bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Azulene as Visual Aid to Monitor Column Chromatographic Fractionation of Samples for Pesticide and Polychlorinated Biphenyl Determination
Authors: Nowicki Henry G
Published: February 2020

Environmental samples are cleaned up by Florisil column chromatography, using azulene as a visual aid to monitor column performance. Azulene migrates as a blue band in the 6% ethyl ether-hexane fraction, and the gas chromatograph electron capture detector (GC-ECD) is nonresponsive at the use concentration. This method complements the standardization of Florisil columns by weight adjustment based on adsorption of lauric acid. Spiking of sample with azulene provides a convenient real-time monitor for column channeling, mistakes in polarity of mobile phases, particular sample composition, column overloading, and dynamic changes in the adsorptivity of the stationary phase between lauric acid calibration and use. Using this visual aid, the analyst is alerted to unexpected column behaviors. Normally, polychlorinated biphenyls (PCBs) elute in the 6% fraction, in front of the blue indicator. Experiences with azulene and industrial effluent samples demonstrated that PCBs can elute in the 100% hexane fraction. GC-ECD analysis of the hexane eluate revealed a PCB characteristic chromatogram, not observed with the original extract. Thus, monitoring column performance avoided reporting a false negative result, i.e., no PCBs in the 6% ethyl ether-hexane fraction.
Comparison of Larval Stored Product Beetle Mandibles by Light Microscope and Scanning Electron Microscope
Authors: Kvenberg John E
Published: February 2020

Larval stored product beetle mandibles were studied by comparing images made by scanning electron microscopy with those made by conventional light microscopy. Discussion of morphological characteristics is based on illustrations of 25 species
High Pressure Liquid Chromatographic Determination of Cholesterol in Foods
Authors: Newkirk David R , Sheppard Alan J
Published: February 2020

A high pressure liquid chromatographic method that uses the benzoate ester of cholesterol has been developed for the measurement of cholesterol in foods. A 300 × 3.9 mm id μBondapak C18 column and a variable wavelength ultraviolet detector are used with a 100% methanol mobile phase. Amounts as low as 10 ng cholesterol benzoate can be detected. The results from the analyses of a variety of foods are given and compared with results from gas-liquid chromatographic analyses. The comparison of the 2 chromatographic techniques is favorable.
Extraction and Cleanup of Fish, Sediment, and Water for Determination of Triaryl Phosphates by Gas-Liquid Chromatography
Authors: Muir Derek C G , Grift Norbert P , Solomon John
Published: February 2020

Several techniques were evaluated for extracting triphenyl phosphate (TPP), 14C-labeled TPP, cresyl diphenyl phosphate, and tricresyl phosphate isomers (o-TCP, m-TCP, and p-TCP) from fish and sediment samples. Extracts of fish samples were cleaned up by gel permeation chromatography/alumina column chromatography; sediment extracts received alumina treatment only. Compounds were determined by gas-liquid chromatography (GLC) with nitrogenphosphorus detection. Methanol/Polytron and hexane/ball mill extraction of fish samples fortified at 0.01, 0.1, and 1.0 μg/g levels gave overall recoveries of the 5 compounds of 89 and 97%, respectively. Methanol recovered more radioactivity (97%) from fish exposed to 14C-TPP in aquaria for 24 h than did hexane from fish exposed for 16 h (79%). Refluxing fortified sediment (0.05 and 0.5 μg/g) with methanol-water (9+1) gave significantly higher recoveries (88%) of the 5 triaryl phosphates than did dichloromethane-methanol (1+1) reflux or acetone-hexane (1+1) Soxhlet extraction. Recoveries of TPP and o-, m- and p-TCP from fortified river water (0.5, 5.0, and 50 μg/L) by shaking with dichloromethane ranged from 91 to 118%. Some problems were encountered with interfering GLC peaks at low (μg/g) levels in fish and sediment extracts despite the use of nitrogen-phosphorus specific detectors.
Headspace Sampling and Gas-Solid Chromatographic Determination of Residual Acrylonitrile in Acrylonitrile Copolymer Solutions
Authors: Mcneal Timothy , Breder Charles V
Published: February 2020

A screening procedure, using manual headspace sampling and gas-solid chromatography, is described for the determination of residual acrylonitrile (RAN) in acrylonitrile-based copolymers. The polymers are dissolved in dimethylsulfoxide; the resulting solutions are equilibrated in a closed container at 90°C, and headspace aliquots are injected into a gas chromatograph. A nitrogen-phosphorus selective detector and the method of standard additions are used for quantitation. RAN is measured down to 70 ppb (polymer basis) with a standard deviation of 7%. Polymers analyzed by this method had RAN levels from 0.07 to 23.9 ppm.
Gas Chromatographic Determination of Propionic Acid in Bread and Cake
Authors: Isshiki Kenji , Tsumura Shusaku , Watanabe Tadao
Published: February 2020

A simple and accurate method is presented for gasliquid chromatographic (GLC) determination of propionic acid in bakery products. Propionic acid is extracted with a mixture of dichloromethane and formic acid to which isobutyric acid has been added as an internal standard. The extract is injected directly into the GLC system. A glass column packed with 5% SP-1000 is used. The simplicity and convenience of the method make it suitable for routine determination.
Use of Sunlight to Partially Detoxify Groundnut (Peanut) Cake Flour and Casein Contaminated with Aflatoxin B1
Authors: Shantha Thimmappaji , Murthy Venkateshaiah Sreenivasa
Published: February 2020

Sunlight destroyed 83 and 50% of the toxin added to casein and groundnut cake flour, respectively. Equilibrium dialysis revealed that both casein and groundnut protein bind aflatoxin but the toxin bound to casein appeared more photo-labile than that bound to groundnut protein.
High Performance Liquid Chromatographic Method Using Fluorescence Detection for Quantitative Analysis of Zearalenone and α-Zearalenol in Blood Plasma
Authors: Trenholm H Locksley , Warner Robert M , Farnworth Edward R
Published: February 2020

A sensitive, high performance liquid chromatographic method is described for quantitative determination of zearalenone and α-zearalenol in blood plasma. Blood plasma is extracted with 2-propanol in ether, the extract is evaporated to dryness, and the residue is dissolved in 0.18N NaOH. The aqueous phase is washed with chloroform, dichloromethane, and benzene, neutralized with 0.10M H3PO4, and extracted with benzene. The extract is evaporated, dissolved in methanol, and injected onto a reverse phase column containing LiChrosorb RP-8 under the following conditions: methanol-acetonitrile-water mobile phase, fluorescence detector, excitation wavelength 236 nm, and 418 nm cut-off emission filter. The limit of detectability (twice background) is 0.5 ng standard which is equivalent to 0.6 ng standard/mL blood plasma. Linear standard curves are observed over the range of 0-35 ng of injected zearalenone and α-zearalenol. The recoveries from blood plasma are 76-101% in the range of 1.5-6.0 ng standard/mL blood.
Turbidimetric Assay for Virginiamycin in Feeds and Premixes
Authors: Mueller-Brennecke Dorothy , Reed Shirley J , Barkate John A
Published: February 2020

A turbidimetric assay method applicable to virginiamycin at levels ranging from 5 g/ton in feeds to 50% inapremix is described. Incubation period is 4 h. Test organism is Streptococcus faecium ATCC 8043. On 6 levels of feed-grade material, the overall mean recovery was 95.4%, and the relative standard deviation (RSD) was 6.75%. Standard recovery studies resulted in RSD values ranging from 2.01 to 3.88% and a mean standard recovery of 100%.
High Pressure Liquid Chromatographic Determination of Phenol in Honey
Authors: Sporns Peter
Published: February 2020

A method is described for determining phenol in honey by using high pressure liquid chromatography (HPLC). An internal standard, 2-phenylethanol, was added to honey which was steam-distilled and chromatographed on a 25 cm × 3.2 mm id Spherisorb 5 µm silicic acid column using water as the mobile phase. Absorbance was monitored at 195 nm. Using a mixed standard of known concentration and peak height measurements, the amount of phenol in the honey could be quantitated. Recovery of added phenol was checked at levels from 0.1 to 33 ppm.
Determination of Color Intensity of Whisky and Other Alcoholic Products
Authors: Strunk Duane H , Timmel Bertha M , Hamman Jack W , Andreasen Arthur A
Published: February 2020

A comparison is presented of color intensity values of aged and caramel-colored distilled alcoholic products obtained with spectrophotometers and colorimeters operated at different wavelengths. Absorbances measured by a narrow (≤1 nm) and an 8 nm bandwidth spectrophotometer at 430,525, and 610 nm are compared. Colorimeters evaluated include the Klett-Summerson equipped with Nos. 42, 54, and 60 regular filters and 520, 540, and 560 nm narrow bandpass filters and a Coleman Nepho-Colorimeter, equipped with a 525 nm filter. A conversion chart can be used to convert colorimeter units to absorbance units. The procedure suggested uses an instrument with a bandwidth ≤10 nm at a wavelength of 525 nm; results are reported in absorbance units.
Ultraviolet Detection Procedure for Liquid Chromatographic Determination of Indole in Shrimp
Authors: Chambers Theodore L , Staruszkiewicz Walter F
Published: February 2020

In an ultraviolet detection procedure, indole was extracted from shrimp by blending with carbonate buffer and then partitioned into ethyl acetate. Before quantitation by high pressure liquid chromatography (HPLC), interferences were removed by the use of a polyamide cleanup column. Concentrated column effluent was injected into the chromatograph. Indole was detected by monitoring absorbance at 217 nm and quantitated by comparison of indole peak height to that of an internal standard, 2-methylindole. Recoveries of indole ranged from 72 to 117%. Results agreed well with those by the official AOAC gasliquid chromatographic (GLC) method.
Comparison of Manual and Benzenesulfonyl Chloride-Semiautomated Thiochrome Methods for Determination of Thiamine in Foods
Authors: Soliman Abdel-Gawad M
Published: February 2020

A semiautomated procedure was used to measure the fluorescence of sample extracts before and after the addition of benzenesulfonyl chloride (BSC). Addition of BSC inhibited thiochrome formation and provided a more representative blank based on the fluorescence of all the reactants except thiochrome. Thiamine standard was added to each sample extract so that thiamine concentration could be calculated after correcting for sample matrix effects on thiochrome fluorescence. Twenty food products were analyzed using this method, and the results were compared with those obtained using the manual AOAC method. The mean percent recoveries and standard deviations were 100.2 ± 5.3 and 101.1 ± 10.1 for the BSC-semiautomated and the AOAC manual methods, respectively. Replicate analyses using the BSC method gave an average coefficient of variation of 2.8%. Linear regression analysis showed that the BSC method gave higher values, with a mean increase of 14.8%, than those obtained using the manual method. Sixty-four percent of this difference was due to elimination of the column purification step and 36% was due to correcting for sample matrix effects on thiochrome and blank fluorescence. The BSC method provides a rapid, accurate, and reproducible method for thiamine assay in different food products, especially for those foods with low thiamine levels.
High Pressure Liquid Chromatographic Determination of Melengestrol Acetate in Dry Feed Supplements
Authors: Roybal Jose E
Published: February 2020

A high pressure liquid chromatographic (HPLC) method is described for the quantitative determination of melengestrol acetate (MGA) in dry animal feed supplements containing 0.000027-0.000220% MGA (0.125-1.00 mg/lb). Ground feed is Soxhletextracted with hexane, and the extract is partitioned from hexane into aqueous methanol and then into methylene chloride, followed by mixed column chromatography. MGA is then quantitated by HPLC. Average recovery of standard MGA through the method at 1.00 ppm (0.454 mg/lb).was 94.8% with a 3.58% standard deviation. Average spike recovery of MGA in fortified feed at 0.100 ppm (0.0454 mg/lb) to 2.00 ppm (0.907 mg/lb) level was 97.8% with a standard deviation of 5.39%. In addition, the method includes a 2-dimensional thin layer chromatographic confirmatory test for MGA.
Effect of Boiling, Frying, and Baking on Recovery of Aflatoxin from Naturally Contaminated Corn Grits or Cornmeal
Authors: Stoloff Leonard , Trucksess Mary W
Published: February 2020

Corn grits naturally contaminated with aflatoxins were used for making boiled grits, and portions of the boiled grits were used for making pan-fried grits; cornmeal naturally contaminated with aflatoxins was used for making corn muffins. Procedures and recipes were derived from cookbook and market package recommendations. From analyses of the products for aflatoxins before and after preparation of the table-ready products, it was determined that 72±9% (n = 15) of the aflatoxin found in the original grits could be recovered after the grits were boiled. The recovery of aflatoxin B1 after the grits were fried was either 66±10% (n = 6) or 47±8% (n = 9), depending on whether 3 cups of water or 4 cups of water per cup of grits, respectively, were used for preparing the boiled grits before frying. Similarly, it was determined that 87±4% (n = 9) of the aflatoxin B1 found in the original cornmeal could be recovered from the baked muffins. No detectable aflatoxin B2a was present in the extracts from any of the table-ready products.
Gas-Liquid Chromatographic Determination of Hexestrol Residues in Adipose Tissue
Authors: Tobioka Hisaya , Kawashima Ryoji
Published: February 2020

A gas-liquid chromatographic (GLC) method is described for determining hexestrol residues in adipose tissue. The extraction and purification procedures were based on a published method for determining diethylstilbestrol. To increase precision and sensi-(ivy, the sample was further cleaned up by silica gel column chromatography. The heptafluorobutyric (HFB) derivative of hexestrol was used for GLC analysis with HFB-docosanol as an internal standard. A variety of acetone-benzene mixtures were compared to determine the optimum ratio for hexestrol acylation. Acetone-benzene (90 + 10) or 100% acetone provided 16% higher GLC response than did a 50 – 50 mixture (P <0.001) and was selected for use in the acylation procedure. A system for evaporating excess reagents was also studied. Overall percent recovery reached 72 ± 5. The method can be used to determine residual hexestrol at the 0.1 ppb level.
Modified Storherr Method for Determination of Organophosphorus Pesticides in Nonfatty Food Total Diet Composites
Authors: Carson Louis J
Published: February 2020

The method of Storherr et al. for organophosphorus pesticide residues in nonfatty foods has been modified to permit its use in analyzing the composites of nonfatty foods in the Food and Drug Administration Total Diet Program. Modifications were designed to permit the examination by gas-liquid chromatography (GLC) of the larger weight (100 mg) of sample equivalent required by the Total Diet program. To achieve a limit of quantitation of 2 ppb parathion, the organophosphorus pesticides are determined by GLC equipped with flame photometric detector (P-mode) and/or KCl thermionic detector. Recovery data, ranging from 70 to 133%, are presented for fortification (2-10 ppb) of organophosphorus pesticides in 7 nonfatty food Total Diet composites. The modified Storherr method was successfully tested in an intralaboratory method trial of 2 Total Diet composites (potatoes and legumes) fortified at 5-13 ppb with malathion, parathion, paraoxon, and monocrotophos. In addition, the modified Storherr method was compared to existing FDA Total Diet methodology for the determination of incurred organophosphorus residues. Residue levels found by both methods were similar for malathion (30 ppb), parathion (7 ppb), and diazinon (1 ppb), but only the modified Storherr method was capable of determining about 10 ppb dimethoate and phorate in the cereals and grains composite.
Gel Permeation System for Removal of Fats During Analysis of Foods for Residues of Pesticides and Herbicides
Authors: Hopper Marvin L
Published: February 2020

A gel permeation chromatography system has been developed for the rapid cleanup of fatty foods in the analysis for pesticide residues. The narrow elution bands of fats and pesticides coupled with the ease of evaporating the eluting solvent makes this system efficient because of the savings in time and solvents. This system allows a wide range of compounds including organochlorine pesticides, organophosphorus pesticides, industrial chemicals, herbicides, carbamates, and drugs to elute in the cleaned-up fraction.
General Method for Determination of Pesticide Residues in Samples of Plant Origin, Soil, and Water. III. Gas Chromatographic Analysis and Confirmation
Authors: Ambrus Árpád , Visi Éva , Zakar Ferenc , Hargitai Éva , Szabó László , Pápa Ágoston
Published: February 2020

Gas-liquid chromatography is widely used in pesticide residue analysis, and numerous packings of various polarity are recommended. We selected OV-22, OV-101, NPGS, SE-30 (3% on Gas-Chrom Q), and 1.95% SP-2401/1.5% SP-2250 on Supelcoport as basic packings. Relative retention times for aldrin and parathion-methyl were determined at 140,160, 180, or 200°C and during temperature programming. OV-22 and OV-101 were most suitable for general purposes. A study on the performance of thermionic delectors suggested that their performance can be characterized and should be regularly controlled with test substances containing different hetero elements. Columns as short as 45-90 cm were suitable for screening purposes, and their advantages over traditional long columns are demonstrated. The fractionation of pesticides in an extract on silica gel columns was effective and practical for the confirmation of pesticides.
Gas-Liquid Chromatographic Determination of Aniline Metabolites of Substituted Urea and Carbamate Herbicides in Aqueous Solution
Authors: Hargesheimer Erika E , Coutts Ronald T , Pasutto Franco M
Published: February 2020

A simple gas-liquid chromatographic (GLC) method has been developed which provides sensitivity and specificity for the analysis of complex mixtures of the commonly occurring herbicide metabolites aniline, 3-chloroaniline, 4-chloroaniline, 4-bromoaniline, and 3-chloro-4-methylaniline. All of these anilines react with acetic anhydride directly in basified aqueous solution. Further reaction of the acetylated anilines with trifluoroacetic anhydride gave diacyl derivatives which were readily resolved by gas chromatography. The structures of the N-acetylated and IV-trifluoroacetylated derivatives of benzylamine (internal standard) and the anilines were confirmed by GLC-mass spectrometry. In distilled water the minimum detectable concentrations of aniline and the substituted anilines, using electron capture GLC, are 0.1 nmole/100 mL and 0.05 nmole/100 mL, respectively. The detection limit for the anilines is 1 nmole/100 ml distilled water, using GLC with flame ionization detection. The technique was applied to the determination of anilines added to urine samples obtained from the general population.
Bromination Methods for Determination of Phenylephrine Hydrochloride in Nose Drops, Salicylamide in Tablets, and Tetracycline Hydrochloride in Capsules
Authors: Elsayed M Abdel-Hady , Obiakara A Christian , Uzodinma S Uchenna
Published: February 2020

Two methods, kinetic and titrimetric, based on an electrophilic substitution reaction with bromine, are described for the assay of phenylephrine hydrochloride in nose drops, salicylamide in tablets, and tetracycline hydrochloride in capsules. The kinetic method depends on the linear relationship between concentration of the drug (μg/mL) and time (s) for nuclear monobromination, indicated by bleaching of the methyl orange acid color. The titrimetric method is based on addition of excess of bromatebromide with subsequent determination of excess bromine by an iodide-thiosulfate procedure. This method is also used to count the number of bromine atoms necessary for the electrophilic substitution reaction. Preservatives or tablet/capsule bases do not interfere in either method. Recoveries of drugs added to laboratory-prepared samples were good. As indicated by the F-test, the methods are equally reproducible.
High Performance Liquid Chromatographic Determination of Clotrimazole in Pharmaceutical Formulations
Authors: Hoogerheide John G , Strusiak Suzanne H , Taddei Carlo R , Townley Edward R , Wyka Bruce E
Published: February 2020

A simple stability-indicating high performance liquid chromatographic (HPLC) method has been developed which separates clotrimazole from impurities and decomposition products in bulk drugs, creams, tablets, and solutions. Average recovery data for drug substance added to placebos were: tablet, 99.8%; solution, 99.5%; and cream, 100.0%. Average reproducibilities (RSD) on drug substance and formulations were: drug substance, 1.3%; tablets, 1.8%; solutions, 1.1%; and creams, 0.6%. HPLC assay results for both fresh and degraded samples agree with USP XX titration assay results. The method allows for the simultaneous determination of (o-chlorophenyl)-diphenylmethanol hydrolysis product impurity.
High Performance Size Exclusion Chromatograph with Computerized Data Reduction for Analysis of Polyethylene and Oligomers
Authors: Snyder Roger C , Breder Charles V
Published: February 2020

A liquid chromatograph is described for the size exclusion chromatography (SEC) of polyethylene and oligomers. The rigid column packing material was 10 µm diameter porous silica. An infrared spectrophotometer was used as the detector. The chromatograph was designed and operated to minimize the degree of chromatographic peak shape distortion resulting from factors such as system dead volume, detector cell design, sample injection volume, and sample concentration. To compensate for peak spreading and skewing, the chromatographic data were analyzed with an IBM 370/168 computer using an APL program. The molecular weight range covered by this SEC system was 100-500 000. Precision and accuracy of Jhe calculated weight average molecular weight (Mw) values for polyethylene standards over this range were ±3 and s±4%, respectively.
Thin Layer Chromatographic Determination of Aflatoxin in Corn Dust
Authors: Shotwell Odette L , Burg William R , Diller Thomas
Published: February 2020

Methods adopted by the AOAC and the American Association of Cereal Chemists for determining aflatoxin in corn were modified, and techniques were developed for application to samples of <1 to 10 g instead of the specified 50 g samples. Analysis included chloroform extraction of dust samples or dust collected from glass fiber filters, purification of extracts on a silica gel column of appropriate size, and measurement of aflatoxin by either 1- or 2-dimensional thin layer chromatography (TLC). The solvent for 1-dimensional TLC was chloroform-acetonewater (91 + 9 + 1). Solvents for 2-dimensional TLC were, first direction, ether-methanol-water (95 + 4 + 1, lined tank) and second direction, chloroformacetone- water (91 + 9 + 1, unlined tank), or first direction, chloroform-acetone-water (91 + 9 + 1, unlined tank) and second direction, toluene-ethyl acetate- formic acid (60 + 30 + 10, unlined tank). When samples weighed ≤0.1 g, the entire concentrated extract was applied to the TLC plate. About 0.5-1.0 ng aflatoxin B1 could be detected on the plate, making the limit of detection about 9 ng/g for 0.1 g samples.
High Performance Liquid Chromatographic Determination of Furazolidone in Feed and Feed Premixes
Authors: Smallidge Robert L , Rowe Norman W , Wadgaonkar Nandan D , Stringham Rodger W
Published: February 2020

Furazolidone is separated from finished feeds by acetone-water extraction on a Goldfisch apparatus. Extracting solvent is removed, and the residue is dissolved in dimethylformamide-5% tetraethylammonium bromide (1 + 1), clarified, and chromatographed on a reverse phase C18 column. The mobile phase is CH3CN-2% acetic acid (20 + 80) with detection at 365 nm. The method was tested for linearity, recovery, and ruggedness, and compared with the AOAC colorimetric assay by using field samples containing 0.0055-0.055% furazolidone. Precision data suggest a cumulative relative standard deviation of 1.43% within days and 1.78% between days. The ruggedness test predicts a between-laboratory relative standard deviation of 3.67%. Recovery was 97.5 ± 2.0% and linearity was excellent (r2 = 0.9994) up to 0.06% furazolidone. Premixes are extracted by shaking with dimethylformamide. An aliquot of the extract is diluted (1 + 1) with 5% tetraethylammonium bromide, clarified, and chromatographed.
Neutron Activation Analysis of Total Diet Food Composites for Iodine
Authors: Allegrini Massimo , Boyer Kenneth W , Tanner James T
Published: February 2020

The iodine content of Total Diet food composites was measured using neutron activation analysis. The interfering element chlorine was separated using a modified combustion and gas phase procedure. The average recovery was 94.8% (standard deviation 2.9) for the 10 matrices that were tested. In addition, iodine was measured in National Bureau of Standards Standard Reference Materials, which have no certified values for this element. Preliminary findings ofiodine content of adult Total Diet market baskets collected during Fiscal Year 1980 in different regions of the United States ranged from 292 to 901 μg/day for a 2900 kcal intake.
Interlaboratory Evaluation of the AOAC Method and the A-l Procedure for Recovery of Fecal Coliforms from Foods
Authors: Andrews Wallace H , Wilson Clyde R , Poelma Paul L , Bullock Linda K , Mcclure Foster D , Gentile Dorothy E
Published: February 2020

An interlaboratory evaluation was made of the 96 h AOAC method and the 24 h A-l procedure for the enumeration of fecal coliforms in samples of yellow corn meal, rye flour, mung beans, raw ground beef, and raw oyster homogenate. Results indicated that the efficiency of the A-l procedure, measured in terms of recovery of fecal coliforms, and the reproducibility of that recovery were dependent on the particular food being analyzed. Accordingly, until its efficiency can be more fully demonstrated, the A-l procedure is recommended only as a screening procedure for fecal coliforms in foods.
Temperature-Programmed Gas Chromatographic Determination of Polychlorinated and Polybrominated Biphenyls in Serum
Authors: Needham Larry L , Burse Virlyn W , Price Harold A
Published: February 2020

An analytical method was developed to quantitate polychlorinated and polybrominated biphenyls (PCBs and PBBs, respectively) in human serum. The method includes denaturation of the proteins in serum, extraction, adsorption chromatography, and gas chromatography with electron capture detection. The coefficients of variation for determining the in vivo bound PCBs and PBBs ranged from 11.7 to 29.8% and 7.1 to 14.0%, respectively. The method is capable of measuring 10 ng PCBs and PBBs/mL in 4 mL serum.
Liquid Scintillation Counting of 14C for Differentiation of Synthetic Ethanol from Ethanol of Fermentation
Authors: Martin Glenn E , Noakes John E , Alfonso Felipe C , Figert Donald M
Published: February 2020

Samples containing ethanol are fractionated on a column so that the resultant ethanol content is >93%. Determination of 14C by liquid scintillation counting on the ethanol fraction differentiates ethanol produced by fermentation from synthetic ethanol produced from fossil fuel sources. Twenty-seven samples were fractionated and analyzed for the 14C isotope. Six samples were synthetic ethanol derived from ethylene gas (direct and indirect process), and yielded a mean value for 14C isotope of 0.167 dpm/g carbon with a standard deviation (SD) of 0.066 dpm/g carbon (disintegrations per minute per gram of carbon). The remaining samples were ethanol derived from the fermentation of natural materials, such as corn, pear, sugar cane, grape, cherry, and blackberry, and yielded a mean value for 14C isotope of 16.11 dpm/g carbon with an SD of 1.27. The 14C values for specific mixtures of a synthetic and a natural ethanol compare favorably with the analytical values obtained by this procedure.
Colorimetric Method for Determination of Ethanol in Presence of Methanol
Authors: Sane Ramesh T , Kamat Sudhir S , Pandit Amulya D
Published: February 2020

A method is described for the determination of ethanol in the presence of methanol without pre-separation. The sample is oxidized to give acetaldehyde and formaldehyde. 2-Thiobarbituric acid reagent is added and selectively forms a pink adduct with acetaldehyde, but not with formaldehyde. The method is sensitive, obeys Beer’s law in the concentration range 18–80 μg/mL, and has an advantage over other methods because it does not detect any “apparent normal value” of alcohol in blood.
Simultaneous Electron Capture Detection of Chlorpyrifos and Its Major Metabolite, 3,5,6-Trichloro-2-Pyridinol, after Gel Permeation Chromatography
Authors: Guinivan Richard A , Thompson Neal P , Bardalaye Promode C
Published: February 2020

Preparative gel permeation chromatography of ethyl acetate extracts of Southern Pea vines precedes the simultaneous quantitation by electron capture gas chromatography of chlorpyrifos [0,0-diethyl O- (3,5,6-trichloro-2-pyridyl)-phosphorothioate] and its major metabolite 3,5,6-trichloro-2-pyridinol, which is analyzed as its iV,0-bis(trimethylsilyl)acetamide derivative. The dark green extract of a pea vine sample (spiked with both the pesticide and its metabolite) is concentrated and chromatographed on a Bio-Beads S-X3 column. Fractions are monitored for cleanup effectiveness by measuring the absorbance at 490 nm and also by gas chromatographic analysis for chlorpyrifos and 3,5,6-trichloro-2-pyridinol recovery. Results showed that the pesticide and its metabolite are separated from the bulk of optically absorbent compounds. Recoveries from 25 g spiked pea vine samples, cleaned up on the Bio-Beads column, are 100% at levels of 0.2 ppm (5 μg) and above, and 62% at levels ranging from 0.01 (0.25 μg) to 0.2 ppm. This analytical procedure provides a fast, sensitive method for simultaneous quantitation of these compounds which were previously determined by 2 separate procedures.
Extraction of Aquatic Herbicide Fluridone from Water and Determination by High Pressure Liquid Chromatography
Authors: West Sheldon D , Day Edgar W
Published: February 2020

Fluridone is extracted from water onto a Sep-Pak C18 cartridge, and then eluted with a small volume of methanol. Fluridone is concentrated and then is measured by reverse phase high pressure liquid chromatography with UV detection at 254 nm. The method is sensitive to approximately 0.001 ppm and has resulted in recoveries averaging 103.1 ± 19.4,94.8 ± 5.9, and 93.5 ± 8.5% for control water fortified with 0.001, 0.010, and 0.100 ppm (μg/mL) fluridone, respectively.
High Performance Liquid Chromatographic Determination of Cyanuric Acid in Human Urine and Pool Water
Authors: Briggle Thomas V , Allen Larry M , Duncan Robert C , Pfaffenberger Carl D
Published: February 2020

A reverse phase high performance liquid chromatographic (HPLC) assay for the quantitative determination of cyanuric acid (CA) in urine and water is described. For purification, samples are passed through a pre-activated reverse phase C18 column. The effluent is dried by lyophilization, and the residue is reconstituted in hexane-washed water and then passed through a prewashed Dowex-1 column. The effluent is again dried by lyophilization, and the dry residue is extracted with hot dioxane. The solution is cooled to ambient temperature and centrifuged. The supernatant liquid is removed, dried under a nitrogen steam, and dissolved in water for final extraction by reverse phase chromatography. This effluent is dried, dissolved in the sodium phosphate monohydrate in methanol (pH 7.0) mobile phase, and injected into a pre-equilibrated chromatographic system. An external standard is used for quantification by peak height comparison. A sample of HPLC column effluent is collected, dried, dissolved in methanol, and used for mass spectrometric confirmation by a solid probe insert procedure. Average combined recovery determined at 1.0, 5.0 and 10.0 μg CA/mL is 103 ± 3% with an average coefficient of variation of 8.6%. Standard deviations for the 3 concentration levels are 0.04, 0.58, and 0.76, respectively, with average precisions of 4.28, 10.92, and 7.61%. The limits of detection are approximately 0.05 μg/mL for urine and 0.1 μg/mL for swimming pool water. Recorder response to CA is linear over the concentration range 1-10 μg/mL.
Gas Chromatographic/Mass Spectrometric Study of Isoequilin A
Authors: Roman Robin , Yates Claire H , Millar John F , Vandenheuvel William J A
Published: February 2020

Isoequilin A, which is produced by the acid-induced isomerization of equilin, has been resolved into 3 major components by gas chromatography. Tentative identification of the 3 compounds was made by using combined gas chromatography/mass spectroscopy. One of these compounds, identified as 8-dehydroestrone, closely resembled a component previously identified in pregnant mares’ urine.
Atomic Absorption Spectrometric Determination of Tin in Canned Foods Using Nitric Acid-Hydrochloric Acid Digestion and Nitrous Oxide-Acetylene Flame
Authors: Dabeka Robert W , Mckenzie Arthur D
Published: February 2020

Foods (5-40 g) are digested sequentially with HNO3 and HC1, diluted to 100 mL, and filtered, and tin is determined by atomic absorption using an N2O-C2H2 flame. Synthetic standards in 10% HC1 are used. A positive interference by potassium is compensated by adding 100 µg potassium/mL to both standards and samples. Recoveries for 17 foods spiked with tin at levels between 40 and 500 µg/g ranged from 85 to 110% with a mean of 101%. Results agreed well with a solvent extraction atomic absorption method and a direct X-ray fluorescence method.
Simple Paper and Micro Thin Layer Chromatographic Method for Separation and Detection of Mercuric Chloride, Copper Sulfate, Cadmium Sulfate, and Silver Nitrate in Fresh Water
Authors: Devi Yalavarthy Prameela , Kumar Nanguneri V Nanda
Published: February 2020

Simple concentration techniques are described for delecting heavy metals in water. Copper sulfate and cadmium sulfate are precipitated with alkaline' phosphate buffer (pH 8.2); mercuric chloride and silver nitrate are concentrated through evaporation. Compounds redissolved in citric acid are suitable for paper and micro thin layer chromatographic-enzymatic separation by a 0.1% NaCl solvent system. The heavy metal compounds can be detected by horse liver acetone powder succinate dehydrogenase inhibition, using 2-(4-iodophenyl-3-(4-nitrophenyl)-5-phenyltetrazolium chloride (INT)-sodium succinate-N-methyl phenazonium methosulfate mixture as the chromogenic reagent. Microgram amounts of Cu, Ag, Hg, and Cd can be separated and identified by using this method.
Microwave Oven Drying in the Gravimetric Phosphorus Method
Authors: Melton James R , Hoover William L
Published: February 2020

The gravimetric quinolinium molybdophosphate method for determining P2O5 in fertilizers, AOAC 2.026–2.028, has been modified to permit the precipitate to be dried in a microwave oven rather than a conventional drying oven. After the yellow quinolinium molybdophosphate precipitate is formed, cleaned up, and washed, it is placed in a microwave oven at 600 watts until dry. The quantity of precipitate remaining after microwave drying was equal to that obtained by drying according to AOAC 2.028 for several fertilizer samples. A distinct advantage of the described method is that the yellow precipitate will not char with reasonably excessive drying. Also, much less energy is expended with the microwave oven than with the drying oven.
Data Handler/Controller System with Application to P2O5 and K2O in Fertilizers
Authors: Kane Peter F , Bennett Brian R , Gulik Stefan
Published: February 2020

An automated data handler/controller system performs 2 main functions: As a data handler, it finds peak maxima, does standard curve fitting, performs peak height correction for drift, gain, and carryover, and does limited calculation of results with a printed record. It may also control modules of an analyzer system to allow both manual operation and completely automatic, unattended startup, operation, and shutdown. Such a system has 2 main advantages, and one disadvantage. The automatic control features extend the useful operational hours, and the data handling features make possible a level of sophistication above manual treatment of the data, with no computer expertise required. To achieve these ends, however, the flexibility that comes with control over software modification has been sacrificed. The ability to correct peak heights for drift, gain, and, particularly, carryover, allows a wider range of standards and/or faster sampling rates. In the phosphorus method, it was possible to eliminate much labor-intensive aliquoting of extracted samples by using a broader range of standards. Alternatively, if desired, the sampling rate could be increased from 40 to 60 per hour. With computer-corrected peak heights, either alternative is still more precise than the usual method without correction. For the potassium method, the maximum concentration is limited by the detector of the flame photometer and therefore the standard range cannot be significantly expanded. However, dramatic increases in sampling rate are possible with peak height correction. Data indicate that sampling rates can be increased from the usual 40–50 per hour up to 90 or possibly 120 per hour, with equivalent precision.
Systematic Identification of Antioxidants in Lards, Shortenings, and Vegetable Oils by Thin Layer Chromatography
Authors: Peteghem Carlos H Van , Dekeyser Diana A
Published: February 2020

A simple and reliable method is described for rapid identification of ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, ethoxyquin, gallates (lauryl, octyl, propyl), nordihydroguaiaretic acid, 3,3’-thiodipropionic acid, tocopherol, t-butylhydroquinone, and 2,4,5-trihydroxybutyrophenone in lards, shortenings, and vegetable oils. The antioxidants are extracted with 95% methanol, concentrated under vacuum at ≤45°C, and analyzed by thin layer chromatography. Three elution solvents, 2 adsorbent types, 2 visualization sprays, and UV viewing at 254 and 366 nm are used. Sunflower and corn oil samples, fortified with 100 ppm antioxidant, were analyzed to establish the validity of the method.
High Pressure Liquid Chromatographic Determination and Fluorescence Detection of Aflatoxins in Corn and Dairy Feeds
Authors: Cohen Huguette , Lapointe Michel
Published: February 2020

A high pressure liquid chromatographic (HPLC) method is described for the determination of aflatoxins B1, B2, G1, and G2 in animal feeds at levels as low as 2.5 ppb. Samples are extracted with acetonitrile-water and initially purified by using a Sep-Pak silica cartridge. The aflatoxins are then reacted with trifluoroacetic acid and acetonitrile-water (1 + 1). After filtration, the aflatoxins are completely resolved on a 10 μm C18 column using a radial compression separation system with an acetonitrile-water solvent system. Aflatoxins G2a, B2a, G2, and B2 were reported in less than 30 min, using fluorescence detection. The method was successfully applied to samples at levels of 20-2.5 ppb added aflatoxins with recoveries in the range of 82-99%.
Citrus Artifact Interference in Aflatoxin M1 Determination in Milk
Authors: Price Ralph L , Jorgensen Karen V , Billotte Michael
Published: February 2020

Dried citrus waste was fed to dairy cows, their milk was extracted, and aflatoxin M1 was quantitated by using both high pressure liquid chromatography (HPLC) and thin layer chromatography (TLC). Results indicate that a compound from the citrus waste, which is excreted into the milk, interferes with the HPLC determination of aflatoxin M1 in milk and causes a false positive test. This interference can be overcome by using TLC with proper selection of developing solvents.
Multicomponent Analysis of Meat Products
Authors: Bjarnø Ole-Christian
Published: February 2020

A new method for rapid multicomponent analysis of meat products is reported. The sample is homogenized, and then dispersed by treatment with an alkaline aqueous solution combined with mechanical subdivision. Constituents are determined by infrared transmission spectrophotometry in the fundamental IR absorption bands. It is possible to measure protein, fat, and carbohydrate in about 5 min with an accuracy and precision comparable to that of well established standard methods, and no expensive or dangerous chemicals are used.
Ion Pairing High Pressure Liquid Chromatographic Determination of Amaranth in Licorice Products
Authors: Hurst William J , Mckim James M , Martin Robert A
Published: February 2020

A high pressure liquid chromatographic method is described for the determination of amaranth (FD&C Red No. 2; Red No. 2) in licorice products. The Red No. 2 is extracted with a basic buffer solution, cleaned up on a Sep-Pak column, chromatographed on a reverse phase column in the ion pairing mode, and detected at 254 nm. The procedure is time-conservative with accurate and precise results. Recovery data ranged from 93 to 104%, and coefficients of variation were less than 4% for standards and samples.
Polarographic Analytical Study of Oxyphenbutazone
Authors: Ellaithy Moustafa M , El-Tarras M Fayez , Amer Sawsan M
Published: February 2020

The polarographic behavior of the widely used anti-inflammatory agent, oxyphenbutazone, was studied. It is determined polarographically by conversion to the nitroso derivative characterized by a cathodic, irreversible, diffusion-controlled wave. The method is applied to the determination of 2.5-10 mg/100 mL of oxyphenbutazone, with an accuracy of 99.9 ± 1.38%. By differential pulse polarographic analysis, as little as 10 ppm oxyphenbutazone can be determined with an accuracy of 99.70 ± 0.99% in pure powder and in some pharmaceutical formulations.
Colorimetric Determination of Certain Phenol Derivatives in Pharmaceutical Preparations
Authors: Hassan Sayed M , Walash Mohammed I , El-Sayed Sanaa M , Abou Ouf Abdel Malek
Published: February 2020

Simple colorimetric methods are reported for determining both acetaminophen and oxyphenbutazone. These methods are based on coupling between the phenolic compound and the diazonium salts of both sulfanilic acid and p-nitroaniline; the optimum conditions for the reactions were carefully studied. For acetaminophen, the reaction products with diazosulfanilic acid and diazo-p-nitroaniline show maximum absorbance at 480 and 425 nm, respectively. The mean percentage recoveries for authentic samples were 99.5 ± 1.1 and 100.6 ± 0.66, respectively (P = 0.05). For oxyphenbutazone, the obtained colors showed maxima at 385 nm with diazosulfanilic acid and 490 nm with diazo-p-nitroaniline reactions. The mean percentage recoveries for authentic samples were 99.8 ± 0.27 and 100.1 ± 0.57, respectively (P = 0.05). The proposed methods were successfully applied to the analysis of commercial preparations; results were statistically compared with those of other methods.
Determination and Confirmation of N-Nitrosodimethylamine in Beer
Authors: Andrzejewski Denis , Havery Donald C , Fazio Thomas
Published: February 2020

A qualitative method has been developed for the confirmation of N-nitrosodimethylamine (NDMA) in beer by capillary gas chromatography-mass spectrometry (GC/MS) from full mass scans after quantitation, using a gas chromatograph interfaced to a thermal energy analyzer (GC/TEA). The GC/MS method has a lower limit of confirmation of 5 ppb. In a survey of 22 imported and 42 domestic beers, NDMA was found in 60 samples by GC/TEA at levels up to 7.7 ppb, and was confirmed by GC/MS in 5 samples.
Gravimetric Determination of Ethoxylated Mono- and Diglycerides in Bread
Authors: Lawrence James F , Iyengar Jagannath R , Conacher Harry B S
Published: February 2020

A gravimetric method is described for the quantitative determination of ethoxylated mono- and diglycerides (EMGs) in bread at levels as low 0.42% (dry sample). The air-dried pulverized samples are Soxhlet-extracted 22 h with an azeotropic mixture of n-propanol-water. The contents are evaporated to dryness, and then treated with 5% HCl in methanol to trans-esterify the fatty acids present which are then removed by petroleum ether extraction. The EMGs are subsequently precipitated from aqueous solution with phosphomolybdic acid in the presence of barium ions. The precipitate is weighed and compared with known amounts of standard carried through the same procedure.
Fast Cleanup of Difficult Substrates for Determination of Fenitrothion and Some Derivatives
Authors: Haché Patrick , Marquette René , Volpé Gilles , Mallet Victorin N
Published: February 2020

A simple method is described for the fast recovery of fenitrothion, an organophosphorus insecticide, from soil, chicken liver, urine, clams, and pine needles. The substrate is homogenized with acetonitrile or methanol, diluted with water, and passed through a column containing Amberlite XAD-7. Fenitrothion is recovered quantitatively by eluting with 4 portions of 25 mL ethyl acetate. After evaporation, the compound is determined quantitatively by gas-liquid chromatography with a flame photometric detector. The procedure is also suitable for some derivatives of fenitrothion, namely, fenitrooxon and S-methylfenitrothion. As low as 0.05 ppm of the parent compound may be determined.
Sulfur Oxidation in Fertilizers using Nitric-Perchloric Acid
Authors: Melton James R , Hoover William L , Koska Janice , Anderson Wendy H
Published: February 2020

AOAC 2.160-2.161 is inadequate for determining total sulfur in fertilizers. The bromine-nitric acid combination does not oxidize all reduced forms of sulfur to sulfate; consequently, some findings are biased low. A perchloric-nitric acid mixture was used as the oxidizing mixture, and recovery of sulfur from 3 standards was complete. Also, quantitative results on fertilizer samples compared favorably with a potassium permanganate-nitric acid procedure that has been successfully used in the authors’ laboratory for about 16 years. The described method is recommended for determining all forms of sulfur found in fertilizers except elemental sulfur. A procedure is described for determining elemental sulfur.
Titrimetric Method With Ion Selective Electrode for Determination of Acetylenic Hypnotics
Authors: Rizk Mohamed S , Walash Mohamed I , El-Brashy Amina
Published: February 2020

An ion selective electrode has been used for indirect titrimetric assay of ethchlorvynol, ethinamate, and meparfynol carbamate. These acetylenic hypnotics form silver acetylide in the presence of excess silver. Excess silver is determined potentiometrically with standardized iodide solution and an iodide selective electrode. With this technique, 0.10-20 mg drug was determined with 95.7 ± 1.3-110.8 ± 5.9% accuracy. The procedure has been successfully applied to different pharmaceutical dosage forms.