bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection and Separation of Fenpropathrin, Flucythrinate, Fluvalinate, and PP 321 by Thin-Layer Chromatography
Authors: Khazanchi Rajesh , Handa Swadesh K
Published: February 2020

Four synthetic pyrethroids having α-cyano ester groups, i.e., fenpropathrin, flueythrinate, fluvalinate, and PP 321, are separated by thinlayer chromatography and detected by a new set of chromogenic reagents. Synthetic pyrethroids containing the α-cyano group react with sodium hydroxide to liberate cyanide which forms pink spots with o-dinitrobenzene and p-nitrobenzaldehyde. The detection limit is 0.1 μg and the method can be applied for identification and confirmation of these synthetic pyrethroids in vegetables.
Changing Pesticide Technology in Meat and Poultry Products
Authors: Ellis Richard L
Published: February 2020

In response to consumer concerns about pesticide residues in meat and poultry, a National Residue Program was introduced in the 1960s. Rapidly developing analytical methods and instrument capability resulted in a laboratory-based program of sufficient size and technical capability to quantitatively determine an increasing number of pesticides. In 1985, at the request of the Food Safety and Inspection Service, the National Academy of Sciences evaluated the program and recommended that more emphasis be placed on preventing residues and providing a higher degree of safety to consumers. In response, FSIS made a commitment to increase and improve capability to test for more residues, including pesticides, and to develop or purchase rapid test systems to facilitate the planned expansion of the National Residue Program. Such systems are now being evaluated and integrated into the program. Factors important for acceptability of rapid tests are reviewed in detail.
Determination of Diastereomeric Purity of Tranylcypromine Sulfate by Proton Magnetic Resonance Spectroscopy with Lanthanide Shift Reagent
Authors: Hanna George M , Lau-Cam Cesar A
Published: February 2020

Use of proton nuclear magnetic resonance spectroscopy and the lanthanide shift reagent, Eu(hfc)3, resulted in a simple and reliable method for determination of the diastereomeric purity of rrans-2- phenylcyclopropylamine sulfate (tranylcypromine sulfate). Eu(hfc)3 effectively simplified the complex overlapping pattern of the 5 nonequivalent phenyl protons to a virtually first order pattern. At a shift reagent to substrate molar ratio of 0.75, and a substrate concentration of 0.25M (as the free base) in CDC13, the resonances for the cisand frans-orf/io-phenyl protons at 11.39 and 9.99 ppm, respectively, were sufficiently resolved to be of use in quantitative work. Analysis of synthetic diastereomeric mixtures of 2-phenylcyclopropylamine sulfate by the proposed method yielded results that were in close agreement with the expected values. The mean recovery (SD) of rrans-diastereomer was 100.51% (0.40) (n = 6). Levels of <2% of c/s-diastereomer were measurable in cis-trans mixtures
Liquid Chromatographic Determination of Chloramphenicol Residues in Meat:
Interlaboratory Study
Authors: Aerts Rene M L , Keukens Henk J , Werdmuller Geziena A
Published: February 2020

A liquid chromatographic (LC) method for the determination of chloramphenicol (CAP) residues in meat at the 10 Mg/kg level was tested in an interlaboratory study. The method used, based on aqueous extraction and sample cleanup with a cartridge containing Extrelut, was published earlier. A prestudy to familiarize collaborators with the method was performed before the actual interlaboratory precision study. The meat samples used in the precision study were prepared by diluting dosed chicken and pig muscle tissues with blank tissues from other species. Fourteen laboratories received 20 meat samples; 13 laboratories actually participated in the study. Two blank samples and 2 positive samples each of pig, calf, chicken, lamb, and cow meat were tested. The chloramphenicol concentrations in the positive samples ranged from 6.5 to 21 Mg/kg. The overall mean reproducibility coefficient of variation was 17.9% after the results per laboratory were corrected for the mean recovery obtained within each sample series. The overall mean recovery was 55.1% with a coefficient of variation of 18.0% at the 10 Mg/kg level. The limit of detection, based on chromatograms of blank samples, was estimated to be 1.5 Mg/kg of chloramphenicol. No false positives or false negatives were observed in the concentration range tested; only 2 false positive results above the detection limit (1.7 and 6 Mg/kg) on a total number of 60 blank analyses (3.3%) were observed.
Rapid and Simple Method for Isolation and Gas Chromatographic Determination of N-Nitrosodimethylamine in Dimethyldithiocarbamate Formulations
Authors: Wigfield Yuk Y , Mclenaghan Charles C
Published: February 2020

A rapid and simple method to isolate and determine JV-nitrosodimethylamine (NDMA) in formulations of ferbam or dibam has been developed. Depending on the type of formulation, the sample is extracted or diluted with water which is subsequently extracted with dichloromethane. NDMA is isolated by passing the organic fraction through a silica gel column and eluting the column with acetone. The acetone eluate is analyzed directly for NDMA by using a gas chromatograph connected to a thermal energy analyzer detector (GC/ TEA). The limit of detection (LOD) is 40 pg (0.04 ppm) and the limit of quantitation (LOQ) is 100 pg (0.1 ppm). The recovery range for this method is 85-112% for ferbam spiked at 0.33-0.75 ppm, and 91- 113% for dibam spiked at 0.32-1.09 ppm. Sixteen commercial samples of ferbam and 4 of dibam were analyzed; one ferbam sample contained 19.8 ppm NDMA while all others contained less than 1 ppm. Chem-Elut extraction tubes were found to generate trace quantities of nitrosamine from samples containing amine. If amine is absent, an extraction tube could be used in place of dichloromethane extraction to give similar values in recovery range, LOD, and LOQ.
Determination of Total Vitamin C by Ion Exclusion Chromatography with Electrochemical Detection
Authors: Kim Hie-Joon
Published: February 2020

A rapid and sensitive liquid chromatographic method for determination of total vitamin C in foods and beverages is described. Ascorbic acid and dehydroascorbic acid are extracted with sulfuric acid solution, and the dehydroascorbic acid in the extract is reduced to ascorbic acid by dithiothreitol at pH 7. The reduction is complete in 2 min at room temperature. The resulting total ascorbic acid is separated on an anion exclusion/high speed column with 20mM sulfuric acid as eluant and detected amperometrically with a platinum electrode operating at +0.6-0.8 V vs Ag/AgCl reference electrode. Dithiothreitol (retention time, 3.2 min) does not interfere with the separation and detection of ascorbic acid (retention time, 1.3 min). The dehydroascorbic acid content can be estimated as the difference in ascorbic acid content measured with and without reduction by dithiothreitol. The completeness of the reduction was demonstrated by purposely allowing the oxidation of ascorbic acid in the food extract and determining the total vitamin C after reduction. The determinations of vitamin C content in selected foods and beverages were in good agreement with the expected values. Total analysis time for vitamin C is 10 min and the detection limit is 0.1 ng. The method is specific for vitamin C, and interference by other food constituents is minimal.
Gas Chromatographic Determination of Cholesterol in Egg Products
Authors: Beyer J D , Milani F X , Dutelle M J , Bradley R L
Published: February 2020

A method has been developed for quantification of cholesterol in fresh egg yolks, spray-dried egg yolks, fresh whole eggs, and spray-dried whole eggs. The method uses saponification followed by petroleum ether extraction of cholesterol. Separation of organic and aqueous layers is enhanced by sodium chloride. Petroleum ether extracts are dried under nitrogen and redissolved in chloroform-methanol (2 + 1) for injection into a gas chromatography Cholesterol is separated and quantitated on a high temperature capillary column coated with 5% diphenyl and 95% dimethyl polysilicone crosslinked gum. The method was compared with the current AOAC method 17.017-17.022, and results indicated no significant difference (α = 0.05). However, the proposed method allowed separation and analysis of 16 samples in 7 h while the current AOAC method allowed separation and analysis of only 4 samples in 9 h.
One-Step Sample Preparation Technique for Broad Spectrum Gas Chromatographic/Mass Spectrometric Determination of Organic Priority Pollutants in Water
Authors: Alfieri Angelo , Crawford George , Ahmad Ijaz
Published: February 2020

A rapid and cost-effective sample preparation technique is described for the qualitative and quantitative determination of a broad spectrum of organic contaminants in water. The technique involves simultaneous in-situ acetylation of phenols with acetic anhydride and onestep extraction of phenol acetates and basic and neutral organic compounds from water. The extract is concentrated and analyzed by gas chromatography/mass spectrometry. The recovery and precision data of selected base, neutral, and phenolic compounds are given. The advantages and disadvantages of the in-situ acetylation/extraction technique are discussed
Liquid Chromatographic Determination of Total Formaldehyde in Drinking Water
Authors: Tomkins Bruce A , Mcmahon John M , Caldwell William M , Wilson David L
Published: February 2020

Formaldehyde is readily quantitated at fig/L levels in drinking water. The analyte present in 1 L water samples is derivatized with 2,4- dinitrophenylhydrazine in a 2M acid medium and then extracted with chloroform. After the solvent is exchanged for methanol, the product is separated and quantitated using reverse-phase liquid chromatography with UV detection (365 nm). Reporting limits as low as 20μg/L (corrected for laboratory blank) are routinely achieved. Formaldehyde recovery typically exceeds 90% at 20-200 μg/L. The method was applied to hot and cold water samples from thirty-four 1- and 2- story houses equipped with poly(acetal) plumbing elbows and tees. The drinking water samples were accompanied by sets of blanks and spikes specified by a quality assurance/quality control plan. Formaldehyde was observed above the reporting limit in 80% of hot and cold water samples from the 1-story dwellings, but in less than 50% of those from the 2-story dwellings. The results may depend on both the construction of the houses (1- vs 2-story) and the time of year the water is sampled (mid-summer).
Determination of Carbofuran and Its Metabolites in Rice Paddy Water by Using Solid Phase Extraction and Liquid Chromatography
Authors: Beauchamp Keith W , Liu Dave D W , Kikta Edward J
Published: February 2020

A procedure for the determination of carbofuran and its metabolites (carbamate and phenolic) in rice paddy water is described. Water samples are concentrated on a C-18 solid phase extraction (SPE) column and eluted with methanol-water. The eluate is analyzed by reverse-phase liquid chromatography (LC) and measured by a wavelength programmable ultraviolet (UV) detector. The limit of detection for the method is 0.4 μg/L. Recovery studies were carried out at levels ranging from 1 to 15 μg/L in both rice paddy water and distilled water; recoveries ranged from 85.9 to 112.9%.
Availability of Phosphorus in Bone Meal
Authors: Baker Alice M , Trimm Joe R , Sikora Frank J
Published: February 2020

Two commercially available bone meal products (grades 0-12-0 and 6-12-0) were examined. Samples were prepared according to AOAC method 2.007, and total and available phosphorus contents were determined. Portions of these preparations were reground to pass through successively smaller sieves, and subsequent analyses indicated the availability of phosphorus to be directly proportional to fineness of grind. A quantity of the citrate-insoluble fraction of the bone meal was obtained by following AOAC extraction procedures. Agronomic studies were conducted that compared this insoluble fraction with the original bone meal material and with reagent grade Ca(H2P04)2,H20. The data indicated poor correlation between the analytically defined and agronomically determined availability of phosphorus.
Liquid Chromatographic Determination of Vitamin D in Infant Formula
Authors: AGARWAL Vipin K
Published: February 2020

A method is described for the determination of vitamins D2 + D3 in milk- and soy-based infant formula. Vitamins D2 and D3 are extracted from the saponified sample and converted to isotachysterols with acidified butanol. Reverse-phase liquid chromatography (LC) is used to remove interferences, and total vitamin D is quantitated using normal-phase LC. Recoveries of spiked samples averaged 97.6% for milk-based infant formula, and 98.8% for soy-based infant formula. This method quantitates vitamin D2 + D3 in infant formulas containing as low as 40 IU/qt when prepared according to label direction
Liquid Desorption of Organic Solvents from Industrial Sludges
Authors: Ceccon Luciano , Turello Alessandro , Mocellin Graziella , Colugnati Luigi
Published: February 2020

Analysis of organic solvent residues in industrial sludges is usually based on preliminary extraction of solvents from the matrix, followed by gas chromatographic determination. Liquid desorption with carbon disulfide is one of the most frequently used methods of recovery. Because of the number of parameters that can affect desorption efficiencies, we evaluated recoveries from 2 wastes with different physicochemical characteristics. Results were similar for both matrixes. The study of the kinetics of recovery showed that equilibrium was reached within about 5 min. On the other hand, specific adsorption phenomena were observed not only for strongly polar solvents even at the highest concentrations, but also for weakly polar compounds at the lowest concentrations. Water content of the matrix had little effect on recovery of the solvents examined, except for 2- ethoxyethanol, which yielded notably lower extractions when the moisture content of the matrix increased.
Liquid Chromatographic-Atomic Absorption Spectrophotometric Method for Determination of Methyl Mercury in Seafood: Collaborative Study
Authors: Holak Walter
Published: February 2020

A previously developed method that uses a simplified sample preparation procedure and atomic absorption detection of liquid chromatographic eluates for the determination of methyl mercury in seafood has been collaboratively studied. The unique feature of the method involves the use of a specially designed interface for the generation of mercury vapor. Methyl mercury is isolated from the blended sample by chloroform elution from a diatomaceous earth-hydrochloric acid column. The organomercury compound is then extracted into a small volume of 0.01M sodium thiosulfate solution. An aliquot of this solution is injected onto a Zorbax ODS column and eluted with methanol-ammonium acetate solution (3 + 2), pH 5.7, containing 0.01% mercaptoethanol. Mercury is detected by flameless atomic absorption spectrophotometry using the interface. The samples analyzed in the study were unspiked swordfish, unspiked and spiked lobster, and unspiked and spiked tuna. The spiked samples contained methyl mercury both above and below the U.S. Food and Drug Administration guideline level of 1 fig Hg/g. Reproducibility relative standard deviations ranged from 10.5% at 1 fig Hg/g to 18.2% at about 0.1 fig Hg/g. Accuracy, measured by comparison to reference values obtained by the Associate Referee, ranged from 94.4 to 99.6%. The method has been adopted official first action.
Reliability of Repeatability and Reproducibility Measures in Collaborative Trials
Authors: Karpinsk K F
Published: February 2020

The acceptability of a new analytical method is generally assessed in terms of repeatability and reproducibility estimates derived from a collaborative study. Procedures are presented for calculating confidence intervals and operating characteristic curves for acceptance criteria based on the repeatability and reproducibility estimates. Comparisons of the reliability of estimates are provided for various numbers of collaborators. With a small number of collaborators, the estimates of reproducibility are not reliable and decisions regarding acceptability of a method will be heavily based on the method’s repeatability rather than the property of most interest, namely, the reproducibility of the method.
Confirmation of Phorate, Terbufos, and Their Sulfoxides and Sulfones in Water by Capillary Gas Chromatography /Chemical Ionization Mass Spectrometry
Authors: Stout Steven J , Dacunha Adrian R , Boyd John E , Devine James M
Published: February 2020

A gas chromatographic/mass spectrometric method capable of confirming phorate, terbufos, their sulfoxides, and sulfones in water is reported. Parents and their metabolites are separated in less than 5 min using a short capillary GC column and high carrier gas linear velocities. Positive ion chemical ionization mass spectrometry generates (M + H) ions indicative of the different molecular weights of the analytes and at least one confirmatory fragment ion for each analyte. Residues have been qualitatively confirmed at the 1 ppb level in fortified water samples from a variety of sources. Apparent residues in control water were less than 0.1 ppb.
Pesticide Residues in Milk and Fish Samples Collected from Two Egyptian Governorates
Authors: Dogheim Salwa M , Nasr Eslam N , Almaz Monir M , EL-Tohamy Mahmoud M
Published: February 2020

Because of the intensive use of pesticides for the control of certain pests In Egypt, country-wide residue monitoring programs must be established that can cover all the Egyptian Governorates exposed to pesticide treatments. To do so, limited programs must be adopted first, so that current situations and future needs for improved programs are identified. The present paper reports results from a limited monitoring program, which started in 1985 in one governorate and then expanded to include another in 1986. Fish and milk samples were the commodities selected for residue analysis. The results showed that milk samples collected from Beni-Suef Governorate in 1986 had lower levels of organochlorine residues compared to those collected in 1985. Residues in boltifish and catfish samples in 1986 were much higher than those detected in 1985. In comparison with Beni-Suef Governorate, and contrary to expectations, milk derived from Fayoum Governorate in 1986 was more contaminated with pesticides. While the amount of residues in boltifish was comparatively higher, catfish samples were less contaminated.
Reprint: The Collaborative Test
Authors: Youden W J
Published: February 2020

This paper discusses (a) the planning of collaborative tests, (b) a technique to establish that a procedure is ready for a collaborative test, and (c) the interpretation of the results of a collaborative test.
Methodology for Evaluation of Compatibilities of Cosmetic Perfumes and Plastic Containers
Authors: Taverna Myriam , Baillet Arlette E , Baylocq Danielle
Published: February 2020

The study was designed to investigate compatibility of plastic containers and perfumes. First, a gas chromatographic/ mass spectrometric (GC/MS) system was developed for identification of fragrance components. Then a quantitative extraction and GC analysis was developed. Honeysuckle fragrance was added to a cosmetic emulsion at 0.5 mg/100 mg level. The cosmetic was stored for 2 months at 37° C in 6 different plastic containers and in a glass bottle as a test control. The cosmetic was extracted with dichloromethane and analyzed by GC. The results obtained after storage were compared with the original analysis and showed an important loss of some perfume components stored in different plastic containers. Sorption of these components was then studied by extracting components fixed by the plastic; some of the physicochemical factors involved in such interactions are identified.
Criteria for Determining Purity of Fusarium Mycotoxins
Authors: Bennett Glenn A , Shotwell Odette L
Published: February 2020

Physical and chemical properties that may be used to determine the purity of several Fusarlum mycotoxins have been investigated. A combination of analytical procedures, which include high performance thin-layer chromatography (HPTLC), liquid chromatography (LC), gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), ultraviolet spectrometry (UV), and nuclear magnetic resonance (NMR) spectrometry have been used to examine mycotoxin standards obtained from commercial sources and from laboratory fermentations. Results of this investigation indicate that commercially available standards are greater than 90 % pure, but the label weight of purchased reference standards in individual containers should be verified. Mycotoxin standards, determined to be greater than 98 % pure by HPTLC, LC, and GC/MS, were examined by UV spectrometry and the coefficients of extinction were determined. An interlaboratory study, involving 5 collaborators who determined coefficients of extinction (in methanol) for identical samples, gave the following results: α-zearalenol (λ236 = 28 538 ± 558); β- zearalenol (λ238 = 24 963 ± 747); deoxynivalenol (λ219 = 6395 ± 349, lot 1), (6020 ± 228, lot 2); and T-2 toxin (λ202 = 3681 ± 255). UV maxima and coefficients of extinction are also reported for HT-2 toxin (λ202 = 1959), diacetoxyscirpenol (λ203 = 2487), neosolaniol (λ203 = 2644), nivalenol (λ220 = 5142), and fusarenon-X (λ217 = 5997).
Liquid Chromatographic Determination of the Herbicide Isoxaben and Its Soil Metabolite in Soil and Soil-Turf Samples
Authors: Rutherford Bonnie S
Published: February 2020

A method Is described for the determination of residues of isoxaben and its principal soil metabolite In soil and soil-turf samples. Both compounds are extracted from samples by refluxing with methanol-water. An aliquot of the extract Is partitioned Into dichloromethane and purified by alumina column chromatography. Separate fractions containing isoxaben and metabolite are collected and subjected to liquid chromatography at conditions that are optimized for each compound. The detection limit for both compounds is 0.005 ppm. Residue identities are confirmed by chromatography on a different LC system.
Quantitative Multiresidue Analyses for Volatile Organics in Water and Milk, Using a Fused Silica Open-Tubular Wide-Bore Capillary Column and Automated Headspace Gas Chromatography
Authors: Mcneal Timothy P , Hollifield Henry C
Published: February 2020

A modified multiresidue capillary gas chromatographic (GC) procedure has been developed using automated headspace sampling and a wide-bore fused silica open-tubular (FSOT) capillary column for the determination of volatiles in water and milk. Compounds are quantltated by the method of standard additions. An IBM System 9000 computer with the CAPMC3 chromatographic applications package and a BASIC linear regression program are used for data reduction. Data are presented for solutions prepared by fortifying water and milk with volatile solvents such as acetone, methyl ethyl ketone, benzene, methylene chloride, and chloroform, which are commonly used in the manufacture of packaging materials and adheslves. The wide-bore FSOT capillary columns showed dramatically improved detection for certain compounds, compared with normal-bore capillary GC columns. Data presented for various chemicals demonstrate the improved limits of detection from the use of automated headspace gas chromatography with wide-bore capillary columns and flame ionization detection.
Sulfamethazine (Sulfadimidine) Residues In Canadian Consumer Milk
Authors: Larocque Lyse , Carignan Germain , Sved Stephen
Published: February 2020

A survey on the presence of sulfamethazine (sulfadimidine) residues In consumer milk has been conducted In 10 cities across Canada. In each city, homogenized milk was purchased at 3 different retail outlets, each supplied by different processing plants. A total of 30 samples was analyzed by a liquid chromatographic method. The limit of quantitation was 5 ppb. In addition to automatic integration, visual inspection of the chromatograms was required to distinguish between low concentrations of sulfamethazine and 2 unknown interfering peaks. Two samples, from different cities, contained 11.4 and 5.24 ppb of the drug. Drug Identity was confirmed by mass spectrometry. All other samples appeared to be free of the drug.
Diagnostic Data Evaluation. Part IV. Evaluation of A Check Sample Series To Determine Analyst Performance
Authors: Malanoski Anthony J
Published: February 2020

Data from a check sample series were subjected to diagnostic data evaluation. The chemical analyses that were performed were moisture, protein, and fat In meat products. Four performance outliers were Identified (1 protein, 1 moisture, and 2 fat values). With the performance outliers excluded from the statistical evaluation, the analyst standard deviation ranged from 0.088 to 0.218 for protein, 0.145 to 0.393 for moisture, and 0.271 to 0.378 for fat. No bias was present. All laboratories were able to meet the established standards. With the limited number of samples it was not possible to attribute any reasons for the outliers.
Comparison of Two Immunochemical Methods with Thin-Layer Chromatographic Methods for Determination of Aflatoxins
Authors: Trucksess Mary W , Young Kathryn , Donahue1 Kevin F , Morris Deborah K , Lewis Ernie
Published: February 2020

Three different methods were compared for the determination of total flatoxins in corn and peanuts naturally contaminated with aflatoxins and In corn, peanuts, cottonseed, peanut butter, and poultry feed spiked with aflatoxins Bi, B2, and d . The 3 methods were an enzyme-linked Immunosorbent assay (ELISA) screening test; a monoclonal antibody-affinity column-solld-phase separation method; and the AOAC official thin-layer chromatography (TLC) methods for all except poultry feed, for which Shannon's TLC method for mixed feed was used. The ELISA test is designed to provide only positive results for total aflatoxins at >20 ng/g or negative results at <20 ng/g. The affinity column separation Is coupled with either brominatlon solution fluorometry to estimate total aflatoxins or liquid chromatography (LC) to quantltate Individual aflatoxins. Fluorodensitometry was used to determine aflatoxins In commodities analyzed by the TLC methods. The LC and TLC results were In good agreement for all the analyses. The results for the affinity column using brominatlon solution fluorometry were similar except those for cottonseed, which were about 60% higher. The ELISA screening method correctly Identified naturally contaminated corn and peanut positive samples. No false positives were found for controls. The correct response for spiked corn, raw peanuts, peanut butter, and cottonseed at >20 ng aflatoxlns/g was about 90%. The correct response for spiked poultry feed at >20 ng aflatoxlns/ g was about 50%.
Solid-Phase Extraction of Carbofuran, Atrazine, Simazine, Alachlor, and Cyanazine from Shallow Well Water
Authors: Nash Ralph G
Published: February 2020

Extraction of several nitrogen-containing pesticides from water on solid-phase C18 cartridges was rapid and accurate. One analyst can extract >48 samples/day. Recovery efficiencies were 77, 95, 92, 90, and 99% with detection limits of 0.20, 0.05, 0.05, 0.20, and 0.10 /μg/L for carbofuran, atrazine, simazine, alachlor, and, cyanazine, respectively. Extraction of the atrazine and simazine dealkylation products (deethylatrazlne and deethylsimazine) was less efficient, e.g., 26 and 9%, respectively. Comparisons with 10 U.S. Geological Survey samples gave similar results
Sensitive Streptavidin-Biotin Enzyme-Linked Immunosorbent Assay for Rapid Screening of Chloramphenicol Residues in Swine Muscle Tissue
Authors: Water Cornelis Van De , Haagsma Nel
Published: February 2020

A sensitive, competitive enzyme-linked Immunosorbent assay (ELISA) for chloramphenicol (CAP) in swine muscle tissue has been developed. The ELISA Is based on an earlier procedure. To Improve sensitivity, different optimization procedures were Investigated. The introduction of a streptavldln- biotln system and the use of a coating antigen with a lower CAP Incorporation resulted In the most sensitive ELISA: the CAP concentration giving 50% Inhibition decreased from 125 ng/mL to 3.0 ng/mL. This ELISA procedure was applied for a rapid screening of CAP residues In swine muscle tissue. The tissues were extracted with demlneral- Ized water. A concentrated phosphate-buffered saline solution was added to the filtered aqueous extract and this sample solution was directly submitted to the ELISA procedure. The results were compared to values obtained by analysis of a corresponding blank. This blank was prepared by treating a part of the aqueous sample solution with an immobilized monoclonal antibody preparation. This treatment was necessary because aqueous extracts of different swine muscle tissues showed a high variation In dose-response curves, probably caused by the complexity and variability of the matrix. In spiked tissues, the presence of CAP at concentrations of 10 μg/kg and higher can be easily demonstrated.
Study of Carbendazin Residue Accumulation on Greenhouse and Field-Grown Strawberries, after Successive Treatments with Benomyl
Authors: Mònico-Pifarré A , Xirau-Vayreda M
Published: February 2020

Benomyl, a systemic fungicide used In preharvest treatments to prevent Botrytls and other fungal diseases, metabolizes to carbendazlm (MBC). A study was undertaken to determine if the total residues of MBC of greenhouse and field-grown Douglas strawberries accumulate In fruits after successive fortnightly treatments with a commercial preparation of benomyl. Statistical analysis of the data obtained Indicates that residues of MBC do not accumulate In fruits; on the contrary, they decrease over time.
Determination of Nitrite in Cured Meats by Ion-Exclusion Chromatography with Electrochemical Detection
Authors: Kim Hie-Joon , Conca Karen R
Published: February 2020

A rapid liquid chromatographic (LC) method was developed for a sensitive determination of nitrite In cured meats, using ion-exclusion chromatographic separation and electrochemical detection (IEC-EC). The current AOAC colorimetric method requires 2 h shaking In a steam bath to eliminate Interference from reducing compounds such as ascorbic acid. In the present method, nitrite was analyzed In the presence of ascorbic acid without interference, and the extraction time was reduced to 1 mln. The extracted nitrite was determined by ion chromatography using anion-excluslon/ HS column and amperometric detector equipped with platinum or glassy carbon electrode operating at +1.0 V vs Ag/ AgCI reference electrode. The detection limit was 1 ppb as NO-2. The recoveries of 50 ppm nitrite added to frankfurter and meat stick were 103 and 99.6%, respectively, with relative standard deviations less than 4%. The high speed, sensitivity, and selectivity make the new method a useful alternative to the AOAC colorimetric method.
Integration of Enzyme-Linked Immunosorbent Assay with Conventional Chromatographic Procedures for Quantitation of Aflatoxin in Individual Cotton Bolls, Seeds, and Seed Sections
Authors: Lee Louise S , Wall James H , Cotty Peter J , Bayman Paul
Published: February 2020

Integration of an enzyme-linked Immunosorbent assay (ELISA) with conventional chromatographic methods proved the versatility of ELISA as a research tool and allowed for rapid assessment of aflatoxin In Individual cottonseeds, parts of cottonseed, and composite samples of seeds taken from Individual cotton bolls. Aqueous acetone was substituted for methanol In the extraction procedure prescribed by ELISA. The substitution allowed the use of a common extract for all analytical methods. An aliquot of the extract was used to screen samples by ELISA. Negative samples were Identified, and toxin levels between 1 and 70 ng/g were quantltated by ELISA. Samples with toxin levels beyond the upper limit of detection by ELISA were then subjected to more time-consuming conventional cleanup prior to quantitation by liquid chromatography (LC) or thin-layer chromatography (TLC). Toxin levels detected by LC or TLC ranged from 100 to 845 000 ng/g sample. The screen by ELISA detected large numbers of toxin-negative cotton bolls or Individual seeds in minimum analysis time. The combination of techniques verified the presence of seed with no toxin adjacent to toxincontaining seed In the same lock. Toxin-negative portions of Individual seed with high toxin In another portion were Identified for the first time. Integration of techniques provided needed Information on distribution patterns of aflatoxin In cotton so that preventive measures can be developed.
Establishment of Standard Reference Material Purity by Using 31P FT-NMR Comparison to Surrogate Material
Authors: Slahck Stephen C
Published: February 2020

Chromatography, thermal methods, and other associated physical determinations have been applied to the assignment of purities to standard reference materials. Each of these techniques has limitations, and each generally requires a primary standard of known purity. The establishment of purities on organophosphorus compounds can easily be performed without the availability of a typical primary standard by using proton decoupled 31P FT-NMR comparison to surrogate materials of known purity. A proposed analytical standard reference material of oxydemeton-methyl was evaluated using a 7.3 Tesla FT-NMR (300 MHz proton) using inverse-gated WALTZ decoupling. The resulting phosphorus singlet was compared with that of trlmethyl phosphate. This technique for purity assignment was confirmed by 2 additional experiments: (1) comparison of an established standard and a blind sample of demeton-S-methyl (Metasystox-I®) , with trlmethyl phosphate and (2) comparison of an established standard of disulfoton (Dl-Syston®) vs 0,0,0-trimethyl phosphorothloate.
Improved Hydrophobic Grid Membrane Filter Method, Using EF-18 Agar, for Detection of Salmonella in Foods: Collaborative Study
Authors: Entis Phyllis
Published: February 2020

A collaborative study was carried out in 30 laboratories to validate Improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were Included In the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each Inoculated In advance with low levels of Individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the Improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved Interim official first action for all foods to replace the HGMF official final action method, 985.42.
Artifact Formation During Smoke Trapping: An Improved Method for Determination of iV-Nitrosamines in Cigarette Smoke
Authors: Caldwell William S , Conner James M
Published: February 2020

Studies In our laboratory revealed artlfactual formation of Nnltrosamlnes during trapping of mainstream and sldestream tobacco smoke by the method of Hoffmann and coworkers (2, 4). Both volatile and tobacco-specific Af-nltrosamlnes were produced. This artifact formation took place on the Cambridge filter, which Is part of the collection train used In the previously published procedure. When the filter was treated with ascorbic acid before smoke collection, artifact formation was inhibited. The improved method resulting from these studies was applied to a comparative analysis of Nnltrosamlnes In smoke from cigarettes that heat, but do not burn, tobacco (the test cigarette) and several reference cigarettes. Concentrations of volatile and tobacco-specific Af-nltrosamlnes In both mainstream and sldestream smoke from the test cigarette were substantially lower than In the reference cigarettes
Liquid Chromatographic Determination of Multiple Sulfonamide Residues in Bovine Milk
Authors: Smedley Michael D , Weber John D
Published: February 2020

A liquid chromatographic method has been developed for simultaneous determination of residues of 10 sulfonamide drugs at 10 ppb and above In raw bovine milk. The method Is based on a chloroform-acetone extraction, evaporation of organic phase, dissolution of residues in an aqueous potassium phosphate solution, and extraction of fatty residue Into hexane. The aqueous layer is collected, filtered, Injected onto an LC system, and detected by ultraviolet absorption at 265 nm. To elute all 10 sulfonamides Isocratlcally, 2 chromatographic conditions are required. Seven sulfonamides can be quantltated with 12% methanol in the mobile phase; 4 sulfonamides can be quantltated with 30% methanol. Sulfamethazine, the most widely used sulfonamide, Is detected on both systems. Recoveries are 44-87% for Individual sulfonamides, with only 2 below 60%. Coefficients of variation are 3-13% at 10 ppb.
Turbidimetric Assay of Tylosin in Animal Feeds Containing Urea
Authors: Coleman Mark R , Mowrey Daniel H
Published: February 2020

A turbidimetric method Is described for determination of tylosin in animal feeds containing urea. This method Includes several modified or new steps to existing turbidimetric and AOAC plate assays that Improve the extraction of tylosin, remove interferences from feeds, free tylosin activity, concentrate tylosin from low-level feeds, and reduce variability of assay results. A larger analytical sample size has been incorporated Into the assay to decrease variability of assay results. A methanol-phosphate buffer extraction solution has replaced the hot buffer and methanol extraction solution. A hydrolysis step, which Is not contained in the AOAC plate assay, was developed to free tylosin from the tylosin urea adduct that forms over time In feeds containing urea. A disposable C18 column was used to concentrate tylosin from feeds at levels less than 15 ppm. By Increasing the analytical sample size from 25 to 100 g, the coefficient of variation for 12 weighings of cattle feed was reduced from 28.4 to 9.3%. Average recoveries from cattle rations containing tylosin at levels of 8,10, and 100 ppm were 94, 94, and 91 %, respectively.
Simultaneous Determination of Benefin and Trifluralin in Pesticide Formulations by Gas Chromatography
Authors: Fitzpatrick Timothy M , Gehrig Connie C
Published: February 2020

Formulations containing benefin and trifluralin are extracted In hexane and determined using direct splltless capillary gas chromatography with flame Ionization detection. Resolution of the Isomers Is approximately 0.8 for run times of 20 mln. Least-squares regression of peak areas against concentrations for the simultaneous determination of the 2 Isomers produced correlation coefficients of 0.9999 and 0.9990 for benefin and trifluralin, respectively. These compare favorably with the linearities of each Isomer Individually. Quadruplicate analyses of 4 ground fertilizer formulations produced an average relative standard deviation of 1.98%. Recoveries were erratic for granular fertilizer formulations but were 105 ± 3.6% for a liquid trifluralin formulation spiked with both trifluralin and benefin.
Determination of Sulfur Dioxide in Grapes: Comparison of the Monier-Williams Method and Two Ion Exclusion Chromatographic Methods
Authors: Kim, Hie-Joon , Conca Karen R , Richardson Michelle J
Published: February 2020

Results for determination of sulfur dioxide In grapes were compared by 3 methods: the modified Monier-Wllllams method, acid dlstlllatlon/lon exclusion chromatography with electrochemical detection (AD/IEC-EC), and alkali extraction/ ion exclusion chromatography with electrochemical detection (AE/IEC-EC). An unusual positive response was observed during the later stage of the Monier-Wllllams distillation of both control grapes and sulfited grapes. Development of volatile acidic compounds in parallel with this Monier- Wllllams response and darkening of sample was also observed by collection In an alkali trap and analysis using anion exclusion chromatography and photodlode array detection. No parallel Increase In sulfite was observed by the more selective AD/IEC-EC method, which clearly demonstrated that the response observed during the later stage of the Monier-Wllllams method Is a false positive, probably due to caramellzatlon reaction products. Monier-Williams results for grapes containing ca 10 ppm sulfite were In reasonably good agreement with those by either the AD/IEC-EC or AE/ IEC-EC methods, presumably because the false positive response In the Monier-Wllllams analysis compensated for the somewhat Incomplete recovery of sulfite. The AE/IECEC method Is recommended because it is rapid, sensitive, straightforward, and free from interference. Accurate results by Monier-Wllllams analysis could be obtained by limiting distillation to 60 min and correcting for recovery.
High-Volume Enzyme Immunoassay Test System For Sulfamethazine in Swine
Authors: Ram Bhanu P , Singh Prithipal , Martins Lorelei , Brock Teri , Sharkov Nikolai , Allison David
Published: February 2020

A high-volume enzyme immunoassay (EIA) system for slaughterhouse screening of sulfamethazine In swine plasma/ serum has been developed. The system Includes a robotic sample processor that performs most of the liquid handling requirements in the assay. The assay gives good correlation with the widely used thin layer chromatographic method for determination of sulfamethazine in serum and plasma (r = 0.826). Inter- and Intra-assay coefficients of variation are less than 10%. Approximately 2,400 serum/ plasma samples can be analyzed In a normal working day (8 h) with this system.
A Model for Statistical Evaluation of Precision Parameters of Microbiological Methods: Application to Dry Rehydratable Film Methods and IDF Reference Methods for Enumeration of Total Aerobic Mesophilic Flora and Coliforms in Raw Milk
Authors: Piton Christine , Grappin Rémy
Published: February 2020

A new statistical approach for collaborative study data of microbiological methods Is proposed. This Includes a confirmatory test to the Polsson distribution of the number of colonies. In addition, 2 new statistical parameters are used to express precision as a percent of the original unit: the geometric relative standard deviation (GRSD) and the critical relative difference between 2 measurements (RD95). This statistical approach was applied to an Interlaboratory study to assess and compare the precision of both dry rehydratable film (PetrlfUrn® SM and Petrifllm® VRB) methods and International Dairy Federation (IDF) reference methods [total aerobic mesophilic plate count (TAMPC) and violet red bile lactose agar (VRBL) methods] for estimation of total bacteria and collform, respectively, in raw milk. Each of the 14 laboratories In the study analyzed 40 laboratory samples (20 different materials In blind duplicates) for total bacteria and collform counts by both the Petrifllm and standard methods. Repeatability standard deviations (In log10 unit) of TAMPC, Petrifllm SM, VRBL, and Petrifllm VRB were 0.106, 0.089, 0.219, and 0.171, respectively; their reproducibility standard deviations were 0.170,0.167,0.348, and 0.199, respectively.
Direct Aqueous Injection-Liquid Chromatography with Post-Column Derivatization for Determination of N-Methylcarbamoyloximes and N-Methylcarbamates in Finished Drinking Water: Collaborative Study
Authors: Edgell Kenneth W , Biederman L Anne , Longbottom James E
Published: February 2020

An Interlaboratory method validation study was conducted on EPA Method 531.1, Measurement of N-Methylcarbamoyloxlmes and N-Methylcarbamates In Water by Direct Aqueous Injection HPLC with Post Column Derivatization, to determine the precision and mean recovery for determination of 10 carbamate pesticide compounds In reagent water and In finished drinking waters. The study design was based on Youden's nonreplicate plan for collaborative tests of analytical methods. The waters were spiked with 10 carbamate pesticides at 6 concentration levels, as 3 Youden pairs. Eight laboratories analyzed the samples by direct aqueous injection, with separation by reverse-phase liquid chromatography and post-column hydrolysis of the carbamates and carbamoyloxlmes to methylamine, followed by reaction of the methylamine with 𝑜-phthalaldehyde and 2-mercaptoethanol using fluorescence detection. Results were analyzed using an EPA computer program, which measured precision and recovery for each of the 10 compounds and compared the performance of the method between water types. The method was acceptable for all analytes tested. After removal of a nonrepresentatlve data set for aldlcarb sulfoxide, no matrix effects were observed; the statistics for the pooled drinking waters were not significantly different from the statistics for the reagent waters. The method has been adopted official first action by AOAC.
Conductometric and Colorimetric Determination of Volatile Acidity of Vinegars by Flow-Injection Analysis
Authors: Tubino Matthieu , Barros Flavio G
Published: February 2020

Recent methods for determination of the volatile acidity of vinegars are relatively slow (about 40 mln) and involve techniques subject to a variety of errors (ca 2.5%). The present paper describes a method that provides results in a shorter time (ca 2 mln, Including dilution), with a smaller relative error rate (ca 1%). Conductometric analysis consists of the Injection of the sample In a deionlzed water stream that then flows past a PTFE membrane separator. Acetic acid diffuses through the membrane to another deionlzed water stream that passes through a conductivity cell. Colorimetric analysis also consists of sample injection into a deionlzed water stream that passes through the same PTFE membrane separator. However, the acetic acid diffuses into a bromocresol purple solution stream at pH 7. This solution passes through a flow cell In a spectrophotometer set at 540 nm. Before injection, samples were treated with hydrogen peroxide to ensure complete oxidation of sulfite to sulfate. Results of the proposed method were also compared with another similar method. At a 95% confidence level, the statistical t-test Indicates no significant difference between them. Typical estimates of the relative standard deviations obtained with the new methods are ca 1%. Analyses were performed with red and white wine vinegars.
Determination of Total Dietary Fiber in Japanese Foods
Authors: Nishimune Takahiro , Sumimoto Tatsuo , Yakusiji Tsumoru , Kunita Nobuharu , Ichikawa Tomio , Doguchi Masao , Nakahara Sumio
Published: February 2020

Total dietary fiber was determined In Japanese foods by the Prosky-AOAC method. To accomplish the analyses of unsuitable samples, we Introduced a few minor modifications to the versions for (I) seaweed and fruits, (II) cereals, and (ill) fish and meats. These modified methods were used together with the standard method to obtain results with reasonably good relative standard deviation for 231 foods and 21 groups of mixed foods. In this study, dietary fiber was defined so as not to exclude the nondlgestlble polysaccharide portions of animal foods. A method was proposed which could estimate more accurately the fiber components of animal foods by measuring the "nondlgestlble protein" of the fiber sample by the Biuret colorimetric method, Instead of the Kjeldahl method, to avoid deducting the values for aminopolysaccharides. In Japanese diets, the amount of fiber obtained from animal foods was less than 5 % of the total Intake of dietary fiber.