bluuebunny/crossref_metadata_2025 huggingface dataset:
Assay of Volatile Acids Induced by Autoxidation of Nonionic Surfactants by Liquid Chromatography with Direct Denvatization
Authors: Miwa Hiroshi , Yamamoto Magobei
Published: February 2020

Direction derivatization in conjunction with liquid chromatography is described for assay of volatileacids induced by autoxidation of nonionic surfactants. The method is based on the reaction of acids with 2-nitrophenylhydrazine hydrochloride to produce nonvolatile hydrazine derivatives, which are separatedisocratically on a YMC-FA (C8) column within 10 min. In this study, formic acid was produced copiously in autoxidations, principally from C-C fission of hydroperoxides or free radicals. The method is superior with regard to stoichiometric measurement of acid formation, which is related to the extent of oxidation of nonionic surfactants.
Easy Enzyme-Linked Immunosorbent Assay for Spectinomycin in Chicken Plasma
Authors: Tanaka Touichi , Ikebuchi Hideharu , Sawada Jun-Ichi , Okada Mariko , Kido Yasumasa
Published: February 2020

An easy, sensitive, competitive indirect enzyme- linked immunosorbent assay (CI-ELISA) for specti nomycin in chicken plasma was developed. Preparation of a spectinomycin-bovine serum albumin conjugate in which the hapten is linked to the carrier protein through the C-4 position is described. Antibodies raised against antigens in rabbits had excellent specificity for spectinomycin, exhibiting a cross-reactivity of 44.0% with dihydrospectinomy-cin and 13.8% with tetrahydrospectinomycin. No cross-reactivity was observed with other antibiotics. The detection limit of the CI-ELISA was 2 ng/mL (equivalent into 40 ng/mL undiluted chicken plasma) spectinomycin. Known amounts (0.1-100 μg/mL) of spectinomycin were added to chicken plasma and then analyzed. Average recoveries were 97-110%. This procedure may be used without prior extraction of samples.
A Simple and Rapid Solvent ExtractionMethod for Determining Total Lipids in Fish Tissue
Authors: Lee Chong M , Trevino Belzahet , Chaiyawat Mayuree
Published: February 2020

Solvent systems that have been developed for lipid extraction include chloroform–methanol, n-hexane– isopropyl alcohol, and methylene chloride–metha nol. The extraction methods are labor intensive, lack precision, or require a large volume of solvent. Correct computation of lipid content calls for full recovery of solvent after extraction, but recovery always is incomplete because of unaccounted solvent residue that remains in jar, filter paper, and homogenized tissue. A rapid and simple extraction method coupled with correct computation was developed for determining total lipids in fish tissue. The method uses chloroform–methanol and an Eberbach blending jar. Variables examined were chloroform–methanol ratio, solvent-to-sample ratio, and phase separation time. Precision was within 0.5%. Conventional computation of lipid content depends on the volume of chloroform measured after filtration. This volume does not include unaccounted solvent residue. Thus, a time-consuming second extraction is required for complete recovery. The mass balance of each extraction and filtration step confirmed that the correct volume of chloroform (measured plus unaccounted) was close to the theoretical volume. The procedure eliminates problems associated with laborious filtration and variation in chloroform volume readings and does not require an exact reading of chloroform volume. Instead it allows use of a theoretical volume, which depends on solvent volume and ratio used.
Organohalogen and Organophosphorus Pesticides in Mixed Feed Rations: Findings from FDA’s Domestic Surveillance During Fiscal Years 1989-1994
Authors: Lovell Randall A , McChesney Daniel G , Price William D
Published: February 2020

During Fiscal Years 1989–1994, the U.S. Food and Drug Administration (FDA) collected and analyzed 545 domestic surveillance samples of mixed feed rations (172 for cattle, 125 for poultry, 83 for swine, 61 for pets, 56 for fish, and 48 miscellaneous).All samples were analyzed by gas-liquid chromatography for organohalogen and organophosphorus pesticides. Of the 545 samples, 88 (16.1%) did not contain detectable pesticide residues. In the 457 samples with detectable pesticide levels, 804 residues (654 quantitable and 150 trace) were found. None of these 804 residues exceeded regulatory guidance. Malathion, chlorpyrifos-methyl, diazinon, chlorpyri fos, and pirimiphos-methyl were the most commonly detectedpesticides. These 5 organophosphorus pesticides accounted for 93.4% of all pesticide residues detected (malathion, 52.9%; chlorpyrifos-methyl,25.2%; diazinon, 7.7%; chlor pyrifos, 4.9%; and pirimiphos-methyl, 2.7%).Their median values in samples containing quantitable levels ranged from 0.014 to 0.098 ppm. The most commonly detected organohalogen compounds were methoxychlor, DDE, PCB, dieldrin, pentachlo- ronitrobenzene, and lindane. These 6 compounds combined accounted foronly 4.1 % of all residues detected. FDA is continuing its pesticide surveillance of feeds tohelpensure animal safety and prevent violative residues in food derived from animals.
Reliability of the Determinations of Polychlorinated Contaminants (Biphenyls, Dioxins, Furans)
Authors: Horwitz William , Albert Richard
Published: February 2020

Precision performance parameters from results of 34 interlaboratory performance studies of polychlorinated aromatic ring compounds (biphenyls, dioxins, and furans) (PCCs) have been recalculated by using the International Union of Pure and Applied Chemistry-1987 harmonized protocol. Most studies of 1052 test samples, 56 analytes, 19 matrixes, and 2 types of detectors (electron capture and mass spectrometers) provide among-laborato- ries relative standard deviations (RSDRs), that are considerably better than those predicted from the Horwitz equation at fractional concentrations of 10−6 down to 10−15. The explanation suggested is that supplying common reference calibration solutions, as was done in many of these studies, does not reflect realistic operating conditions. Furthermore, the ability to repeat, discuss, and reassess aberrant reported values results in underestimating the true RSDR. The commonly reported problems of preparation of standard calibrating solutions, instability of the detection system, and failure to follow quality control instructions and good laboratory practices may be important sources of interlaboratory variability in PCC determinations
Worldwide Survey of Fumonisin Contamination of Corn and Corn-Based Products
Authors: Shephard Gordon S , Thiel Pieter G , Stockenström Sonja , Sydenham Eric W
Published: February 2020

As part of a comprehensive risk assessment study for fumonisins, reliable data on exposure of populations to these dietary toxins must be obtained. To assess the extent of worldwide exposure, the published literature on the contamination of food and feed supplies has been reviewed and supplemented with unpublished material from various international sources. Fumonisin contamination of corn and corn-based products occurs in many countries. Animal mycotoxicoses such as equine leukoencephalomalacia and porcine pulmonary edema are caused by heavily contaminated animal feeds. For example, as much as 330 μg/g fumonisin B1 (FB1) has been found in swine feed. Although commercially available refined corn products for human consumption are generally contaminated at levels below 1 μg/g FB1, individual products in certain countries can reach far higher levels. Health risks associated with consumption of these products depend on the extent to which they are consumed in a varied diet. Home-grown corn in certain rural areas, where it also constitutes the staple diet, can be contaminated at >100 μg/g. Consumption of corn contaminated at these high levels has: been associated with a high incidence of esophageal cancer in these areas.
Gas Chromatographic Differentiation of Virgin, Refined, and Solvent-Extracted Olive Oils
Authors: Jiménez De Blas Oroncio , Del Valle González Amando
Published: February 2020

An analytical method based on gas chromatography using a capillary column was used to determine fatty acids in olive oils. The method was applied to 50 samples of virgin olive oil, 50 of refined olive oil, and 30 of solvent-extracted olive oil. Results were compared, with special emphasis on peaks of minor fatty acids to distinguish virgin, refined, and solvent-extracted oils. Some peaks are probably due to trans Isomers of the fatty acids. Statistically significant differences were observed among the 3 types of olive oil.
Testing for Compliance with Migration Limits: Determination of 1,2-, 1,3-, and 1,4-Dihydroxybenzenes in Food-Simulating Solvents by Liquid Chromatography
Authors: Philo Mark R , Jickells Sue M , Castle Laurence
Published: February 2020

A method, intended for regulatory purposes, for quantitative determination of the plastics monomers 1,2-, 1,3-, and 1,4-dihydroxybenzene in foodsimulating solvents is described. Liquid chromatography is used with UV detection and 2-methyl- 1,3-dihydroxybenzene as internal standard. Repeatability, stability, and migration tests were conducted. The limits of detection were in the range 0.03–0.40 mg/kg for the 3 phenols in aqueous and fatty food simulants. Relative repeatability standard deviations at migration limits of 6,2.4, and 0.6 mg/kg for 1,2-, 1,3-, and 1,4-dihydroxybenzene, respectively, ranged from 0.8 to 4.8% for the food simulants tested. A commercial sample of polyetherketone made from 1,4-dihydroxybenzene was tested with the method. No polymer-derived interferences were found. The method is thus suitable for testing against migration limits for the 3 monomers.
Gas Chromatographic Determination of Propamocarb in Agricultural Commodities
Authors: Nagayama Toshihiro , Kobayashi Maki , Shioda Hiroko , Tomomatsu Toshio
Published: February 2020

A simple and efficient gas chromatographic (GC) method is described for quantitative determination of propamocarb in agricultural commodities. Propamocarb is extracted into acetone–water (or acidified solvent for dry products) and then cleaned up by extraction with diethyl ether. The analyte is extracted from the aqueous fraction under basic conditions with diethyl ether and then analyzed by GC with nitrogen–phosphorus detection. The minimum detection limit is 0.01 μg/g in original samples (signal-to-noise ratio > 5). Recovery of propamocarb spiked at 0.1 μg/g into various samples is >75%, except for lettuce (41%).
Determination of Aromatic Amines in Soils
Authors: Pace Christopher M , Donnelly Joseph R , Jeter Jeffrey L , Brumley William C , Sovocool G Wayne
Published: February 2020

A rapid liquid chromatographic (LC) method with ultraviolet (UV) or fluorescence detection was developed for parts-per-billion levels of aromatic amines in soils. 2,4-Diaminotoluene, pyridine, aniline, 2-pi-coline, 2-toluidine, 5-nitro-2-toluidine, 2-methyl-6-ethylaniline, 4-aminobiphenyl, 4-nitroaniline, 1-naphthyl-amine, 2-methoxyaniline, and 2-naphthyiamine were tested. The method involves extraction by sonication with 1% ammonium hydroxide–acetonitrile and analysis by LC using gradient elution with aqueous 0.01 M ammonium acetate–0.0005% triethylamine and acetonitrile. Recoveries of 67–106% (9.2 and 34% for 1-and 2-naphthylamines, respectively) were obtained from sand and organic-containing soils spiked in the parts-per-million range. Recoveries from sand spiked at 8.5–25 ppb were 88–105%. Recoveries from organic soil varied from nondetectable to 86% at spikes of 85–500 ppb. Detection limits ranged from 0.5 ppb for highly fluorescent 2-naphthyiamine (by fluorescence detection) to 0.5 ppm for nonfluorescing pyridines (by UV detection).
Determination of Imazalil Residues in Lemons by Gas Chromatography with Nitrogen–Phosphorus Detection
Authors: Yamazaki Yoshie , Ninomiya Takahiro
Published: February 2020

A simple and reliable method was developed for determination of imazalil residues in whole lemons. Imazalil was extracted from lemon samples with ethyl acetate under basic conditions. The ethyl acetate in the extract was evaporated, and the residue was dissolved in dichloromethane. The solution was applied to a solid-phase extraction (diol- bonded silica) cartridge. Imazalil was eluted with methanol and determined by gas chromatography (GC) with nitrogen–phosphorus detection. Recoveries at 4 fortified levels (0.1,1.0,2.0, and 5.0 μg/g) ranged from 93.3 to 97.8%, with coefficients of variation ranging from 0.2 to 3.0%. The detection limit was 0.05 μg/g. Fifteen commercial lemon samples were analyzed for imazalil residues; 10 were positive. Concentrations of imazalil residues ranged from 0.22 to 4.44 μg/g. Imazalil-positive samples were confirmed by GC with mass–selective detection (m/z 173,215, and 217).
Estimating Analytical Variances in Measurement of Polycyclic Aromatic Hydrocarbons and Application to Monitoring Contaminants in American Lobster (Homarus americanus)
Authors: Uthe John F , Misra Rajendra K , King Thomas L , Musial Charles J
Published: February 2020

A method is presented for estimating replicate polycyclic aromatic hydrocarbon (PAH) concentrations in American lobster (Homarus americanus) digestive gland tissue based on recoveries of added perdeuterated surrogates from a single satisfactory analysis. PAH concentrations demonstrated a large interanimal variance, even in specimens captured at the same time in the same place. Principal component analysis showed that the variability of the total system of biological variables (carapace length, lobster weight, and digestive gland weight) could be adequately summarized by the first principal component alone in each data set. Ranks provide ordered classification of individuals, allowing data analysis by statistical methods for continuous variables (i.e., analysis of variance). PAH concentrations in individual lobsters were generally highly sensitive to animal size, sex, and fishing area. Efficient monitoring would result from analyzing individual animals of a single sex from a study area, using as small a geographical study area as possible, measuring a single biological variable, and using individual specimens of as narrow a size range as possible.
Determination of Heterocyclic Aromatic Amines in Process Flavors by a Modified Liquid Chromatographic Method
Authors: Perfetti Gracia A
Published: February 2020

A liquid chromatographic method for determining heterocyclic aromatic amines (HAAs) was modified so that it can be used to quantitate the following 5 HAAs in complex process flavors: 2-amino-3-methylimidazo[4,5-f]quinoline (IQ); 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MelQ); 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx); 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (diMelQx); and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). By changing the initial extraction procedure, PhIP recovery improved from 35 to 87%. An additional cleanup step using ion-exchange solid-phase extraction reduced the levels of interfering components, thus allowing determination of low levels of the amines. Recoveries from process flavors spiked at 25 ppb averaged 83–90%.
Optimization and Automation of AOAC Official Method 971.47 for Determination of Roxarsone in Feed
Authors: Webster Gregory K , Mandzu Rostyk , Drong Lisa A , Williams William H , Mess Brian G , Wodke Norbert
Published: February 2020

AOAC Official Method 971.47 was optimized for use with solid-phase extraction (SPE) using the same activated carbon referenced in the original method. The optimization of AOAC 971.47 begins after the roxarsone is extracted into the 2% K2HPO4 solution of the original method; instead of 30 mL, 9 mL is pipetted into a test tube. Next, to flocculate the protein, 300 μL HCI is pipetted into the tube and mixed. After 15 min, the contents of the tube are filtered through a 0.45 μm nylon membrane filter equipped with a glass prefilter. Next, 7 mL clear filtrate is pipetted into a new test tube, followed by the addition of 234 μL NaOH, and the contents of the tube are mixed. The filtrate is then passed through a 400 mg bed of activated carbon packed in a 3 mL SPE tube at a flow rate of 1 mL/min. The spectrophotometric analysis of the eluate is not changed from the original AOAC 971.47. The optimized method was validated and semiautomated. Results of roxarsone determination by the optimized procedure were found to be acceptable at all levels of approved claims. For the commercial feed samples analyzed, recoveries by the automated method ranged from 93.7 to 104% of the results reported by an independent laboratory using AOAC 971.47.
Simultaneous Determination of Five Fasciolicides in Milk by Liquid Chromatography with Electrochemical Detection
Authors: Takeba Kazue , Itoh Takeshi , Matsumoto Masao , Nakazawa Hlroyuki , Tanabe Shinzo
Published: February 2020

A sensitive and specific method is described for determination of 5 fasciolicides in milk. The drugs are used to control liver flukes in cattle. The milk sample was homogenized with acetone and acetonitrile, sonicated, and centrifuged. The supernatant was extracted with dichloromethane. The extract was evaporated to dryness, dissolved in 1 % sodium hydrogen carbonate, and purified on a C18 cartridge. The 5 drugs were separated from the matrix by reversed-phase liquid chromatography (LC) and determined by dual-electrode coulometric detection on a Kaseisorb LC ODS-300-5 column. The mobile phase was acetonitrile-0.05M potassium dihydrogen phosphate (55 + 45) at pH 3.0. The flow rate was 1 mL/min at 40°C. The applied potentials of detectors 1 and 2 were set at 0.20 and 0.55 V, respectively. The average recovery of the drugs added to milk at 0.01 and 0.1 µ g/mL was 89.6%, and the coefficient of variation was 4.7%. The detection limits of the drugs in milk were 4-20 ng/mL. The method is used to monitor commercial milk samples and to determine the residual levels of these drugs in milk from cows treated with a fasciolicide.
Determination of Atrazine and Hydroxyatrazine in Agricultural Runoff Waters by Liquid Chromatography and Fast Atom Bombardment-High Resolution Mass Spectrometry
Authors: Cai Zongwei , Monson Steven J , Spalding Roy F
Published: February 2020

Agricultural surface water samples were collected after the first 2 major runoff events in 1994 for determination of atrazine (ATR, 2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and hydroxyatrazine (HA, 2-ethylamino-4-hydroxy-6-isopropylamino-striazine). After addition of. 13C3-labeled ATR and 13C3-labeled HA as internal standards, the chemicals were quantitatively extracted and eluted from water samples by liquid-solid extraction with a carbon black cartridge. Liquid chromatography and fast atom bombardment-high resolution mass spectrometry were used to analyze the sample extracts. Concentrations of ATR ranged from 8.2 to 15.1 parts per billion (ppb) in the samples collected after both runoff events from a highly agricultural watershed in south-central Nebraska. HA concentrations ranged from 0.25 to 2.7 ppb in the water samples. Results obtained from both analytical procedures agreed within a 15% deviation. As predicted from runoff events, the highest levels occurred in samples from the first collection on June 24,1994, for both ATR and HA, whereas samples collected on July 5,1994, contained much lower levels of HA.
Viscometric Determination of p-Glucanase and Endoxylanase Activity in Feed
Authors: Engelen Adrianus J , Van Der Heeft Fred C , Randsdorp Peter H G
Published: February 2020

A method is described for viscometric determination of enzymatic activity of β-glucanase and endoxylanase in feed samples. The method is based on determination of the decrease in viscosity as a result of hydrolysis of glycosidic bonds in β-glucan and xylan at pH 3.5. This method does not require a blank sample (feed without enzyme addition), and it does not need standard addition for reliable quantitation.
Comparison of Supercritical CHF3 and CO2 and Methanol-Modified CHF3 and CO2 for Extraction of Sulfonamides from Chicken Liver
Authors: Ashraf-Khorassani Mehdi , Taylor Larry T , Schweighardt Frank K
Published: February 2020

Supercritical CHF3 and methanol-modified CHF3 were compared with supercritical CO2 and methanol- modified CO2 for extraction of sulfonamides from fortified chicken liver admixed with Hydromatrix. Results showed that solvating power and selectivity were higher for supercritical and methanolmodified CHF3 than for supercritical and methanolmodified C02. Visual observation showed that chicken liver extract obtained with methanol-modified CHF3 was cleaner than that obtained with methanol-modified C02. Fat precipitated in the solvent trap when CO2 was used as the extraction medium. Also, simple off-line collection of fortified chicken liver extract obtained with CO2 in a solidphase extraction cartridge (packed with either C18 or alumina) followed by phosphate buffer-methanol (50 + 50) rinse yielded an extract that required no further cleanup for analysis.
Rapid Screening for Mancozeb in Exposure IHals by Inductively Coupled Plasma-Atomic Emission Spectrometric Determination of Manganese
Authors: Headley John V , Massiah William , Laberge Donald , Purdy John R
Published: February 2020

An inductively coupled plasma-atomic emission spectrometric method was developed for rapid screening of samples for the dithiocarbamate fungicide mancozeb. The method was based on determining the level of manganese, which forms a major part of the compound formulation, and was used to analyze urine, wash water, tank mixes, cellulose acetate filters, gauze patches, and clothing in field operator exposure trials. Sample preparation was fast and simple, requiring only acid digestion in nitric acid or a nitric acid-hydrogen peroxide mixture, and subsequent analysis of the diluted digestate. Urine was acidified with nitric acid as soon as possible after collection and analyzed directly. The method detection limit for mancozeb was 0.020 mg/L (based on 0.004 mg Mn/L) in urine, wash waters, and tank mixes and 0.5 μg (based on 0.1 μg Mn) in cellulose acetate filters, gauze patches, and clothing. The working range of the method was 0.020-250 mg mancozeb/L (r2 ≥ 0.999) in urine, wash water, and tank mixes and 0.5- 6250 μg mancozeb (r2 ≥ 0.999) in filters, patches, and clothing. Higher levels may be determined by appropriate dilution.
Determination of Monensin in High-Moisture Cattle Rations by Liquid Chromatography with Postcolumn Derivatization
Authors: Bridges Debbie A , Roth Doug M , Cleveland Christine M , Moran John W , Coleman Mark R
Published: February 2020

An existing liquid chromatographic method using postcolumn derivatization has been used extensively to quantitate monensin in animal feeds. Because of the relatively high moisture content of many cattle feed rations, some modifications were made to this method. Several sample-processing steps were evaluated to determine optimum sample-processing procedure. The sample weight/sample diluent ratio was modified, and method linearity was validated for the lower monensin concentrations anticipated in high-moisture cattle rations. The accuracy and precision of data generated at these lower concentrations were also determined. Because of the high moisture content of these rations, data analysis for this method required correction of feed potency for loss on drying. With these modifications, monensin can be accurately determined in high-moisture cattle rations.
Fourier Transform Infrared Spectroscopic Determination of Fenvalerate in Emulsifiable Concentrate Formulation
Authors: Gupta Suman , Sharma Krishan K , Handa Swadesh K
Published: February 2020

Fenvalerate [(RS)-α-cyano-3-phenoxybenzyl-(RS)-2-(4-chlorophenyl)-3-methylbutyrate] is extracted from formulation with acetone. The extract is subjected to preparative thin-layer chromatography, and the fenvalerate zone is scraped from the developed plate. Fenvalerate is then eluted from the adsorbent with chloroform and determined by Fourier transform infrared spectroscopy by measuring the carbonyl absorption band at about 1755 cm−1. Recoveries from laboratory-prepared and commercial formulations were 93–99%. The validity of the method was further confirmed by comparing results with those obtained by liquid chromatography.
Microbiological Method for Determining Macrolides in Animal Feeds in the Presence of Other Drugs by Thin-Layer Chromatography Detection
Authors: Markakis Pantelis K
Published: February 2020

A method was developed to separate, detect, and quantitate erythromycin (ERY) and tylosin (TYL) in animal feeds in the presence of 11 other drugs: 3 nitrofurans, 2 tetracycline antibiotics, 3 sulfonamides, 2 coccidiostats, and 1 antibacterial growth promoter. ERY and TYL were separated from coexisting drugs, detected by thin-layer chromatography, and quantitated microbiologically by an agar diffusion method. Analysis of 125 experimental animal feed samples fortified at 5 levels (7.5–400 ppm) with ERY and TYL and at 1 level (50 ppm) with the rest of the drugs gave limits of quantitation of 2 and 5 ppm, recoveries of 90.3 and 92.4%, and relative standard deviations of 4.3–7.3% and 3.6–6.1%, respectively.
Quantitative Analysis of Lamotrigine in Plasma and Tablets by Planar Chromatography and Comparison with Liquid Chromatography and UV Spectrophotometry
Authors: Dreassi Elena , Corbini Gianfranco , Corti Piero , Ulivelli Monica , Rocchi Raffaele
Published: February 2020

A method using planar chromatography (PC) was developed for determining lamotrigine (LTG; 3,5- diamino-6-[2,3-dichlorophenyl]-1,2,4-triazine) in human plasma and tablets. LTG was extracted with acetonitrile in the presence of sodium carbonate. 3,5-Diamino-6-(2-methoxyphenyl)-1,2,4-triazine was used as internal standard. The detection limit was 0.27 μg/mL plasma and the recovery from human plasma fortified with various concentrations of LTG was 91.3 ± 3.4%. Interference from other common antiepileptic agents was checked. Results obtained with the PC method were compared with those obtained by a method using liquid chromatography (LC) for analysis of plasma and with methods using LC and UV for assay of tablets.
Headspace Gas–Liquid Chromatographic Determination of Dithiocarbamate Residues in Fruits and Vegetables with Confirmation by Conversion to Ethylenethiourea
Authors: Ahmad Nazir , Guo Lin , Mandarakas Peter , Farah Viola , Appleby Semeone , Gibson Trevor
Published: February 2020

Ethylene-bis-dithiocarbamate (EBDC) residues were determined as carbon disulfide (CS2) by an improved headspace gas-liquid chromatographic (GLC) procedure. Among 837 samples of 30 agricultural commodities tested, 43% contained residues above the detection limit for the method: 100% of broccoli samples; 80% of cabbage, kiwifruit, and grape samples; and 71% of cucumber samples. Most of the residues in kiwifruit were on or near the skin. Elimination of false-positive detections by the improved method was confirmed with kiwifruit in 2 independent procedures. Whole fruits were washed with 5% EDTA to remove surface residues of EBDC. Analysis of washes for CS2 by the headspace procedure after treatment with acidic stannous chloride and for ethylene thiourea by LC after prolonged treatment at 60°C qualitatively identified the EDTA-soluble residues as EBDC. Although the improved method does not produce false-positive results, peak area responses of CS2 and the internal standard, thiophene, are influenced by chemical composition of the matrix. With matrixes high in sugar or lipids, the apparent CS2 content may be overestimated by 4-fold. Accurate determination of EBDC residues in these sample types requires appropriate adjustments to matrixes.
Multiresidue Method for Determination of Organochlorine Insecticides and Polychlorinated Biphenyl Congeners in Fatty Processed Foods
Authors: Sannino Anna , Mambriani Paola , Bandini Mirella , Bolzoni Luciana
Published: February 2020

A previously published gel permeation chromatographic (GPC) procedure for determination of organophosphorous insecticides is used to determine 24 organochlorine (OC) pesticide and 9 polychlorinated biphenyl (PCB) residues in 8 fatty preserved foods of vegetable and animal origin. Samples are extracted with methylene chloride and cleaned up by automated GPC with a Biobeads SX3 column and a methylene chloride–cyclohexane (15 + 85) eluant. Compounds are quantitated by gas chromatography/mass spectrometry (GC/MS) with selected ion monitoring using a DB-5 column. Average recoveries of OC pesticides from samples fortified at 0.010–0.080 mg/kg ranged from 73 to 98%. Average recoveries of 9 PCB congeners spiked at 2 levels (0.0025 and 0.020 mg/kg) were between 85 and 104%. Quantitation limits were between 0.002 and 0.025 mg/kg, depending on the compound. The purified extracts were analyzed further by GC with electron capture detection (ECD), and the results were compared with those obtained by MS. Determination of some OC pesticides and PCB congeners was not possible by ECD because of matrix interference.
Potential Interference by Free Fatty Acids in Determination of Tricyclazole in Brown Rice by Gas Chromatography with Flame Thermionic Detection
Authors: Tsumura Yukari , Nakamura Yumiko , Tonogai Yasuhide , Shibata Tadashi
Published: February 2020

A convenient method is described for the determination of tricyclazole in brown rice, and the interference of free fatty acids with flame thermionic detection (FTD) is reported for the first time. Brown rice is extracted with acetone, the extract is filtered, and the filtrate is evaporated. To the residue is added 10% (w/v) NaCI solution, and the mixture is extracted with ethyl acetate. The extract is charged on a Sep-Pak Plus silica cartridge. Free fatty acids are removed from the rice by washing with diethyl ether, and tricyclazole is eluted with acetone-n-hexane (1 + 1). Tricyclazole is determined on a DB-1 capillary column by gas chromatography with FTD (GC–FTD). Linoleic acid and oleic acid, which have essentially the same retention time as tricyclazole, cannot be detected by FTD. Thus, without the Sep- Pak Plus silica cleanup, the peak height of tricyclazole in the chromatogram decreased, the extent depending on the concentration of linoleic acid, n-Hexane–acetonitrile partitioning was not used for cleanup because it could not remove 50% of the free fatty acids. Recoveries (mean ± standard deviation, n = 5) of tricyclazole from rice fortified at 2 and 0.1 ppm were 90.5 ±9.4% and 81.3±10.6%, respectively. The limit of quantitation was 0.05 ppm.
Determination of Decabromobiphenyl Ether in Water and Sediment Samples by Gas Chromatography with Electron Capture Detection
Authors: Yamamoto Hitoshi , Okumura Tameo , Nishikawa Yoshinori , Konishi Hiroe
Published: February 2020

Traces of decabromobiphenyl ether (DBBE) in water and sediment were determined by capillary gas chromatography with electron capture detection. Rapid sample preparation techniques such as disk-type C18 solid-phase extraction and cartridge- type Florisil extraction were used to clean up water and sediment samples, respectively. The detection limits of DBBE were 0.12 ng/mL and 9.7 ng/g in water and sediment, respectively. Average recoveries of DBBE added to river water, sea water, and sediment were 103%, with a relative standard deviation (RSD) of 8.6%; 87%, with an RSD of 10.7%; and 91%, with an RSD of 6.3%, respectively.
Determination of Boron in Plants and Plant-Derived Foods by Ultrasonic Nebulization-Inductively Coupled Plasma Atomic Emission Spectrometry with Addition of Mannitol
Authors: Sun Da-Hai , Waters James K , Mawhinney Thomas P
Published: February 2020

An ultrasonic nebulization-inductively coupled plasma (ICP) atomic emission spectrometry procedure was developed to determine boron in plants and plant-derived foods. Samples were ashed at 550°C for 4 h, and the resulting ash was dissolved into a mannitol-nitric acid solution to form a boron- mannitol complex. Solutions were directly nebulized into ICP by an ultrasonic nebulizer. The memory effect—the main drawback for determining boron with the ultrasonic nebulizer—was minimized with addition of mannitol. Two National Institute of Standards and Technology (NIST) standard reference materials (SRM 1515 apple leaves and SRM 1547 peach leaves) and 25 food and plant materials spiked with NIST SRM 1515 were analyzed to verify method accuracy. Boron contents found in NIST standard samples were in excellent agreement with certified values. A detection limit (2σ) of 0.5 μg/L and typical recoveries of 93 to 106% from spiked selected samples were obtained.
Assurance Escherichia coli 0157:H7: A Comparative Validation Study
Authors: Feldsine Philip T , Forgey Robin L , Falbo-Nelson Maria T , Brunelle Sharon L
Published: February 2020

A wide variety of food products, with emphasis on raw meat products, were analyzed simultaneously by 3 methods: the Assurance Escherichia coli 0157:H7 (EHEC) enzyme immunosorbent assay (EIA), the EHEC visual immunoprecipitate assay (VIP), and a modified Bacteriological Analytical Manual (BAM) culture method. This paper reports results of a comparative study of the Assurance and modified BAM methods. In this comparative study, 1050 samples and controls gave false-negative rates of 1.0 and 0%, respectively, for the Assurance EIA and the modified BAM culture methods. The overall agreement between the 2 methods was 99.4%. Cultural confirmation of presumptive positive samples was problematic because competitive flora were present in higher levels than EHEC in the enrichment broth after incubation and the target organism had nondescript characteristics on the primary selective agar, hemorrhagic coli agar, which necessitated picking of additional colonies in many instances.
Determination of Platinum in Wine by Graphite Furnace Atomic Absorption Spectrometry
Authors: Cabrera-Vique Carmen , Teissedre Pierra-Louis , Cabanis Marie-Thérèse , Cabanis Jean-Claude
Published: February 2020

A method based on graphite furnace atomic absorption spectrometry (GFAAS) was developed for determining platinum in wine. Wine samples were prepared by microwave acid digestion or dry mineralization. The method of standard addition was used for Pt determination in untreated wine samples and mineralized samples. Analyte modifiers and furnace conditions were optimized. Effects of cations (Mg2+, Ca2+, K+, Na+, and NH|) and anions (PO43, SO42) were tested separately and in combination. Analytical characteristics of the method were optimized for analyte recovery and signal enhancement. Recoveries ranged from 92.5 to 102%, and precision reproducibility relative standard deviation varied from 7.5 to 10%. Red, rosé, and white wines from France were analyzed. Platinum levels found in most wines were very low (<10 μg/L).
Evaluation of Nonlinearity Testing Procedures on Simulated Data
Authors: Feinberg Max H , De La Rochette Arnauld J
Published: February 2020

When calibrating a method, use of a straight line is highly favorable because it is easy to compute sensitivity and the blank to be used to predict an unknown concentration. Therefore, when validating an analytical method, it is necessary to check whether linearity is acceptable over the method’s whole application range before trying another model. Available procedures for checking linearity are reviewed by using a simulation model that gives a complete family of curved calibration lines. From the simulated data, it is possible to compute the prediction error generated by the model curva ture as the relative difference between the linear extrapolated value and the observed value. It appears that the power of the classical “linearity test” depends on experimental design and that at least 25 measurements are necessary to detect curvature for an acceptable prediction error. An alternative model-fitting criterion, based on the χ2 probability law, also was evaluated. It is also applicable but seems less stable and more sensitive to data size. The question of the definition of nonlinearity is also raised because it is directly connected to the comparison of nonlinearity detection techniques.
Liquid Chromatographic Determination of Chloramine-T and Its Primary Degradation Product, ρ-Toluenesulfonamide, in Water
Authors: Dawson Verdel K , Davis Ruth A
Published: February 2020

N-sodium-N-chloro-ρ-toiuenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes. BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species. This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, ρ-toluenesulfonamide (ρ-TSA), in water. The procedure involves reversed-phase (C18) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg chloramine-T or ρ-TSA/L. Mean recoveries were 96.4 ± 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 ± 4.6% for water samples fortified with 0.005 mg ρ-TSA/L. Limits of detection without sample enrichment for chloramine-T and ρ-TSA are 0.01 mg/L and 0.001 mg/L, respectively.
Volatile Antifungal Compounds in Maize Kernels: Effect of Ear Position on Aflatoxin Production
Authors: Zeringue Hampden J
Published: February 2020

Volatiles produced by ground maize kernels from 3 zonal areas of Pioneer Hybrid 3136 maize ear inhibited the growth of aflatoxigenic Aspergillus flavus and, therefore, production of aflatoxin B1 in a static culture bioassay. Volatiles from kernels obtained from the medial zonal area of the maize ear resulted in 75% mean inhibition of A. flavus radial growth and 76% mean inhibition of aflatoxin contamination. Volatiles from kernels obtained from the apical zone resulted in 19% mean inhibition of radial growth and 33% mean inhibition of aflatoxin contamination. Volatiles from kernels obtained from the basal zone resulted in 23% mean inhibition of radial growth and 37% mean inhibition of aflatoxin contamination. Volatiles were purged on Tenax columns and analyzed by gas chromatography/mass spectrometry. Compounds highly toxic to A. flavus, such as C4-C6 aldehydes, benzothia-zole, methyl jasmonates, and 2-furancarboxaldehy-des, were found mostly in volatiles from kernels obtained from the medial zone. These results demonstrate a relationship between volatile fungi-toxic compounds from kernels obtained from different zonal areas and aflatoxin contamination.
Determination of Sulfonylurea Herbicides in Water by Capillary Electrophoresis and by Liquid Chromatography/Mass Spectrometry
Authors: Krymtsky Alexander J
Published: February 2020

A capillary electrophoresis (CE) method and an electrospray ionization (ESI) liquid chromatography/mass spectrometry (LC/MS) confirmatory method were developed to analyze 12 sulfonylurea herbicides and one sulfonamide (Flumetsulam) in runoff water. The water used for fortification was collected from a local marsh that contained high levels of potentially interfering compounds. Good recoveries and adequate sensitivity at the 0.2 ppb level (limit of quantitation) were obtained. A portion of the water was acidified and extracted with reversed- phase solid-phase extraction (SPE). Extracts were cleaned up with a tandem system consisting of a strong-anion exchange SPE cartridge stacked on an alumina SPE cartridge. CE/ultraviolet quantitation was achieved by capillary zone electrophoresis at pH 4.75 with 50 mM ammonium acetate buffer and an acetonitrile modifier. ESI LC/MS quantitation was achieved by using a time-scheduled selective-ion monitoring (positive mode) of the M+H ions for each compound. The extraction/cleanup procedure provided extracts such that in-source collision-induced dissociation gave product ions for confirmation at the 0.2 ppb fortification level.
Simplified Determination of Imidazolinone Herbicides in Soil at Parts-per-Billion Level by Liquid Chromatography/ Electrospray Ionization Tandem Mass Spectrometry
Authors: Stout Steven J , Dacunha Adrian R , Safarpour Maximilian M
Published: February 2020

Imidazolinones are a significant new class of low-use-rate, reduced-environmental-risk herbicides for protection of a wide variety of agricultural commodities. Because of their low rates of application, residues of imidazolinones in soil need to be monitored at low parts-per-billion (ppb) levels. Greatly simplified cleanup procedures were reported recently for determining imidazolinones in soil at the 1 ppb level by combining microwave-assisted extraction (MAE) with gas chromatography/electron capture negative chemical ionization mass spectrometry (GC/ECNCI) and for determining imidazolinones in water by using liquid chromatography/electrospray ionization mass spectrometry (LC/ESMS) and liquid chromatography/electrospray ionization tandem MS (LC/ESMS/MS). By merging the extraction and cleanup procedures for determining imidazolinones in soil with LC/ESMS/MS, instrumental analysis time was reduced to that approximating sample preparation time, and the drawbacks of in situ methylation required for GC/ECNCI were eliminated. Recoveries of imazethapyr, the most widely used imidazolinone, from a variety of soil types fortified at 1–50 ppb averaged 92% with a standard deviation of 9.7%. Control soil extracts gave apparent residues of <0.2 ppb. These results were almost identical to those previously reported for GC/ECNCI.
Determination of Pesticides in Soils by Gas Chromatography-Ion Trap Mass Spectrometry
Authors: Papadopoulou-Mourkidou Euphemia , Patsias John , Kotopoulou Athena
Published: February 2020

A multiresidue method is reported for determination of a variety of chemical classes of pesticides (organochlorines, organophosphates, triazines, phenylureas, acetanilides, pyrethroids, carbamates, and miscellaneous others) in soils. Soil samples are extracted with an acetonitrile-water mixture, and the pesticides are partitioned into petroleum ether-diethyl ether for direct analysis by gas chromatography-ion trap mass spectrometry (GC-ITMS) with the mass spectrometer operated in the electron ionization mode. Recovery values determined for a fortification range of 20–1000 ppb were >80% for most of the pesticides. Detection limits determined in the full-scan mass spectrum mode were in the 1–10 ppb range for most analytes. This simple and rapid multiresidue method for determination of pesticides at trace levels in soils is appropriate for environmental behavior and pollution monitoring studies.
Liquid Chromatographic Determination of Nitrofuran Residues in Bovine Muscle Tissues
Authors: Angelini Nora M , Rampin Oscar D , Mugica Héctor
Published: February 2020

A liquid chromatographic (LC) method was developed and statistically validated for simultaneous determination of nitrofurazone, nitrofurantoin, furazolidone, and furaltadone residues in bovine muscle tissues. These antimicrobial residues in samples stabilized at pH 6.0 were extracted with acetonitrile and purified by liquid-liquid partition between dichloromethane-ethyl acetate and hexane saturated with acetonitrile. The acetonitrileethyl acetate extract was concentrated, and drug residues were dissolved in LC mobile phase, filtered, and determined by LC. A Cis reversed-phase (ODS Hypersil) column at 35°C, a mobile phase of 0.01 M sodium acetate buffer (pH 4.5)-acetonitrile (70 + 30), and a UV/visible diode array detector at 365 nm were used. The retention times and UV spectra of peaks in spiked samples were compared with those of known nitrofurans. Limits of detection (LD) and quantitation (LQ) were 1 and 2 μg/kg, respectively. Average recoveries were 76% (range, 60-110%). Relative standard deviations ranged from 6 to 18% at 5 fortification levels from 1.5 to 20 μg/kg. (Fortification levels for furaltadone were 3 to 40 μg/kg). The method was used to analyze 350 samples per year from 1993 to 1995.
Determination and Degradation of Methomyl in Tomatoes and Green Beans Grown in Greenhouses
Authors: Garcia M D Gil , Vidal Martínez , Galera M Martínez , Torreblanca C Rodríguez , Gonzalez C
Published: February 2020

A liquid chromatographic (LC) method using UV detection at 233 nm was used to study the degradation of methomyl in tomatoes and green beans grown in greenhouses. A liquid-liquid extraction with CH2CI2-methanol (90 + 10, v/v) and a cleanup step with Florisil were combined with LC to isolate, recover, and quantitate the pesticide. Average recoveries obtained at spike levels of 0.03 and 0.40 mg/kg were 83.2-84.7% for tomatoes and 83.387.5% for green beans. Determination limits were 0.03 mg/kg for tomatoes and 0.01 mg/kg for green beans. Levels of methomyl residues were studied in tomatoes and green beans grown in an experimental greenhouse to establish the effect of the kind of greenhouse, application dose, species grown, and climatic conditions on the degradation of this pesticide. Analysis of variance showed that doses did not affect the response. The half-life, however, is greater in a flat-roof greenhouse than in an asymmetric-roof greenhouse and is significantly longer for green beans than for tomatoes and longer in winter than in spring. A preharvest time of about 5 days may be suitable for green beans sprayed with methomyl. Tomatoes show residue levels at the time of application lower than Spanish minimum residue levels.
Planar Chromatography for the Multiclass, Multiresidue Screening of Chloramphenicol, Nitrofuran, and Sulfonamide Residues in Pork and Beef
Authors: Abjean Jean-Pierre
Published: February 2020

A method is described for multiclass and multiresidue qualitative detection of chloramphenicol, nitrofuran, and sulfonamide residues in animal muscle. The drugs are extracted from 1 g tissue with 2 mL ethyl acetate and purified by silica solidphase extraction. After elution of the cartridge, the collected solution is evaporated, and the residue is dissolved in methanol and chromatographed on a Si60 high-performance thin-layer chromatography plate. After evaporation of solvent, nitrofurans are visualized first by their specific UV photochemical reaction with pyridine. Then chloramphenicol is reduced to its amino derivative, and this derivative and the sulfonamides are visualized by long-wave UV after reaction with fluorescamine. Chloramphenicol, nitrofurans, and sulfonamides are detected at residue level of 10, 5, and 100 μg/kg, respectively, or less in pork and beef.
Liquid Chromatographic Determination of Inositol Hexanicotinate in Formulated Preparations
Authors: Nagarajan Mythili , Waszkuc Ted W , Sun Jidong
Published: February 2020

A precise and selective liquid chromatographic procedure for determining inositol hexanicotinate (IHN) in formulated preparations was developed and validated. IHN was dissolved in dimethyl sulfoxide, diluted with acetonitrile, chromatographed on a Nova-Pak C18 column with a mobile phase of water-methanol (40 + 60, v/v), and detected at 262 nm. The correlation coefficient of the calibration curve was 0.9995 over the range 0.050.15 mg/mL. Overall recovery of IHN was >97%. Coefficients of variation for intra- and interday precisions were <2%.
Determination of Glucose in Nonalcoholic Beverages by a Biosensor Coupled with Microdialysis Fiber Samplers
Authors: Centonze Diego , Zambonin Carlo G , Palmisano Francesco
Published: February 2020

Glucose in soft drinks, fruit juices, and milk was determined by an interference-free amperometric biosensor coupled with microdialysis fiber samplers. The biosensor was based on glucose oxidase (GOx) immobilized on a platinum electrode by an electroproduced bilayer of overoxidized polypyrrole (Pt/PPyox,GOx/PPyox). The first undercoating of PPyox entrapped GOx, and the second, grown onto the first, limited glucose diffusion, hence improving linearity of response. Such a biosensor coupled with microdialysis sampling extended the linear range to 500 mM. The biosensor response was not affected by sample pH variations in the range 2–10. The influence of flow rate on biosensor response was also investigated. The glucose response of the device in both continuous and discontinuous flow injection experiments showed good repeatability and sensitivity. Real samples containing high glucose concentrations were easily analyzed without pretreatment such as dilution or filtration. Results were in good agreement with those of the reference method.