bluuebunny/crossref_metadata_2025 huggingface dataset:
U.S. Food and Drug Administration Monitoring of Pesticide Residues in Infant Foods and Adult Foods Eaten by Infants/Children
Authors: Yess Norma J , Gunderson Ellis L , Roy Ronald R
Published: February 2020

The U.S. Food and Drug Administration uses 3 approaches to monitor pesticide residues in foods: regulatory monitoring, incidence/level monitoring, and the Total Diet Study. The results of monitoring infant foods and adult foods that may be eaten by infants/children under these 3 approaches are presented. Under regulatory monitoring, which is performed to enforce tolerances set by the U.S. Environmental Protection Agency (EPA), during fiscal years 1985-1991, over 10 000 such domestic and imported food samples were collected and analyzed, and under the Total Diet Study, in which pesticide residue intakes are estimated in foods prepared for consumption, the food items in 27 market baskets were analyzed. Under incidence/level monitoring, which is complementary to regulatory monitoring, over 4000 analyses were performed on infant foods and adult foods eaten by children. Fewer than 50 of the 10 000 regulatory samples had violative residues; nearly all of those were residues for which there was no tolerance for the particular commodity/pesticide combination. Under incidence/ level monitoring and the Total Diet Study, the levels of pesticide residues found in infant foods and adult foods eaten by children were well below tolerances set by EPA.
Improved Liquid Chromatographic Determination of Neomycin B in Bovine Kidney
Authors: Shaikh Badar , Jackson Jean
Published: February 2020

An improved liquid chromatographic (LC) method was developed for the determination of neomycin B in bovine kidney tissue. The tissue is homogenized twice in phosphate buffer; homogenate is centrifuged, and the supernatant is deproteinated by heat. The extract is acidified and mixed with ionpair concentrate, and neomycin B is determined by an LC system consisting of an ion-pairing mobile phase, a reversed-phase ODS column, postcolumn derivatization with o-phthalaldehyde reagent, and fluorometric detection. Average recoveries of neomycin B from kidney tissues spiked at 3,6, and 12 ppm were 103, 99, and 104%, with 9.7,7.9, and 3.7% intralaboratory coefficients of variation, respectively, using a standard curve prepared in buffer. The method was used to determine neomycin B in kidney tissue obtained from a calf killed 14 days after intramuscular dosing with neomycin (5 mg/lb). The tissue was found to contain about 3 ppm neomycin B. The LC conditions were also used to assay control samples of muscle, liver, milk, plasma, and urine. No interfering peaks were noted at the elution position of neomycin B.
Optimization of a Liquid Chromatographic Method for Determination of Oxytetracycline, Tetracycline, and Chlortetracycline in Milk
Authors: White C R , Moats W A , Kotula K L
Published: February 2020

A liquid chromatographic (LC) method was developed for the simultaneous identification and quantitation of oxytetracycline, tetracycline, and chlortetracycline in milk. Milk samples (5 mL) were deproteinized by adding 1 mL 1N HCI and 24 mL acetonitrile, and filtering. Dichloromethane and hexane were added to 15 mL filtrate to separate the water layer. The organic layer was washed with 1 mL deionized water, and the combined water layers were diluted to 4 mL. Sample aliquots of 1000 μL were then injected directly and analyzed on an LC system. The sensitivity limit of the method is 5 ppb for each antibiotic; no interferences are present at their retention times. Mean recoveries from milk spiked at 0.01-1 ppm ranged from 87 to 99%, and precision was good.
Liquid Chromatographic Determination of Abamectin in Fruits and Vegetables
Authors: Chamkasem Narong , Papathakis Michael L , Lee S Mark
Published: February 2020

A simplified extraction and cleanup procedure was developed for determining abamectin in fruits and vegetables. Abamectin is extracted from sample matrices by acetonitrile, and the acetonitrile phase is separated from the aqueous phase by saturating the extract with sodium chloride. Abamectin is then partitioned into hexane from the acetonitrile, and the hexane layer is cleaned up with an aminopropyl solid-phase extraction (SPE) system. The fluorescent abamectin derivative is formed by dehydration with trifluoroacetic anhydride-1-methylimidazole in dimethylformamide for 1 h at 30°C and with methanolic ammonium hydroxide for another 30 min at 30°C. The derivatized residues are separated from the reaction mixture by a silica SPE. The abamectin derivative is determined by reversedphase liquid chromatography with a fluorescence detector. The method yields recoveries of 85-97% at fortification levels of 10 and 50 μg/kg for orange, pears, spinach, and celery.
Organochlorine Pesticides and Polychlorinated Biphenyl Congeners in Commercial Fish from the Great Lakes
Authors: Newsome W Harvey , Andrews Paul
Published: February 2020

Fillets from 11 species of commercial fish from the Great Lakes were analyzed for residues of 39 polychlorinated biphenyl (PCB) congeners and 24 other organochlorine compounds. Eel and trout contained the highest amount of PCB (753 and 633 ppb wet weight, respectively) and other organochlorines (607 and 1404 ppb, respectively); perch and carp contained the lowest residues. The pentaand hexachlorinated PCBs were the major congeners in all species except whitefish, in which the tetrachlorinated congeners predominated. Toxaphene was the most abundant organochlorine pesticide in trout; p,p′ -DDE was the major component of this class in eel. Residue concentrations in commercial carp were compared with residues present in carp from a fishery closed to commercial operation. Although both PCB and organochlorine pesticide levels in carp were among the lowest for all commercial fish samples, levels from the contaminated area were among the highest.
Detection of Salmonella in Dry Foods Using Refrigerated Pre-Enrichment and Enrichment Broth Cultures: Interlaboratory Study
Authors: D’Aoust Jean-Yves , Sewell Anne M , Greco Paula ,   Collaborators:, Benson J , Boleszczuk P , Brodsky M , Cirigliano M , Coignaud C , Fain A , Flowers R , Gour L , Hamann W T , Huszczynski G , Jesset K , Konkel P , Lacasse P , Laffey P J , Laperriere G , Mclntyre K , Morrow A , Oggel J , Philippe L M , Purvis U , Richter E R , Thomas M D , West W , Zandstra W
Published: February 2020

An interlaboratory study was performed in 11 laboratories to validate the use of pre-enrichment and tetrathionate brilliant green (TBG35) and selenite cystine (SC35) enrichment cultures refrigerated 72 h at 2-5°C for greater analytical flexibility in the detection of Salmonella in dry foods. Productivities of refrigerated pre-enrichment and enrichment cultures were compared with that of the AOAC/Bacteriological Analytical Manual (BAM) procedure using 4 food types: whole egg powder, milk chocolate, animal feed, and instantized skim milk powder. Uninoculated and inoculated samples were included in each food group. There was complete agreement between the results obtained by the standard AOAC/BAM procedure and the 2 refrigeration procedures. Of 660 samples tested, the AOAC/BAM procedure identified 393 contaminated samples that were readily detected from the corresponding refrigerated pre-enrichment cultures and from the combined productivity of homologous refrigerated TBG35 and SC35 cultures. Refrigeration (72 h) of preenrichment or enrichment cultures for greater analytical flexibility and laboratory productivity in the examination of dry foods is under review for adoption by AOAC International.
AutoMicrobic System for Biochemical Identification of Listeria Species Isolated From Foods: Collaborative Study
Authors: Harris Loralyn , Humber John ,   Collaborators:, Agin J , Black J , Boling R , Calicchia M , Cooper C , Dickinson S , Heisick J , Kelly M , Knight M , LaClair D , Marshall C , Newman S , Presla L , Romine A , Schulke M , Scott J , Scott T , Sivey C , Tardio J , Twohy C , Vorhies I , Wagner T , Wazenski T
Published: February 2020

A collaborative study was conducted to evaluate the performance of the AutoMicrobic System Gram- Positive Identification (GPI) and Gram-Negative Identification (GNI) test kits to biochemically characterize Listeria spp. Thirteen laboratories each tested 97 food and environmental isolates, representing the 7 species of Listeria, as well as 11 additional genera of Gram-positive rods. Each collaborator inoculated both a GPI and a GNI card with a pure culture of each organism. The AutoMicrobic System identified the isolates and printed out the biochemical results. The GPI card is used to obtain a species identification and a mannitol reaction result, and the GNI card is used to obtain rhamnose and xylose reaction results. Organisms are classified into species groups and can be further distinguished on the basis of hemolysis or nitrate reduction tests. The AutoMicrobic System method correctly classified 90.8% of the Listeria spp. isolates and 100% of the non-Listeria isolates. The AutoMicrobic System method was adopted first action by AOAC International for the biochemical characterization of Listeria spp. isolated from food and environmental sources.
Rapid and Accurate Method for Determination of Niclosamide Released from Molluscicidal Formulations
Authors: Emara Laila H
Published: February 2020

A rapid, simple, and reproducible method was developed for quantitative determination of niclosamide ethanolamine salt (NES) — the most widely used molluscicide against snail vectors of schistosomiasis — in both distilled and natural canal waters. The biocide is extracted completely from water samples by passing through Sep-Pak C18 cartridge and eluting the cartridge with methanol. The eluate is then analyzed directly for NES by UV/vis spectrophotometry at 330 nm. This method was found sensitive enough to detect 0.1–5 ppm, and it is highly reproducible (standard deviation, 0.006–0.012). The standard curve obeyed Beer’s law. The method also successfully measured the release rate of NES from controlled-release elastomeric formulations. The release study suggests that NES loading and certain rubber additives are not the key factors that govern the release of the biocide.
Evaluation of Soxtec Extraction Procedure for Extracting Organic Compounds from Soils and Sediments
Authors: Lopez-Avila Viorica , Bauer Karin , Milanes June , Beckert Werner F
Published: February 2020

A study was carried out to evaluate the Soxtec extraction of 29 target compounds (7 nitroaromatic compounds, 3 haloethers, 7 chlorinated hydrocarbons, and 12 organochlorine pesticides) from spiked sandy clay loam and clay loam. The study also compared 2 solvent mixtures (hexane–acetone (1 + 1) and methylene chloride–acetone (1 + 1)) and investigated the effect on method recovery of 5 factors (matrix type, spike level, anhydrous sodium sulfate addition, total extraction time, and immersion/ extraction time ratio), their 2-way interactions, and a 3-way interaction (matrix × spike × time). Of the 5 factors investigated, matrix type, spike level, and total extraction time had a significant effect on method performance at the 5% significance level for 16 of the 29 target compounds (4 compounds were not recovered at all, and analysis of variance was not significant at the 5% significance level for 9 compounds). Anhydrous sodium sulfate addition and immersion/extraction time ratio had insignificant effects for all but one of the target compounds. This effect may have been a random occurrence. The data indicate that the 2 solvents performed equally well and 4 compounds were not recovered at all. These 4 compounds were apparently lost from the spiked matrix. Experiments were performed to determine compound recovery at each step in the extraction procedure. Limited experimental work was performed with 64 basic/neutral/acidic compounds spiked onto clay loam and with 3 standard reference materials certified for polynuclear aromatic hydrocarbons. From the 64 compounds spiked onto clay loam at 6 mg/kg, 20 had recoveries of greater than 75%, 22 had recoveries from 50 to 74%, 12 had recoveries from 25 to 49%, and 10 had recoveries of less than 25%.
Liquid Chromatographic Method for Determination of Diquat and Paraquat Herbicides in Potatoes: Collaborative Study
Authors: Worobey Brian L ,   Collaborators:, Béraldin F , Bruns G , Embleton J , Heck A , King R , McLeod K , Ward R
Published: February 2020

A liquid chromatographic (LC) method for the determination of diquat and paraquat herbicides/desiccants in potatoes was collaboratively studied in 6 laboratories. Analytes are extracted from 5 g sample with dilute acid by using a microreflux procedure; the hydrolysate is adjusted to pH 9–10 and passed through a disposable silica cartridge for rapid cleanup and preconcentration. Analytes are separated on a reversed-phase LC column and are measured as their heptanesulfonate ion pairs by UV detection. Each collaborator determined diquat and paraquat at 4 levels (0.05,0.1,0.5, and 1.0 ppm) in blind duplicate samples plus 2 blind negative control samples. Potatoes, obtained from each participant’s region, were spiked by the collaborators with unknown aqueous solutions containing no analyte or a mixture of diquat and paraquat standards. Repeatability and reproducibility relative standard deviations (RSDr and RSDR) averaged 17.1 and 29.0%, respectively, for determination of diquat and 10.8 and 29.5%, respectively, for paraquat. For analysis of standard solutions, RSDr and RSDR values were 6.3 and 12.0%, respectively, for diquat and 7.3 and 13.9%, respectively, for paraquat. Accuracy, measured by comparison with true spiking values (absolute recovery) averaged 77.6 and 76.2% for diquat and paraquat, respectively, and ranged from 71.8 to 88.0% for both compounds. The method was adopted first action by AOAC International.
Simple Method for Determination of Dietary Fiber in Frozen Foods
Authors: Al-Hasani Sami M , Hlavac Jan , Huntsman Mark A
Published: February 2020

A simple method was developed for the determination of dietary fiber in multicomponent foods. The method involves dispersing the sample into pH 7.4 phosphate buffer and adding bile and pancreatic enzyme as described. Results were comparable to AOAC methods with correlation coefficients of 86% for multicomponent dinners and 89% for breakfast foods. Coefficients of variation ranged from 7.4 to 20.0% for multicomponent foods and 1.0 to 3.6% for single component foods. In addition, blind duplicate samples had a correlation of 0.99. The described method required less time, labor, and manipulation than AOAC methods
A Simplified Alternative to the AOAC Official Method for Cholesterol in Multicomponent Foods
Authors: Thompson Raymond H , Merola George V
Published: February 2020

An AOAC official method for quantitating cholesterol in multicomponent foods, which was first published in the 13th edition of the Official Methods of Analysis, is rarely used. The method includes so many operations and manipulations—all described in excruciating detail—that most laboratories shun it altogether. Intent on finding an alternative, laboratories have developed their own methods for specific foods. As a result, new methods have proliferated, but still no practical method has been developed for the broader categories of multicomponent foods. The aim of AOAC, which is to promote greater accuracy and uniformity of analytical results primarily through collaborative testing, has not been well served under these circumstances. A different approach guided the work reported in the present paper. This approach was directed toward updating and dramatically simplifying the existing AOAC official method. The method's chloroformmethanol-water mixed-solvent extraction is preserved; however, all the remaining steps have been streamlined, updated, or eliminated by using newer technology. Cholesterol is quantitated with highly specific capillary gas-liquid chromatography using the internal standardization technique. The lipid extract is prepared for the chromatography step by a brief saponification carried out in a culture tube. The resulting method has been validated by using Standard Reference Materials and the standard addition method. Because a simplified method is now available for quantitating cholesterol in the lipid extracts, the expectation is that more attention can be given to the development of improved and efficient extraction methods. This step remains as the central difficulty in any number of methods of analysis for lipid analytes.
Gas Chromatographic/Electron Capture Detection Method for Determination of Chlorinated Acids in Water: Collaborative Study
Authors: Edgell Kenneth W , Erb Elizabeth J , Wesselman Raymond J , Longbottom James E ,   Collaborators:, Dodhiwala N , Fencl M , Hanisch R , Levan L , Manmade D , Neslund C , Wait D , Winslow M
Published: February 2020

A U.S. Environmental Protection Agency (USEPA) inter laboratory method validation study was conducted on USEPA Method 515.1, "Determination of Chlorinated Acids in Water by Gas Chromatography with an Electron Capture Detector. "This method is one of the 6 pesticide methods developed for the USEPA National Pesticide Survey (NPS). Method recovery and precision for analyses of sub-ppb to low-ppb concentrations of chlorinated acids were determined in reagent water and finished drinking waters. The analytes evaluated in the study included the 12 pesticides that were quantitatively measured in the National Pesticide Survey (bentazon, 2,4-D, 2,4-DB, 3,5-dichlorobenzoic acid, DCPA-diacid, dicamba, dichlorprop, 5-hydroxydicamba, pentachlorophenol, picloram, 2,4,5- T, and 2,4,5-TP) and 5 pesticides (acif luorfen, chloramben, dalapon, dinoseb, and 4-n it ro phenol) that were only qualitatively assessed in the National Pesticide Survey because of recognized method imprecision. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with 17 chlorinated acids, each at 6 concentration levels, prepared as 3 Youden pairs. Eight laboratories extracted the spiked test waters at pH <2 with ethyl ether, performed a solvent exchange with methyl tert-butyl ether, prepared methyl esters of the extracted acids using diazomethane, and analyzed an aliquot of each derivatized extract by gas chromatography with electron capture detection. The submitted data were analyzed using a USEPA computer program, which measured recovery and precision for each of the 17 compounds and compared the performance of the method between water types. Method 515.1 was judged acceptable for the 12 NPS analytes recovered quantitatively; mean percent recoveries at 10-15 times the method detection limits ranged from 79 to 105% in reagent water and from 75 to 123% in finished drinking water. In reagent water, overall precision (reproducibility relative standard deviation, RSDR) ranged from 9.6 to 34.2% and in finished drinking water, the RSDR ranged from 11.9 to 37.0%. Single-analyst precision (RSD for repeatability, RSDr) ranged from 5.8 to 17.7% in reagent water and from 4.6 to 27.9% in drinking water. Results for the 5 other NPS analytes were too inaccurate or imprecise and, for these compounds, supported use of the method for qualitative measurements only; the 5 compounds are not included in the adopted method. The method has been adopted first action by AOAC INTERNATIONAL for determination of residues of 12 chlorinated acids in finished drinking water.
Determination of Methylene Chloride Acceptability and Its "Purification" for Ethylenethiourea Methodology
Authors: Sack Chris A , Kendall Donald C , Krause Richard T
Published: February 2020

A liquid chromatographic-electrochermcal method for the determination of ethylenethiourea (ETU) residues uses methylene chloride in the cleanup. Distilled-in-glass grade methylene chloride produced erratic ETU recoveries ranging from 0 to 106% for vacuum rotary evaporation of the solvent. ETU recoveries were found to be dependent on the bottle of methylene chloride used, not on supplier or lot. When GC2 grade methylene chloride from Burdick &Jackson Laboratories was used, ETU recoveries ranged from 92 to 110%. "Acceptable" ETU recoveries were defined as those values between 90 and 110%. Passing "unacceptable" methylene chloride through a column containing anhydrous sodium sulfate, sodium carbonate, and alumina was found to adequately purify methylene chloride. Treated methylene chloride provided acceptable ETU recoveries for up to 1 month after "purification."
Liquid Chromatographic Determination of Glyburide (Glibenclamide) and Its Related Compounds in Raw Materials
Authors: Beaulieu Normand , Graham Susan J , Lovering Edward G
Published: February 2020

A liquid chromatographic method has been developed for the determination of glyburide and 3 known related compounds in drug raw materials. The lower limit of quantitation of the related compounds is about 0.02%. Evaluation of 9 drug raw materials revealed total impurities ranging from 0.17 to 0.65%. The relative standard deviation of the assay method is <1%.
Rapid Determination of Tryptophan in Intact Proteins by Derivative Spectrophotometry
Authors: Fletouris Dimitrios J , Botsoglou Nickos A , Papageorgiou Georgios E , Mantis Antonios J
Published: February 2020

A method for rapid determination of total tryptophan in intact proteins was developed. Sample is homogenized with 0.1 M sodium hydroxide, and the homogenate, if it contains suspended material, is centrifuged. Tryptophan is directly quantified in sample extract on the basis of its fourth-derivative UV absorption spectrum. Protein hydrolysis and/or extract purification is not required because the fourth-derivative transformation of the conventional analytical band around 285.5 nm virtually eliminates interferences arising from both tyrosine and other UV-absorbing components. When pure proteins were analyzed by the method, the values of tryptophan residues found coincided well with literature data based on sequence analysis. The applicability of the method was also tested on several food and feed ingredient samples selected to include a range of protein content and a variety of protein sources. Owing to its simplicity and reliability, the method is particularly recommended for everyday analysis of a large number of samples.
The Chinese Total Diet Study in 1990. Part II. Nutrients
Authors: Chen Junshi , Gao Junquan
Published: February 2020

This paper reports the intakes of 72 nutrients and their dietary sources obtained from the Chinese total diet study in 1990. Most of the nutrient intakes are close or equal to their corresponding recommended daily allowances (RDAs). Both the total energy intake (2203 kcal) and the proportions contributed by protein, fat, and carbohydrate meet the current Chinese RDAs and the World Health Organization (WHO) nutrient goals. The average protein intake was 64 g/day. The intake of essential amino acids all exceeded the Chinese RDA, and their proportions were generally consistent with the WHO recommended pattern. The average fat intake was 51.2 g/day (21.2% of the total energy intake). However, the dietary fat intake has been increasing significantly in the Chinese diet and the proportion of animal fat has reached 53% of the total fat intake. The total saturated:total monounsaturated:total polyunsaturated fatty acid ratio was 1.0:1.5:1.0. Although the average cholesterol intake was only 179 mg/day, it was 248 mg/day in the South 1 region. The intakes of thiamine and riboflavin were below the RDA. Retinol intakes in all the 4 regions were low. Most (80%) of the retinol (equivalent) intakes were from carotenoids. The average intake of total tocopherol was 89% of the RDA, and among the 4 regions, only the South 2 region has relatively low intake. The intakes of iron, copper, manganese, sodium, and phosphorus were adequate. The intakes of calcium, zinc, and potassium were insufficient, and intakes of selenium and magnesium were a little low. High sodium and low potassium intake is a traditional problem in the Chinese diet.
Simultaneous Determination of Nitrofurazone and Furazolidone in Shrimp (Penaeus vannamei) Muscle Tissue by Liquid Chromatography with UV Detection
Authors: Rupp Heidi S , Munns Robert K , Long Austin R
Published: February 2020

A liquid chromatographic (LC) method was developed for the simultaneous determination of nitrofurazone (NFZ) and furazolidone (FZD) in shrimp muscle tissue. The drugs are extracted from the tissue with acetonitrile, and the lipids and lipophilic pigments are removed from the extract with hexane. The remaining acetonitrile extract is evaporated by rotary evaporation, and the resultant residues are dissolved with LC-grade water, applied to a preconditioned C18 solid-phase extraction column, and eluted with acetonitrile. The acetonitrile eluant is then dried under nitrogen, and the resultant drug residues are dissolved with mobile phase and filtered. The drugs are determined by LC by using a C18 reversed-phase (octyldecylsilyl Hypersil) column, a mobile phase of acetonitrile- 1% aqueous acetic acid (25 + 75, v/v), and a photodiode array UV detector at 375 nm. NFZ and FZD were determined in shrimp tissue at each of 5 spiking levels (64,32,16, 8, and 4 ng drug/g tissue). Absolute recoveries ranged from 70.6 to 78.4%, and relative standard deviations ranged from 4.0 to 13.6%. The limit of detection of pure standard of each drug was approximately the equivalent of 1 ng drug/g tissue, and the limit of determination in a sample was 4 ng drug/g tissue.
Determination of Menthol in Honey by Gas Chromatography
Authors: Maojuan Li , Nelson Donald L , Sporns Peter
Published: February 2020

A gas chromatographic method was developed for the determination of L-menthol in honey at levels as low as 0.1 ppm. The method includes steam distillation and hexane extraction with an internal standard (2,6-dimethylphenol). Beehives treated to control Acarapis woodi over 21 days with 30-60 g L-menthol contained L-menthol residues in honey and beeswax. L-menthol was found only in treated portions of the hive and not later transferred to added honey supers. The highest levels of residues in honey (18 ppm) and beeswax (2790 ppm) were found when pure L-menthol was adsorbed into foam strips placed on top of the hives. L-menthol residues in honey were not reduced by storage in open containers at room temperature for up to 55 days. Untrained panelists could not detect L-menthol in honey until the levels approached 36 ppm.
Inductively Coupled Plasma Atomic Emission Spectrometric Determination of Tin in Canned Food
Authors: Sumitani Hidenobu , Suekane Sachiko , Nakatani Aya , Tatsuka Kiyoaki
Published: February 2020

Various canned foods were digested sequentially with HNO3 and HCI, diluted to 100 mL, and filtered, and then tin was determined by inductively coupled plasma atomic emission spectrometry (ICP/AES). Samples of canned Satsuma mandarin, peach, apricot, pineapple, apple juice, mushroom, asparagus, evaporated milk, short-necked clam, spinach, whole tomato, meat, and salmon were evaluated. Sample preparations did not require time-consuming dilutions, because ICP/AES has wide dynamic range. The standard addition method was used to determine tin concentration. Accuracy of the method was tested by analyzing analytical standards containing tin at 2 levels (50 and 250 (μg/g). The amounts of tin found for the 50 and 250 μg/g levels were 50.5 and 256 μg/g, respectively, and the repeatability coefficients of variation were 4.0 and 3.8%, respectively. Recovery of tin from 13 canned foods spiked at 2 levels (50 and 250 μg/g) ranged from 93.9 to 109.4%, with a mean of 99.2%. The quantitation limit for tin standard solution was about 0.5 μg/g.
Multiresidue Analysis of Pesticides in Wines by Solid-Phase Extraction
Authors: Holland Patrick T , McNaughton Donald E , Malcolm Colin P
Published: February 2020

A method is described for screening wine for 74 pesticide residues. Aliquots of wine (10 mL) are extracted with 500 mg C18–silica solid-phase extraction (SPE) columns after addition of carbophe-nothion internal standard at 0.1 mg/L. The column is washed with 20% ethanol–water (4 mL), and pesticide residues are eluted with 1 mL ethyl acetate. The extract is made up to 2 mL final volume with isooctane for screening by gas–liquid chromatography (GC) using a narrow-bore FSOT column (5% phenyl–95% methyl-silicone bonded phase) with effluent splitting to electron capture (ECD) and nitrogen–phosphorus (NPD) detectors. A second GC system, using a 50% phenyl–50% methyl-silicone FSOT column with effluent splitting to ECD and flame photometric detector (P mode), is used for confirmation. The SPE method was rapid, robust, and reproducible. Recovery of pesticides added at 0.2 mg/L were 70–110% for the majority of pesticides, with standard deviations (SDs) of 1–18%. Some highly polar pesticides gave low recoveries. At a fortification level of 1 mg/L in wine, 13 fungicides gave recoveries of 80–118%, with SDs of 2–14%. At 0.02 mg/L, some less stable pesticides exhibited enhanced recoveries due to the protective effects of coextractives during GC. Detection limits were 0.01–0.02 mg/L with no major interferences observed from a range of wines. The multiple GC column and detector combinations and the internal standard provided a high degree of assurance in the identification of residues in wine.
Liquid Chromatographic Determination of Bentazon in Technical and Formulated Products: Collaborative Study
Authors: Schmitt Thomas M
Published: February 2020

An isocratic reversed-phase liquid chromatographic (LC) procedure for measuring bentazon in commercial herbicide products and aqueous formulations was collaboratively studied by 16 laboratories. Samples are dissolved in LC eluent [0.075M sodium acetate–methanol (60 + 40)] and analyzed by LC on a 30 cm × 3.9 mm octadecylsilyl column with detection by UV absorbance at 340 nm. The quantity of active ingredient is determined by comparing the mean response factor (RF) of the sample to the mean RF of standards injected just before and after each pair of sample injections. The average relative standard deviation (RSDR) for 3 formulations studied was 1.54%; the RSDR for a technical sample was 0.77%. The method has been adopted first action by AOAC INTERNATIONAL.
Determination of Tylosin and Tilmicosin Residues in Animal Tissues by Reversed-Phase Liquid Chromatography
Authors: Chan Wayne , Gerhardt Geoff C , Salisbury Craig D C
Published: February 2020

A method for the simultaneous determination of ty-losin and tilmicosin residues in animal tissues is reported. Solid-phase extraction columns are used to isolate the drugs from tissue extracts. Determination is accomplished by reversed-phase liquid chromatography with UV detection at 287 nm. Mean recoveries from spiked tissues were 79.9% (coefficient of variation [CV], 8.1%) for tylosin and 92.6% (CV, 8.7%) for tilmicosin. Detection limits for tylosin and tilmicosin were 0.020 and 0.010 ppm, respectively.
Simultaneous Determination of Nitrofurazone, Nitrofurantoin, and Furazolidone in Channel Catfish (Ictalurus punctatus) Muscle Tissue by Liquid Chromatography
Authors: Rupp Heidi S , Munns Robert K , Long Austin R , Plakas Steven M
Published: February 2020

A liquid chromatographic (LC) method was developed for the simultaneous determination of nitro-furazone (NFZ), nitrofurantoin (NFT), and furazolidone (FZD) in catfish muscle tissue. The drugs were extracted from the tissue with acetonitrile, and the lipids were removed from the extract with hexane. The acetonitrile extract was evaporated by rotary evaporation, and the resultant drug residues were dissolved with LC mobile phase. The mixture was sonicated, centrifuged, and filtered. The drugs were determined by using LC with a Cie reversed-phase (ODS Hypersil) column, a mobile phase of acetonitrile–1 % aqueous acetic acid (25 + 75), and a photodiode array ultraviolet detector at 375 nm. NFZ, NFT, and FZD were each determined in catfish tissue at 5 fortification levels (80, 40, 20,10, and 5 ng drug/g tissue). Average recoveries of each of the 3 drugs at each level ranged from 70.7 to 101.5%, and relative standard deviations ranged from 2.2 to 18.6%. The limit of detection of each drug was approximately 1 ng drug/g tissue, and the limit of quantitation was 5 ng drug/g tissue. In the second part of the study, the method was used to determine nitrofuran residues incurred in catfish tissue. Live channel catfish were intravascularly dosed (10 mg/kg body wt) with NFZ to generate drug-incurred fish muscle tissue. Incurred NFZ levels exceeded 400 ng drug/g tissue at 2 h after dosing but decreased rapidly to approximately 1 ng drug/g tissue by 8 h after dosing, as determined by this method.
Determination of the Presence of Listeria monocytogenes in Milk and Dairy Products: IDF Collaborative Study
Authors: Twedt Robert M , Hitchins Anthony D , Prentice George A
Published: February 2020

A collaborative study was conducted on the recovery of viable Listeria monocytogenes from milk and dairy products (Camembert cheese, Limburger cheese, skim milk powder, and ice cream). Test portions were homogenized with Listeria-selective liquid enrichment medium and cultured at 30°C for 48 h. The enrichment culture was then subcultured onto a solid isolation medium at 37°C for 48 h. Suspected Listeria colonies were identified by appropriate conventional morphological, physiological, and biochemical tests. Five kinds of dairy matrixes were spiked with L. monocytogenes at 2 levels: 12 and 120 colony forming units (cfu)/25 g. Each of the 18 collaborating laboratories analyzed 15 blind test portions from each matrix, comprising 5 replicates at each spiking level and 5 uninoculated controls, for a total of 1350 analyses. The specificity of the method was 100%; its sensitivity was 94–100% at the high spiking level and 89–98% at the low spiking level, except for Limburger cheese, which was only 68%. No specificity or sensitivity differences were observed between laboratories for all matrixes at the high spiking level and for all except Limburger cheese at the low spiking level. The calculated 50% detection limit for all products except Limburger cheese was 1.6 cfu/25 g; the 50% detection limit for Limburger cheese itself was 4.1 cfu/25 g. The method was adopted first action by AOAC INTERNATIONAL.
Determination of Polychlorinated Biphenyls with Non-o-Chlorine Substituent in Aroclor Mixtures and in Soil Using Porous Graphitic Carbon Columns
Authors: Al-Haddad Ameera
Published: February 2020

Polychlorinated biphenyls (PCBs) with non-o-chlo-rine substituent were determined in several Aroclor mixtures and in PCB-contaminated soil samples. Non-o-CI substituted PCBs were isolated using porous graphitic carbon/liquid chromatographic columns. Columns of this type provide a simple, rapid, and efficient method for the isolation of these compounds from different types of sample matrixes. The average percent recovery of non-o-CI substituted PCBs from porous graphitic carbon columns was found to be 87%, with an average coefficient of variation of 3.1%.
The Persistence of Fecal-Borne Antibiotics in Soil
Authors: Gavalchin Jerrie , Katz Stanley E
Published: February 2020

One aspect of the use of antibiotics in animal agriculture, which to date has received modest attention, concerns the effects of antibiotics excreted by animals upon the environment. The persistence of 7 antibiotics that are commonly used in feeds was studied in a typical agricultural soil. The antibiotics studied were bacitracin (BAC), penicillin (PEN), streptomycin (STR), tylosin (TYL), bambermycins (BAM), erythromycin (ERY), and chlortetracycline (CTC). The level incorporated into the soil with feces was 5.6 μg antibiotic/g soil. After incubation in soil for 30 days at 30°C, 44% of CTC and 23% of BAC remained; however, no detectable amounts of TYL, ERY, BAM, STR, and PEN remained. At 20°C, 88% of CTC, 33% of BAC, and 25% of ERY remained after 30 days; however, no STR, BAM, TYL, and PEN could be found. At 4°C, essentially all of the CTC, ERY, and BAM; 23% of BAC; and 40% of TYL remained after 30 days; however, PEN and STR were undetectable.
Analysis of Penicillin G in Milk by Liquid Chromatography
Authors: Boison Joe O K , Keng Lily J-Y , Macneil James D
Published: February 2020

A liquid chromatographic (LC) method that was previously developed for penicillin G residues in animal tissues has been adapted to milk and milk products. After protein precipitation with sodium tungstate, samples are applied to a C18 solid-phase extraction cartridge, from which penicillin is eluted, derivatized with 1,2,4-triazole-mercuric chloride solution, and analyzed by isocratic liquid chromatography (LC) on a C18 column with UV detection at 325 nm. Quantitation is done with reference to penicillin V as an internal standard. Penicillin G recoveries were determined to be >70% on standards fortified at 3-60 ppb. Accuracy approached 100% using the penicillin V internal standard. The detection limit for penicillin G residues was 3 ppb in fluid milk. Samples may be confirmed by thermospray/LC at concentrations approaching the detection limit of the UV method.
International Validation Study for the Determination of Chloramphenicol in Bovine Muscle
Authors: Epstein Robert L , Henry Carolyn , Holland Kathleen P , Dreas John
Published: February 2020

A gas chromatographic (GC) procedure for the quantitation and GC/negative ion chemical ionization mass spectrometric (NICIMS) confirmation of chloramphenicol in calf muscle tissue was the subject of a validation study. Five analysts representing 5 laboratories in 4 countries participated in the quantitative method and analyzed 7 randomly numbered blind triplicates at 4 fortified and 3 incurred tissue concentrations on 3 separate days. The chloramphenicol concentrations ranged from 0 to 2.5 ppb. All data were reported to 3 significant figures. The coefficients of variation were 9.5-28.7% for repeatability and 14.6-38% over the study range for reproducibility. NICIMS data representing 3 laboratories in 3 countries successfully confirmed chloramphenicol in samples at 0.6 ppb or greater with no false positives in blank tissues.
Detection of Pork in Heated Meat Products by the Polymerase Chain Reaction
Authors: Meyer Rolf , Candrian Urs , Lüthy Jürg
Published: February 2020

A new method for the specific, sensitive, and semiquantitative detection of pork (Sus scrota) in heat-treated meat products has been developed. DNA was isolated from meat samples by using a DNA-binding resin and subjected to polymerase chain reaction (PCR) analysis. First, oligonu-cleotides yielding a specific 137-base-pair (bp) fragment from eucaryotic DNA amplified from a highly conserved region of the 18-S ribosomal gene was used to assess DNA quality. Second, the presence of pork DNA was determined with specific oligonu-cleotides yielding a 108-bp fragment amplified from the porcine growth hormone gene. The test detected pork in fresh or heated meat mixtures of pork in beef at levels below 2%. This approach was superior to commercially available immunological tests that were not able to detect levels of pork less than 20% in cooked meat or less than 10% in fresh meat.
Predicting the Distribution of Aflatoxin Test Results from Farmers’ Stock Peanuts
Authors: Whitaker Thomas B , Giesbrecht Francis G , Wu Jeremy , Hagler Winston M , Dowell Floyd E
Published: February 2020

Suitability of the negative binomial function for use in estimating the distribution of sample aflatoxin test results associated with testing farmers1 stock peanuts for aflatoxin was studied. A 900 kg portion of peanut pods was removed from each of 40 contaminated farmers1 stock lots. The lots averaged about 4100 kg. Each 900 kg portion was divided into fifty 2.26 kg samples, fifty 4.21 kg samples, and fifty 6.91 kg samples. The aflatoxin in each sample was quantified by liquid chromatography. An observed distribution of sample aflatoxin test results consisted of 50 aflatoxin test results for each lot and each sample size. The mean aflatoxin concentration, m; the variance, s2xamong the 50 sample aflatoxin test results; and the shape parameter, k, for the negative binomial function were determined for each of the 120 observed distributions (40 lots times 3 sample sizes). Regression analysis indicated the functional relationship between k and m to be k = 0.000006425m0.8047. The 120 observed distributions of sample aflatoxin test results were compared to the negative binomial function by using the Kolmogorov–Smirnov (KS) test. The null hypothesis that the true unknown distribution function was negative binomial was not rejected at the 5% significance level for 114 of the 120 distributions. The negative binomial function failed the KS test at a sample concentration of 0 ng/g in all 6 of the distributions where the negative binomial function was rejected. The negative binomial function always predicted a smaller percentage of samples testing 0 ng/g than was actually observed. However, the negative binomial function did fit the observed distribution for sample test results at a concentration greater than 0 in 4 of the 6 cases. As a result, the negative binomial function provides an accurate estimate of the acceptance probabilities associated with accepting contaminated lots of farmers' stock peanuts for various sample sizes and various sample acceptance levels greater than 0 ng/g.
Enzymatic/Chemical Analysis of Dietary Fiber
Authors: Theander Olof , Åman Per , Westerlund Eric , Graham Hadden
Published: February 2020

The Uppsala methodology for rapid analysis and characterization of total dietary fiber, defined as the sum of dietary fiber polysaccharides (DFP) and Klason lignin, was studied. A sugar- and starch-free residue was prepared by treatment with a thermo-stable amylase and amyloglucosidase. Neutral DFP residues were quantified by gas chromatography as alditol acetates after acid hydrolysis of this residue, and the acidinsoluble fraction, Klason lignin, was determined gravimetricaliy. Uronic acid residues were quantified by decarboxylation of the original sample. The efficacy of the Uppsala methodology was tested with foods varying in fiber content and composition, including heat-treated samples. The present method allowed the analysis of up to 40 samples per week. It had good repeatability and coefficients of variation of 3-5% for the main fiber components. Fiber contents determined with the method were higher than those determined with a similar method that excludes Klason lignin and starch resistant to amylases but soluble in dimethyl sulfoxide and lower than those determined with an enzymatic/gravimetric method. Important aspects of fiber analysis, like enzyme purity and the recovery of soluble fiber on ethanol precipitation, also were investigated.
Preparation of Spiked Soils by Vapor Fortification for VolatUe Organic Compounds Analysis
Authors: Hewitt Alan D
Published: February 2020

This paper describes a vapor fortification method for preparing quality assurance/quality control soils for volatile organic compound analysis. Treatment of soils with volatile organic compounds occurs in a closed container in a manner somewhat analogous to the way the vadose zone often becomes contaminated. One advantage of this method for preparing soils for quality assurance/quality control purposes is that the efficiency of various extraction methods can be reliably compared. Furthermore, by substantially reducing the error due to sample inhomogeneity, the error associated with the determinative step can also be properly evaluated.
Corruption at the Data Capture Stage and Good Laboratory Practices
Authors: Ziegler Engelbert , Lenk Horst
Published: February 2020

Possible sources of data corruption at the data capture stage include errors from the analogue input signal to be sampled, incorrect timing of the realtime sampling, loss of data on the data transmission path, and malfunctions of hardware and software components. Hardware and software measures to avoid such errors and provisions to adhere to good laboratory practice rules are discussed.
Analysis of Buprofezin Residues in Vegetable Crops by Gas Chromatography with Mass Selective Detection in Selected Ion Monitoring Mode
Authors: Valverde-García Antonio , Fernández-Alba Amadeo R , Herrera Jose C , Roldan Emilio
Published: February 2020

A gas chromatographic/mass selective detection (GC/MSD) method in selected ion monitoring (SIM) mode was used to determine buprofezin residues in vegetable samples. The electron impact ionization mass spectrum of buprofezin shows 3 characteristic peaks at m/z 105 (base peak), 172, and 305 (molecular ion peak), which were selected to quantify and confirm buprofezin residues in samples. Samples were extracted with ethyl acetate and sodium sulfate, and the extracts were cleaned up by gel permeation chromatography in an SX-3 Envirobeads column before GC/MSD analysis on a 25 m narrow-bore capillary column. Buprofezin recoveries from fortified samples of cucumber, pepper, tomato, squash, and eggplant were determined. The average recovery from cucumbers fortified at different levels (0.01, 0.05, 0.20, and 0.61 mg/kg) was 78%, and the standard deviation was 10% (n = 12). Very similar values were obtained for the 5 vegetable samples fortified at 0.20 mg/kg (n = 15). The limit of quantitation of the method for buprofezin in cucumbers was 0.01 mg/kg.
A Microbial Sensor for Determination of Sulfite in Wines
Authors: Kawamura Yoshiya , Kubo Nobuko , Arata Haruhiko , Ito Yoshio , Tamura Masao , Yamamoto Katsuhiko
Published: February 2020

The method developed for determining sulfite in wines uses a microbial sensor that consists of sulfur-oxidizing autotrophic bacteria and an oxygen electrode (SO2 meter; SOM), which selectively determines free sulfite in an acidified wine sample. Total sulfite is determined after alkaline extraction; ferrous sulfate is added to the extractant to prevent oxidation. The SOM data showed a coefficient of a variation of 1 % or less (n = 5). The total sulfites in wine determined by SOM were compared with those determined by the Monier–Williams method. Excellent agreement was achieved, as indicated by the regression line for the data: Y = 1.01 X − 1.39 (r = 0.993). With SOM, sulfite can be determined rapidly and accurately with excellent repeatability.
Determination of Nitrogen in Fertilizer by Combustion: Collaborative Study
Authors: Tate Donald F
Published: February 2020

Fourteen laboratories participated in a collaborative study to compare abilities of AOAC modified copper catalyst Kjeldahl method, 978.02, and the generic combustion method, 990.03, to analyze the nitrogen content of fertilizer materials. Combustion analyses are more time efficient, more accurate, and less hazardous than Kjeldahl analyses. There were 3 different types of instrumentation involved in the collaborative study: (1) Leco FP-428 Nitrogen Determinator; (2) Perkin-Elmer 2410 Series II Nitrogen Analyzer; (3) Carlo-Erba 1500 Series II Nitrogen Analyzer. Thirty samples of fertilizer containing 1–67% N included 2 ACS grade standard materials: ammonium nitrate, theory 35.00% N; and dicyandiamide, theory 66.64% N. A diammonium phosphate and urea mixture (3 + 1 ; 1.0 mm grind) and 2 ACS grade standard materials of ammonium nitrate and ammonium sulfate were supplied for repetitive combustion analyses. Overall method performance of the combustion method was at least as good as the modified Kjeldahl method. Repeatability standard deviation (Sr) values for the combustion method ranged from 0.09 to 0.34 vs the modified Kjeldahl method range of 0.06–0.49; reproducibility standard deviation (SR) values for the combustion method ranged from 0.13 to 1.07 vs the range of 0.09–3.57 for the modified Kjeldahl method. The grand mean was 20.78% for the combustion method, and 20.79% for the modified Kjeldahl method using various fertilizers. The average ranges of sr and SR for the methods were, respectively, 0.17 and 0.29 for the combustion method, and 0.19 and 0.54 for the modified Kjeldahl method. The method was adopted first action by AOAC INTERNATIONAL.