bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Organophosphorus Pesticide Residues in Citrus Fruits from the Valencian Community (Spain)
Authors: Torres Carmen M , Picó Yolanda , Marín Rosa , Mañes Jordi 
Published: February 2020

Abstract
Approximately 200 citrus samples from markets of the Valencian Community (Spain) were analyzed to establish their residue levels in 12 organophosphorus pesticide residues during the 1994-1995 campaign. The organophosphorus pesticides carbophenothion, chlorpyriphos, chlorfenvinphos, diazinon, ethion, fenitrothion, malathion, methidation, methylparathion, phosmet, quinalphos, and tetradifon were simultaneously extracted by matrix solidphase dispersion and determined by gas chromatography- mass spectrometry using selected ion monitoring mode. A total of 32.25% contained pesticide residues and 6.9% exceeded the European Union Maximum Residue Levels (MRLs). The pesticides found in the samples with residues above MRLs were carbophenothion, ethion, methidathion, and methyl parathion. Lower level residues of these and the other pesticides studied (except diazinon) were frequently found. The estimated daily intake of the 12 organophosphorus pesticide residues during the studied period was 4.87 x 10−4 mg/kg body weight/day. This value is lower than the provisional tolerances dairy intakes proposed by the Food and Agriculture Organization and the World Health Organization.
Determination of Fish Flesh Content in Frozen Coated Fish Products (Modification of AOAC Official Method 971.13): Collaborative Study
Authors: Dobson Jane E Fox , McClure Foster D , Rainosek Alvin P ,   Collaborators:, Dashiell K , Fox Dobson J , Harris M , Jones R , Maher E , McGuire A , Noonan J , Petrillo T , Picard M , Romero C , Sabia M 
Published: February 2020

Abstract
An intralaboratory1collaborative study evaluated a modified version of AOAC Official Method 971.13 for determining the fish flesh content (FFC) in frozen coated fish products by comparing it with the on-line method. Eleven collaborators analyzed 36 products (a total of 6336 test samples). Each product targeted one of 4 percent fish flesh (PFF) levels (35,50,65, and 80). Products were manufactured from one of 3 raw materials (fillet blocks, minced blocks, and natural fillets) and processed in one of 4 forms (sticks, portions, formed portions, and fillets) and one of 4 styles (raw breaded, batter-dipped, precooked, and fully cooked). Each “official” test sample was tracked through the processing system and weighed (1) before battering and/or breading and, depending on product style, before frying; and (2) after battering and/or breading and, depending on product style, after frying; so that it served as its own control.
Mainstream Smoke Collection by Electrostatic Precipitation for Acid Dissolution in a Microwave Digestion System Prior to Trace Metal Determination
Authors: Rhoades Charles B , White Ralph T 
Published: February 2020

Abstract
A method is described for collection and preparation of mainstream smoke condensate from cigarettes for determination of trace metal constituents. A sample of mainstream smoke was collected from 300 cigarettes in a final volume of 25 mL. Extremely clean laboratory conditions during sample preparation were essential to avoid contamination and improve precision and accuracy for trace element determination. The clean laboratories maintained a positive pressure of HEPA-filtered air with constant temperature and humidity control. Mainstream cigarette smoke was collected by electrostatic precipitation (EP) on a modified rotary smoking machine located in a wooden CORESTA cabinet. The EP unit was equipped with a high tension generator supplying 17.5 kV to a tungsten electrode followed by 2 secondary acid traps. Samples were collected under 2 smoking regimens: FTC (35 mL puff volumes, one puff every 60 s, and puff duration 2 s) and “Extreme” (75 mL puff volumes, one puff every 35 s, puff duration 2 s). Condensate was extracted from collection tubes with methanol into Teflon microwave digestion vessels and evaporated in an environmental evaporation chamber (EEC). The EEC provided an ultraclean environment for sample evaporation and predigestion steps that eliminated most of the sample matrix. The remainder was decomposed in a programmable closed vessel microwave digestion system. Digested sample solutions were analyzed by graphite furnace atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry for aluminum, arsenic, cadmium, chromium, nickel, and silicon.
Determination of Water in Forages and Animal Feeds by Karl Fischer Titration
Authors: Erem Terri Van , Thiex Nancy , Pohmer Jörg , Poffenbarger Michael W , Smith Victor , Patel Elena 
Published: February 2020

Abstract
Oven methods for determining moisture (volatiles) in forages and other animal feeds are empirical. The moisture concentration obtained depends upon the time and temperature the sample was dried and is influenced by the presence of other volatiles than water. A validated reference method to measure water in forages and animal feeds could be used to evaluate the appropriateness of oven methods for various types of animal feeds and forages. Karl Fischer titration is a well-established method for determining water. However, thorough extraction of water from forages and feeds is a challenge because they often contain cellular structures that release water slowly. Water was successfully extracted into methanol-formamide (50 + 50) by high-speed homogenization and then titrated directly at 50 C with a one-component Karl Fischer reagent based on imidazole. The method is described in detail, results of day-to-day repeatability and laboratory-to-laboratory reproducibility are reported, and preliminary comparison data between oven methods are provided.
Simple, At-Site Detection of Diethylene Glycol/Ethylene Glycol Contamination of Glycerin and Glycerin-Based Raw Materials by Thin-Layer Chromatography
Authors: Kenyon Allen S , Xiaoye Shi , Yan Wang , Wai Har Ng , Prestridge Robert , Sharp Kirsten 
Published: February 2020

Abstract
This paper describes a rapid, inexpensive thin-layer chromatographic (TLC) method that separates diethylene glycol (DEG) from glycerin and other glycols. Studies with collaborating laboratories of the World Health Organization have shown that about 6% DEG in glycerin and about 2% DEG in acetaminophen (paracetamol) elixirs may be detected by direct visual inspection of the developed TLC sheets. Staining the sheet permits detection of DEG at less than 0.1%. The method costs less than $1.00 per test and takes 20 min by visual inspection, longer when staining is required. The visual method can be performed without laboratory facilities by personnel having little previous training. Samples testing positive by the visual method can be submitted to a laboratory for confirmation and quantitation of DEG.
Contemporary Thin-Layer Chromatography in Pharmaceutical Quality Control
Authors: Renger Bernd 
Published: February 2020

abstract
The progress in layers, instrumentation, and the development of automated scanning densitometers have led to a remarkable improvement of the features of thin-layer chromatography (TLC) and especially its high performance version (HPTLC). Contemporary TLC or HPTLC combines the techniques' inherent advantages which include high sample throughput, simultaneous processing of standards and samples, flexibility, easy postchro matographic visualization techniques, and the ability to handle complex or crude samples with minimum sample cleanup—with improved selectivity, sensitivity, and accuracy. It is a very economical chromatographic technique that competes with and complements HPLC. Development and validation of procedures can be performed rapidly in full accordance with all current international guidelines.
Comparison of the VITEK Gram-Negative Identification Card and an Enhanced Version for Identification of Salmonella, Escherichia coli, and Other Enterobacteriaceae:. Method Modification
Authors: Gravens Carol K 
Published: February 2020

abstract
Comparison of the VITEK® Gram-Negative Identification Card (GNI) was compared to an enhanced version of the test kit, the GNI+ Card. The GNI Card is an official AOAC method (991.13) for identification of Salmonella, Escherichia coli, and other Enterobacteriaceae in foods. In this comparison 5 replicates of 124 gram-negative stock culture strains were evaluated to determine equivalency. Isolates were obtained primarily from food sources, with 108 of the isolates representing 15 genera within the family Enterobacteriaceae. Overall agreement between the GNI Card and the GNI+ Card was 98.2%. Of the 23 strains of Salmonella tested, the longest identification time for the GNI Card was 10 h, with 43.5% of the strains identifying in 4 h or less. The longest identification time of the same Salmonella strains tested with the GNI+ Card was 8 h, with 95.7% of the strains identifying within 4 h. The GNI+ Card provided increased speed of identification while retaining the accuracy of the GNI Card. The GNI method for identifying Salmonella, Escherichia coli, and other Enterobacteriaceae was approved as a method modification by AOAC INTERNATIONAL.
A Kinetic Approach for Determination of Cefadroxil in Pharmaceuticals by Alkaline Hydrolysis
Authors: Helaleh Murad I H , Abu-Nameh Eyad S M 
Published: February 2020

abstract
A new, simple, and sensitive kinetic spectrophotometric method is described for analysis of cefadroxil by measurement of its absorbance at 470 nm after hydrolysis with NaOH at 80°C. Studies of the method's precision and accuracy gave a standard deviation of 0.44 μg/mL and a relative standard deviation of 1.93%. The method determines cefadroxil over the concentration range 10- 100 ug/mL. Calculated activation parameters were 12.42, 25.54, 26.25, and 69.00 Kcal/mole for AE*, AG*, Ahf, and AS*, respectively. Cefadroxil concentrations can be determined from the regression line equation y = 0.627x- 8.14 x 10"5, with a correlation coefficient of &lt;1.0000. The method was validated by assay of cefadroxil in commercial capsules and tablets. Recoveries of common excipients were 99.6,100.00, 99.2, 99.6, and 100.4% for lactose, glucose, starch, sucrose, and fructose, respectively. Results were compared with those of a reference method. Calculated f and F values indicate no significant difference between the 2 methods. The degradation products of cefadroxil do not affect determination of cefadroxil.
Routine Analysis of Proteins by Kjeldahl and Dumas Methods: Review and Interlaboratory Study Using Dairy Products
Authors: Wiles Peter G , Gray Ian K , Kissling Roger C ,   Collaborators:, Delahanty C , Evers J , Greenwood K , Grimshaw K , Hibbert M , Kelly K , Luckin H , McGregor K , Morris A , Petersen M , Ross F , Valli M 
Published: February 2020

abstract
The Kjeldahl and Dumas (combustion) methods were compared in 11 laboratories analyzing samples of milk, skim milk powder, whole milk powder, whey protein concentrate, infant formula, casein, caseinate, 2 reference compounds (glycine and EDTA), and a secondary reference skim milk powder. The comparison was conducted by using international standards where applicable. Overall means were 8.818 g N/100 g by the Kjeldahl method and 8.810 g N/100 g by the Dumas method. No evidence was found for a consistent bias between methods that may be of concern in the trading of dairy produce. A review of more than 10 related trials revealed a lack of consensus in the bias between the 2 methods, suggesting that differences in methodology and sources of systematic error may be contributors. For samples containing &gt;2 g N/100 g, the Dumas relative repeatability and reproducibility standard deviations were consistently about 0.35 and 0.75%, respectively, whereas the corresponding Kjeldahl values declined generally with N content and were significantly larger. The Dumas precision characteristics may be due to the dominance of Leco analyzers in this trials, and in most other recent trials, rather than an inherent method attribute. Protein determination methods for dairy products need to be reviewed and updated. The Dumas method needs Codex Alimentarius status as a recognized test method.
Analysis of Fumonisin Bi and Its Hydrolysis Product in Tortillas
Authors: Stack Michael E 
Published: February 2020

Abstract
Fumonisins are toxic metabolites of Fusarium moniliforme, a fungus that occurs widely in corn. Fumonisins cause leukoencephalomalacia in horses and pulmonary edema in swine and have been suggested as a possible cause of an increased incidence of neural tube defects among people living along the Texas-Mexico border. As part of an effort to determine levels of fumonisins in human food, a liquid chromatographic (LC) method was devised for determining fumonisin Bi (FB1) and the total hydrolysis product of FB1 (HB1) in tortillas. The method uses acetonitrile-0.1M phosphate buffer (pH 3; 1 +1) extraction, solidphase C18 cleanup, ophthalaldehyde and 2-mercaptoethanol derivatization, and reversed-phase LC. Average recoveries from tortillas spiked with FB1 and HB1 at 250, 500, and 1000 ng/g were 86.5℅ for FB1 and 82.6℅ for HB1. Tortillas (54) and masa (8) from the Texas-Mexico border were analyzed for FB1 and HB1. Average amounts of FB1 and HB1 in tortillas were 187 and 82 ng/g, respectively. Average amounts of FB1 and HB1 in masas were 262 and 64 ng/g, respectively. The results show that fumonisin B1 and its hydrolysis product are present in tortillas consumed by a population experiencing an increased incidence of neural tube defects.
Analysis of Fumonisins and Alternaria alternata Toxin by Liquid Chromatography-Enzyme-Linked Immunosorbent Assay
Authors: Yu Feng-Yih , Chu Fun S 
Published: February 2020

Abstract
Use of a direct competitive enzyme-linked immunosorbent assay (ELISA) as a postcolumn monitoring system after liquid chromatography (LC) is described for analysis of different fumonisin analogs. Without cleanup and derivatization, sample extracts are directly injected into a C18 reversedphase column and then subjected to LC. Fractions (0.5 mL each) are collected and then analyzed by ELISA. LC using a water-methanol gradient separated the 3 major fumonisins FmB1, FmB2, and FmB3, and as low as 0.1 ng FmB1 could be detected. Recovery of FmB1 added to ground corn (100-1000 ng/g) and then extracted with CH3CNH2O (1 + 1, v/v) was 78.8℅. Analysis of fumonisins in one starch and 14 naturally contaminated corn samples showed that FmB1 was the major fumonisin. Ten samples also were contaminated with FmB2, but only 2 samples were contaminated with FmB3. The method also was used to analyze extracts from cultures of 3 Alternaria alternata(AAL) strains. Both FmB1 and the AAL toxin TA were detected in the culture extracts, and their amounts varied considerably with the cultures tested.
Determination of Phenylurea Herbicide Residues in Vegetables by Liquid Chromatography after Gel Permeation Chromatographyand Florisil Cartridge Cleanup
Authors: Sannino Anna 
Published: February 2020

Abstract
A liquid chromatographic method for quantitative determination of 9 phenylurea herbicide residues (metoxuron, metobromuron, monolinuron, chlortoluron, isoproturon, diuron, linuron, chloroxuron, and neburon) in potatoes, carrots, and mixed vegetables is described. Samples are extracted with acetone, partitioned with ethyl acetate-cyclohexane (50 + 50, v/v) and cleaned up by gel permeation chromatography with ethyl acetate-cyclohexane (50 + 50, v/v) as eluant. A small column (1 cm id) packed with Biobeads SX3 resin is used to reduce solvent consumption and analytical time. After solid-phase extraction on a Florisil cartridge, herbicide residues are successfully separated on a C18 column by gradient elution and determined by UV detection at 242 nm. Average recoveries of 9 compounds from different samples range from 70 to 98% at 0.010 and 0.100 mg/kg fortification levels. Quantitation limits are 0.010 mg/kg
Determination of Diethanolamine and N-Nitrosodiethanolamine in Fatty Acid Diethanolamides
Authors: Chou Hardy J 
Published: February 2020

Abstract
Diethanolamine (DEA) is a precursor of N-nitrosodiethanolamine (NDELA), an animal carcinogen. A gas chromatographic (GC) method was developed for determining DEA in fatty acid diethanolamides that are commonly used in cosmetic products. Methanolic solutions of the amides were analyzed by GC with flame ionization detection on either a wide-bore methyl silicone (Rtx-1) or 95% dimethyl- 5% diphenyl polysiloxane (SPB-5) capillary column. Recovery of DEA from fatty acid dialkanolamides at fortification levels of 0.50,1.00, and 5.00% ranged from 94 to 100%. In a survey of commercial fatty acid diethanolamides, DEA was found at levels ranging from 1.1 to 14.0%, and most were in good agreement with manufacturer's DEA specifications. Fatty acid diethanolamides also were analyzed for NDELA by liquid chromatography interfaced to a thermal energy analyzer. Recovery of NDELA from fatty acid diethanolamides at fortification levels of 50,100, and 200 ppb averaged 95%. No NDELA was found in any of the fatty acid diethanolamide samples analyzed
Determination of Pseudoephedrine Hydrochloride and Carbinoxamine Maleate in Combination Drug Formulation by Liquid Chromatography
Authors: Mansour Ali M 
Published: February 2020

Abstract
An isocratic, reversed-phase liquid chromatographic (LC) method was developed for simultaneous determination of pseudoephedrine hydrochloride (I) and carbinoxamine maleate (II) in a pharmaceutical dosage form. Analysis was conducted on a CN column (10μm), with a mobile phase consisting of acetonitrile-methanol-phosphate buffer (pH 5.3)-water (140 + 170 + 40 + 100) and at a detection wavelength of 262 nm. The method was validated for linearity, precision, system reproducibility, and accuracy. Recoveries at 80-120% of labeled claim ranged from 97.4 to 100.7% and from 98.5 to 100.2% for I and II, respectively. Results were linear (correlation coefficient, r &gt; 0.9995 for I in the range 250-750 (μ/mL and r &gt; 0.9999 for II in the range 20-60 μg/mL)
Rapid Gas Chromatographic Method for Simultaneous Determination of Cholesterol and α-Tocopherol in Eggs
Authors: Botsoglou Nickos , Fletouris Dimitrios , Psomas Ioannis , Mantis Antonios 
Published: February 2020

Abstract
A new method was developed for simultaneous determination of cholesterol and α-tocopherol in eggs. It involves rapid and simple sample preparation accomplished in one tube and chromatographic separation that does not require derivatization of analytes. Total analysis time per sample is 40 min. Labor, cost, and use of hazardous chemicals are minimized. To ensure selectivity, accuracy, and precision, critical analytical parameters were investigated. Overall recoveries were 98.8 and 99.2% for cholesterol and α-tocopherol, respectively. Linearity was acceptable for both analytes (r = 0.9964 for cholesterol and 0.9996 for α-tocopherol) in the fortification range examined. Precision data based on within-day and between-days variation gave overall relative standard deviations of 2.0% for cholesterol and 7.0% for α-tocopherol.The method was applied successfully for quantitation of cholesterol and α-tocopherol in eggs.
Determination of Phosphine Residues in Whole Grains and Soybeans by Ion Chromatography via Conversion to Phosphate
Authors: Carlson Marvin , Thompson Richard D 
Published: February 2020

Abstract
An ion chromatographic (IC) method was developed for determining phosphine (PH3) in whole grains (barley, corn, oats, rice, rye, and wheat) and soybeans. The method converts phosphine to phosphate (i.e., orthophosphate) and isolates the phosphate by IC with eluent-suppressed conductivity detection. Recoveries of unbound phosphine by the method were similar to those obtained by an established colorimetric method for 7 different products fortified at 3 levels. Mean recoveries were low (i.e., 30-60%) and varied with product type and level of fortification. Recoveries of PH3 from previously fumigated products fortified with aluminum phosphide ranged from 19.0% for barley fortified at 0.734 ppm to 88.3% for corn fortified at 1.691 ppm. Precision data from 3 products based on replicate analyses (n = 4 or 5) gave relative standard deviations of 1.78-4.66% for mean laboratory-fumigated PH3 levels of 0.679-1.309 ppm. Estimated limits of detection (LOD) and quantitation (LOQ) for PH3 were 0.010 μg/g (10 ppb) and 0.0275 μg/g (27.5 ppb) at signal-to-noise ratios (S/N) of 4:1 and 10:1, respectively. These values were also determined for a nonchemically suppressed IC system with LOD of 0.02 μg/g (20 ppb) and LOQ of 0.055 μg/g (55 ppb) at S/N of 4:1 and 10:1, respectively. Phosphate response was linear over the concentration range equivalent to 0.30-10.0 fig P/mL, with a mean correlation coefficient of 0.9988 based on replicate standard curves. The relationship of product composition to recovery from various products was also examined.
Determination of Neutral Lactase Activity in Industrial Enzyme Preparations by a Colorimetric Enzymatic Method: Collaborative Study
Authors: Engelen Adrianus J , Randsdorp Peter H G ,   Collaborators:, Cassaigne R , Dutta S M , Harboe M , Harju M , van der Heeft F C , Hirota T , McKellar R C , Playne M , Rogers D , San José C , de Vrese M 
Published: February 2020

Abstract
Thirteen laboratories participated in a collaborative study to validate a colorimetric assay for determining neutral lactase activity in industrial enzyme preparations. Each laboratory received 5 duplicate samples with activity levels of 2000 and 5000 neutral lactase units provided by 4 commercial suppliers. Two laboratories did not return results. Method performance was calculated according to AOAC guidelines. From the 11 remaining laboratories, 3 were excluded from statistical analysis because of invalid data determined during initial review by Youden pair, value versus laboratory. Repeatability relative standard deviation (RSDr) values ranged from 3.20 to 8.62%, and reproducibility relative standard deviation (RSDR) values ranged from 8.77 to 16.35%. With outliers excluded, RSDr values ranged from 2.94 to 5.01%, and RSDRvalues ranged from 7.50 to 13.84%. The colorimetric enzymatic method for determining neutral lactase activity in industrial enzyme preparations has been adopted first action by AOAC INTERNATIONAL.