bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanized System for Liquid Chromatographic Determination of 4-Nitrophenol and Some Other Phenolic Pesticide Metabolites in Urine
Authors: Ott Daniel E
Published: February 2020

Protecting the health of workers who are exposed to pesticides is of concern. One helpful approach is to periodically analyze the urine of such workers for metabolites of those pesticides encountered in the working environment. Therefore, an analytical system for several urinary pesticide metabolites, which incorporates a high degree of mechanization, has been developed. Urine samples (ca 8 ml) are placed in a sampler module. An acid hydrolysis step, a steam distillation step, and a combined liquid chromatographic separation and UV absorption determinative step are performed automatically, except for the need for an operator to turn a loop valve injector for the liquid chroma tograph at an exact time after the start of sampling each sample. At the slowest rate, a sample is analyzed every 24 min with a lower limit of detectability from 1 to 2 ppm added 4-nitrophenol in urine. Acid hydrolysis is included to cleave urinary conjugates of the analyte(s) of metabolic origin; steam distillation provides considerable cleanup. The method, with minor adjustment of chromatographic conditions, also responds to <5 ppm each of the other phenols derivable from the below-named (and some other) pesticides. Alternative conditions permit detection of <1 ppm 1-naphthol. Exact limits lower than the numerical values stated have not been determined. The method has the capability for assessing human exposure primarily to parathion, paraoxon, methyl parathion, and EPN, but also to carbaryl, Landrin, 2-phenyIphenol, bromophos, bromophos-ethyl, iodofenphos, 2,4,5-trichlorophenol, 2,4,5-trichlorophenoxyacetic acid, fenoprop, trichloronat, and fenchlorphos. The applicability of the method was demonstrated by fortifying urine with phenolic standards corresponding to the phenolic moieties as metabolically produced from these pesticides or to the phenolic parent pesticide.
Collaborative Study of the Gas-Liquid Chromatographic Determination of Malathion in Formulations and Technical Materials
Authors: Wayne Richard S
Published: February 2020

A gas-liquid chromatographic method was studied collaboratively for determining malathion in wettable powders, an emulsifiable concentrate, a dust, and the technical grade product. Flame ionization detection, m-diphenoxybenzene as the internal standard, and a column containing 5% SP-2401 or OV-210 on 100-120 mesh Gas-Chrom Q or Supelcoport were used for the determination. Agreement between replicates in individual laboratories was excellent. Agreement between laboratories was satisfactory. The method offers improved specificity and ease of operation when compared to the official first action methods. The method has been adopted as official first action.
Detection of Salmonella in Onion and Garlic Powders: Collaborative Study
Authors: Andrews Wallace H , Wagner Dean , Roetting Mary Jo
Published: February 2020

The relative efficiency of trypticase soy broth with added 0.5% K2SO3 and lactose broth as pre-enrichment media for recovering Salmonella from onion powder and garlic powder was collaboratively studied. For each spice, 13 collaborators each received 5 duplicate samples; 4 of the 5 replicate samples were inoculated with 1 of 4 levels of S. thompson ranging, at initiation of analysis, from <3 to 93 organisms/g onion powder and <3 to 43 organisms/g garlic powder. Salmonella growth was inhibited in each of these spices as evidenced by a rapid decline of most probable number values in samples determined immediately after and 7 days following inoculation. Collaborative results of cultural analyses demonstrated superiority of the modified trypticase soy broth for recovering Salmonella in each of the 2 spices. The improved method of detecting Salmonella in onion and garlic powders has been adopted as official first action.
Semiautomated Method for the Analysis of Formulations of Chlorpheniramine Maleate and Brompheniramine Maleate
Authors: Cox Don C , Kirchhoefer Ross D
Published: February 2020

The determination of chlorpheniramine maleate and brompheniramine maleate in tablets, capsules, injections, and elixirs has been automated. The active ingredient is dissolved in dilute HCl. The dilute acid solution is sampled, made basic with dilute NaOH, and extracted with isooctane. The isooctane phase is resampled and the drug is re-extracted into dilute HCl. The absorbance of the acidic aqueous layer is monitored at 265 nm. The method is an automated version of the general USP XIX assay for salts of organic nitrogenous bases. The results from the semiautomated procedure agree well with the USP XIX and NF XIV official methods. Recoveries were 100% from an authentic tablet material. The system is linear from 0 to 300% of declared potency. The procedure is free from common excipient and dye interferences. Precision data are included for both the automated and official methods.
Survey of Some Market Basket Commodities for Polynuclear Aromatic Hydrocarbon Content
Authors: Joe Frank L , Roseboro Emma L , Fazio Thomas
Published: February 2020

The Food and Drug Administration multicomponent regulatory procedure for determining polynuclear aromatic hydrocarbons in foods was recently used to survey 24 foodstuffs for the presence of these compounds. The procedure has a reliable limit of quantitation of 2 ppb. The potent carcinogen benzo (a) pyrene was detected in only one of the 24 products analyzed, at a level of 3 ppb. Pyrene and/or fluoranthene were found in 19 of the 24 samples examined, at levels ranging from less than 1 ppb to about 75 ppb. A comparison of the recent survey data to that obtained approximately 10 years ago reveals that the types and levels of polynuclear aromatic hydrocarbons found are essentially unchanged.
Determination of Chlorinated Pesticide Residues in Foods. III. Simultaneous Analysis of Chlorinated Pesticide and Phthalate Ester Residues by Using AgNO3-Coated Florisil Column Chromatography for Cleanup of Various Samples
Authors: Suzuki Takashi , Ishikawa Kiyoshi , Sato Nobutoshi , Sakai Kei-Ichi
Published: February 2020

A simplified method suitable for simultaneous analysis of chlorinated pesticide and phthalate ester residues in various foods was developed. Chemical residues were quantitatively extracted from fatty and vegetable samples with acetonitrile as follows: Chemical standard in 0.5 mL ethanol solution was added to 10 g homogenized sample. After 3 hr, pork and beef were extracted 3 times with 20 mL portions of acetonitrile. The acetonitrile layers were diluted with water and extracted with n-hexane. Rice samples were combined with 10 mL water, 5 mL acetonitrile, and 1 mL ethanol and extracted 3 times with 20 mL portions of n-hexane. The re-hexane concentrate from each sample was submitted to AgNO3-coated Florisil column chromatography. The AgNO3 coating adequately adsorbed interfering coextractives. Extracts of fish and vegetable samples were separated into 2 fractions by the above column chromatography. Supplemental cleanup procedures were also developed to accurately determine phthalate esters eluted in the second fraction. Satisfactory gas chromatograms were obtained for most samples.
Sampling Variances of Bulk-Blended Dry Fertilizers
Authors: Pettygrove G Stuart , Schneider Paul S
Published: February 2020

Probe and stream samples were collected from 50 loads of dry bulk-blended fertilizer at 21 blending plants in central Iowa. The variances in N, P2O5, and K2O content attributable to sample collection were much larger than those used to compute the fertilizer Investigational Allowances recommended by the American Association of Plant Food Control Officials. Manufacturing conditions in this study were not controlled and could have inflated the sample collection variance, but no relationship was observed between the variance and a number of manufacturing parameters, including nutrient level and particle size mismatch of blending ingredients. Therefore, it seems that the sample collection variance used to compute the Investigational Allowance underestimates the inherent variability that occurs in sampling of physically blended fertilizers. Probe samples tended to be lower in N and P2O5 content and higher in K2O content than were stream samples. The use of materials poorly matched in particle size, coupled with slow blender discharge, tended to result in larger differences between probe and stream samples.
Confirmation of Organothiophosphorus Insecticide Residues in Fruit and Vegetables by Oxidative Derivatization
Authors: Singh Joginder , Cochrane William P
Published: February 2020

Oxidative derivatization of 10 organothiophosphorus insecticides at nanogram levels, with neutralized sodium hypochlorite (NaOCl) produced their respective P = O oxygen analogs, as shown by GC/MS and FT-IR analysis. In addition, phorate resulted in phorate oxon sulfoxide while methidathion gave a mixture of oxidation products. Four macro-scale oxidation products of methidathion were isolated by thin layer chromatography and 3 were identified, namely, methidaoxon, bis(2-methoxy-Δ2-1,3,4-thiadiazolin-5-on-4-yl) sulfide, and the corresponding disulfide, by comparison of their infrared and mass spectra with those of authentic samples. The relative response to sulfide and disulfide products of the flame photometric detector in both the P- and S-modes is discussed. This derivatization is applied to the confirmation of chlorpyrifos, ethion, phorate, DMPA (Zytron), leptophos, and methidathion in celery, potatoes, lettuce, tomatoes, and apples at 0.25–0.5 ppm fortification levels.
Investigation and Simplification of the Sweep Co-Distillation Cleanup of Pesticide Residues in Animal Fats
Authors: Heath Andrew B , Black Robert R
Published: February 2020

The sweep co-distillation technique of Storherr et al. was investigated and simplified. Six organochlorine pesticides in animal fats were cleaned up under various distillation conditions as follows: No solvent was used, or solvent injection rates were 1 mL/min or 2 mL/3 min. Distillation tubes of 6.7 and 9.0 mm id diameter were compared. Distillation temperatures were varied from 150 to 300°C The complex condenser of Storherr et al. was compared with a simpler pipet condenser. A U-tube condenser which allows direct introduction onto a Florisil column for secondary cleanup was evaluated. The following modifications to the sweep co-distillation technique resulted: no solvent introduction, distillation temperature 230°C, nitrogen flow rate 600 mL/min, 6.7 mm id distillation tubes with simplified packing, and incorporation of the U-tube condenser. The new technique gave recoveries comparable to those of Storherr et al., but it is faster than most bisolvent partition methods and no large volumes of solvent are required.
Liquid Chromatographic Determination of Desoxycorticosterone Acetate in Oil Injections
Authors: Smith Edward
Published: February 2020

To determine desoxycorticosterone acetate in oil injections, reverse phase partition chromatography on silanized, purified siliceous earth was used to separate the corticosteroid ester from the bulk of the oil vehicle. The latter was retained on the column while the steroid and the sterol and triterpenoid fractions of the oil were eluted. An internal standard was added to this eluate, which was then subjected to reverse phase high performance liquid chromatography (HPLC). The desoxycorticosterone acetate was quantitatively separated in the HPLC procedure from any free desoxycorticosterone, preservatives, and minor components of the oil. The suitability of the HPLC procedure was verified with a number of C18 packing materials, both pellicular and microparticular. The desoxycorticosterone acetate was adequately resolved from the internal standard, progesterone, with most C18 packing materials evaluated. The proposed procedure provides a suitable stability-indicating assay for desoxycorticosterone acetate in oil injections.
Mass Spectrometric 13C/12C Determinations to Distinguish Honey and C3 Plant Sirups From C4 Plant Sirups (Sugar Cane and Corn) In Candied Pineapple and Papaya
Authors: Doner Landis W , Chia David , White Jonathan W
Published: February 2020

Stable carbon isotope ratio analysis was applied to concentrated extracts of authentic honey-processed pineapple and papaya samples and imported candied samples alleged to have been processed with honey. The 9 imported samples had δ13C values ranging from –11.1 to –15.0%0, while pineapple and papaya samples known to be processed with honey had values of –25.0 and –25.2%0, respectively. The results show that the imported samples were processed with sugar sirups derived from plants using the Hatch-Slack (C4) photosynthetic cycle, such as sugar cane and corn, rather than with honey which is derived from Calvin (C3) floral sources.
High Pressure Liquid Chromatographic Determination of Ochratoxin A and Zearalenone in Cereals
Authors: Josefsson Egon , Möller Tord
Published: February 2020

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

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

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

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

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

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 >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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Thin Layer Chromatography Reflectometric Determination of Benzoic and Sorbic Acids in Fruit Beverages
Authors: Mandrou Bernadette , Bressolle Francoise
Published: February 2020

A procedure is proposed for the quantitative determination of both benzoic and sorbic acids in fruit beverages. This method is carried out by direct ultraviolet spectrophotometric measurements in silica chromatoplates after development with chloroform-methanol-water (65+35+7) and makes use of an internal standard. Applied to samples spiked with benzoic and sorbic acids, this technique gives accurate and reliable results with good recoveries. The sensitivity (about 1 ppm) is particularly convenient for trace level determination.
Application of Sparging to the Automated Ion Selective Electrode Determination of Kjeldahl Nitrogen
Authors: Roy Ram B , Jansen John , Sahn Michael
Published: February 2020

An automated method has been developed for the determination of total Kjeldahl nitrogen. Sample digests are mixed with a NaOH solution and allowed to make contact with air flowing at 1000 mL/min. The mixture enters the inlet of a heating bath maintained at 75°C. On exit, ammonia gas separates from a sparging vessel and is trapped as ammonium sulfate in a dilute H2SO4 solution. An aliquot of the acid solution is resampled and made alkaline to generate ammonia, which is measured by an ammonia sensing probe. A comparison of this procedure with AOAC method 7.025 shows that the procedure is accurate and that there is no statistically significant difference between them. This procedure introduces a new approach to eliminate the interfering species present in sample digests after Kjeldahl digestion for automated ion selective electrode measurements of ammonia. Thirty samples/h can be analyzed by this method.
Study of Vacuum Oven Drying in Official Method for Moisture in Eggs and Egg Products
Authors: Taber Lawrence E
Published: February 2020

Discrepancies occur when moisture or solids determinations on eggs and egg products are done by the vacuum oven method as opposed to the atmospheric oven method. The vacuum oven method requires a temperature of 100°C to a point of constant weight (about 5 h) at 25 mm of Hg. When compared with the same samples dried to constant weight in an atmospheric oven at 100°C the vacuum dried product will show a 10 to 50% greater loss of weight depending on carbohydrate content. The difference in the product color from the 2 drying methods indicates a carbohydrate reaction in the vacuum dried product.
Extent of Microencapsulation in Pesticide Formulations of Diazinon, Methyl Parathion, and Ethyl Parathion
Authors: Argauer Robert J
Published: February 2020

A method is described that compares the amount of encapsulated pesticide and the amount of free pesticide as a percentage of the total pesticide content of a formulation. Formulations that contained pesticides encapsulated in a nylon-type polymer skin were more than 99% encapsulated. The method can be extended further to measure the amount of nonencapsulated pesticide (e.g., emulsifiable concentrates) in mixtures with encapsulated pesticides. The formulations studied were Knox-Out (encapsulated diazinon), Penncap-M (encapsulated methyl parathion), and Penncap-E (encapsulated parathion).
International Mycotoxin Check Sample Program. Part I. Report on the Performance of Participating Laboratories
Authors: Friesen Marlin D , Walker Ernest A , Castegnaro Marcel
Published: February 2020

Three aflatoxin-contaminated samples, raw peanut meal, finished peanut butter, and white corn meal, were analyzed by 139 laboratories in 34 countries. Sufficient data were obtained to permit a statistical comparison of the performance of laboratories using the BF, CB, and Pons methods and those using high performance liquid chromatography for quantification. A raw peanut meal sample showed no significant differences among means for laboratories using the four methods, and a white corn meal sample showed only one such significant difference; however, a finished peanut butter sample containing less than 10 μg total aflatoxins/kg showed 10 significant differences among means for laboratories using the 4 methods considered
Optimization of Chromatographic Conditions for the Separation of p,p´-DDE from Aroclor 1254 on Silica, Using Azulene as Indicator
Authors: Griffin Donald A , Marin Anna B , Deinzer Max L
Published: February 2020

Aroclor 1254 is separated from p,p´-DDE on a fully activated silica gel column with the aid of azulene as a visual marker. The azulene is useful in determining the best cutpoint for separating these compounds and has been valuable in characterizing the effects of several parameters of the separation system, such as the aromatic content of the eluting solvent, adsorbent activity, and lipid and pesticide load capacity. Several brands of silica are compared for their ability to separate these compounds.
Sample Preparation of Carbadox, Furazolidone, Nitrofurazone, and Ethopabate in Medicated Feeds for High Pressure Liquid Chromatography
Authors: Thorpe Virginia A
Published: February 2020

Medicated feeds (pelleted or mash) containing guarantees of carbadox, furazolidone, nitrofurazone, and ethopabate are pretreated with water, extracted with 95% dimethylformamide overnight at room temperature, cleaned up on a column of alumina, and injected into a high pressure liquid chromatograph for quantitative measurement. Carbadox, nitrofurazone, and furazolidone can be separated; chromatograms show excellent baseline resolution, and results are in good agreement with colorimetric methods. The same extraction and cleanup can be used to improve colorimetric methods for furazolidone and nitrofurazone.
Evaluation of Bacterial and Fungal Growth Media for Ability to Neutralize Cosmetic Preservatives
Authors: Littell Allan M , Palmieri Michael J , Bisciello Neil B
Published: February 2020

Standard methods agar (SMA) and letheen agar (essentially SMA plus lecithin and Tween 80) were compared for bacterial growth and ability to neutralize cosmetic preservatives. Potato dextrose and malt extract agars (each prepared with and without lecithin and Tween 80) were compared with letheen agar and SMA in similar studies with fungi. Twelve bacterial strains, representing 8 species, and 2 fungal species were used as inocula. Plate counts of bacterial cultures (no preservatives present) ranged from 0 to 50% higher on letheen agar than on SMA except for 3 strains of Staphylococcus, which were 8-29% lower. Fungal counts were about the same on all media. Cosmetics (10 g) representing 4 preservative systems (hexachlorophene, benzoin, formaldehyde, and parabens) were inoculated with diluted cultures. Counts at 10−1 and 10−2 dilutions were typically 10-200% higher on letheen agar; however, in one case (benzoin, S. aureus, 10−1) the count was 400 on SMA vs 20 000 on letheen agar. Although differences in fungal counts were not as great, letheen agar partially neutralized the preservatives’ action. Results show that product dilution does not sufficiently reduce the effects of preservative carryover and neutralizers should be incorporated into plating media for this purpose.
Improved Method for Gas-Liquid Chromatographic Determination of Clopidol in Chicken Tissues
Authors: Suzuki Etsuko , Matsuda Mihoko , Momose Atsushi , Namekata Masaya
Published: February 2020

A sensitive and specific gas-liquid chromatographic (GLC) method has been developed for determining low levels of clopidol in chicken tissues. Clopidol is extracted from the tissues with methanol, and cleaned up on an alumina column and an anion exchange resin column with 0.1% acetic acid–methanol as eluate. Clopidol is methylated with diazomethane, and then determined by GLC. 2,4-Dinitro-l-chlorobenzene is used as an internal standard. The method is applicable to levels as low as 2 ppb in chicken tissues. Recoveries of 2–20 ppb clopidol added to tissues averaged 87% for muscle, 84% for liver, 80% for kidney, and 76% for fat.
Influence of Extraction Techniques on Determination of α-Tocopherol in Animal Feedstuffs
Authors: Mcmurray Cecil H , Blanchflower William J , Rice Desmond A
Published: February 2020

Methods were compared for α-tocopherol determination involving saponification in the preparation of feed extracts for high performance liquid chromatography. The effects of antioxidant and saponification times used were also examined. The data obtained showed that saponification before solvent extraction more efficiently released natural α-tocopherol from the feedstuffs than extraction before saponification. Increases in α-tocopherol content of 0–144% were obtained for the range of feedstuffs examined. Ascorbic acid and pyrogallol used as antioxidants gave similar results, and extraction efficiency was independent of the time of saponification within the range 5–40 min.
High Pressure Liquid Chromatographic Determination of Aflatoxins in Soy Sauce and Fermented Soybean Paste
Authors: Wei Ru-Dong , Chang Shenq-Chyi , Lee Shiuh-Sheng
Published: February 2020

A procedure for the quantitative determination of aflatoxins B1, B2, G1, and G2 in soy sauce and fermented soybean paste is proposed using high pressure liquid chromatography with ultraviolet detection after CB extraction and SEP-FAK and preparative thin layer chromatographic cleanups. Recoveries of 71.3 to 89.3% were obtained for soy sauce spiked with 1, 5, 20, and 100 ppb aflatoxins. Similar recoveries (77.0 to 90.8%) were obtained with concentrated soy sauce and fermented soybean paste spiked at 20 and 100 ppb. In comparison with other procedures, the proposed procedure is relatively fast and precise and gives good recoveries. Aflatoxins were not stable in soy sauce. During storage, half of aflatoxins B1, and G1, were deteriorated at 60 and 120 days, respectively.
Mycotoxins in Coffee
Authors: Levi Colette
Published: February 2020

This report reviews studies concerning the susceptibility of green coffee beans to mycotoxin contamination. Included are investigations on normal mold flora, toxin production in inoculated beans, effect of experimental roasting on aflatoxin, ochratoxin, and sterigmatocystin, and survey on the presence of these toxins in commercial green coffee. Because of the extremely low frequency of findings, the low levels of toxins, and the experimental data showing 70–80% destruction by the roasting process of toxin added to green coffee, further study on this topic has been discontinued.
High Performance Liquid Chroma tographic Analysis of Dicofol Acaricide
Authors: Rothman Alan M
Published: February 2020

Kelthane Technical, a dicofol acaricide marketed by Rohm and Haas Co., and 18 impurity components can be resolved by a new reverse phase high performance liquid chromatographic (HPLC) method using a methanol-water-acetic acid (75+25+0.2) mobile phase, a high resolution C8 column in series with a short Cl8 s guard column, and detection at 254 nm. Relative elution volumes: and relative sensitivities for all known Kelthane Technical components are reported. This HPLC method has few co-elution problems, can be performed on a basic HPLC system, avoids the thermal degradation of Kelthane experienced in the previously established gas-liquid chromatographic (GLC) procedures, and can detect all impurity components to at least 0.1% level.
Quickfit Florisil Pesticide Trap for Use with Assisted Distillation Technique
Authors: Mcdougall Kerryn W
Published: February 2020

A quickfit Florisil pesticide trap is described for use with the assisted distillation technique for the cleanup of pesticide residues in fats. Recoveries of 80–100% were obtained for 9 pesticides. No cooling is needed and there is no measurable carryover of fat from this Florisil trap.