bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Free Metabolites of Ceftiofur in Animal Tissues with an Automated Liquid Chromatographic Cleanup
Authors: Moats William A , Buckley Sandra A 
Published: February 2020

Abstract
Ceftiofur, a recently introduced antibiotic of the β-lactam group, is rapidly converted to both free and protein-bound metabolites when administered by the prescribed procedure, intramuscular injection. Free metabolites retain antimicrobial activity and may be detected by antibiotic-screening tests based on antimicrobial activity. It is thus desirable to distinguish ceftiofur metabolites from other antibiotics. A multiresidue procedure for β-lactams in milk was adapted for determination of free ceftiofur metabolites by collecting appropriate liquid chromatographic fractions during cleanup. Analysis of tissues from treated animals showed that the principal free metabolite was the desfuroylceftiofurcysteine conjugate.
Methods for the Recovery of Salmonella spp. from Carboxymethylcellulose Gum, Gum Ghatti, and Gelatin
Authors: Amaguaña René Miguel , Hammack Thomas S , Andrews Wallace H 
Published: February 2020

Abstract
Foods analyzed for Salmonella spp. by the procedure in the U.S. Food and Drug Administration's Bacteriological Analytical Manual are preenriched at a 1:9 test portion/broth ratio. Various thickening agents preenriched at this ratio become viscous and nonpipettable after 24 h incubation at 35 C. The effects of 3 factors (presence of inorganic salts, adjustment of pH, and presence of enzymes) on the viscosity of the test portion/preenrichment mixtures of various thickening agents during incubation were determined. Reduction of the viscosities of these thickening agents was accomplished as follows: carboxymethylcellulose gum, addition of cellulase to a final concentration of 0.10℅ in lactose broth preenrichment and incubation with no pH adjustment; gum ghatti, addition of NaCI to a final concentration of 0.10℅ in lactose broth preerichment and adjustment of the pH to 6.5; and gelatin, addition of papain to a final concentration of 0.10℅ in lactose broth preenrichment and adjustment of the pH to 6.8. With these modified preenrichments, one Salmonella spp. cell/25 g (representing an approximate most probable number value of 0.04 cell/g) was generally recovered from the thickening agents.
Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study
Authors: Lynch Joanna M , Barbano David M , Fleming J Richard 
Published: February 2020

Abstract
The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.
Determination of Total Fat in Foods and Feeds by the Caviezel Method, Based on a Gas Chromatographic Technique
Authors: Pendl Roger , Bauer Marcel , Caviezel Rafael , Schulthess Peter 
Published: February 2020

Abstract
This peer-verified method specifies a fast, easy, and reliable quantitative method to determine total fat in foods and feeds in compliance with the new definition of fat from the U.S. Food and Drug Administration. The method takes into consideration all fatty acids, from C4 to C24, and when fat is present at 0.3-100%. The validation study included 9 matrixes, with fat levels ranging from 1 to 79%. Sample and internal standard (IS; tridecanoic acid) are added to solvent (n-butyl alcohol). Fat is extracted and simultaneously saponified by potassium hydroxide. The fatty acid potassium salts are converted to fatty acids by adding an acidic aqueous salt solution, which produces a 2-phase system. The upper phase, containing the fatty acids and IS, is injected into the fat determination system. After gas chromatographic separation, the fat content is calculated from IS and fatty acid peak areas. The fat content is automatically converted to triglyceride content with a predetermined factor. Ten replicates of 9 different food samples, which cover the whole range of different contents in fat, proteins, and carbohydrates, were analyzed by the submitting and the peer laboratories. Repeatability relative standard deviation (RSDr) values ranged from 0.47 to 4.62%. Reproducibility relative standard deviation (RSDR) values ranged from 0.85 to 9.52%. These estimates include between-run variability. The method shows good accuracy. Values for standard reference materials (SRMs) are in agreement with certified values. Regression analysis of the correlation between observed fat and certified value over all matrixes and fat levels indicated good precision and absence of method bias (5 SRMs; 1-30% fat; correlation coefficient, R2 = 99.98%)
Evaluation of Passive Samplers for Analysis of Chlorinated Solvents
Authors: Amin Thakor A , Blndra Sushmeet , Narang Rajinder S 
Published: February 2020

Abstract
Chlorinated solvents like tetrachloroethylene, chloroform, and trichloroethylene were trapped on commercially available diffusive sampling devices and then desorbed with carbon disulfide (1.5 mL) containing surrogate standards. The extract was analyzed by gas chromatography with electron capture detection (ECD). To overcome the incompatibility of carbon disulfide with the electron capture detector, an electronically driven, high-temperature, 6- port valve was attached to the oven of a the gas chromatograph. An RTX 502 (105 m 𝖷 0.53 mm) capillary column was connected between the injector and the detector through the 6-port valve. The solvent peak was vented by rotating the valve before the peak reached the detector, and the valve was rotated to its original position before the peak due to chloroform eluted. The sampling time of 8-24 h and the use of ECD have led to detection limits of 0.5 μg/m3 for many chlorinated solvents
Gel Permeation and Florisil Chromatographic Cleanup and Gas Chromatographic Determination of Organochlorine Pesticides in Eggs
Authors: Furusawa Naoto , Okazaki Kunio , Iriguchi Sachiko , Yamaguchi Hidemasa , Saitoh Minoru 
Published: February 2020

Abstract
Cleanup of residual organochlorine pesticides (OCPs; α-, β-, γ-, and δ-BHC; aldrin; dieldrin; p,p′-DDE; o,p′-DDT; p,p′-DDD; and p,p′-DUX) in eggs by gel permeation chromatography (GPC) and Florisil minicolumn chromatography is described. Ten OCPs in purified extract are determined by gas chromatography with electron capture detection. The lipids extracted from whole egg are cleaned up first by GPC with an Envirogel column and an ethyl acetate-cychlohexane (1 + 1, v/v) mobile phase and then by Florisil minicolumn chromatography with 15% (v/v) diethyl ether-hexane eluant. Cleanup is highly efficient. Average recoveries of 10 spiked OCPs (0.0025-0.0125 ppm) ranged from 81 to 101%, with coefficients of variation between 1 and 14%. The detection limit was 0.001 ppm for the 10 OCPs
Characterization of Balsamic Vinegar by Multivariate Statistical Analysis of Trace Element Content
Authors: Del Signore Antonella , Campisi Barbara , Di Giacomo Franco 
Published: February 2020

Abstract
To characterize vinegars according to the types prescribed by Italian regulations, 8 trace elements (Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb) were determined. The data collected were successively elaborated by 3 statistical techniques: linear principal component analysis (LPCA), linear discriminant analysis (LDA), and cluster analysis (CA). LDA and LPCA best classified and discriminated the 3 types of vinegar under study, separating traditional balsamic vinegars from the other 2 types, nontraditionally aged balsamic vinegars and common vinegars. The latter 2 types were appreciably distinguished only by LDA through bidimensional analysis of discriminant scores
Determination of Ammonia and Aliphatic Amines in Food by Ion Chromatography with Double-Cell Bulk Acoustic Wave Detection
Authors: Yao Shouzhuo , Yang Xiaorong , Zhang Hong , Xie Youtao , Wei Wanzhi 
Published: February 2020

Abstract
An ion chromatographic (IC) method with doublecell bulk acoustic wave (DCBAW) detection is described for determination of ammonia and low-molecular- mass aliphatic amines in food. A 9 MHz AT-cut quartz crystal is used as the resonator. This detection technique provides high sensitivity, good reproducibility, and wide work region. Its sensitivity is independent of background conductivity of the mobile phase in the range 10-2700 μS. Detection limits (peak = 3 δ) for NH4+, CH3NH3+ (CH3)2NH2+and (CH3)3NH+ were 0.02, 0.05, 0.13, and 0.6 μg/mL, respectively. Relative standard deviations for NH4+, CH3NH3+, (CH3)2NH2+, and (CH3)3NH+ were 0.7,1.0, 0.8, and 1.2%, respectively. For IC analysis, the analytical column is a Shim-pack IC-C1 column and the mobile phase is 2.0 mmol/L nitric acid solution at a flow rate of 1.5 mL/min. Detection with DCBAW was compared with series bulk acoustic wave and conventional conductivity. The method was applied to analyses of egg, fish, and cured meat
A Screening Method for β-Lactams in Tissues Hydrolyzed with Penicillinase I and Lactamase II
Authors: Medina Marjorie B , Poole Dana J , Anderson M Ranae 
Published: February 2020

Abstract
Antibiotic residues above tolerance levels are not allowed in foods derived from farm animals. Microbial inhibition assays are used to screen antibiotics in U.S. regulatory laboratories. We developed a screening approach to classify β-lactams through selective hydrolysis of the β-lactam ring with Penase™ or lactamase II, thereby inactivating the β- lactam activity. Optimum conditions for hydrolysis of β-lactams with Penase and lactamase II were determined. p-Lactams were detected by a microbial inhibition assay and with enzyme-linked immunosorbent assays before and after hydrolysis. β- Lactams (10-100 ppb) were spiked in kidney extracts and hydrolyzed. Results indicate a pattern that tentatively classified the β-lactams into 3 subgroups. Desfuroyl-ceftiofur-cysteine, a major metabolite of ceftiofur, was clearly detected. Penicillin G, ampicillin, amoxicillin, and cloxacillin were distinguishable from cephapirin, ceftiofur metabolite, and high levels of hetacillin. Liver and kidney tissue samples were analyzed with the combined enzyme hydrolysis and screening assays, which tentatively identified the residues. This approach can speed up screening analysis of β-lactam residues prior to identification and quantitation by chromatographic analysis, thus enhancing positive identification of residues to provide a safer food supply
Structure-Retention Relationships and Physicochemical Characterization of Solutes in Thin-Layer Chromatography
Authors: Cserháti Tibor , Forgács Esther 
Published: February 2020

Abstract
This review enumerates and critically evaluates experimental methods and calculation procedures used to elucidate the molecular basis of thin-layer chromatography (TLC) separations in both adsorption and reversed-phase modes. It addresses the quantitative relationship between molecular structure and retention and the determination of the solute physicochemical parameters by TLC.
Solid-Phase Extraction Cleanup and Liquid Chromatography with Ultraviolet Detection of Ephedrine Alkaloids in Herbal Products
Authors: Hurlbut Jeffrey A , Carr Justin R , Singleton Emma R , Faul Kent C , Madson Mark R , Storey Joseph M , Thomas Terri L 
Published: February 2020

Abstract
A solid-phase extraction (SPE) cleanup and a liquid chromatographic (LC) method with UV detection is presented for analysis of up to 7 ephedrine alkaloids in herbal products. Alkaloids from herbal products are extracted with acidified buffer, isolated on a propylsulfonic acid SPE column, eluted with a high-ionic-strength buffer, and separated by LC with detection at 255 nm. LC separation is performed by isocratic elution on a YMC phenyl column with 0.1 M sodium acetate-acetic acid (pH = 4.8) containing triethyl-amine and 2% acetonitrile. Ephedrine alkaloids are completely separated in 15 min. Average recovery of 5 common alkaloids from 3 spiked matrixes is 90%, with an average relative standard deviation (RSD) of 4.4% for alkaloid spikes between 0.5 and 16 mg/g. Average quantitation of ephedrine and pseudoephedrine from 6 herbal products is 97% of declared label claims, and average quantitation of synephrine from an herbal dietary product is 85% of label claim (RSD, 3.2%). Recoveries of synephrine, norephedrine, ephedrine, pseudoephedrine, N-methylephedrine, and N-methylpseudoephedrine spiked in 4 herbal products averaged 95%. Results of ruggedness testing and of a second laboratory validation of the procedure are also presented.
A Simple Method for Evaluating Data from an Interlaboratory Study
Authors: Horwitz William , Britton Paul , Chirtel Stuart J 
Published: February 2020

Abstract
Large-scale laboratory- and method-performance studies involving more than about 30 laboratories may be evaluated by calculating the HORRAT ratio for each test sample (HORRAT = [experimentally found among-laboratories relative standard deviation] divided by [relative standard deviation calculated from the Horwitz formula]). The chemical analytical method is deemed acceptable per se if HORRAT ͌ 1.0 (± 0.5). If HORRAT is ≳2.0, the most extreme values are removed successively until an "acceptable" ratio is obtained. The laboratories responsible for the extreme values that are removed should examine their technique and procedures. If ≳15% of the values have to be removed, the instructions and the methods should be examined. This suggested computation procedure is simple and does not require statistical outlier tables. Proposed action limits may be adjusted according to experience. Data supporting U.S. Environmental Protection Agency method 245.1 for mercury in waters (manual cold-vapor atomic absorption spectrometry), supplemented by subsequent laboratory-performance data, were reexamined in this manner. Method-performance parameters (means and among-laboratories relative standard deviations) were comparable with results from the original statistical analysis that used a robust biweight procedure for outlier removal. The precision of the current controlled performance is better by a factor of 4 than that of estimates resulting from the original method-performance study, at the expense of rejecting more experimental values as outliers.
A Liquid Chromatographic Method for Analysis of AU-Rac-α-Tocopheryl Acetate and Retinyl Palmitate in Medical Food Using Matrix Solid-Phase Dispersion in Conjunction with a Zero Reference Material as a Method Development Tool
Authors: Chase G William , Eitenmiller Ronald R , Long Austin R 
Published: February 2020

Abstract
A liquid chromatographic method is described for analysis of all-rac-α-tocopheryl acetate and retinyl palmitate in medical food. The vitamins are extracted from medical food without saponification by matrix solid-phase dispersion and chromatographed by normal-phase chromatography with fluorescence detection. Retinyl palmitate and all-rac-α-tocopheryl acetate are quantitated isocratically with a mobile phase of 0.125% (v/v) and 0.5% (v/v) isopropyl alcohol in hexane, respectively. Results compared favorably with label declarations on retail medical foods. Recoveries determined on an analyte-fortified zero reference material for a milk-based medical food averaged 98.3% (n = 25) for retinyl palmitate spikes and 95.7% (n = 25) for all-rac-α-tocopheryl acetate spikes. Five concentrations were examined for each analyte, and results were linear (r2 = 0.995 for retinyl palmitate and 0.9998 for all-rac-α-tocopheryl acetate) over the concentration range examined, with coefficients of variation in the range 0.81-4.22%. The method provides a rapid, specific, and easily controlled assay for analysis of retinyl palmitate and all-rac-α-toco-pheryl acetate in fortified medical foods.
Analytical Monitoring of Citrus Juices by Using Capillary Electrophoresis
Authors: Cancalon Paul F 
Published: February 2020

Abstract
A capillary electrophoretic method was developed to analyze simultaneously most citrus juice components in a single procedure. After filtration, sample components are separated with an uncoated capillary tubing and a 35 mM sodium borate buffer (pH 9.3) containing 5% (v/v) acetonitrile. Analyses were run at 21 kV and 23°C. Compounds monitored regularly were the biogenic amine synephrine, some flavonoids (didymin, hesperidin, narirutin, neohesperidin, and naringin), the polyphenol phlorin, 3 UV-absorbing amino acids (tryptophan, phenylalanine, and tyrosine), ascorbic acid, an unidentified peak generated by heat and storage, and the preservatives sorbate and benzoate that can be added to citrus products. Separation can be achieved in 20 min, and each compound can be subsequently quantitated. Didymin, narirutin, and phlorin peaks were used with an artificial neural network to assess the volume of added pulp wash, a by-product of juice preparation. This method allows rapid monitoring of citrus juices, giving information on quality, freshness, and possible adulteration of the product. Similar procedures could be used to monitor other fruit juices and quantitate diverse juice blends.
Pesticide Residues in Selected Food Commodities: Results from the Danish National Pesticide Monitoring Program 1995-1996
Authors: Juhler René K , Lauridsen Milter Green , Christensen Mette Rindom , Hilbert Gudrun 
Published: February 2020

Abstract
The paper presents results of analyses of 4182 samples collected from January 1995 to December 1996 for the Danish National Pesticide Monitoring Program. The program basis is a random sample control supplemented with a target control. The objectives of the control are to monitor consumer exposure to health hazards and to enforce national and European Community regulations. The Danish Veterinary and Food Administration is responsible for establishing methods, data manipulation, and evaluation, but actual analyses are performed at 4 regional laboratories. In addition to a description of the Danish National Pesticide Monitoring Program on food, the effects of lowering the reporting limits are discussed. Pesticides included are those in current use as well as chlorinated pesticides like lindane, DDT, and HCB, occurring in food now primarily as a result of environmental contamination. Commodities analyzed are fruits, vegetables, cereals, bran, fish, and animal products such as meat, butter, cheese, fat, and eggs. In fruits and vegetables, residues were detected in 10% of 2515 samples, with higher incidences of detection for foreign commodities. Violation rate was 0.6%. In food of animal origin, low levels of organo- chlorine pesticides were detected in most fish samples and in more than half of the animal product samples. However, no results exceeding maximum residue limits were found. No residues of organo- phosphorus pesticides were detected in the 231 meat samples analyzed.
A Statistical Evaluation of the Youden Matched-Pairs Procedure
Authors: McClure Foster D 
Published: February 2020

Abstract
AOAC INTERNATIONAL currently permits investigators to use the Youden Matched-Pairs Procedure to obtain estimates of the method performance indicators repeatability and reproducibility (sr and sR, respectively). This report explains the statistical model assumptions upon which the procedure is based, provides validity tests for several of these assumptions, explains conditions under which Youdens’ “precision error” is not consistent with precision estimate sr or sR as defined by AOAC INTERNATIONAL, and indicates when precision estimates based on the procedure should be interpreted with caution or should not be used.
Repeatability and Reproducibility of Germicide Tests: A Literature Review
Authors: Tilt Nicola , Hamilton Martin A 
Published: February 2020

Abstract
The results of a quantitative antimicrobial assay can be summarized by the log reduction value. For an assay to be proposed as a standard method, it is usually necessary to conduct a collaborative study to demonstrate that the repeatability and reproducibility standard deviations (SDs) of the log reduction values are sufficiently small. It is not clear, however, precisely how small those SDs should be. This paper describes the results of a literature review conducted to determine the range of repeatability and reproducibility SDs for standard quantitative antimicrobial assays. The underlying premise is that, for an assay to have been accepted as a standard method, its repeatability and reproducibility SDs must have been sufficiently small. This premise implies that the repeatability and reproducibility SDs of standard assays establish de facto guidelines for acceptability. The survey comprised papers where the SDs could be extracted directly or where they could be calculated from accessible data. Papers describing suspension tests as well as hard surface tests were included. For the standard antimicrobial assays reviewed, repeatability SDs ranged from 0.25 to 1.21 and the reproducibility SDs ranged from 0.31 to 1.54.
Gas Chromatographic Analysis of Fosfomycin in Plasma for Pharmacokinetic Analysis
Authors: Webster Gregory K , Bell Robert G 
Published: February 2020

Abstract
An efficient method for gas chromatographic analysis of fosfomycin in plasma was developed for preliminary investigations of the bioavailability in poultry of 3 commercial complexes of fosfomycin: a levorotatory Ca(−) salt, a racemic Ca(±) salt, and a tromethamine (THAM) salt. The method was used to determine whether the less expensive racemic mixture would provide equivalent levels of fosfomycin in blood as the pure Ca(−) form and the THAM salt. The THAM salt, a more expensive product to market, was thought to have the greatest bioavailability. The assay is selective, sensitive, and applicable to pharmacokinetic analysis.