Journal - Association of Official Analytical Chemists

Online ISSN: 0004-5756
Publications
Article
A new method for determining 1,1-dimethylhydrazine (UDMH) in peaches and apples is presented. The method consists of extraction with L-ascorbic acid, derivatization with 2-nitrobenzaldehyde to the corresponding hydrazone, and cleanup on an alumina column. The hydrazone derivative is determined by gas chromatography using an electron-capture detector. Recoveries were determined from 10 to 100 ppb. Stability of the UDMH residues on frozen peaches was investigated, and results indicate that the residues degrade even while frozen.
 
Article
The cis- and trans-isomers of 1,1,2,3,4-pentachloro-4-[1-methylethoxy]-1,3-butadiene have been identified as contaminants in fish caught from the Mississippi River at St. Louis, MO, and as far as 150 miles south of that location. Up to 0.1 ppm of the cis-isomer and 0.8 ppm of the trans-isomer were determined by using a method based on the AOAC multiresidue method for detecting organochlorine and organophosphorus pesticides. In tests of the modified AOAC method on spiked fish, both isomers were quantitatively recovered (95-106%). A mixture of the cis- and trans-isomers was synthesized by reacting hexachlorobutadiene with sodium isopropoxide. Separation of the reaction products by Florisil column chromatography provided reference standards of the individual isomers for identification and quantitation of the residues. The stereospecificity of the synthesis reaction and the infrared and mass spectral data used to verify the structures of the products are discussed.
 
Article
A simple and accurate spectrophotometric method has been developed for the determination of ascorbic acid in canned fruit juices, cordials, and soft drinks, based on the reduction of iron(III) by ascorbic acid to iron(II), which is then complexed with 1,10-phenanthroline. Background correction is necessary for most samples and can be achieved by copper(II)-catalyzed oxidation of the acid. The calibration graph was linear from 0 to 8 micrograms/mL of ascorbic acid with a slope of 0.12/ppm. The precision for the determination of ascorbic acid in a lemon drink containing 210 micrograms/mL of the acid was 0.9%. Many ingredients commonly found in fruit juices, cordials, and soft drinks do not interfere; however, tannic acid, pyrogallol, and sulfite interfere with the method. A wide range of samples was analyzed for ascorbic acid content by the proposed method. The samples included mango and lemon tea drinks and also grapefruit juices, for which no background correction is needed.
 
Article
The U.S. food supply was examined for pesticide residues during the 7-year period covering Fiscal Years (FY) 1970 through 1976. The results, which are contained in the report summarized here, are a continuation of an earlier report for the 6-year period FY 1964-1969.
 
Article
A semiquantitative method has been developed for the confirmation of vinyl chloride (VC) in foodstuffs. The VC was brominated to give 1-chloro-1,2-dibromoethane which was analyzed by gas-liquid chromatography, using an electron capture detector. The yield of 1-chloro-1,2-dibromoethane varied between 40 and 55%, which permitted a lower limit of confirmation of VC of 15 ppb for vinegar and sherry and 50 ppb for peanut oil.
 
Article
A method is described for the gas-liquid chromatographic determination of traces of selenium in marine biological materials. The method is based on the reaction of Se(IV) with bromo- and chloro-substituted 1,2-diaminobenzenes. The benzoselenadiazoles so formed are sensitive to electron capture detection. The sample is digested in a nitric-perchloric acid mixture and selenium is reduced to the IV oxidation state. Different aliquots of the digest solution are reacted with either 4-bromo- or 4-chloro-1,2-diaminobenzene to quantitatively form the corresponding 2,1,3-benzoselenadiazole. Recovery of added selenite to a fish meal sample was 95% for the bromo derivative and 101% for the chloro derivative. Different portions of a well mixed fish meal sample were analyzed in independent laboratories by the fluorometric method and by atomic absorption spectrophotometry (hydride generation). The following mean values (microgram/g) were found: present method 1.89, fluorometric method 1.91, atomic absorption method 2.1. The lower limit of detection for the method described was 13 ng, using the bromo derivative, and 27 ng, using the chloro derivative.
 
Article
A headspace gas chromatographic procedure has been developed for the determination of 1,3-butadiene in rubber-modified plastics and in some foods. Polymer solutions or foods are equilibrated in sealed vials at 90 degrees C, and headspace samples are injected into a gas chromatograph. 1,3-Butadiene residues are measured using a flame ionization detector and are quantitated by the method of standard additions or an external calibration curve. Refrigerator tubs, vegetable oil bottles, chewing gum, and foods in contact with this type of packaging were analyzed. Limits of quantitation varied with the matrix, ranging from 2 ng/g (ppb) in chewing gum to 20 ng/g in polymers. 1,3-Butadiene was found in one polymer at 53 ng/g with an 8% coefficient of variation. The procedure yields "apparent" trace levels of 1,3-butadiene, and confirmation by a complementary technique is required.
 
Article
Hexachloro-1,3-butadiene (HCBD), a waste product formed in the manufacture of perchloroethylene and trichloroethylene, has been found in fish from the lower Mississippi River basin. The AOAC official method for organochlorine pesticide residues in fatty and nonfatty foods has been modified for the determination of HCBD residues in selected food commodities. Acetonitrile extracts of nonfatty foods, or the combined acetonitrile extracts obtained in acetonitrile-petroleum ether partitioning of fat isolated from fatty foods, are diluted with water and extracted with petroleum ether. The petroleum ether extracts are chromatographed on Florisil and HCBD is eluted with petroleum ether. The elute is analyzed by gas-liquid chromatography with an electron capture detector. Average recoveries of HCBD from fortified samples of fatty and nonfatty foods were greater than 90% in the interlaboratory trials of the method.
 
Article
Borate was directly chelate-extracted from foods with 5% 2-ethyl-1,3-hexanediol (EHD) in n-hexane-n-butyl acetate mixture (8 + 2), from which borate was selectively transferred into 1% NaOH, since EHD-chelated boron did not react with curcumin to develop color. Finally, an aliquot of the alkaline solution was acidified with HCl and reacted with curcumin in a rotary evaporator. Color development was increased by heating for 8 min at 80 degrees C under reduced pressure of 16 mm Hg. Frozen shrimp and prawns (peeled and with shells) and salted jelly fish were analyzed by the proposed method. Results were compared with the contemporary official method of Japan based on curcumin reaction on an incinerated sample. Over 90% of the boric acid was recovered by the proposed method when samples were fortified with 20 ppm boric acid. Recoveries were superior to those of the official method especially for shrimp and prawns with shells and salted jelly fish. Detection limit of boric acid is 1 ppm. Moreover, the method requires only about 1 hr for analysis of one sample, making it suitable for routine analysis.
 
Article
A gas-liquid chromatographic (GLC) method for determining residues of the inseticide-acaricide Supracide (S-[5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)-methyl]O,O-dimethyl phosphorodithioate) and its monoxone metabolite in safflower seed, meal, and oil is presented. Supracide and its monoxone metabolite are separated by partitioning with acetonitrile-sodium sulfate and petroleum ether. The petroleum ether fraction containing the Supracide is extracted with acetonitrile and further cleaned up on Florisil column before determination by GLC, flame photometric detection (FPD). The monoxone metabolite is partitioned from the acetonitrile-sodium sulfate fraction with chloroform and cleaned up on a Florisil column before GLC/FPD. Average Supracide recoveries were 86, 82.5, and 92%, and average Supracide monoxone recoveries were 85.7, 81.5, and 89%, in seed, meal, and oil, respectively. The limit of detection was 0.005 ppm for both compounds on all tissues analyzed.
 
Article
Analytical methods are presented for routine determination of residues of unchanged Supracide (GS 13005; S-[(2-methoxy-5-oxo-Δ2-1,3,4-thiadiazolin-4-yl)methyl]-O,O-dimethyl phosphorodithioate), its oxygen analog (GS 13007), and 2-methoxy-5-oxo-Δ2-1,3,4-thiadiazolin (GS 12956) in different agricultural crops and soil. The unchanged insecticide is determined by gas chromatography, using both sodium thermionic and electrolytic conductivity detectors with a limit of detectability of 0.01 ppm. GS 13007 is detected on thin layer chromatographic plates by fly head cholinesterase inhibition and GS 12956 by silver nitrate with a detection limit of 0.01 ppm each. Average degradation curves from field trials are calculated statistically, and the penetration of GS 13005 into the meat and core of apples has been studied in field and laboratory experiments.
 
Article
A thin layer chromatographic method is presented for separating the reaction by-product 1,3,6-pyrenetrisulfonic acid (trisodium salt) (PTS) from D&C Green No. 8 (8-hydroxy-1,3,6-pyrenetrisulfonic acid). PTS is detected visually, extracted from the adsorbent, and determined spectrophotometrically. Recoveries of PTS added at 0.75-6.73% levels to 8-hydroxy-1,3,6-pyrenetrisulfonic acid ranged from 80.0 to 94.8%.
 
Article
The certifiable color D&C Green No. 5 and the formerly certifiable color External D&C Violet No. 2 may contain small quantities of the intermediate quinizarin, 1,4-dihydroxy-anthraquinone. The quinizarin is separated from the color by solvent extraction and is determined spectrophotometrically. Recoveries averaged 92 and 99% for D&C Green No. 5 and former External D&C Violet No. 2, respectively.
 
Article
Liquid chromatographic (LC) methods have been developed for the determination of carbamazepine, the impurity 10,11-dihydrocarbamazepine, and related compounds in carbamazepine drug substance and tablets. The LC methods specify a 5 micron diol column and a mobile phase of acetonitrile-methanol-0.05% aqueous acetic acid (5 + 5 + 90). Iminodibenzyl and iminostilbene, starting materials for some routes of synthesis, elute late in the LC system; therefore, a thin-layer chromatographic method for their detection at the 0.05% level has been developed. Eight tablet and 13 raw material samples from several sources were examined. The impurities most frequently found were 10, 11-dihydrocarbamazepine and a compound identified as 10-bromocarbamazepine at levels up to 1.3 and 0.5%, respectively; minimum detectable amounts were about 0.01 and 0.03%, respectively.
 
Mean a fat contents (%) obtained by Soxhlet and Mojonnier methods
Article
The Mojonnier method was compared with the conventional Soxhlet method for the determination of fat in 7 different meat products to assess its use as a standard reference method for calibration of commercial quantitative infrared transmission analyzers (e.g., Multispec M, Milkoscan 300 or 104). Results for the meat samples obtained by the Mojonnier method did not differ significantly from those obtained by the Soxhlet method. In addition, the Mojonnier method was less time-consuming and more precise than the Soxhlet; therefore, it can be used as a standard reference procedure for the calibration and assessment of infrared milk analyzers in their potential application to the rapid determination of fat in meat and meat products.
 
Article
A rapid and sensitive microbial assay was developed to detect lethal products of aflatoxin B metabolism by rainbow trout (Salmon gairdneri) Mt. Shasta strain. Bacillus subtilis GSY 1057 (hisA1, uvr-1, metB4), a DNA repair deficient strain, was incubated for 20 min in the 20,000 times g supernate from trout liver homogenates which had been preincubated for 10 min with various levels of aflatoxin B. Serial dilutions of the incubation mixture were plated in triplicate on tryptose blood agar base plates and colonies were counted after 12 hr at 37 degrees C. One mumole aflatoxin B in 3.2 ml incubation mixture reduced viability 60%.
 
Article
Tissues of coyotes and magpies administered known dosages of 1080 were analyzed for residues by an analytical method specifying gas chromatography and electron capture detection. The repeatability of the method was determined for the replicate analyses of coyote muscle tissue samples aged under different storage conditions. The average coefficient of variation (CV) was 6% for quadruplicate determinations of 1080 in fresh tissues, 12-14% for samples stored at - 10 degrees C for 30-60 days, and 24% for samples aged for 7 days at ambient temperatures. The larger CV value obtained for stored samples is attributed more to greater sample variability than to less precision of the analytical method. Residues of 1080 appear to be relatively stable in tissues; there was essentially no change in the concentration of 1080 in samples stored up to 28 days at ambient temperature. Residue levels in the muscle, heart, kidney, and intestine were comparable, slightly lower in the liver, and much higher in the stomach. The concentration of 1080 in the muscle tissue was related to the administered dosages. Correlation analyses of dosages and residue levels in coyote muscle tissue showed a correlation coefficient of 0.99 for 1080 administered by gavage, and 0.88 for 1080 administered by bait. A correlation coefficient of 0.99 was observed between dosages and mean residues in the breast muscle tissues of magpies. The average CV value was 3.5% for duplicate analyses of 1 g samples of magpie tissues.
 
Article
Fluoroacetate residues in various tissues of 1080-poisoned ground squirrels and coyotes are listed. The tissues (excluding the stomach) of squirrels poisoned with an average of 0.8 mg 1080/kg (low dose) contained from 182 to 1309 ppb fluoroacetate. In squirrels poisoned with an average of 4.8 mg 1080/kg (high dose), the tissue residues ranged from 535 to 9754 ppb fluoroacetate. Tissues from coyotes which died after consuming 1080-poisoned ground squirrels were also analyzed for fluoroacetate residues. Residues in these coyote kidneys and livers ranged from less than 10 ppb to 95 ppb fluoroacetate. The residue findings in this research indicate that a diagnostic assay for 1080 in tissues must be reliable at 10 ppb (or less) fluoroacetate.
 
Article
An analytical method is described for the determination of Compound 1080 (sodium fluoroacetate) residues in 1--10 g tissue. Sample extracts of tissues are cleaned up with silica gel, and Compound 1080 (as fluoroacetic acid) is separated by a micro-distillation procedure. The fluoroacetic acid in the distillate is derivatized with pentafluorobenzyl bromide to form pentafluorobenzyl fluoroacetate which is measured by electron capture gas-liquid chromatography. Recoveries of sodium fluoroacetate from fortified tissue samples averaged about 25%. Despite the limited recoveries, results were quite reproducible, and levels as low at 2 ppm were determined in fortified 1 g samples, and 0.2 ppm in 10 g samples. The method is relatively simple and has been used routinely in our laboratory for the analysis of various types of samples such as grain, and tissues from birds, rodents, and larger animals.
 
Article
A method capable of determining 0.1 ppm 1080 (sodium fluoroacetate) in 1 g animal tissue was developed. It involves extraction of 1080 from the sample with acetone-water, and then evaporation of the acetone followed by extraction of 1080 as fluoroacetic acid from water with ethyl acetate. Ethyl acetate is removed by volatilization from fluoroacetic acid which is retained as the triethanolammonium fluoroacetate salt. Fluoroacetic acid is subsequently derivatized with alpha-bromo-2,3,4,5,6-pentafluorotoluene and quantitated by gas-liquid chromatography with an electron capture detector. The method is rapid and requires no special apparatus or equipment and no more than 12 mL of any one solvent. Recoveries of 1080 from tissue samples fortified with 0.1-100 ppm averaged about 85%.
 
Article
A sensitive high pressure liquid chromatographic method was developed for the determination of sodium fluoroacetate (compound 1080) in canine gastric content. The procedure involves extraction of 1080 with water, methyl ethyl ketone, and dilute base, followed by sample cleanup using octadecylsilane bonded phase cartridges and derivatization in ethyl acetate sodium with O-p-nitrobenzyl-N-N'-diisopropylisourea (PNBDI). The compound was chromatographed on a 10 micrometer silica column, and ultraviolet absorbance at 254 and 280 nm was measured. Recovery was greater than 95% for standard 1080 and in the 70-90% range for spiked samples (1-50 ppm).
 
Article
A liquid chromatographic (LC) method is described for the determination of sodium fluoroacetate in meat baits and formulations. Baits were extracted with water, ultrafiltered, partitioned into butanone, back-partitioned into dilute base, and diluted with acetonitrile. Aqueous formulations of 1080 were diluted with acetonitrile. The solutions were esterified with p-bromophenacyl bromide, using crown ether catalysis, and chromatographed on a 10 micron reverse phase column. Ultraviolet absorbance was monitored at 260 nm. Samples spiked to contain 1 mg and 10 mg 1080/100 g meat gave recoveries of 84.0-103.4%.
 
Article
A gas chromatographic-electron capture detection method for determining the concentration of polychlorinated biphenyls (PCBs) as Aroclor 1254 (AR 1254) in serum was evaluated through a 2-phase collaborative study. In Phase I, each collaborator's lot of Woelm silica gel (70-150 mesh) was evaluated for elution and recovery of AR 1254, which had been added in vitro at 25 ng/mL to a serum extract. In Phase II, each collaborator analyzed a series of bovine serum samples that contained the following: (1) in vitro-spiked AR 1254; (2) in vivo AR 1254 and 8 in vitro-spiked chlorinated hydrocarbons; (3) in vivo AR 1254 only; (4) 8 in vitro-spiked chlorinated hydrocarbons only; and (5) neither AR 1254 nor chlorinated hydrocarbons above the detection limit of the method. In Phase I, the average recovery of AR 1254 from silica gel for the 6 collaborators was 87.9 +/- 15.44% (mean +/- 1 SD; N = 18; range = 52.3-105.8%). In Phase II, the analysis of in vitro spikes of AR 1254 in serum at 8.58, 16.8, 41.8, and 84.3 ppb gave mean (means) interlaboratory recoveries of 89.0, 83.3, 79.4, and 76.9%, respectively, with within-laboratory (repeatability) relative standard deviations (RSDr) of 18.8, 20.5, 10.2, and 14.1%, respectively, and among-laboratory (reproducibility) relative standard deviations (RSDR) of 21.5, 21.1, 14.6, and 20.8%, respectively. The determination of in vivo AR 1254 in samples containing approximately 10, 25, 50, and 100 ng/mL of AR 1254 resulted in interlaboratory means of 10, 22, 39, and 79 ng/mL, respectively, with RSDr = 6.7, 9.7, 6.4, and 5.8%, respectively, and RSDR = 20.6, 16.0, 10.9, and 10.3%, respectively. The precision of the method for incurred AR 1254 showed a maximum RSDr of less than 10% and a maximum RSDR of less than 21% for a concentration range of 10-100 ng/mL. The accuracy of the method as demonstrated by the mean recovery of in vitro-spiked AR 1254 over a concentration range of 8.58-843 ng/mL was 82.2%. The method has been approved interim official first action.
 
Article
Extraction, cleanup, and quantitation methods for polychlorinated biphenyls (PCBs) are discussed with reference to the analysis of individual chromatographic peaks as well as total PCBs. Extraction of blood samples with hexane-saturated acetonitrile maintains the integrity of the biologically modified PCB profile and permits accurate description of pharmacokinetic parameters. Individual components are quantitated by measuring peak heights in varying concentrations of Aroclor so that residues can be reported relative to the parent mixture. Absolute quantitation of component peaks can be accomplished by using these relative values and the percentage composition of the Aroclor.
 
Article
The 13C/12C ratios in orange juice are sufficiently uniform and different from those in high fructose corn syrup (HFCS) so that the addition of HFCS to orange juice can be detected. HFCS averages -9.7% (parts per thousand) delta 13C, orange juice averages -24.5%, and mixtures of HFCS and orange juice possess intermediate values. One pure orange juice and 4 orange juice -HFCS mixtures containing from 25 to 70% orange juice were properly classified by 7 collaborators. Samples with delta 13C values less negative than -22.1%, 4 standard deviations from the mean of pure juices, can, with a high degree of confidence, be classified as adulterated. Samples with values more negative than -22.1% must be considered unadulterated with HFCS, because pure orange juices possess a range of delta 13C values. The 13C/12C mass spectrometric method was adopted official first action for detecting HFCS in orange juice.
 
Article
A technique is presented for the analysis of polychlorinated biphenyl mixtures by assigning 13C resonances to the observed peaks and matching these shifts to the shifts of known individual polychlorinated biphenyls. The technique has not proved to be as useful for heavily chlorinated mixtures.
 
Article
The AOAC method for iodine-131, cesium-137, and barium-140 in milk by gamma-ray spectroscopy (48.025-48.029) was extended to include other foods for the radionuclides iodine-131 and cesium-137. Two collaborative studies were performed to validate this extension. In the first study, a food sample containing 119 pCi 131I/kg and 53 pCi 137Cs/kg was sent to each of 45 laboratories for triplicate analyses. For 25 responses, the mean of the reported values was 123.8 pCi/kg for iodine-131, and for 27 responses, the mean was 53.4 pCi/kg for cesium-137. Repeatability (within-laboratory) standard deviations (Sr) for iodine-131 and cesium-137 were 4.6 and 3.7 pCi/kg, respectively. Reproducibility (among-laboratories) standard deviations (SR) for iodine-131 and cesium-137 were 12.1 and 6.0 pCi/kg, respectively. In the second study, a food sample containing 25 pCi 131I/kg and 27 pCi 137Cs/kg was sent to each of 54 laboratories for triplicate analyses. For 21 responses, the mean of the reported values was 25.0 pCi/kg for iodine-131, and for 19 responses, the mean was 28.9 pCi/kg for cesium-137. Sr Values were 4.0 and 1.6 pCi/kg for iodine-131 and cesium-137, respectively, and SR values were 5.0 and 2.8 pCi/kg, respectively. The method extension was adopted official first action.
 
Article
The official method for Cs-137 in milk by gamma-ray spectroscopy was extended to include I-131 and Ba-140. A collaborative study was performed on this method applied to I-131 concentration in cow's milk; the original collaborative study of the method including all 3 nuclides was reviewed. In the I-131 study, 1 aliquot of a milk sample containing 82 pCi/L was sent to each of 60 laboratories for triplicate analyses. From 40 responses, the mean of the reported values was 81.6 pCi/L, indicating a method bias below the 5% statistical detectability limit. Within- and between-laboratory coefficients of variation (CVs) were 7 and 8%, respectively. In the 3-nuclide study, 2 samples were sent to 25 laboratories for triplicate analyses; one sample contained 633, 305, and 515 pCi/L, respectively, of I-131, Cs-137, and Ba-140 and the other contained 98, 52, and 72 pCi/L. For the high-activity sample, within-laboratory CVs were 4-5% for the 3 nuclides and between-laboratory CVs were 4-7%. For the low-activity sample, the corresponding results were 6-9% and 8-16%. The method bias was statistically significant at 95% confidence only for Cs-137 in the high-activity sample; reported results were 3% below the known concentration. The extended method was adopted official first action.
 
Article
Measurement of infrared absorption by the use of a CH stretch filter which isolates wavelengths in the order of 3.4-3.5 microns has been suggested as a replacement for the conventional carbonyl stretch absorption measurement or as an additional measurement for the estimation of fat in aqueous fat emulsions. To determine the merits of this CH stretch measurement, a study was conducted with a series of natural fats selected for their differences in average molecular weight, fatty acid composition, and degree of unsaturation. In this study, the use of the CH stretch filter, the C = O stretch filter, or the combination thereof could predict the fat content with equal accuracy if the fat was consistent in average molecular weight and degree of unsaturation. For a fat which varied in its degree of unsaturation, the CH filter measurement could be used in conjunction with the iodine value to produce accurate results. The combination C = O filter, CH filter, and the iodine value produced the most accurate results when the intent was to analyze a variety of fats on a single calibration.
 
Article
A gamma spectroscopic method, using a sodium iodide (thallium-activated) crystal, was evaluated by 25 collaborators for the determination of cesium-137 in milk. Overall average recoveries of 295±18.1 and 53±5.3 pCi/L were obtained for samples containing 305 and 52 pCi/L, respectively. These samples also contained iodine-131 and barium-140, which did not interfere with the analyses. The slight bias on the low side and the greater dispersion of results for the low level sample were not considered serious. The method has been adopted as official first action.
 
Article
The British Pharmacopoeia test controlling the composition of gentamicin sulfate is based on CW 60 MHz magnetic resonance spectroscopy. Application of this method to FT 90 MHz spectra was evaluated. Results clearly show the limitations of this technique and point out the need for more reliable assay methods. Thus a 13C nuclear magnetic resonance (NMR) procedure for quantitative analysis of gentamicin sulfate was developed. Ratios of 4 gentamicin components (C1, C2, C1a, and C2a) were obtained from peak height measurements of selected resonance signals in spectra recorded under steady-state conditions. Relative response factors were determined from spectra of a reference mixture or, alternatively, from spectra of the individual pure components. Results obtained by the 13C NMR method were in agreement with those obtained by liquid chromatography using pre-column derivatization.
 
Article
Three methods for determining organophosphorus insecticide residues in plant tissues were compared for efficiency of extraction and cleanup of 14C-labeled residues from wheat plants grown in soil treated with Dyfonatering-14C. Blending with ethyl acetate recovered 70.5% of the radioactivity present in the plant tissues and cleanup of the extract by sweep codistillation recovered 99% of the radioactivity. Blending of plants with benzene recovered about 58% of the radioactivity and subsequent cleanup of the extract on a silica gel column recovered about 78% of the activity. Although blending with acetonitrile recovered 59% of the radioactivity present in the plant tissue, partitioning of the extract between water and petroleum ether or chloroform retained only about 14 and 30% of the activity in the organic layer, respectively. Thus, the overall efficiency of this procedure was only between 8 and 18% as compared to 45 and 70% in the other 2 methods.
 
Article
Fourteen polycyclic hydrocarbons in (I) meat, poultry, fish, and yeast, and (II) fats and oils have been isolated and determined. To separate group I homogeneously, 2N methanolic KOH is used. In the first step of concentration (methanol-water-cyclohexane partition (4 + 1 + 5)), a 200 g sample is reduced to 0.2 g of polycyclic fraction without any emulsions. The same effective concentration is found for group II without a saponification step by partition in N,N-dimethylformamide-water-cyelohexane (9 + 1 + 10). Further very effective concentration (100:1) of polycyclics results from filtration on Sephadex LH 20 (solvent:sopropanol). After further cleanup by filtration on silica gel (Woelm, 15% water), phenanthrene, anthracene, pyrene, fluoranthene, chrysene, benzo(a)anthracene, benzo(a)pyrene, benzo-(e)pyrene, benzo(k)fluoranthene, perylene, anthanthrene, benzo(g,h,i)perylene, dibenz(a,h)-anthracene, and coronene are separated on an aluminum oxide column (Woelm, 5.4% water) or equivalent. Recoveries ranged from 75 to 92% for all polycyclics down to the 2 ppb level.
 
Article
A simple, systematic analytical method for multiple mycotoxins was developed for detecting 14 mycotoxins; aflatoxins B1, B2, G1, and G2, sterigmatocystin, T-2 toxin, diacetoxyscirpenol, neosolaniol, fusarenon X, zearalenone, ochratoxin A, citrinin, luteoskyrin, and rugulosin. These mycotoxins were extracted with 20% H2SO4-4% KCl-acetonitrile (2 + 20 + 178), defatted with isooctane, and transferred to chloroform. The chloroform extract was cleaned up by silica gel column chromatography; the first 10 toxins were eluted with chloroform-methanol (97 + 3) and the remaining 4 toxins with benzene-acetone-acetic acid (75 + 20 + 5). Each fraction was analyzed by thin layer chromatography for the final determination. The method has been applied to polished rice, rough rice, corn, wheat, and peanuts as an analytical screening procedure. The detection limits in these commodities ranged from 10.00 to 800.0 microgram/kg, depending on the mycotoxin, but all limits were superior to those obtained for the individual mycotoxins by using other methods.
 
Article
14C-labeled benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate] suspended in a commercial benomyl formulation was sprayed on mustard greens and radishes. At 3 intervals after application, the crops were extracted with methanol, acetonitrile, or acetone. Crops were either blended and leached or repetitively blended followed by Soxhlet extraction. Essentially all of the extractable radioactivity was removed by blending. The 14C was more difficult to extract from radishes than from mustard greens as time increased. Respective percentages of 14C extracted at 1, 7, and 14 days were 99, 98, and 97 from mustard greens and 96, 88, and 79 from radishes. Methanol exhibited the highest extraction efficiency, and the blend-Soxhlet process was better than the blend-leach process. Thin layer chromatography of the organic-soluble extracts indicated that the majority of 14C was recovered as methyl 2-benzimidazole carbamate (MBC), a breakdown product of benomyl. Acid hydrolysis of the extracted tissues released 30--50% of the residual 14C.
 
Article
A successful method to obtain 14C-labeled aflatoxin B1 from Aspergillus parasiticus ATCC 15517 was developed. The nitrogen-free resting culture contained mycelia from a 72 hr primary culture, 0.02M glucose, 0.005M (1 mCi/mmole) acetate-1-14C, salts, and trace metals. It was incubated 12 hr at 30°C. Aflatoxin B1-14C was isolated from chloroform extracts of the resting culture by column chromatography on silica gel H eluted under pressure with a continuous gradient of chloroform to chloroform-methanol (98+2). The ultraviolet spectrum of the 14C-labeled aflatoxin was examined. The ratios of the absorbances at 220/265 and 362/265 nm compared to established values and a reference standard were used as criteria of chemical purity. Label integrity was verified by chromatography, hydrogenation to the tetrahydrodeoxoaflatoxin B1, and conversion to the hemiacetal and the epimeric acetates. After purification, 1.37 mg 14C-labeled aflatoxin B1 of specific activity 744 μCi/mmole was obtained from 2 mCi acetate-1-14C of specific activity 1 mCi/mmole.
 
Article
Specific 14C-activities, percent of modern 14C-activity, and calculated percent of fermentation CO2 are presented for CO2 contained in commercial sparkling wines, labeled as champagne or produced by the bulk (charmat) process. These data are given for the production years 1976-1982. The survey encompassed effervescent wines produced in Spain, Italy, West Germany, California, and New York. Addition of synthetic CO2 to approximately 40 samples represented as sparkling wines was indicated by low 14C-activities of CO2 in these wines. Data for 14C-activity were also presented for the ethanol distilled from sparkling wines for the years 1977-1980. In all cases, the 14C-activity of ethanol was appropriate to the year of vintage.
 
Article
A detailed fractionation of radioactivity in the milk of goats administered 14C-aflatoxin B1 at low doses was performed. The milk collected in the first 24 h following dosing contained radioactivity equivalent to 0.45-1.1% of the dose given. The radioactivity in each sample was partitioned into 4 fractions: ether, protein, dichloromethane, and water-alcohol. Over 80% of the radioactivity was detected in the dichloromethane fraction, of which over 95% was attributable to aflatoxin M1. No aflatoxin B1 or other known aflatoxin metabolites were detected in any fraction. The results indicate that the major metabolite of aflatoxin B1 in goat milk is aflatoxin M1 and that other metabolites, including conjugates, are of minor significance.
 
Article
The resolution of organochlorine insecticides and their related compounds on OV-1/OV-17, OV-210/OV-17, and OV-225/OV-17 mixed phase column systems was investigated. Four BHC isomers and p,p'-DDT, its isomer, and their metabolites (except p,p'-DDE and o,p'-DDE) were resolved on the OV-210/OV-17 system. Heptachlor and heptachlor epoxide were separated on 5% OV-1/2% OV-17 or OV-225/2% OV-17. Resolution of aldrin, dieldrin, and endrin was obtained on 5% OV-210/2% OV-17, p,p'-DDE and o,p'-DDE could not be separated by any of the systems studied.
 
Article
A liquid chromatographic (LC) method has been developed for determination of clobetasone-17-butyrate in ointment using clobetasone propionate as an internal standard. Separation was carried out on a C18 reverse-phase column using water-methanol as a mobile phase. Methylparaben and propylparaben (both sodium salt) used as preservatives did not interfere with separation. Compounds are detected photometrically at 235 nm. Mean assay results for 0.05% commercial ointments were 100.36% (n = 5). Mean recovery of clobetasone-17-butyrate added to commercial ointment was 99.89%.
 
Article
A method is described for the determination of the intermediates in D&C Orange No. 17 by reverse phase liquid chromatography. The pigment is dissolved in boiling dioxane and then precipitated. The filtrate is chromatographed by isocratic elution, which is followed by a wash and equilibration. Peak area calibrations were linear. At the provisional specification levels, 99% prediction limits were 0.200 +/- 0.0012% 2,4-dinitroaniline (2,4-DNA) and 0.200 +/- 0.006% 2-naphthol. The limits of determination were 0.0023% for 2,4-DNA and 0.013% for 2-naphthol at the 99.5% confidence level. Recoveries were 98-100% for 2,4-DNA added at the 0.005-2% level, and 93-103% for 2-naphthol added at the 0.025-2% level. A survey of certified D&C Orange No. 17 samples showed that the lots contained higher levels of the intermediates than were determined previously by a cellulose column method, in which the pigment is not dissolved.
 
Article
The development of an assay for the estrogen estradiol-17beta in bovine muscle, kidney, liver, and uterine endometrium is described in this report. The tissue was homogenized, extracted, partitioned, and subjected to routine radioimmunoassay. Chromatography was not used. The first part of the report presents data on the accuracy, reproducibility, and sensitivity of the assay. The concentration of estradiol-17beta in the tissues compared with muscle was ranked as follows: uterine endometrium (10-fold higher), liver (3-fold), and kidney (3-fold). The estrogen concentration was not significantly different in the muscle between heifers, but was significantly greater (P less than 0.05) in the liver and kidney of heifers and steers. In heifers pre- and post-estrous phase endometrium (a target tissue of E2beta) contained significantly greater concentrations of estradiol-17beta than did luteal phase endometrium (P less than 0.05), but mean levels in the edible tissues were not significantly different (P greater than 0.05) between these 2 of the 4 stages of the estrous cycle.
 
Article
A collaborative study was carried out in 30 laboratories to validate improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were included in the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each inoculated in advance with low levels of individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved interim official first action for all foods to replace the HGMF official final action method, 985.42.
 
Top-cited authors
Jonathan Devries
  • DeVries & Associates
Mary W Trucksess
  • U.S. Food and Drug Administration
Fun Chu
  • University of Wisconsin–Madison
John H Cummings
  • University of Dundee
Steven Barker
  • Louisiana State University