bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Trace 2,4-Dichlorophenoxyacetic Acid in Fresh Produce by Gas Chromatography with Boron Trichloride/2- Chloroethanol Derivatization
Authors: Ting Keh-Chuh , Kho Peng K 
Published: February 2020

Abstract
2,4-Dichlorophenoxyacetic acid (2,4-D) residues in fresh produce is officially analyzed as its methyl ester form by gas chromatography with electron capture detection (GC-ECD). Because of safety concerns with diazomethane, the reagent used to form methyl esters, a less toxic and dangerous reagent, BCI3/2-chloroethanol, was considered. With this alternative reagent, the detecting product is a 2-chloroethyl ester. Compared with the methylester, the 2-chloroethylester has a longer retention time and a better signal-to-noise ratio for trace level analysis by GC-ECD. However, the reagent produces too many unwanted background peaks. If peak retention time is the only information available to identify the residue in case of litigation, the presence of too much background noise increases the ambiguity of identification. Therefore, confirmation by interpretation of the mass spectrum and determination of the compound structure is necessary to ensure the validity of the method. Ten commodities were fortified with 2,4-D at 0.1 ppm. Recoveries of 2-chloroethyl esters and methyl esters were 91 and 92%, respectively. The method is safe, simple, and robust.
Simultaneous Liquid Chromatographic Analysis of the β-Lactam Antibiotics Cefazolin, Cefadroxil, Cephalexin, Ampicillin, and Cephradine in Solution
Authors: Farag Shawky A 
Published: February 2020

abstract
A liquid chromatographic method was developed for the determination of nanogram quantities of 5 broad-spectrum structurally related β-lactam antibiotics (cefazolin, cefadroxil, cephalexin, cephradine, and ampicillin) in solution. The method uses a C18 reversed-phase column, UV absorption (240 nm) detection, and an aqueous mobile phase containing isopropyl alcohol and acetic acid. Relative resolution between the antibiotic peaks ranged from 1.7 to 5.9 for all peaks. Chromatographic retention times were 2.97, 3.92, 4.57, 5.37, and 6.56 min for cefazolin, cefadroxil, cephalexin, ampicillin, and cephradine, respectively. Accuracy, precision, linearity, and long term analytical reproducibility were determined by statistical analysis. Use of the proposed method to evaluate the degradation of cephradine solutions stored at room temperature illustrated its potential as a stability-indicating assay.
Optical Immunobiosensor Assay for Determining Enrofloxacin and Ciprofloxacin in Bovine Milk
Authors: Mellgren Catarina , Sternesjö Åse 
Published: February 2020

abstract
A rapid, sensitive optical immunobiosensor assay was developed and used to determine enrofloxacin and its main metabolite, ciprofloxacin, in milk from healthy cows and cows with clinical signs of mastitis after intramuscular administration of enrofloxacin. Liquid chromatography (LC) was used to confirm results of the biosensor assay. Despite incomplete cross-reactivity between polyclonal enrofloxacin antibodies and ciprofloxacin, the biosensor assay could be used for semiquantitative analysis of the sum of the 2 substances. LC analysis showed that ciprofloxacin persisted at levels exceeding the expected future maximum residue limit in milk for several days after the end of the withdrawal period.
Comparison of Monolayer and Bilayer Plates Used in Antibiotic Assay
Authors: Reamer Richard H , Dey Bhabani P , White Clarence A , Mageau Richard p 
Published: February 2020

abstract
Standard curves of 5 antibiotics were determined in an antibiotic assay using bilayer and monolayer agar plates and AOAC-specified test organisms and agar media. Micrococcus luteus ATCC 9341a and antibiotic medium No. 2 were used to prepare the penicillin G standard curve. The same organism and antibiotic medium No. 11 were used to prepare the erythromycin standard curve. Standard curves for streptomycin, tetracycline, and gentamicin were prepared, respectively, with antibiotic medium No. 5 and Bacillus subtilis ATCC 6633, antibiotic medium No. 8 and B. cereus ATCC 11778, and antibiotic medium No. 11 and Staphylococcus epidermidis ATCC 12228. Assays of inhibition by meat fortified with penicillin, streptomycin, gentamicin, tetracycline, erythromycin also were performed on monolayer and bilayer plates. Differences in standard curves and inhibitory responses obtained with monolayer and bilayer plates were &lt;10%. Thus, monolayer plates are acceptable for use in analyses of meat and poultry for antibiotics residues, with savings in laboratory resources and time.
One-Step Solid-Phase Extraction Cleanup and Fluorometric Analysis of Deoxynivalenol in Grains
Authors: Malone Bruce R , Humphrey Craig W , Romer Tom R , Richard John L 
Published: February 2020

abstract
A rapid, quantitative, inexpensive, efficient method was developed to determine deoxynivalenol (DON) in wheat, barley, corn, wheat middlings, wheat flour, bran, malted barley, and oats. Samples are ground and extracted with acetonitrile-water (86 + 14). A portion of the extract is cleaned up by passage through a MycoSep No. 225 column, evaporated to dryness, and derivatized with zirconyl nitrate and ethylenediamine in methanol. The resulting fluorescent derivative of DON is identified and quantitated with a calibrated fluorometer containing a broad wavelength pulsed xenon light source. This method quantitated DON concentrations from 0.5 to 50 ppm without dilution and was linear when applied to samples of noncontaminated wheat spiked at 0.5, 5, 10, 25, and 50 μg DON/g. Correlation coefficients of the method with LC for multiple analyses (n ≥ 14 for each commodity) applied to wheat, corn, barley, wheat flour, and wheat middlings were 0.99, 0.99, 0.99, 0.93, and 0.98, respectively. Individual analyses were conducted in &lt; 30 min, and 24 samples were analyzed in 2 h.
Determination of Residues of Flumequine and 7-Hydroxyflumequine in Edible Sheep Tissues by Liquid Chromatography with Fluorimetric and Ultraviolet Detection
Authors: Delmas Jean-michel , Chape Anne-marie , Sanders Pascal 
Published: February 2020

abstract
A simple, sensitive, and rapid method for simultaneous determination of residues of flumequine and its microbiologically active metabolite 7-hydroxyflumequine in 100 mg sheep edible tissues (muscle, liver, kidney, and fat) by liquid chromatography is reported. After liquid-liquid cleanup with ethyl acetate, tissue extracts were injected onto a Select B column. The 2 compounds were determined by ultraviolet and fluorimetric detection. The method was repeatable and reproducible for flumequine and 7-hydroxyflumequine in muscle, liver, kidney, and fat, with limits of detection below 2 and 3 μg/kg for flumequine and 7-hydroxyflumequine, respectively. Mean recoveries for flumequine were 90 ± 7, 82 ± 7,89 ± 5, and 82 ± 6% in muscle, liver, kidney, and fat, respectively. Mean recoveries for 7-hydroxyflumequine were 91 ± 2, 90 ± 4, 86 ± 3, and 84 ± 4% in muscle, liver, kidney, and fat, respectively.
Automated Screening Method for Determining Optimum Preservative Systems for Personal and Home Care Products
Authors: Lenczewski Melissa E , Kananen Lafonna L 
Published: February 2020

abstract
A procedure was designed to determine the minimum preservative level (MPL) for personal and home care products. A highly preserved sample and an unpreserved sample were combined at different concentrations within a 96-we 11 microtiter plate by using an autodilutor. A unique tip design made it possible to accurately deliver viscous test materials that cannot be dispensed using vacuumor fluid-filled systems. After inoculation, the sample was evaluated at a specified time interval for the presence of surviving bacteria, yeast, and mold. The lowest concentration of preservative with no microbial growth is the recommended level of preservative for the product. Because sample turbidity may interfere with determination of the endpoint, a colorimetric endpoint was used to indicate growth of microorganisms and to differentiate product from growth. The predicted levels were tested with a modified Cosmetic, Toiletry, and Fragrance Association method. The method successfully predicted effective preservative levels in many personal and home care products with a broad range of viscosities.
Comparison of Six Methods for Determining Aged Phosphine Residues in Wheat
Authors: Desmarchelier James M , Allen Sylvia E , Ren Yong-Lin 
Published: February 2020

abstract
Phosphine (PH3) and methyl bromide (ChhBr) are the main fumigants used on stored grains. Published multiresidue methods, including those based on solvent extraction and on purge-and-trap techniques, give poor recoveries of CH3Br and, in our hands, close to zero recovery of PH3 and carbonyl sulfide (COS), a potential fumigant. We examined factors influencing fumigant analysis, including stability of chemicals in leachates and partitioning of fumigant between leachate and air. The partition ratio, defined as the ratio of fumigant concentration in leachate to that in the headspace, varied between 1.1 for PH3 and &gt;100 for ethylene dibromide (EDB). An official procedure involving solvent extraction followed by partitioning was modified by being performed in sealed flasks. This change raised the recovery of ChfoBr from 28 to 85%. Volatile fumigants, including PH3 and COS, were determined from concentrations in the headspace over the leachate (aqueous acidified acetone). Recoveries were nearly quantitative at levels down to 3 ng PH3/g and 16 ng COS/g, provided that fortified samples were used as analytical standards. Thus an existing multifumigant procedure was adapted to enable determination of the main fumigants used on staple foodstuffs.
Merging Zones Standard Addition Technique for Determination of Copper in Beer by Flow Injection Atomic Absorption Spectrophotometry
Authors: Fernandes Sílvia M V , Rangel António O S S , Lima José L F C 
Published: February 2020

abstract
A flow injection system for determination of copper in beer by atomic absorption spectrophotometry by the standard additions method is described. The manifold, based on the merging zone technique, prevents the burner head from clogging, as observed with the conventional reference method. With 5 standard additions, results are comparable with those of the reference method. Relative deviations were less than 5.8%, precision was better than 6.4%, and sampling rate was about 30 samples/ h. A less precise, less accurate, but faster procedure (75 samples/h) is possible with only 2 standard additions. The detection limit was 5µg/l.
Sensitive Spectrophotometric Method for Determining Pentachlorophenol in Various Environmental Samples
Authors: Agrawal Omi , Sunita G , Gupta Vinay K 
Published: February 2020

Abstract
A new, simple, and sensitive spectrophotometric method is described for determination of pentachlorophenol, a widely used insecticide and herbicide, in various environmental samples. The method is based on the reaction of pentachlorophenol with concentrated nitric acid to form chloranil, which liberates iodine from potassium iodide. The liberated iodine then selectively oxidizes leucocrystal violet to form crystal violet, which has an absorption maximum at 592 nm. Beer's law is obeyed over the concentration range of 0.1-1.6 μg pentachlorophenol/ 25 ml_ (0.004-0.064 ppm). The method was applied satisfactorily to determination of pentachlorophenol in air, water, plant material, textile effluent, and biological samples.
Determination of Methylmercury in Food Commodities by Gas-Liquid Chromatography with Atomic Emission Detection
Authors: Madson Mark R , Thompson Richard D 
Published: February 2020

Abstract
A method was developed for determining methylmercury in various food commodities. The organomercurial species was converted to methylmercuric chloride by treatment of a sample homogenized with 1.8M HCI. The resulting chlorinated species was eluted from a Celite 545-sample homogenate column with methylene chloride. The eluate was treated with stannic chloride, and the analyte was isolated from coextractives by using a wide-bore capillary column with microwave-induced plasma atomic emission detection. The method was applied to both high- and low-moisture commodities during analysis of 32 samples of grains, cereal products, fruits, and vegetables. Methylmercury was found at trace levels (i.e., between a signal-to-noise ratio of 3:1 and 10:1) and up to 0.85 ppb. Recoveries of added methylmercury ranged from 70.0 to 114.0℅. Limits of quantitation and detection were 0.63 and 0.24 pg on column, respectively, corresponding to 0.30 and 0.11 ng Hg/g sample for a 40 g sample treated according to the method.
Determination of Deoxynivalenol in White Flour, Whole Wheat Flour, and Bran by Solid-Phase Extraction/Liquid Chromatography: Interlaboratory Study
Authors: Trucksess Mary W , Page Samuel W , Wood Garnett E , Cho Tae-Hee 
Published: February 2020

Abstract
A liquid chromatographic (LC) method for determining deoxynivalenol (DON) in white flour, whole wheat flour, and bran at or above the U.S. Food and Drug Administration advisory level of 1 μg/g was evaluated by an interlaboratory study. Test samples of processed wheat (flour and bran) were extracted by blending with acetonitrile-water (84 + 16). Extracts were filtered and passed through a solid-phase extraction (SPE) column. The eluate was then chromatographed on a reversed-phase LC column with a water-methanol gradient. DON was measured at 220 nm. Naturally contaminated white flour, whole wheat flour, and bran samples and spiking solutions of DON to be added to the 3 commodities at 0.5,1.0, and 2.0 μg/g were sent to 4 collaborators in Kansas, Louisiana, Missouri, and Washington states. Three collaborators completed the study. Average recoveries of DON from the 3 commodities spiked at 0.5, 1.0, and 2.0 (μg/g were 94, 87, and 97%, respectively. Within-laboratory relative standard deviations for repeatability (RSDr) ranged from 3.1 to 21.7% and between-laboratory relative standard deviations for reproducibility (RSDR) ranged from 10.8 to 38.7%. On the basis of the results of this study, the SPE/LC method for DON in white flour, whole wheat flour, and bran was adopted as a peer-verified method by AOAC INTERNATIONAL
Fluorometric Determination of Acid Phosphatase in Cooked, Boneless, Nonbreaded Broiler Breast and Thigh Meat
Authors: Davis Carl E 
Published: February 2020

Abstract
This method is applicable for determining activity of acid phosphatase (ACP), a heat-labile enzyme, in cooked, boneless, nonbreaded broiler marinated (83.65% meat) and nonmarinated (100% meat) breast and thigh and in a 50:50 blend of breast and thigh meat. The assay uses a self-indicating substrate that, when acted upon by ACP, loses a phosphate radical and becomes a highly fluorescent compound. Cooked meat is added to deionized distilled water in a 1:3 ratio, blended with a hand-held homogenizer, and then centrifuged at 2500 relative centrifugal force for 5 min. ACP activity in the filtrate is measured after shaking on a Vortex mixer 75 μL of the extract with a pH 5.00 acetate buffer containing a nonfluorescent aromatic monophosphoric ester substrate. The rate of fluorophore formation is monitored during a 3 min incubation period (38°C) in a fluorometer, and ACP enzyme activity (mU/kg sample) is calculated. Three laboratories analyzed 6 cooked poultry products (marinated and nonmarinated breast, thigh, and 50:50 breast/thigh blend). Five cooking temperatures were used to generate different ACP activity levels, which were replicated twice with duplicate samples and duplicate sample tests representing 720 data points. Logio ACP activity (mU/kg sample) performance repeatability and reproducibility standard deviations (sr and sR) and relative standard deviations (RSDr and RSDR) over 5 cooking treatments for 6 products were as follows: marinated breast: sr = 0.02, sR = 0.08, RSDr = 0.60%, RSDR = 2.12%; nonmarinated breast: sr = 0.02, sR = 0.04, RSDr = 0.66%, RSDR = 1.29%; marinated thigh: sr = 0.01, sR = 0.01, RSDr = 0.37%, RSDR = 0.37%; nonmarinated thigh: sr = 0.02, sR = 0.05, RSDr = 0.53%, RSDR = 1.43%; marinated 50:50 breast/thigh blend: sr = 0.01, sR = 0.05, RSDr = 0.36%, RSDR = 1.31%; nonmarinated 50:50 breast/thigh blend: sr = 0.01, sR = 0.04, RSDr = 0.32%, RSDR =1.12%
Rapid Determination of Volatile Bases in Fish by Using an Ammonia Ion-Selective Electrode
Authors: Pivarnik Lori F , Thiam Mamadou , Christopher Ellis P 
Published: February 2020

Abstract
A simple and rapid method using an ammonia ionselective electrode (ISE) to measure volatile bases in fish is proposed. Accuracy and precision were determined with 5,10,20, and 30 ppm NH3 standard solutions. Ammonia values obtained with the method correlate strongly with total volatile basic nitrogen (r2 = 0.88). Recoveries of added ammonia to homogenized fish samples ranged from 83.7 to 96.0%. Responses of the probe to trimethylamine (TMA), calculated as NH3 (mg/100 mL), ranged from 74.9 to 91.7%. These findings indicate that the probe measured TMA as well as ammonia. Storage trials on 8 fish species illustrated that the results obtained with the ISE method reflected nitrogen concentrations based on total volatile base (TVB) analysis. This procedure may be used in lieu of the traditional TVB method for on-site rapid screening of fish
Determination of Malathion Residues in Some Medicinal Plants by Liquid Chromatography with Gas Chromatographic/Mass Spectrometric Confirmation
Authors: Tawfic Ahmed Mohamed , Ismail Saad M M , Mosleh Yahia Y 
Published: February 2020

Abstract
A method for determining malathion residues by reversed- phase liquid chromatography (LC) using methanol only as mobile phase is described. Malathion [diethyl(dimethoxyphosphinothiol)succinate] was applied on marjoram, mint, and chamomile. Residues were detected in fresh and dry crops by LC and confirmed by gas-LC/mass spectrometry. Average recovery of malathion was 85%. Residues detected in fresh marjoram, mint, and chamomile were 0.18, 0.23, and 0.083 mg/kg, respectively. Residues detected in dry marjoram and mint were 0.024 and 0.050 mg/kg, respectively. No malathion residues were detected in dry chamomile. The minimum detectable concentration with this method is 0.013 mg/kg. The study suggests it is safe to use malathion up to 2 sprays per season provided the crop is harvested not less than 3 weeks from the last spray
Integration and Calculation Improvements in Monensin Liquid Chromatographic Method
Authors: Krabel Beverly J , Coleman Mark R , Winland Greg W , Cottrell Brent D , Dkon Brenda K , Dickson David A 
Published: February 2020

Abstract
The liquid chromatographic method for monensin in premix and animal feeds was approved by the AOAC INTERNATIONAL Methods Committee on Feeds, Fertilizer, and Related Agricultural Topics and adopted by the Official Methods Board in January 1997. Improvements have been made in the integration and calculation to include additional monensin factors. The original method accounted for monensin factors A and B only. The improved method also includes monensin factors C and D, Monensin factors C and D account for approximately 2.4% of the total biopotency of monensin in both the premix and feed
Delvotest SP for Detection of Cloxacillin and Sulfamethoxazole in Milk: IDF Interlaboratory Study
Authors: Suhren Gertraud , Beukers Robert 
Published: February 2020

Abstract
Under the auspices of the International Dairy Federation's Group E503, a collaborative study of the Delvotest SP multiplate microbial inhibitor test was performed to gain information about the detection limits of 2 antimicrobial agents (a β-lactam and a sulfa compound), the variation of test results between users and 2 batches of the test, and the reasons for deviating results. Lyophilized milk samples spiked with various concentrations of cloxacillin or sulfamethoxazole were analyzed. Each substance/concentration combination was tested with each of 2 test batches 14 or 15 times per participating laboratory. Test results were to be read by more than one person and reported on separate forms. Results were obtained from 29 laboratories, which included 5 with no experience and 11 with limited experience with this test. Detection limits for cloxacillin (22.5 or 30 μg/kg, depending on batch) and sulfamethoxazole (45 μg/kg) were established from dose-response curves. A small difference in cloxacillin detection levels between the 2 test batches was observed. Analyses of samples gave almost unanimous results (≥95%). Of deviating results, defined as anomalous results (1.4% of readings), half could be attributed to human errors and half to procedural errors
Gas Chromatographic Determination of Azoxystrobin, Fluazinam, Kresoxim-Methyl, Mepanipyrim, and Tetraconazole in Grapes, Must, and Wine
Authors: Cabras Paolo , Angion Alberto , Garau Vincenzo L , Pirisi Filippo M , Brandolini Vincenzo 
Published: February 2020

Abstract
Azoxystrobin, fluazinam, kresoxim-methyl, mepanipyrim, and tetraconazole were determined in grapes, must, and wine by a gas chromatographic method with nitrogen-phosphorus (NP) and mass spectrometric (MS) detectors. Pesticides were isolated from the matrixes by online microextraction with acetone-hexane (50 + 50, v/v). Because of the high selectivity of NP and MS detectors, no interfered peaks were present and no cleanup was necessary. Recoveries from fortified grapes, must, and wine ranged from 80 to 111 %, with coefficients of variation ranging from 1 to 14%. Limits of determination were 0.05 mg/kg for kresoxim-methyl and 0.10 mg/kg for the other compounds.
Determination of Bitertanol Residues in Strawberries by Liquid Chromatography with Fluorescence Detection and Confirmation by Gas Chromatography/Mass Spectrometry
Authors: Yamazaki Yoshie , Ninomiya Takahiro 
Published: February 2020

Abstract
A simple and rapid method was developed for determining bitertanol residues in strawberries. Bitertanol was extracted from samples with ethyl acetate. Bitertanol acetate was added prior to extraction as a surrogate standard. The ethyl acetate extract was cleaned up by passing through tandem solid-phase extraction columns consisting of anion-exchange (SAX) and aminopropyl (NH2) bonded silica. The eluate was evaporated to dryness and reconstituted with methanol. Bitertanol residues were determined by liquid chromatography with fluorescence detection. Recoveries at 4 fortified levels (0.05,0.25,0.5, and 1.0 (µg/g), calculated by the internal standard method, ranged from 92.1 to 99.1 %, with coefficients of variation ranging from 0.3 to 4.0%. The detection limit was 0.01 µg/g. Of 25 commercial strawberry samples analyzed for bitertanol residues, 5 contained bitertanol residues at concentrations ranging from 0.02 to 0.51 µg/g. Positive samples were confirmed by gas chromatography/mass spectrometry with mass-selective detection (m/z 170 and 168).
Thin-Layer Chromatographic Determination of Catecholamines, 5-Hydroxytryptamine, and Their Metabolites in Biological Samples: A Review
Authors: Alemany Gaspar , Akaârir Mohamed , Antonio Gamundí , Nicolau Maria C 
Published: February 2020

Abstract
A review of methodology for separation, detection, and quantitative determination of catecholamines, 5-hydroxytryptamine, and their acidic metabolites in biological tissue and fluids by thin-layer chromatography is presented. Selected procedures, including fluorometric scanning densitometry for catecholamine acetyl derivatives and color scanning densitometry for acids, are described.