl, and nitro) analogues were developed for soil analysis. The methods give results in under 5 min/sample. A more quantitative field method for soil and water also was developed. The method can provide data in under 20 min/sample inclusive of sample preparation. Measurement performance of thermal desorption gas chromatography/mass spectrometry (TDGC/MS) for both soil and water samples are presented. MS with selective ion monitoring and a compound-specific data analysis algorithm provides data with measurement precision and accuracy of about 40%. The more quantitative method yields data comparable with those obtained by U.S. Environmental Protection Agency standardized methods, with measurement precision and accuracy of ± 30%.
Effects of Sodium Sulfite on Recovery and Composition of Detergent Fiber and Lignin
Authors: Hintz Rodney W , Mertens David R , Albrecht Kenneth A
Published: February 2020

Use of sodium sulfite to reduce nitrogenous contamination in fiber analysis was evaluated. The effects of sodium sulfite on analytical accuracy and precision were examined for amylase-treated neutral detergent fiber (aNDF), sequentially determined acid detergent fiber (sADF), and acid detergent lignin (sADL) in animal feeds. In one experiment, 0.5 g sodium sulfite was added per sample during neutral detergent (ND) extraction. The treatment consistently reduced aNDF, sADF, and sADL values of 180 alfalfa samples and improved precision (decreased within-sample variance of replicated analyses). The greatest effect was on precision of sADL analysis, with within-sample variance reduced by more than 50%. In a second experiment, 24 animal feeds were analyzed for aNDF, sADF, and sADL with and without addition of 0.5 g sodium sulfite per sample during ND extraction. Nitrogen contents of the recovered fiber fractions were determined. Sodium sulfite reduced fiber and lignin values and decreased nitrogen concentration in residues. Within-sample variance was lower in all analyses. In a third experiment, 23 animal feeds were analyzed for aNDF with sodium sulfite at 0, 0.25, 0.5, and 1.0 g per sample. Average aNDF of feeds was reduced by each additional increment of sodium sulfite; however, 1.0 g sodium sulfite resulted in only a slight reduction in aNDF compared with 0.5 g. Therefore, 0.5 g sodium sulfite per sample should be added to samples prior to aNDF analysis.
Vitamin D in Infant Formula and Enteral Products by Liquid Chromatography: Collaborative Study
Authors: Sliva Matthew G , Sanders James K ,   Collaborators:, Arendsen M , Baars A , Bhandari S , Boerma B , Broge J , Bueno M , Cherix G , Gates G , Hollembaek J , Kaufman M , Kraft C , Oerl L , Santos A , Schuep W , Wehrmann J
Published: February 2020

Results from a collaborative study of a new liquid chromatographic (LC) method for determination ofvitamin D in infant formulas and enteral products are presented. Each of 15 laboratories was provided with 11 blind duplicate samples covering a range ofapproximately 200-500 International Units/quart (normal dilution), a system suitability sample, and the U.S. Pharmacopeia ergo- and cholecalciferol standards. Product types included liquid and powder forms of milk (whey and casein), soy, and hydrolyzed protein-based infant formulas and enteral products. The method includes a single liquid-liquid extraction following saponification, solid-phase extraction,and then concentration by evaporation. An isocratic, nonaqueous, chromatographic system with reversed-phase, zero end- capped C18 column, and UV detector set at 265 nm are used. Statistical evaluation ofdata from participating laboratories showthe average reproducibility and repeatability of the method across all samples to be excellent, with RSDR and RSDr values of 13.48 and 9.44, respectively, after elimination of out liers. The LC method for determination of vitamin D in infant formulas and enteral products has been adopted by AOAC INTERNATIONAL.