bluuebunny/crossref_metadata_2025 huggingface dataset:
A Survey of Benzene in Fruits and Retail Fruit Juices,Fruit Drinks, and Soft Drinks
Authors: Page, Denis B , Conacher, Henry B.S , Weber, Dorcas , Lacroix, Gladys
Published: February 2020

Recent findings of benzene In several fruit-flavored mineral waters at low μg/kg levels, reportedly arising from added benzoate, have prompted a survey of various fruits, juices, and drinks for traces of benzene. Headspace sampling, capillary gas chromatography, and mass spectrometrlc detection enabled detection with confirmation (full-scan spectrum) of benzene as low as 0.03 μg/kg. With selected Ion monitoring, the method detection limit was 0.02 μg/kg, I.e., 3 times the analytical blank, in total, 97 samples were analyzed. Benzene was found at levels ranging from 0.018 to 3.83 μg/kg. Samples labeled to contain added benzoate or believed to contain natural benzoate, such as cranberries, were found to contain benzene at higher levels (n = 41, av. 0.66 μg/kg) than other samples (n = 32, av. 0.082 μg/kg). Average levels of benzene In fruits (as expressed juice), In juices with and without benzoate, In noncarbonated drinks with and without benzoate, and in soft drinks with and without benzoate were 0.042,0.672,0.056,0.395, 0.116,0.793, and 0.062 μg/kg, respectively
Internal Standard Stable Carbon Isotope Ratio Method for Determination of C-4 Plant Sugars in Honey: Collaborative Study, and Evaluation of Improved Protein Preparation Procedure
Authors: White Jonathan W
Published: February 2020

A collaborative study of the internal standard isotope ratio method for measuring C-4 plant sugars in honey Is reported. For 5 Youden pairs of samples containing 2-14% C-4 sugars, analyzed by 9 laboratories, mean sr was 1.92% and SR was 2.19%. Improved performance parameters for determination of δ13C in honey are also presented. The method was adopted first action by AOAC International. Also presented Is an improved purification procedure for the honey protein required for the Internal standard method. The dialysis-precipitation procedure described is considerably less demanding of analyst's time and eliminates possible contamination of the preparation by Indigenous yeasts and molds. No difference In δ13C values was found between the collaboratively studied method and the method when used with the improved procedure to analyze 10 known pure honeys. The dialysis- precipitation procedure is recommended as a substitute for the repeated washing procedure described In the collaboratively studied method.
Determination of Malachite Green and Its Leuco Form in Water
Authors: Allen John L , Meinertz Jeffery R , Gofus Jane E
Published: February 2020

Liquid chromatographic (LC) analysis can detect malachite green residues in water at less than 10µg/L. Water samples were concentrated on disposable diol columns, eluted with 0.05M p-toluenesulfonic acid in methanol, and determined by reversed- phase LC. When combined with a lead oxide postcolumn reactor, the LC method can simultaneously determine both leuco and chromatic forms of malachite green. Recoveries averaged 95.4% for the chromatic form and 57.3% for the leuco form of malachite green oxalate and leuco malachite green in spiked pond water samples. Recoveries of the carbinol form of malachite green (an equilibrium product of the dye in water) from spiked tap water samples averaged 98.6%. Recoveries of leuco malachite green were low and pH-dependent.
Analysis of Polychlorinated Biphenyls in Aqueous Samples Using C18 Glass Column Extraction
Authors: Moltó, Juan C , Picó, Yolanda , Mañes Jorge , Font Guillermina
Published: February 2020

A method for polychlorinated biphenyl (PCB) trace extraction from contaminated water at the part-pertrillion levels is described. This procedure involves quantitative adsorption of PCBs on Cis glass microcolumns. PCBs are retained on the surface and subsequently eluted with n-hexane (5 mL) before gas chromatography. Recovery of water fortified with PCBs was 83.6-108.5%. Compared to liquid-liquid extraction methods, the Cis glass microcolumns give comparable results, lessen solvent costs, and are less time-consuming.
In Vitro Effect of Multiple Antibiotic/Antimicrobial Residues
on the Selection for Resistance in Bacteria
Authors: Sue Brady Marietta , Katz Stanley E
Published: February 2020

A method using a gram-positive and a gram-negative organism was used to investigate the selection for resistant populations after exposure to residue levels of 7 antibiotics and 1 antimicrobial. The organisms were exposed to individual compounds and combinations of 3 compounds for 14 days. The changes in minimum inhibitory concentration (MIC) of a panel of 8 antibiotics and 1 antimicrobial were used as the measure of resistance development/selection. For Staphylococcus aureus ATCC 9144, exposure to residue levels of oxytetracycline, tylosin, penicillin, and virginiamycin resulted in an increased MIC of the compound itself; most individual residues did not result in increased cross-resistance. With combinations of residues, 13 of 45 determinations resulted in significant increases in MIC. Enterobacter cloacae B520, which was much less sensitive to 4 of 9 markers, showed MIC increases only for tylosin and the combination of neomycin-sulfamethazine-oxytetracycline. The results indicate an interaction among residue levels of antibiotics in selection for resistance.
Liquid Chromatographic Determination of Unbound and Acetone-Soluble Bound Gossypol in Cottonseed Meals and Mixed Feeds
Authors: Botsoglou Nickos A
Published: February 2020

A liquid chromatographic method has been developed for the determination of unbound and acetone- soluble bound gossypol in cottonseed meals and mixed feeds at levels of 0.5 ppm. The method involves extraction with aqueous acetone in the presence of ascorbic acid, hydrolysis of the "soluble bound" forms with hydrochloric acid, partitioning into chloroform, and chromatographic separation on a 10 µm C18 column by step gradient elution using a methanol-water mobile phase acidified with phosphoric acid. With minor modifications, the method permitted discriminate determination of unbound gossypol and acetone-soluble hydrophilic and lipophilic forms of bound gossypol. The gossypol peak was characterized by on-line spectral scanning and absorbance rationing. Overall relative standard deviation was 6.7% and overall recovery was 98.1 ± 3.3%. When the method was applied to several cottonseed meal samples, results were inconsistent with those obtained by the official American Oil Chemists' Society method for "free" gossypol determination.
Characterization of the 0-(2,3,4,5,6-Pentafluorobenzyl)- hydroxylamine Hydrochloride (PFBOA) Derivatives of Some Aliphatic Mono- and Dialdehydes and Quantitative Water Analysis of These Aldehydes
Authors: Cancilla Devon A , Chou Chin-Cheng , Barthel Richard , Que Hee Shane S
Published: February 2020

A study was conducted to validate the use of O- (2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride (PFBOA) as an agent for the determination of formaldehyde, acetaldehyde, n-heptanal, n-decanal, and glyoxal, aldehydes commonly found as byproducts in drinking and other water after a prior ozonation step. The study involved synthesis and characterization of the pure PFBOA-oxime derivatives and their subsequent use in validation studies in various types of chemically defined waters. The yields of the synthesized PFBOA-oximes exceeded 80%. They were characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet (UV) and infrared (IR) spectrophotometry, and gas chromatography/electron impact positive ion mass spectrometry (GC/MS) to assess their purity and define the suitability of these techniques in aldehyde quantitation. The syn/anti isomers of the oximes were detected by GC/MS and both NMR techniques, but not by IR or UV. The most sensitive technique was selected ion monitoring GC/MS, which allowed picogram quantitation over a wide linear range. A high PFBOA concentration (10 mg/mL) with 3 hexane extractions, initial pH adjustment, and microwave heating proved superior (<80% recoveries) to a published method involving room temperature, low PFBOA concentration (1 mg/mL), and a single hexane extraction for many defined waters. The use of standard reference materials as defined matrixes for aldehyde spiking recovery experiments to account for matrix effects is novel, and demonstrates that the method is quantitative (<80% recoveries) in a wide variety of matrixes.
Gravimetric Determination of Moisture and Ash in Meat and Meat Products: NMKL Interlaboratory Study
Authors: Kolar Kurt
Published: February 2020

Fourteen laboratories participated in a collaborative study of gravimetric methods for determination of moisture and ash in meat and meat products. The determination of moisture by drying without sand at 102-105C for 16-18 h and to constant weight was compared with the official NMKL method using drying with sand to constant weight. The incineration was performed at 550°C. The method was tested on 16 blind duplicate samples of fresh meat and meat products ranging in moisture content from 44.1 to 74.8 g/100 g, and in ash content from 1.0 to 5.4 g/100 g. Drying without sand for 16-18 h and to constant weight gave no significant difference. Therefore, the labor-intensive drying to constant weight is not necessary to obtain reliable results. In comparison with the official NMKL method based on drying with sand, the mean values, repeatability, and reproducibility of the drying method without sand for 16-18 h agree very well. Therefore, there is no reason to retain the more complicated and labor-intensive sand drying method. The conditions of the proposed method differ only slightly from the conditions used in the official AOAC method, 950.46 B(a). The collaborative results for the determination of both moisture and ash gave estimates for precision according to the HORRAT values
Determination of Arsenic in Vegetable Samples by Hydride
Generation Atomic Absorption Spectrometry
Authors: Navarro Miguel , Lopez Maria C , Lopez Hermbmia , Sanchez Mercedes
Published: February 2020

A procedure is described for the determination of arsenic in vegetable samples by hydride generation atomic absorption spectrometry. The samples are mineralized in a microwave acid digestion bomb with nitric acid in the presence of small amounts of vanadium pentoxide. The determination of arsenic is made by the standard addition method. A certified reference sample is analyzed, and the result obtained agreed well with the certified value. The detection limit (dry weight) was about 0.020 μg/g. Reproducibility relative standard deviations ranged from 6.45% at 0.152 μg A μ/g to 8.31 % at 0.059 μg A μ/g. The concentrations of arsenic in vegetable samples ranged from 0.029 to 0.444 μg/g (fresh weight)
Graphite-Furnace Atomic Absorption Spectrometric Determination And Survey Of Total Aluminum, Copper, Manganese, Molybdenum, And Tin In Infant Formulas And Evaporated Milks
Authors: Dabeka Robert W , Mckenzie Arthur D
Published: February 2020

A graphite-furnace atomic absorption spectrometric (GFAAS) method using a single simple digestion was developed to determine aluminum, copper, manganese, molybdenum, and tin in infant formulas and evaporated (evap.) milks. Citric acid (0.5 mL 20%) and 3 mL HNO3 were added to 2 g formula (ready-to-use basis) in unwashed polystyrene test tubes. Tubes were capped, and solutions were digested 6-18 h at 55C. Digests were diluted to 10 mL with water and analyzed. Standards were prepared in a matrix of 30% HNO3 and 1% citric acid without digestion. Palladium (1 μg) was used as matrix modifier for aluminum and tin determinations. The mean detection limits of the method were 0.021,0.043, 0.006, 0.063, and 0.073 μg/g for aluminum, copper, manganese, molybdenum, and tin, respectively. The elements were determined in 191 Canadian infant formulas and evap. milk samples. Means, medians, and ranges (μ/g) of metals in soy-based ready-to-use formulas were as follows: 1.62, 0.54, and 0.23-5.2 for aluminum; 0.87,0.88, and 0.71-1.14 for copper; 0.63,0.22, and 0.042-2.4 for manganese; 0.068, <0.049, and <0.048-0.14 for molybdenum; and 0.20, 0.15, and <0.074-0.54 for tin. Means, medians, and ranges (μg/g) of metals in milk-based ready-to-use formulas were as follows: 0.18,0.13, and <0.011-0.66 for aluminum; 0.61, 0.58, and 0.44-0.93 for copper; 0.097,0.094, and 0.053- 0.16 for manganese; 0.033, <0.042, and <0.012- 0.067 for molybdenum; and 0.23,0.18, and 0.067-0.91 for tin. Respective levels in evap. milks (as sold) were as follows: 0.08, 0.051, and <0.017- 0.27 for aluminum; 0.103, 0.087, and 0.045-0.31 for copper; 0.071, 0.062, and 0.048-0.16 for manganese; 0.14, <0.17, and <0.07-<0.19 for molybdenum; and 2.84,0.46, and 0.032-48 for tin.
HPLC Receptorgram: A Method for Confirmation and Identification of Antimicrobial Drugs by Using Liquid Chromatography with Microbial Receptor Assay. I. Sulfonamides in Milk
Authors: Zomer Eliezer , Saul Steven , Charm Stanley E
Published: February 2020

A determinative method was developed for confirmation, identification, and quantitation of 12 sulfonamide residues and p-aminobenzoic acid (PABA) in milk. This method, termed "HPLC receptorgram," uses liquid chromatography in conjunction with the microbial receptor assay (MRA) to monitor sulfonamides. The MRA for sulfonamides (commercialized as the Charm II test) uses a microcrobial receptor and [3H]sulfamethazine tracer. Sulfonamides in milk bind to the receptor and inhibit the binding of the tracer to the receptor. Milk samples spiked at 10 ppb for each sulfonamide result in at least a 50% decrease in binding on the HPLC receptorgram, with the exception of sulfanilamide and sulfacetamide, which give approximately a 25% decrease. Additionally, milk samples spiked at the minimum detection level of the MRA assay can be confirmed, identified, and quantitated with coefficients of variation (%) of 7.6-24. Analysis of market milk samples found positive by the MRA showed 9 samples containing sulfamethazine, 4 samples containing sulfadimethoxine, 2 samples containing sulfadoxine, 2 samples containing sulfadiazine or sulfathiazole, and 1 sample each containing sulfisoxazole or sulfapyridine. Three samples contained multiple sulfonamide residues. Ten sulfonamides are determined with an isocratic buffer elution system containing 22% acetonitrile mobile phase. p-Aminobenzoic acid (PABA), an interfering sulfonamide analog, sulfanilamide, and sulfacetamide are eluted by using a 10% acetonitrile mobile phase
Methods of Analysis for Toxic Elements in Foods. Part IV. General Method of Ashing for the Determination of Toxic Elements
Authors: Skurikhin Igor M
Published: February 2020

As a result of the request of the Codex Alimentarius Committee on Methods of Analysis and Sampling, a general method for ashing of foods for the determination of toxic elements was assembled. This method consolidates the results of more than a decade of interlaboratory work of numerous USSR food laboratories and specifies the details of wet and dry ashing procedures.
Simultaneous Determination of Multiple Tetracycline Residues in Milk Using Metal Chelate Affinity Chromatography
Authors: Carson Mary C
Published: February 2020

A method was developed for the determination of 7 tetracyclines in milk. Raw milk samples are defatted, acidified, and centrifuged to remove proteins, and the tetracyclines are specifically absorbed from the milk by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns. The tetracyclines are removed from these columns with EDTA-containing buffer, and the extracts are further cleaned up by centrifugal ultrafiltration. Finally, the extracts are concentrated and analyzed simultaneously by on-line concentration. This method has limits of detection for individual tetracyclines of <5 ng/mL and was validated with fortified milk samples at 15,30, and 60 ng/mL. Recoveries exceeded 60% for all tetracyclines at all levels, with good precision. The method was also tested on milk from cows dosed with each of the tetracyclines. Advantages of this method over existing methods include its sensitivity, minimal use of organic solvents, and speed; with an autosampler, at least 14 samples can be processed and analyzed in 1 day.
Development of Enzyme Immunoassay for Captan and Its Degradation Product Tetrahydrophthalimide in Foods
Authors: Newsome W Harvey , Yeung Jupiter M , Collins Peter G
Published: February 2020

A simple, sensitive, and precise enzyme-linked immunosorbent assay (ELISA) is described for the quantitation of captan as its degradation product tetrahydrophthalimide (THPI) in foods using polyclonal antibodies. Three hapten analogues of THPI with different alky I spacer arm lengths were synthesized. Immunogens and coating proteins were prepared by coupling these haptens to human serum albumin and ovalbumin, respectively. A 5-carbon spacer arm appeared to be optimum for the production of antibodies. Heterologous coating proteins did not improve the sensitivity, but reduction of homologous coating protein concentration did improve the sensitivity, resulting in a concentration of test compound required to inhibit binding by 50% of 15.5 ng/mL The antiserum is specific for captan, captafol, and THPI, but not other structurally related compounds. The minimum detection limit was 1 ng/mL; the linearity was 1-200 ng/mL. The overall recoveries of captan and THPI from 11 commodities spiked at 4 levels were 92 and 100%, respectively. The intra-assay and interassay coefficients of variation were 9.1 and 16.8% for apple blanks and 5.9 and 4.2% for apple spiked with 3 ppm THPI, respectively. The ELISA described is suitable for measuring captan and THPI at levels comparable to those typically found in fruit.
Liquid Chromatographic Analysis of Niacin in Fortified Food Products
Authors: Chase G William , Landen William O , Soliman Abdel-Gawad M , Eitenmiller Ronald R
Published: February 2020

An ion exchange liquid chromatographic (LC) method using an anion exchange resin column was developed for the determination of niacin in fortified foods. Samples were extracted by autoclaving with H2SO4 (1+1). Florisil open column chromatography was used to remove interferences from the sample extracts. Niacin levels were quantitated by an LC system using a 250 x 4.1 mm Hamilton PRP-X100 column, a mobile phase of 2% glacial acetic acid in water, and UV detection at 254 nm. The limit of detection was 0.11 μg niacin/mL, and the standard curve was linear from 0.24 to 0.80 jag niacin/mL. The system reproducibility was evaluated by completing 10 repetitive analyses on an infant formula and a macaroni product, which gave an average CV of 2.7%. Mean recovery (± standard deviation) was 99.8 ± 7.7 (n = 15). The results compared favorably with those by the AOAC microbiological method.
Liquid Chromatographic Determination and Liquid Chromatographic-Thermospray Mass Spectrometric Confirmation of Nicarbazin in Chicken Tissues: Interlaboratory Study
Authors: Leadbetter Mary G , Matusik Jean E ,   Collaborators:, Koscinski W W , Leadbetter M G , Matusik J E , Nightengale C T , Schenck F J , Vasco G A
Published: February 2020

The U.S. Food and Drug Administration sponsored an interlaboratory study of a liquid chromatographic determination with ultraviolet detection of nicarbazin in chicken liver and muscle tissues. The method determined the 4,4’-dinitrocarbanilide(DNC) portion of nicarbazin. The interlaboratory study of the determinative method was successful for nicarbazin at the 4 ppm level. Results showed good reproducibility for the fortified liver and muscle samples. Mean interlaboratory recoveries and percent coefficients of variation at about 4 ppm were 87.1 and 10.9%, respectively, for muscle and 87.4 and 7.5%, respectively, for liver. The interlaboratory analyses of the dosed liver and muscle tissues produced concentration levels similar to those obtained by the sponsor. The confirmatory procedure, which identified DNC in purified tissue extracts, used liquid chromatography-thermospray/mass spectrometry. The confirmatory procedure was successfully evaluated by one FDA laboratory.
Factors Affecting the Precision of Dietary Fiber Measurements in Potatoes
Authors: Wolynetz Mark S , Mullin William J
Published: February 2020

The measurement of dietary fiber in foods is becoming increasingly important. In the widely accepted gravimetric methods for measuring fiber, a common feature is the use of crucibles, with sintered glass frits, to collect insoluble and precipitated material; in this laboratory, P2 crucibles are used in insoluble fiber determinations. Evidence from 3 experiments indicated a significant amongcrucible variance component (P <0.001) that was at least 50% larger than the residual variation; this component may be as large as the commonly encountered among-time component. The crucible effect has implications with respect to experimental design, data analysis, and measurement of insoluble fiber in particular materials such as biological reference materials.
Determination of Cephapirin and Desacetylcephapirin in Milk Using Automated Liquid Chromatographic Cleanup and Ion-Pairing Liquid Chromatography
Authors: Moats William A
Published: February 2020

A simple and sensitive method was developed for determination of cephapirin and its metabolite, desacetylcephapirin, in milk. For extraction/ deproteinization, 2 mL 0.2M tetraethylammonium chloride and 28 mL acetonitrile are added to 10 mL milk, and 20 mL clear filtrate (= 5 mL milk) is collected. Filtrate is evaporated to 1-2 mL and made up to 4 mL with water, filtered, and transferred to 4 mL autosampler vials. For cleanup, 2 mL filtrate is loaded onto a Supelcosil LC-18 column in 0.01 M KH2PO4 (A) using a Waters WISP autosampler. The column is eluted with an acetonitrile (B) gradient from 100%A (0-3 min) to 70%A:30%B (24 min). Fractions corresponding to cephapirin and desacetylcephapirin are collected. A 0.02M pH 2.26 buffer of 0.01 M decanesulfonate-acetonitrile was used for cephapirin (80 + 20) and 0.02M pH 1.96 buffer of 0.01 M decanesulfonate-acetonitrile was used for desacetylcephapirin (84 + 16) on a Polymer Laboratories PLRP-S column. Recoveries at 0.01-10 ppm were 91-98%; estimated detection limits were near 2 ppb and were comparable to sensitive screening tests.
Interiaboratory Evaluation of an Off-Line Supercritical Fluid Extraction/Infrared Spectrometric Method for Determination of Petroleum Hydrocarbons in Solid Matrixes
Authors: Lopez-Avila Viorica , Young Richard , Kim Robert , Beckert Werner F ,   Collaborators:, Bruce M , David P , Eckert-Tilotta S , Emery A P , Hecht C , Hedrick J , Levy J , Liebman S , McNally M E , Porter N , Pyle S , Snyder J L , Tehrani J
Published: February 2020

A collaborative study was conducted, with 14 laboratories participating, to determine the method accuracy and precision of the proposed U.S. Environmental Protection Agency Methods 3560 and 8440. These methods involve the extraction of petroleum hydrocarbons from solid matrixes with supercritical carbon dioxide at 340 atm and 80°C for 30 min (dynamic), collection of the extracted materials in tetrachloroethene (Method 3560), and analysis of the extracts by infrared (IR) spectrometry (Method 8440). The study design was based on the AOAC blind replicate design with balanced replicates. The study samples consisted of 4 solid matrixes that had petroleum hydrocarbon contents ranging from 614 to 32 600 mg/kg. Each of the 4 matrixes was extracted in triplicate, and the extracts were analyzed with 2 different IR spectrometers. In addition, each of the participating laboratories extracted a sample of unspiked clay soil, the same clay soil spiked with corn oil and reference oil at 1000 mg/kg each, and the same clay soil wetted to 30% water content and spiked with motor oil at 10 000 mg/kg (the latter 3 samples were extracted only once). Results indicated that the overall method accuracy for concentrations ranging from 614 to 32 600 mg/kg was 82.9%; the mean recoveries of petroleum hydrocarbons for each of the 4 solid matrixes ranged from 77.9 to 107% for analyses performed with the Perkin-Elmer Fourier transform IR spectrometer and from 75.9 to 101% for analyses performed with the Buck-Scientific IR spectrometer; the differences between the 2 instruments on a sample-bysample basis were less than 17% for the total petroleum hydrocarbon determinations. The interiaboratory method precisions (RSDR) appeared to be matrix-dependent and ranged from 17.3 to 45.4% for analyses performed with the Perkin- Elmer Fourier transform IR spectrometer and from 16.7 to 47.9% for the Buck-Scientific IR spectrometer. The intralaboratory method precisions (RSDr) appeared to be less matrix-dependent and ranged from 11.5 to 17.0% for analyses performed with the Perkin-Elmer FTIR spectrometer and from 11.1 to 18.2% for the Buck-Scientific IR spectrometer. Method accuracy and precision data are also presented for the 5 laboratories that used Isco supercritical fluid extraction systems and for the 7 laboratories that used vessels with volumes of 3.5 mL or less with different supercritical fluid extraction systems.
Continuous Flow and Liquid Chromatographic Determination of p-Toluenesulfonamide in Ice Cream: Interlaboratory Study
Authors: Beljaars Paul R , Dijk Remmelt Van , Brands Arie ,   Collaborators:, Anderegg M , Arnold M , Bodegraven P J , Bosman I , Burgers L , Gend H W , van der Horst G M , Hoven K , Kaman R , Leeuwen W van , Lukkenaer J , Nijboer L , Roukema J , Scholten J , Sens J , van Veldhuizen C J , Visschedijk M B C , Wijma E
Published: February 2020

A collaborative study of the continuous flow (CF) and liquid chromatographic determination of p-toluenesulfonamide (p-TSA) in ice cream was conducted by the Project Group on Collaborative Studies (PCS) of the Inspectorate for Health Protection, Food Inspection Service, The Netherlands. The procedure involves extraction of samples with water followed by cleanup of the extracts by dialysis in the CF system. Dialysates are injected by using a loop injector (500 μL) on a reversed-phase octadecylsilane bonded-phase (C18) column, chromatographed with methanol-water (25 + 75, v/v) as mobile phase, and quantitated by fluorescence detection at 230 nm (excitation) and 295 nm (emission). Seven ice-cream samples containing 0-6.35 mg/kg p-TSA at 4 different levels (1 blank and 3 pairs of split-level samples) were singularly analyzed according to the proposed procedure by 11 laboratories. The data were analyzed by the International Union of Pure and Applied Chemistry/ International Organization for Standardization/ AOAC protocol for statistics. No Cochran and Grubbs outliers were found among the participants. For all samples analyzed, repeatability relative standard deviations (RSDr) varied from 2.08 to 3.67%, whereas the reproducibility relative standard deviations (RSDR) ranged from 7.79 to 11.68%. The average p-TSA values for the split levels 1,2, and 3 were 0.55, 1.02, and 4.44 mg p-TSA/kg, respectively, with mean recoveries ranging from 76 to 79% (overall recovery range for all levels, 63-101%). No false-positive results were reported for the blank sample, and no interference was encountered by the presence of vanilla in samples.
Oligosaccharide Generation in Acidic Sugar Media
Authors: Cancalon Paul F
Published: February 2020

Oligosaccharides were shown to be present in beet medium invert sugar, but the origin of these molecules has remained obscure. The present study reveals that oligosaccharides are not a contaminant of purified beet sucrose. They appear during sucrose hydrolysis but are not specific to inversion. Sugars in a solution containing hydrogen ions generate oligosaccharides whose nature and proportion is determined by the original sugar composition. Because the sugar composition changes constantly during the course of sucrose inversion, the oligosaccharide pattern of a medium invert sugar is determined by the sugar distribution existing when the hydrolysis is stopped. As a consequence, the oligomer composition of a solution does not depend on the botanical origin of the sugar. Nearly identical oligosaccharide profiles were obtained from beet, cane, and citrus saccharides inverted in the laboratory or obtained from an industrial source. The amount of oligomers generated by an acidic solution increases exponentially with the sugar concentration. In diluted medium invert sugar solutions or in single-strength juices, the equilibrium between monomers and oligomers shifts toward depolymerization and eventually leaves only monosaccharides. In concentrated solutions of sugars or citrus juices, on the other hand, the process is directed toward oligomerization. These reactions occur slowly at room temperature but are greatly sped up by temperature. Therefore, results from the quantitation of oligosaccharides should be carefully interpreted if an accurate monitoring of medium invert sugar adulteration is to be performed. The nature of the product (single-strength or concentrate) and the types of treatment to which the product was submitted must be considered. Although monitoring of oligosaccharides provides a rapid method for the detection of added invert sugar, some results may need to be corroborated by methods such as isotopic analysis.
Simultaneous Determination of Xylazine and Its Major Metabolite, 2,6-Dimethylaniline, in Bovine and Swine Kidney by Liquid Chromatography
Authors: Holland David C , Munns Robert K , Roybal José E , Hurlbut Jeffrey A , Long Austin R
Published: February 2020

A liquid chromatographic (LC) method is described for the simultaneous determination of xylazine (XY) and its major metabolite, 2,6-dimethylaniline (2,6- DMA), in bovine and swine kidney in the 25– 100 ppb range. XY and 2,6-DMA are extracted from kidney with chloroform, followed by cleanup on an acidic Celite 545 column. A μBondapak phenyl column is used for LC separation with UV determination at 225 nm. The mobile phase is a mixture of acetonitrile, water, sodium acetate, and acetic acid. Mean recoveries from bovine kidney were 78.3% for XY, with a standard deviation (SD) of 7.45 and a coefficient of variation (CV) of 9.51 %, and 87.2% for 2,6-DMA, with an SD of 8.38 and a CV of 9.61 %. Mean recoveries from swine kidney were 80.8% for XY, with an SD of 5.92 and a CV of 7.33%, and 86.7% for 2,6-DMA, with an SD of 6.16 and a CV of 7.10%.
Combustion Method for Determination of Crude Protein in Meat and Meat Products: Collaborative Study
Authors: Marcia King Brink , Joseph G. Sebranek ,   Collaborators:, Anthony C , Coleman P , Cottingham B , Culmo R , Curtis R , Dingman L , Johnson R , Lehman G , Loughran J , Martinez S , Moody J , Paisley C , Radloff H , John A St , Schrader E , Sizemore J , Wenger J , White G
Published: February 2020

Twelve laboratories participated in a collaborative study to compare a combustion method with the AOAC mercury catalyst Kjeldahl method (928.08) for the determination of crude protein in meat and meat products. Three different combustion instruments were used; consequently, the combustion method for this study is written in generic terms describing the principle, the apparatus specifications, and the performance requirements needed. Fifteen sample pairs were used for the study; each pair consisted of the same commercial meat product from each of 2 different manufacturers. Protein content of all samples ranged from about 10 to 20%. In addition, nicotinic acid and lysine monohydrochloride were used as standards to assess combustion equipment performance. All laboratories and all instruments performed the combustion method satisfactorily on the basis of results for the standards. For the meat samples, repeatability standard deviations (sr) ranged from 0.11 to 0.40 for the Kjeldahl method and from 0.12 to 0.41 for the combustion method; the repeatability relative standard deviations (RSDr) ranged from 0.82 to 2.41% and from 0.60 to 2.23% for the Kjeldahl and combustion methods, respectively. Reproducibility standard deviations (SR) ranged from 0.20 to 0.49 for the Kjeldahl method and from 0.18 to 0.46 for the combustion method, whereas the reproducibility relative standard deviations (RSDR) ranged from 1.59 to 2.84% for the Kjeldahl method and from 1.32 to 3.35% for the combustion method. Overall grand means were 15.59% protein for the Kjeldahl method and 15.75% protein for the combustion method. The combustion method was adopted first action by AOAC International.
Determination of Free and Bound Cd, Zn, Cu, and Ag Ions in Lobster (Homarus americanus) Digestive Gland Extracts by Gel Chromatography Followed by Atomic Absorption Spectrophotometry and Polarography
Authors: Chou Chiu L , Uthe John F , Guy Robert D
Published: February 2020

Gel-permeation chromatography followed by atomic absorption spectrophotometric and polarographic analyses were used to measure free and bound divalent metal ions in lobster digestive gland extracts prepared with or without oc-toluenesulfonyl fluoride, a protease inhibitor. Chromatography on Sephadex G-50 or G-100 yielded 3 UV-absorbing peaks, which corresponded, respectively, to the void volume, a medium molecular weight fraction, and a low molecular weight fraction that contained free divalent metal ions. In protease-inhibited extracts, only Zn+2 was found, whereas Cd, Cu, and Ag were bound in high and medium molecular weight fractions. Cd+2 and Zn+2 were rapidly released from their bound forms in the absence of a protease inhibitor, and their presence was confirmed by polarography with EDTA. Gel-permeation chromatography coupled with atomic absorption spectrophotometry offers a rapid method for following changes in the concentrations of bound and free metal ions during processing of shellfishbased foodstuffs.
Ochratoxin A in Cow’s Milk and in Human Milk with Corresponding Human Blood Samples
Authors: Breitholtz-Emanuelsson Anna , Olsen Monica , Oskarsson Agneta , Palminger Ira , Hult Karl
Published: February 2020

A method for determining ochratoxin A in milk has been elaborated in which the sample was subjected to a liquid-liquid extraction step and then purified on a silica gel column packed in a Pasteur pipet. The purified samples were analyzed by ion-pair liquid chromatography with fluorescence detection. The detection and quantitation limits for determination of ochratoxin A in cow’s milk were 10 and 40 ng ochratoxin A/L milk, respectively. The same limits were valid for the analysis of human milk. A total of 36 cow’s milk and 40 human milk samples were analyzed. All samples were collected in Sweden. Ochratoxin A was found in 5 (14%) of the cow’s milk samples (range 10-40 ng/mL) and in 23 (58%) of the human milk samples (range 10-40 ng/L). Blood samples were collected from the mothers who gave milk samples. A total of 39 samples were analyzed. All blood samples contained ochratoxin A in concentrations exceeding the quantitation limit (60 ng/L blood). The mean concentration of ochratoxin A in the samples was 167 ng/L blood (range 90-940 ng/L). The concentration of ochratoxin A in human milk was ≤0.1 of that in the human blood.
Determination of Methyl 2-Benzimidazolecarbamate in Wine by Competitive Inhibition Enzyme Immunoassay
Authors: Bushway Rodney J , Paradis Lance R , Perkins Lewis B , Fan Titan S , Young Barbara E S , Walser Paul E
Published: February 2020

A benomyl polyclonal enzyme immunoassay (EIA) commercial kit was used to quantitate methyl 2- benzimidazolecarbamate (MBC), a degradation product of benomyl in wine. Total analysis time, including sample preparation, was 30 min. As many as 8 samples can be analyzed simultaneously with a limit of quantitation of 5 ppb. The assay logarithmic response was linear from 0.4 to 26 ppb MBC. Intra-assay percent coefficients of variation (%CVs) ranged from 2.4 to 13 for standards and from 7.4 to 21 for actual wine samples. Interassay %CVs varied from 2.6 to 15 for the standards and from 6.9 to 23 for the samples. Average recovery from samples spiked at 10–10 000 ppb was 93% for evaporated red and white wines. MBC was determined in 134 different wines by immunoassay and liquid chromatography (LC). Of these samples, 98 were positive for MBC by both methods with a correlation coefficient (r) of 0.986. The other 36 samples had MBC levels that either were not detectable by either procedure or were below the 10 ppb limit of quantitation for LC. Concentrations of MBC in wine ranged from 5 to 1329 ppb, with the majority ranging from 10 to 300 ppb. Also, a mini-study was conducted using the plate EIA format.
Supercritical Fluid Extraction of Poultry Tissues Containing Incurred Pesticide Residues
Authors: Snyder Janet M , King Jerry W , Rowe Loyd D , Woerner Julie A
Published: February 2020

A method using supercritical carbon dioxide to extract fat from poultry tissue was developed. Tissues used in this study were peritoneal fat, breast tissue, leg and thigh tissue, and liver from chickens fed rations containing heptachlor, dieldrin, and endrin. The fat was isolated from the peritoneal tissue by supercritical fluid extraction (SFE) and by thermal rendering. The fat was removed from the breast tissue, leg and thigh tissue, and liver by SFE and solvent extraction. The results indicate that recoveries of organochlorine pesticide from the peritoneal, breast, leg, and thigh tissues by SFE extraction are equivalent to those obtained by conventional extraction methods. The pesticide recoveries by SFE extraction of the liver were higher than those obtained by solvent extraction.
pH Method for Determination of Cholinesterase in Whole Blood: Collaborative Study
Authors: Imerman Paula Martin ,   Collaborators:, Banton M , Casteel S , Edwards W , Everson R , Felice L , Holcomb M , Landgraf W , Magera M , Reagor J , Rottinghaus G
Published: February 2020

A collaborative study of an indirect method for determination of cholinesterase activity was conducted with cattle blood. Ten collaborators analyzed 8 samples of varying degrees of cholinesterase inhibition. The sample is diluted with a buffer, and the pH change that results from the hydrolysis of acetylcholine is monitored. Repeatability relative standard deviations (RSDr) ranged from 6.6 to 8.6%, and reproducibility relative standard deviations (RSDR) ranged from 10.7 to 17.3% for mean activities of 0.60-0.40 ΔpH/h. All samples that were completely inhibited were detected. The method was adopted first action by AOAC International for determination of cholinesterase activity in whole bovine blood.
Structures and Environmental Significance of Heptachlor Epoxide Isomers
Authors: Donnelly Joseph R , Sovocool G Wayne , Titus Richard L
Published: February 2020

Historically, both endo- and exo-epoxides of heptachlor are known. The exo-epoxy isomer of heptachlor epoxide is a remarkably stable metabolite of heptachlor and is generally found in the environment where heptachlor was introduced. In this study, the nuclear magnetic resonance and mass spectral characteristics of the 2 epoxide-containing isomers ("A" and "B") were investigated to verify their structural assignments. We believe that the metabolite, Isomer B, is the only isomer found in the environment resulting from environmental contamination by chlordane and heptachlor.
Determination of Pesticides in Indoor Air and Dust
Authors: Roinestad Kurt S , Louis Judith B , Rosen Joseph D
Published: February 2020

Improved analytical and sampling methods were developed for the multiresidue determination of pesticides in indoor air. Air analysis consists of adsorption of the pesticides in 1 m3 of air onto Tenax TA via an air sampling pump, desorption with acetone, and determination and quantitation by gas chromatography/mass spectrometry (GC/MS) with chemical ionization on an ion trap mass spectrometer. Limits of detection for the 23 pesticides studied ranged from 0.5 ng/m3 for chlorpyrifos and diazinon to 30 ng/m3 for o-phenylphenol (approximately 0.5-30 parts per trillion on a w/w basis). A simple method for the detection of pesticides in dust was also developed. This method involves emptying the contents of a vacuum cleaner bag into a standard household food processor and extracting 1 g homogenized dust with acetone before GC/MS. Limits of detection were 25-100 ppb because of interferences by common household chemicals. However, pesticide concentrations were higher in dust than in air, therefore, analysis of dust is a better indicator of indoor pesticide exposure.
Pesticide Residues in Composited Milk Collected Through the U.S. Pasteurized Milk Network
Authors: Trotter William J , Dickerson Richard
Published: February 2020

The U.S. Food and Drug Administration (FDA) has implemented a comprehensive monitoring program to determine the incidence and levels of organohalogen pesticide residues in milk representing most of the U.S. supply consumed in metropolitan areas. Residue findings for 806 composite milks collected through the Pasteurized Milk Program by the U.S. Environmental Protection Agency (EPA) in 1990-1991 are reported. Milk was collected on a monthly basis from 63 stations selected by EPA for radionuclide monitoring. These stations provide an estimated 80% of the milk delivered to U.S. population centers. At each station, milk from selected sources had been composited to represent the milk routinely consumed in its metropolitan area. Portions of these composites were forwarded to an FDA contract laboratory for pesticide residue analysis. Pesticide residues were found in 398 (49.4%) of 806 test samples, on the basis of a 0.0005 ppm limit of detection for each residue on a whole-product basis. A total of 455 occurrences of pesticide residues were found; p,p’-DDE and dieldrin accounted for 384 (84.4%) of these occurrences. The highest level was 0.019 ppm p,p’- DDE.
Determination of Paraquat and Diquat in Low-Moisture Food Crops Using Silica Column Cleanup and Liquid Chromatography with UV Detection
Authors: Chichila Tina M P , Gilvydis Dalia M
Published: February 2020

A sample cleanup method was developed for the determination of paraquat (PQ) and diquat (DQ) in low-moisture food crops. Low-moisture commodities, such as milled dry navy beans, are digested in acid. PQ and DQ are isolated from the digestates by using a 4 g column of preconditioned silica gel. The analytes are concentrated and then determined by liquid chromatography with a silica analytical column, sodium chloride as an ion-pairing reagent, and acetonitrile as an organic modifier. PD and DQ are determined simultaneously with a diode array UV absorbance detector. Recoveries for PQ and DQ were determined on 3 different fortified low-moisture crops. Fortification levels ranged from 0.01 to 0.30 ppm; average recoveries ranged from 47.5% (DQ) to 95.3% (PQ).
Interlaboratory Study of a Thermospray-Liquid Chromatographic/Mass Spectrometric Method for Selected N-Methyl Carbamates, N-Methyl Carbamoyloximes, and Substituted Urea Pesticides
Authors: Lopez-Avila Viorica , Jones Tammy L ,   Collaborators:, Anderson B , Behymer T , Christensen R , Dougherty T , Getek T , Ilnicki L , Richards D , Shalaby L , Vestal C
Published: February 2020

A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3 N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pesticides (diuron and linuron), and 1 ester of a substituted carbamic acid (carbendazim). The purpose of this study was to establish whether these 9 compounds can be reliably detected and quantitated with this method, and to establish the interlaboratory precision and accuracy of the method with currently available instrumentation. The study design was based on AOAC INTERNATIONAL’S blind replicate design with balanced replicates. The samples consisted of solutions of the 9 test compounds in methanol at 3 concentrations that were unknown to the participating laboratories and that covered the linear range of the method. Nine volunteer laboratories participated in the study. Linear regression equations are presented that calculate the accuracy of the method, i.e., the percent recovery of each of the 9 compounds at any concentration within the range of concentrations tested (5–90 (μg/mL for each compound, except carbendazim, for which the range was 1.25–22.5 μg/mL). The intra laboratory precisions of the TS-LC/MS method ranged from 6.5 to 33.1 % relative standard deviation, depending on the compound. The interlaboratory method precisions ranged from 29.8 to 98.2% relative standard deviation over the concentration range tested. Analysis of variance indicates that for all compounds tested, the variation from laboratory to laboratory is greater than that attributed to analytical error displayed within laboratories. There are many operational parameters that could contribute to interlaboratory variability; one of them, the thermospray tip temperature, can play a major role in adduct formation and ion fragmentation in the case of thermally labile carbamate pesticides and, therefore, needs to be monitored and controlled carefully. The correlation of mass spectral data with the thermospray tip temperature was attempted using principal component analysis.
Determination of Formetanate Hydrochloride in Selected Fruits by Coupled-Column Cation Exchange Liquid Chromatography
Authors: Niemann Richard A
Published: February 2020

A strong cation exchange (SCX) liquid chromatographic (LC) method is described for determination of formetanate hydrochloride residue in pome, citrus, and stone fruits. A test portion of fruit, homogenized with the peel left on, was blended with acidified acetonitrile and filtered. A portion of extract was finely filtered, and a 500 μL aliquot (ca 0.2 g test sample equivalent) was loaded onto an SCX solid-phase extraction (SPE) LC column, which replaced the injection loop of the LC injection valve. Cations were selectively enriched; noncations were eluted by acetonitrile in a pre-separation cleanup. Turning the valve to the inject position coupled the SPE column to an SCX analytical column for separation and detection at 250 nm. The mobile phase was 0.4M pH 3.0 ammonium phosphate buffer–water–acetonitrile (50 + 25 + 25). Formetanate cation was quantitated by peak area and regression coefficients from a 5-point linear calibration covering a 100-fold range. Recovery of duplicate fortifications of apple, pear, orange, and peach averaged 89–99% at the respective U.S. tolerances of 3,3,4, or 5 ppm and averaged 93–99% at onetenth of the respective tolerance level. Peel pigments or variable peel bulk of crop varieties tested, as well as other endogenous fruit material, contributed interference that was below the 0.02 ppm limit of detection. In a 1991 limited survey comprising 15 samples, none were found violative. Residues were found in 2 samples, but only 1 measurement was quantifiable, near the 0.06 ppm limit of quantitation.
Fluorometric Determination of Total and Bound Sulfite in Wine by N-(9-Acridinyl)maleimide
Authors: Akasaka Kazuaki , Ohrui Hiroshi , Meguro Hiroshi , Suzuki Tateo , Miwa Harufumi
Published: February 2020

N-(9-Acridinyl)maleimide (NAM) reacts with sulfite in wine and gives strong fluorescent derivatives that lead to highly sensitive fluorometry of both total and bound sulfite in wine. Values of free and bound sulfite in wine determined by the NAM method and the modified Rankine method agreed. Sulfite was determined in <200 μL wine within 2 h.
Determination of Sulfur Dioxide in Wines and Beverages by Flow Injection Analysis with Reductive Amperometric Detection and Electrolytic Cleanup
Authors: Cardwell Terence J , Cattrall Robert W , Nan Chen Guo , Cardwell Terence J , Scollary Geoffrey R , Hamilton Ian C
Published: February 2020

A new flow injection method is described for the determination of sulfur dioxide in red and white wines and other beverages. A dual-electrode electrochemical detector eliminates interferences by reduction at an upstream coulometric electrode before reductive detection of sulfur dioxide at the amperometric electrode. The data for free and total sulfur dioxide in wines and other beverages agree well with those obtained by the standard aspiration oxidation method.