bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Pressure Liquid Chromatographic Determination of Ochratoxin A and Zearalenone in Cereals
Authors: Josefsson Egon , Möller Tord 
Published: February 2020

Abstract
A high pressure liquid chromatographic (HPLC) method has been developed for determining ochratoxin A and zearalenone in cereals. The sample is extracted with phosphoric acid and chloroform. The extract is cleaned by washing on a silica gel column with cyclohexane-ethylene dichlorideethyl ether. After eluting zearalenone with chloroform, ochratoxin A is eluted with chloroformformic acid. Zearalenone is extracted into alkaline solution, washed with chloroform, the pH is adjusted, and the zearalenone is extracted back into chloroform. Ochratoxin A is purified by chromatography on aqueous sodium bicarbonate-Celite. The mycotoxins are determined by using a liquid chromatograph with 2 columns in series packed with Spherisorb ODS 10 μm and 5 μm, respectively. Ochratoxin A is detected with a spectrophotofluorometer, coupled in series with an ultraviolet detector for estimation of zearalenone. Detection limits are 1-5 μg/kg for ochratoxin A and 2 μg/kg for zearalenone.
Use of Background Correction to Improve the Accuracy of the Selective Reduction Method for Determining Methyl Mercury in Fish
Authors: Chvojka Ramon , Kacprzak Jurgen L 
Published: February 2020

Abstract
Background correction is used with a previously published flameless atomic absorption method for the concurrent determination of inorganic and methyl mercury. The use of background correction simplifies the procedure, but, more importantly, eliminates errors in mercury readings due to broad band absorption by other volatile compounds produced during the determination.
Sample Preparation of Some Shelled Treenuts and Peanuts in a Vertical Cutter-Mixer for Mycotoxin Analysis
Authors: Francis Octave J 
Published: February 2020

Abstract
A procedure has been devised for more rapid preparation of large samples of nutmeats (10-80 lb) for mycotoxin analysis without the use of grinding aids, by combining the grinding and mixing steps into one operation. Ease of cleaning equipment facilitates the preparation of several samples in a short time. The procedure was tested using shelled raw and roasted peanuts, and raw almonds, walnuts, and pecans. The reduction of particle size to pass a 20 mesh screen was attained using a 25 qt Hobart vertical cutter-mixer (VCM) equipped with standard serrated blades and a 40 qt VCM using either a standard serrated blade or a smooth-edge blade modified with sharp-edge notches to increase its cutting ability. Portions of ground composite were removed at various time intervals and particle sizes were measured. Original and check analyses of 12 naturally contaminated samples over a 3 year period indicate that this procedure is practical and reproducible.
Microcomputer Controlled Titration for Determination of Protein Nitrogen in Feeds and Wheat
Authors: Wu Alan H B , Rotunno Taddeo , Malmstadt Howard V 
Published: February 2020

Abstract
The determination of protein nitrogen in feeds and wheat by microcomputer controlled titration is described. The method involves direct titration of ammonia with standard hypochlorite titrant in the presence of bromide. The titrant is delivered by an automatic buret, and the microcomputer controlled, automatically computed potentiometric end points are precise to 0.1% over a 5-fold concentration range of nitrogen. Digestions performed with both mercury and copper catalysts show comparable results. Samples are weighed before digestion by an electronic balance interfaced to the computer which records sample number and weight. An automatic pipet aliquots, dilutes, and buffers samples directly from the digestion tubes; the samples can be immediately titrated with the automatic titrator. The results for protein in NBS standards and check feed samples from an official testing program compare closely with average values reported for these standards. Results show that feed and wheat samples contained 10- 100% protein. Precision for successive aliquots of the same digests is 0.1-0.4% relative standard deviation; precision for multiple digestions of the same sample is 0.1-0.8%.
Infrared Estimation of Fat, Protein, and Lactose in Milk: Evaluation of Multispec Instrument
Authors: Biggs Delmar A 
Published: February 2020

Abstract
Thirty-eight milks (including homogenized and unhomogenized herd milks, individual cow milks, and packaged milks) were pre-analyzed by accepted standard methods and then analyzed in duplicate with a Multispec instrument on 2 different days. For the combined data, mean differences between duplicates were 0.01% or less within days and 0.025% or less between days. Standard deviations of difference between duplicates were 0.02% or less. Overall mean differences between Multispec and standard results were 0.02% or less with standard deviations of difference of 0.041%, but means for protein in packaged milks were 0.038% lower and means for lactose in individual cow milks were 0.04% higher than standards. Standard deviations of difference for fat were lower (0.016%) than average for packaged milks and higher (0.06%) than average for individual cow milks. Differences between Multispec results for homogenized and unhomogenized samples of the same herd milks were small, averaging 0.013% for fat, 0.005% for protein, and 0.011% for lactose. Regression equations for the combined data gave standard errors of estimate of about the same magnitude as the standard deviations of difference. Single calibrations would give good estimates for all components in all of the types of milk analyzed, but for best accuracy the instrument should be calibrated with the type of milk to be analyzed.
Quantitation of the Contaminants in Technical Fenitrothion by Reverse Phase High Pressure Liquid Chromatography
Authors: Cochrane William P , Lanouette Monique , Greenhalgh Roy 
Published: February 2020

Abstract
Technical grade samples of fenitrothion were analyzed by high pressure liquid chromatography (HPLC) on a reverse phase LiChrosorb RP-8 column, using 3 solvent systems and a UV detector set at 269 nm. All commercial samples analyzed contained &gt;94% fenitrothion; in addition, 9 contaminants were identified and quantitated. Bisfenitrothion was the major contaminant, with average amounts of 2.46% from one manufacturer and 1.17% from another. The second most abundant toxicant was S-methyl fenitrothion, which was present at an average level of 0.71% in one source but only 0.16% in the other. The amount of fenitrooxon was 0.046% or less in samples from 2 manufacturers. Other contaminants quantitated include the 2 demethyl fenitrothion isomers, 3-methyl-4-nitrophenol, 3-methyl-6-nitrophenol, 3-methyI-4-nitroanisole, and bis-S-methyl fenitrothion. The total amount of the constituents quantitated in 9 commercial samples was 99.07 ± 1.81%. By comparing the amounts of bis-fenitrothion and phenols present in technical grade fenitrothion, it should be possible to identify the specific manufacturers of the various products.
Microbiological Determination of Penicillin G, Ampicillin, and Cloxacillin Residues in Milk
Authors: Vilim Arnost B , Moore Steven D , Larocque Lyse 
Published: February 2020

Abstract
A fast cylinder plate microbiological method was developed for the quantitative determination of penicillin G, ampicillin, and cloxacillin in milk. Agar plates seeded with stable spores of Bacillus stearothermophilus var. calidolactis were used and incubated at 64°C for 4½ hr. Standard curves were obtained for the following ranges of concentration of antibiotics: 0.004-0.064 IU penicillin G/mL, 0.0025-0.04 μg ampicillin/mL, and 0.03-0.48 μg cloxacillin/mL. The method is suitable for detecting penicillin residues in milk and for quantitative milk-out studies of the above antibiotics used in treatment of bovine mastitis.
Gas-Liquid Chromatographic/Mass Spectrometric Screening Method for T-2 Toxin in Milk
Authors: Collins George J , Rosen Joseph D 
Published: February 2020

Abstract
A method for the analysis of T-2 toxin in milk is presented. Ethyl acetate extracts of milk samples which had been spiked with T-2 toxin were purified by thin layer chromatography and derivatized with N,O-bis(trimethylsilyl)acetamide to produce the T-2 toxin trimethylsilyl ether (T-2 toxin-TMS). N,O-bis(trimethylsilyl-d9)acetamide was used to make T-2 toxin d9-trimethylsilyl ether (T-2 toxin-d9TMS) which was added to the derivatized milk extract as an internal standard. Samples were analyzed by combined gas-liquid chromatography/mass spectrometry using either electron impact ionization or chemical ionization mass spectrometry. In electron impact ionization analyses, simultaneous monitoring of the T-2 toxin-TMS fragment ion at m/z 436 and the T-2 toxin-d9TMS fragment ion at m/z 445 gave a T-2 toxin-TMS detectability estimated at 6 μg/kg. In chemical ionization analyses, the T-2 toxin-TMS fragment ion at m/z 377 and the T-2 toxin-d9TMS fragment ion at m/z 386 were simultaneously monitored to give a T-2 toxin-TMS detectability estimated at 3 μg/kg. Average recovery was 85% at 200 μg/kg and 65% at 20 μg/kg.
Analysis of Fat-Soluble Vitamins. XXIII. High Performance Liquid Chromatographic Assay for Vitamin D in Vitamin D3 and Multivitamin Preparations1
Authors: Vries Ellen J De , Zeeman Jakob , Esser Robert J E , Borsje Ben , Mulder Frits J 
Published: February 2020

Abstract
Vitamin D is determined in preparations containing other fat-soluble vitamins by high performance liquid chromatography (HPLC). The unsaponifiable residue is extracted and separated from interferences by reverse phase chromatography; the fraction corresponding to vitamin D3 is collected and quantitated using normal phase chromatography (amylalcohol-n-hexane as mobile phase) by measuring the vitamin D3 and previtamin D3 peaks at 254 nm. Previtamin D3 content is calculated as vitamin D3 with a conversion factor (determined on the equipment used). Application of the method to vitamin AD3 mixtures in oils gives 98-102% recovery. The reproducibility, using an external standard, is 2-3%, calculated as the coefficient of variation; with an internal standard, the coefficient of variation is 1-1.5%. The method measures potential vitamin D3 content in preparations containing ≽ 200 IU/g in the presence of all known vitamin D3 isomers, vitamin A, and vitamin E.
High Performance Liquid Chromatographic Determination of Quinizarin, p-Toluidine, and D&C Violet No. 2 in D&C Green No. 6
Authors: Cox Elizabeth 
Published: February 2020

Abstract
High performance liquid chromatography was used to determine quinizarin, p-toluidine, and D&C Violet No. 2 in D&C Green No. 6. Recoveries averaging 102, 105, and 104% were obtained for quinizarin, p-toluidine, and D&C Violet No. 2, respectively. Multiple runs on one sample of D&C Green No. 6 indicated variability in the amount of p-toluidine found.
Effect of Injection Solvent on Gas Chromatographic Quantitation of Some Polar Organophosphorus Pesticides
Authors: LeBel Guy L , Williams David T 
Published: February 2020

Abstract
Hexane solution aliquots containing 4 ng dimethoate and 8 ng β-phosphamidon gave peak heights on gas chromatographic analysis only 64% and 43%, respectively, of those from corresponding aliquots of acetone solutions. The low values with hexane solutions were caused by adsorption of these compounds in the syringe. Acetone solutions of these compounds showed no losses due to syringe adsorption.
Application of Gel Permeation Chromatography and Nonaqueous Reverse Phase Chromatography to High Pressure Liquid Chromatographic Determination of Retinyl Palmitate in Fortified Breakfast Cereals
Authors: Landen William O 
Published: February 2020

Abstract
A high pressure liquid chromatographic (HPLC) method was developed for determining retinyl palmitate in cereals. Retinyl palmitate is fractionated from other methylene chloride-soluble components by using high pressure gel permeation chromatography (HP-GPC) followed by quantitation with nonaqueous reverse phase HPLC (RPHPLC). HP-GPC fractionation was accomplished using 2 µStyragel (100Å) columns connected in series on sample extracts in methylene chloride with methylene chloride as the mobile phase. A valve designed to facilitate the collection of the vitamin A fraction was installed in-line between the refractive index and absorbance detectors. RPHPLC quantitation was achieved on µBondapak C18 (10 µm) using methylene chloride–acetonitrile (30+70). Based on 23 repetitive analyses, recovery of vitamin A as retinyl palmitate in cereal products was 95.4±4.2% with spiking levels between 21.4 and 140 µg/g. Vitamin A in 15 cereals, representing bran, corn, oats, rice, and wheat, ranged from 34 to 194% of the declared level. The HPLC procedure was compared with the AOAC official colorimetric method and with an ultraviolet spectrophotometric method.
Liquid Chromatography with Amperometric Detection for Determining Phenolic Preservatives
Authors: King William P , Joseph Kuriakose T , Kissinger Peter T 
Published: February 2020

Abstract
Liquid chromatography with amperometric detection is a rapid and sensitive method for determining commonly encountered phenolic antioxidants including 3(2)-tert-butyl-4-hydroxyanisole, tert-butylhydroquinone, n-propyl gallate, nordihydroguaiaretic acid, and 2,6-di-tert-butyl-4-hydroxymethylphenol (Ionox-100), and the antimicrobial parabens, in a variety of commercial products. Sample extracts are chromatographed directly with few interferences on the reverse phase system. The typical linear range extends from 10−11 to 10−6 mole of injected analyte. Pertinent experimental factors are discussed with regard to the requirements of the detector and optimizing the determination of this class of compounds
Effect of Cupric Ions on the Analysis of Ethylenebis(dithiocarbamate) Residues in Tomato Juice
Authors: Lesage Suzanne 
Published: February 2020

Abstract
Cupric ions interfered with the carbon disulfide evolution assay method for dithiocarbamate residues in tomato juice and in aqueous solution. Amounts of residue determined were reduced when CuSO4 and a formulation of copper fungicide (Copper-Count-N) were present in the solutions analyzed.
Spectrofluorometric Determination and Thin Layer Chromatographic Identification of Serotonin in Foods
Authors: García-Moreno Concepcion , Ales-Alarcon Ana Nog , Gómez-Cerro Auxiliadora , Marine-Font Abel 
Published: February 2020

Abstract
A method is described for determining serotonin in foods, based on alkaline butanol-sand column elution followed by spectrofluorometric and spectrofluorometric determination with thin layer chromatographic confirmation. The method has been applied to fresh bananas, banana-based baby foods, and fresh and canned tomatoes. The average recovery was 91%. The amounts of serontonin found were 10–30 ppm in bananas, 0.1–1.9 ppm in banana-based baby foods, 4.4–5.6 ppm in fresh tomatoes, and 2.8–5.6 ppm in canned tomatoes
Lipid Extraction Procedure for Some Food Products Containing Surfactants
Authors: Flor Richard V , Prager Manfred J 
Published: February 2020

Abstract
Total lipids were extracted from food products by heating the sample under total reflux for 15 hr with a mixture of chloroform-methanol (70+30) in the ratio 6.67 mL solvent/g sample. The solution was filtered and evaporated, and the lipids were dissolved in petroleum ether, filtered, and evaporated to yield the crude lipids and surfactants. The purified lipids are suitable for butterfat determination directly, or are readily separated from the surfactants by alumina chromatography. The method is particularly suited to the milk products studied, which produced troublesome emulsions if aqueous treatments were used. The method also allows ready extraction of total fats from drained feta cheeses, whereas Soxhlet extraction with petroleum ether sometimes fails. The effects of reflux time and varying ratios of chloroform to methanol were studied.
Gas-Liquid Chromatographic Determination of Mirex and Photomirex in the Presence of Poly chlorinated Biphenyls: Interlaboratory Study
Authors: Norstrom Ross J , Won Henry T , Holdrinet Micheline Van Hove , Calway Patrick G , Naftel Caroline D 
Published: February 2020

Abstract
Mirex and photomirex (8-monohydromirex) were separated from polychlorinated biphenyls (PCBs) and other aromatic compounds by nitration with fuming nitric acid-concentrated sulfuric acid and removal of nitro-PCBs on an alumina microcolumn; the compounds were then determined by gas-liquid chromatography. Recoveries of Mirex and photomirex were 102±8 and 104±5%, respectively, from standard solutions which had a PCB-to-Mirex and photomirex ratio of 1000. Recoveries from fortified, uncontaminated samples of sediment, fish, and eggs averaged 93±7 and 92±3% for Mirex and photomirex, respectively. The coefficients of variation for repeatability and reproducibility averaged 8 and 15%, respectively, in an interlaboratory study conducted by 4 laboratories using extracts of naturally contaminated substrates (sediment, carp, eel, and gull egg). Levels of Mirex in the samples ranged from 0.1 to 8 mg/kg, and levels of PCB ranged from 0.5 to 166 mg/kg.
Gas-Liquid Chromatographic Determination of Bromacil Residues
Authors: Ting Keh-Chuh , Root George A , Tichelaar George R 
Published: February 2020

Abstract
A simple, fast, and accurate method has been developed to determine residues of bromacil (5-bromo-3-sec-butyl-6-methyluracil) herbicide. Following sample extraction, filtration, and concentration, the herbicide is determined using a gas chromatograph equipped with a thermionic nitrogen/phosphorus detector. The method has been used to recover 0.04 ppm bromacil added to citrus, pineapple, soil, and water, and 0.1 ppm bromacil added to alfalfa hay.
Confirmation of Low μg/kg Amounts of Volatile N-Nitrosamines in Foods by Low Resolution Mass Spectrometry
Authors: Hotchkiss Joseph H , Libbey Leonard M , Scanlan Richard A 
Published: February 2020

Abstract
Volatile N-nitrosamines were confirmed in foods at concentrations of less than 10 μg/kg by full scan low resolution mass spectrometry. Ground samples were vacuum-distilled from mineral oil and condensed in liquid nitrogen-cooled vapor traps. The thawed distillate was extracted, the extract was cleaned up and concentrated, and the N-nitrosamine content was determined by combined gas chromatography-thermal energy analysis. Positive samples were further cleaned up, trapped from a gas chromatographic column, and purged into a gas chromatograph-mass spectrometer for qualitative confirmation by full scan low resolution mass spectrometry. This procedure Was applied to foods spiked at 1 μg/kg and to fried commercial bacons with volatile N-nitrosamine contents of 2 to 5 μg/kg.
Colorimetric Determination of Acetylenic Hypnotics by Formation of Silver Acetylides
Authors: Rizk Mohamed S , Walash Mohamed I , El-Brashy Amina 
Published: February 2020

Abstract
A colorimetric method is described for the determination of certain mono-substituted acetylenic hypnotic drugs—ethinamate, methyl pentynol carbamate, and ethchlorvynol. Silver acetylide is formed and extracted into isobutyl methyl ketone. After acidification, an equivalent amount of silver ions is liberated which is assayed colorimetrically as silver dithizonate (λ max. 472 nm). About 10–50 μg compound could be assayed with good accuracy. The procedure is reproducible and precise (standard deviation 1.5–2.19%). The procedure was successfully applied to different pharmaceutical dosage forms.
Migration of Ethylene Glycol from Polyethylene Terephthalate Bottles into 3% Acetic Acid
Authors: Kashtock Michael , Breder Charles V 
Published: February 2020

Abstract
Migration of ethylene glycol (EG) from polyethylene terephthalate (PET) bottles into the food simulant 3% acetic acid was studied using 32 fluid oz PET bottles filled with 3% acetic acid and stored at 32° C for 6 months. Final concentration of EG in the 3% acetic acid migration solution was about 100 ppb, which is equivalent to about 94 µg EG /bottle. A gas-liquid chromatographic procedure for quantitating EG was developed which is capable of measuring EG levels as low as 50 ppb in the migration solution.
Improved Cleanup of Large Lipid Samples for Electron Capture Gas Chromatographic Quantitation and Gas Chromatographic-Mass Spectrometric Confirmation of Organochlorine Residues
Authors: Veierov Dan , Aharonson Nadav 
Published: February 2020

Abstract
A new cleanup method for large lipid samples is described for the analysis of organochlorine traces. The method allows both electron capture gas chromatographic (GC) quantitation of subppb levels and confirmation by GC-mass spectrometry. The lipid is extracted with concentrated sulfuric acid from a 2-5% solution of light petroleum ether. The method has been scaled up without increasing the petroleum volume by the alternate addition of lipids and sulfuric acid. Recovery studies were performed with 11 common organochlorine contaminants spiked in butterfat nd in vegetable oils at the ppb level. The method is characterized by low lipid carryover of 0.02% by minimal use of solvent (about 2-3 mL/g lipid), and by its simplicity. A 50-200 g sample can be cleaned up in one day. Five μg of incurred p,p′- DE has been cleaned up from a 50 g butterfat sample and purified by one TLC run. The eluted compound was analyzed by GC-MS and showed one peak (flame photometric detector) with a mass spectrum identical to authentic p,p′-DDE.
Determination of Uranium in Phosphate Rock and Wet-Process Phosphoric Acid by Argon Plasma Emission Spectrometry
Authors: Woodis Terry C , Trimm J R , Holmes John H , Johnson Frank J 
Published: February 2020

Abstract
A method for determining uranium, based on extraction with trioctylphosphine oxide and measurement by argon plasma emission spectrometry at 424.17 nm, is described. Results from the argon plasma method compare favorably with results from other methods and are within 1 standard deviation of the composite average of all methods used in an 11-laboratory study.
Assessment of Rat Growth Methods for Estimating Protein Quality: Interlaboratory Study
Authors: Mclaughlan J Murray , Anderson G Harvey , Hackler L Ross , Hill Douglas C , Jansen G Richard , Keith Murray O , Sarwar Ghulam , Sosulski Frank W 
Published: February 2020

Abstract
An interlaboratory study involving protein efficiency ratio (PER), net protein ratio (NPR), relative NPR (RNPR) and relative nitrogen utilization (RNU) was carried out. Six collaborators assayed 6 samples, including casein plus methionine which was used as a reference protein. Collaborators prepared their own diets and analyzed the diets for nitrogen. Test proteins were added at the 8% level (N × 6.25). PER values varied more than NPR values which varied more than either RNPR or RNU. RNU and RNPR produced almost identical values, but RNPR remains the official method of choice, because it is a well established method.
Determination of Capsicum Pungency by High Pressure Liquid Chromatography and Spectrofluorometric Detection
Authors: Woodbury James E 
Published: February 2020

Abstract
A method has been developed to determine pungency due to capsaicinoids in capsicums and their oleoresins. Capsaicinoids are extracted from the capsicums with 95% ethanol saturated with sodium acetate, separated by high pressure liquid chromatography (HPLC) and detected by spectrofluorescence. The method is sensitive to 2 ppm (approximately 30 Scoville), with a standard deviation of 9 ppm at 150 ppm and a standard deviation of 129 ppm at 1500 ppm. Depending on the pungency level, 20–50 samples can be analyzed in 8 hr. Comparative data for pungency determined organoleptically and by this method gave a correlation coefficient of 0.98 on samples ranging from 100 to 700 ppm capsaicin.