Showing papers in "Journal - Association of Official Analytical Chemists in 1978"
120Â citations
TL;DR: The main improvements are replacing the Griess reagent with a mixture of sulfanile acid and N-(1-naphthyl)-ethylenediamine, providing for adjustment of pH of the sample suspension during extraction and digestion by heating, and maintaining constant pH by controlled addition of buffers and acids during color development.
Abstract: A method is described for determining nitrate and nitrite in cured meat products, cheeses, and vegetables. The nitrite is determined colorimetrically by diazotization of sulfanilic acid and subsequent coupling with N-(1-naphthyl)-ethylenediamine. The concentration of nitrate plus nitrite is determined similarly but after reduction of the nitrate to nitrite on a cadmium column. The difference of the 2 values is a measure of the nitrate concentration. The main improvements are replacing the Griess reagent, which contains a carcinogen, with a mixture of sulfanile acid and N-(1-naphthyl)-ethylenediamine, providing for adjustment of pH of the sample suspension during extraction and digestion by heating, and maintaining constant pH by controlled addition of buffers and acids during color development. The method was successfully applied to the analysis of 15 samples of meat products, 23 cheeses, and 6 different vegetables. The average recovery of sodium nitrite added at levels ranging from 10 to 30 ppm was 95% and recovery of sodium nitrate added at levels from 30 to 400 ppm was 94% (corrected for cadmium column efficiency).
61Â citations
TL;DR: Results for homogenized and unhomogenized milk were different for most instruments, indicating the need to calibrate for them separately, and systematic errors for fat increased to about 0.07% and were larger at high fat levels.
Abstract: Thirty-six milks pre-analyzed by accepted standard methods were analyzed with Milko-scan instruments at 6 laboratories. Using pairs comparisons as described by Youden, precision errors for fat were about 0.033% for the first and 0.022% for the second of duplicate tests, indicating a carry-over effect for the first tests. Precision errors for protein were about 0.021% for both tests. Systematic errors for fat were about 0.17% with calibrations based on reference analyses at each laboratory but were reduced to about 0.044% with calibrations by reference analyses from one laboratory. With homogenized milks, systematic errors for fat increased to about 0.07% and were larger at high fat levels. This effect could be minimized by changing the wavelength of maximum transmission for the fat filter. Systematic errors of about 0.067% for protein were reduced to about 0.03% with calibrations based on common reference analyses. Satisfactory calibrations for lactose were obtained with the 2 Milko-scan 203 models with standard errors of estimate of 0.034 and 0.033%. Results for homogenized and unhomogenized milk were different for most instruments, indicating the need to calibrate for them separately.
56Â citations
Journal Article•
51Â citations
Journal Article•
47Â citations
TL;DR: The legal, analytical, and practical requirements to be considered in developing and submitting these procedures will be presented on current requirements and past experiences.
Abstract: Mass spectrometry is a technique capable of providing unambiguous confirmation of drug residues in edible tissues at trace levels. This has led to an increase in the number of new animal drug applications containing a mass spectrometry procedure as the confirmatory test. Written guidelines do not exist to cover the requirements to be met for acceptance of these procedures. The legal, analytical, and practical requirements to be considered in developing and submitting these procedures will be presented on current requirements and past experiences.
39Â citations
TL;DR: A multimycotoxin thin layer chromatographic method is described for the analysis of corn, and the following recoveries were obtained for corn samples: aflatoxin B1 71, ochratoxin A 87, and zearalenone 85.
Abstract: A multimycotoxin thin layer chromatographic method is described for the analysis of corn. Aflatoxins are extracted from the samples with acetonitrile-water, and sodium bicarbonate is added to separate the acidic ochratoxin from zearalenone and aflatoxin B1. After chloroform extraction, 1N NaOH is added to separate zearalenone and aflatoxin B1. The separated mycotoxins are spotted on TLC plates, which are then examined under ultraviolet light. The following recoveries (%) were obtained for corn samples: aflatoxin B1 71, ochratoxin A 87, and zearalenone 85. The limits of detection for the respective mycotoxins were 2, 40, and 200 ppb.
38Â citations
TL;DR: The individual peak method shows improved interlaboratory precision and/or accuracy in PCB quantitation over existing methods.
Abstract: Weight per cent compositions of individual peaks of Aroclors 1016, 1242, 1248, 1254, and 1260 were determined under standard gas-liquid chromatographic (GLC) conditions. The GLC peak compositions were determined by using a Hall electrolytic conductivity detector for chlorine measurement and chemical ionization mass spectrometry with single ion monitoring for molecular weight characterization. The Aroclors used are available as reference materials for individual peak quantitation of polychlorinated biphenyl (PCB) residues by electron capture GLC. On the basis of a limited interlaboratory study and a collaborative study, the individual peak method shows improved interlaboratory precision and/or accuracy in PCB quantitation over existing methods.
33Â citations
TL;DR: A reverse phase high pressure liquid chromatographic method is presented for the simultaneous separation and determination of quinic, malic, and citric acids in single strength, undiluted cranberry juice.
Abstract: A reverse phase high pressure liquid chromatographic method is presented for the simultaneous separation and determination of quinic, malic, and citric acids in single strength, undiluted cranberry juice. After a 1 : 10 dilution and cleanup through a disposable column, major organic acids in cranberry juice are separated on a Bondapak/C18 column and quantitated by using a differential refractometer. Twenty-seven samples of different single strength cranberry juice were analyzed using this method; the mean content of quinic, malic, and citric acids were 1.32 (std dev. 0.150), 0.92 (std dev. 0.079), and 1.08% (std dev. 0.111), respectively. Mean percent recoveries of each acid were quinic 95.4 (std dev. 6.8), malic 96.6 (std dev. 5.8), and citric 94.0% (std dev. 4.8).
26Â citations
TL;DR: An investigation of one processing facility showed that the production of histamine in swiss cheese may have been a result of a hydrogen peroxide/low temperature treatment of the milk supply.
Abstract: Thirty-one samples of cheese obtained from retail outlets were analyzed for histamine, using an official AOAC fluorometric method The types of cheese analyzed and the ranges of histamine found were: colby, 03--28; camembert, 04--42; cheddar, 12--58; gouda, 13--24; provolone, 20--235; roquefort, 10--168; mozzarella 16--50; and swiss, 04--250 mg histamine/100 g Ten of the 12 samples of swiss cheese contained less than 16 mg histamine/100 g The remaining 2 samples which contained 116 and 250 mg histamine/100 g were judged organoleptically to be of poor quality An investigation of one processing facility showed that the production of histamine in swiss cheese may have been a result of a hydrogen peroxide/low temperature treatment of the milk supply Recovery of histamine added to methanol extracts of cheese ranged from 93 to 105% Histamine content was confirmed by high pressure liquid chromatographic analysis of the methanol extracts
26Â citations
TL;DR: A method was developed for determining theobromine and caeffine in cocoa and chocolate products by high pressure liquid chromatography by using a reverse phase C18 column and a mobile phase of methanol-water-acetic acid.
Abstract: A method was developed for determining theobromine and caeffine in cocoa and chocolate products by high pressure liquid chromatography. After a simple hot water extraction, both theobromine and caffeine were separated by using a reverse phase C18 column and a mobile phase of methanol-water-acetic acid (20 + 79 + 1). Theobromine and caffeine were quantitated at 280 nm; average recoveries were 98.7 and 95.0%; and coefficients of variation were 2.31 and 3.91%, respectively.
TL;DR: A bulk purification procedure is described for moniliformin, a mycotoxin produced by Fusariummoniliforme, and a pKa value of 1.70 as well as molar absorptivities of 19100 (lambda (H2O) max 229 nm) L/mole/cm are reported.
Abstract: A bulk purification procedure is described for moniliformin, a mycotoxin produced by Fusarium moniliforme. The method involves methanol extraction of suitably molded maize, aqueous extraction of the methanol-free residue, ion exchange chromatography with a NaCl concentration gradient, desalination, and crystallization. A pKa value of 1.70 as well as molar absorptivities of 19100 (lambda (H2O) max 229 nm), 5600 (lambda (H2O) max 260 nm), and 4700 (lambda (MeOH) max 260 nm) L/mole/cm are reported for moniliformin.
TL;DR: Radioimmunoassay (RIA) is valuable for sensitive and specific routine measurements of hormones in body fluids, but in any case knowledge of the metabolic profile of the compounds is necessary, especially since the specificity of the RIA group analysis is limited.
Abstract: Radioimmunoassay (RIA) is valuable for sensitive and specific routine measurements of hormones in body fluids. The method is also applicable to determine tissue levels of hormones which, according to tracer studies and depending on the compound, are scattered in the lower ng and pg/g range. For practical assay application it must be decided whether the parent compound or a major metabolite should be measured. Both toxicological and practical regulatory aspects have to be considered, but in any case knowledge of the metabolic profile of the compounds is necessary, especially since the specificity of the RIA group analysis is limited. When applying extraction and purification steps, differences between compounds and between tissues have to be considered; generally more difficulties are encountered than with plasma. Validation of the method should first demonstrate no unspecific interference with the antigen-antibody reaction; then the other reliability criteria have to be established. So far RIAs for the quantitation of estrogens, testosterone, progesterone, and trienbolone--a synthetic androgen--in various bovine tissue samples have been developed. The lower limit of sensitivity ranges between 10 and 70 pg/g. Quantitation of physiological levels of testosterone and progesterone is possible, but there are still some problems with estrogens.
TL;DR: A semiquantitative microbiological screening test for antibiotics, a sensitive and quantitative microbiological assay, and a fluorometric method specific for tetracyclines are described, which can be detected in tissues like organs, muscles, and bones.
Abstract: A semiquantitative microbiological screening test for antibiotics, a sensitive and quantitative microbiological assay, and a fluorometric method specific for tetracyclines are described. Using these procedures, tetracycline residues in animals derived from feed can be detected in tissues like organs, muscles, and bones. Meat contaminated with chlortetracycline (CTC) and oxytetracycline (OTC) and stored at +8 degrees C and -22 degrees C showed very little decrease in antibiotic concentration; however, heating above 65 degrees C reduced the tetracycline content in meat. Temperatures above 130 degrees C were necessary to destroy CTC in bones, CTC in bones was insoluble above pH 4. Manufacturing products with contaminated meat reduced the tetracycline content only if heating was involved.
TL;DR: The patulin content ranged from less than 1 to 220 microgram/L for the 140 samples analyzed, and the mean recovery of patulin added to apple juice was 82.6 +/- 2.8 %.
Abstract: Patulin was extracted from apple juice with ethyl acetate and the extract was purified by elution from a silica gel column with ethyl acetate-toluene. The eluate was concentrated, and patulin was determined by reverse phase high pressure liquid chromatography using a 25 cm Partisil-10 ODS column. The lower detection limit was 1 microgram/L and the mean recovery of patulin added to apple juice was 82.6 +/- 2.8 %. The patulin content ranged from less than 1 to 220 microgram/L for the 140 samples analyzed.
TL;DR: A method is described for determining citrinin in corn and barley using high pressure liquid chromatography or thin layer chromatography, and recovery of addedcitrinin from corn by this method is 60--87% at levels of 50--4000 microgram/kg.
Abstract: A method is described for determining citrinin in corn and barley. The initial extraction uses an aqueous acidified acetonitrile solution, and the resulting solution is partially purified by several partition steps. Citrinin is determined by using either high pressure liquid chromatography (HPLC) or thin layer chromatography (TLC). For HPLC, the extract is injected on a reverse phase column, eluted with either 0.25N H3PO4-methanol (45 + 55) or 0.25N H3PO4-acetonitrile (50 + 50), and detected by fluorescence (excitation 325--385 nm, emission above 451 nm). Recovery of added citrinin from corn by this method is 60--87% at levels of 50--4000 microgram/kg. For TLC, the chromatographic plates are impregnated with oxalic acid by dipping them in an oxalic acid-methanol solution before spotting and development. Recovery of added citrinin from corn, using TLC, is 40--100% at levels of 50--40000 microgram-kg.
TL;DR: A screening method using gas-liquid chromatography with flame photometric detection has been developed for determining phosphine in wheat, and phosphine concentrations as low as 0.04 ppm were easily determined.
Abstract: A screening method using gas-liquid chromatography with flame photometric detection has been developed for determining phosphine in wheat. Phosphine is measured as the sum of physically bound intact phosphine and that derived from residual aluminum phosphide. Wheat is extracted in a closed, partially evacuated glass system by refluxing with 10% sulfuric acid. Liberated gases are swept into a gas-collection flask fitted with rubber septa to permit gas sampling. Aliquots of collected gas are injected into a gas chromatograph. Phosphine is quantitated by peak area as determined by an electronic integrator. Recoveries varied with concentration: 67% was recovered at 0.10 ppm and 98% was recovered at 19 ppm. For concentrations less than 1.5 ppm, the coefficient of variation was 9.95%. Using flame photometric detection, phosphine concentrations as low as 0.04 ppm were easily determined in wheat.
TL;DR: Variations in the AOAC official first action rat hemoglobin repletion test for iron yielded results comparable to those obtained with the present official method, and it is recommended that the present method remain in first action status.
Abstract: Variations in the AOAC official first action rat hemoglobin repletion test for iron were studied. These changes included (1) use of a simplified basal diet to eliminate ingredients which sometimes contribute too much iron; (2) increased fortification of the basal diet with vitamin E, pantothenic acid, and pyridoxine; (3) increased dietary copper; (4) variations in the carbohydrate source in the basal diet; (5) changes in the length of the depletion and repletion periods; and (6) comparison of prophylactic and curative procedures. The changes yielded results comparable to those obtained with the present official method. Further study may reveal that the depletion period can be shortened or eliminated. To fully meet the rat's vitamin requirements, increased levels of vitamin E, pantothenic acid, and pyridoxine are recommended. It is further recommended that the present method remain in official first action status, and that study be continued.
TL;DR: An assay procedure for streptomycin was developed, using a surfactant-pH 8 buffer extraction, heating at 85 degrees C to eliminate inhibition from lysozyme activity, and centrifuging to remove physical barriers to diffusion.
Abstract: An assay procedure for streptomycin was developed, using a surfactant-pH 8 buffer extraction, heating at 85 degrees C to eliminate inhibition from lysozyme activity, and centrifuging to remove physical barriers to diffusion. Recoveries of streptomycin from supplemented eggs averaged 42% over the range of 0.33--2.05 microgram streptomycin/g egg. Eggs were supplemented at 3.0, 30.0, and 300 microgram streptomycin/g and subjected to various cooking procedures: frying, poaching, scrambling, and hard boiling. There was little or no loss of activity as a result of the various cooking procedures with the exception of one of the hard boiled varieties where there was a 40% loss only at the 3.0 microgram/g supplementation. Streptomycin residues were quite stable to normal egg preparation procedures.
TL;DR: Results of the study indicate that the 24-hr modified A-1 test can be used as an alterantive test for the standard 72-hr EC test as an adjunct to the sanitary survey for the classification and control of shellfish-growing areas waters.
Abstract: A study was conducted to compare recovery and enumeration capability of two 24-hr multitube fermentation tests with the standard EC test for fecal coliform levels in shellfish-growing waters. The 2 tests were the A-1 test developed by Andrews and Presnell, specifying 24-hr incubation in A-1 medium at 44.5 degree C; and a modification of the A-1 test requiring a 3-hr resuscitation of 35 degree C before incubation at 44.5 degree C for 21 hr. Fifteen State, Federal, and Provincial laboratories examined 10 routine shellfish-growing area samples per month in parallel by the 3 methods for 1 year. IMViC tests (indole, methyl red, Voges-Proskauer, and citrate) were conducted on all gas-positive tubes. The modified A-1 test recovered higher levels of fecal coliforms than the A-1 test. Although there were seasonal and geographic variations in recovery and enumeration by the modified A-1 test, overall there was good correlation of the modified A-1 test with the EC test. Both the A-1 and modified A-1 tests were more specific for Escherichia coli than the EC test. Results of the study indicate that the 24-hr modified A-1 test can be used as an alterantive test for the standard 72-hr EC test as an adjunct to the sanitary survey for the classification and control of shellfish-growing areas waters.
TL;DR: A method is reported for determining zearalenone in corn at levels as low as 10 ng/g and it was successfully applied to the analysis of 11 samples of cornmeal; zearAlenone was detected in 9 of the samples at levels from 11 to 69 ng/G.
Abstract: A method is reported for determining zearalenone in corn at levels as low as 10 ng/g. Samples are extracted with chloroform-water and cleaned up by liquid-liquid chromatography, and the zearalenone is detected by a fluorescence detector after separation by reverse phase high pressure liquid chromatography (HPLC). Recoveries of zearalenone added to corn at levels from 10 to 200 ng/g averaged greater than 89%. In addition, a confirmation procedure is described which involves sequential HPLC analysis of the sample and a zearalenone standard, using 4 different excitation wavelengths and comparing fluorescence responses obtained. This method was successfully applied to the analysis of 11 samples of cornmeal; zearalenone was detected in 9 of the samples at levels from 11 to 69 ng/g.
TL;DR: In this article, the identity of aflatoxin M1 can be confirmed directly on a thin layer plate by reacting M1 with trifluoroacetic acid (TFA).
Abstract: The identity of aflatoxin M1 can easily be confirmed directly on a thin layer plate by reacting aflatoxin M1 with trifluoroacetic acid (TFA). This confirmation reaction is carried out on the thin layer plate which has been developed in 2 dimensions and used for the quantitation of aflatoxin M1 in the sample. TFA is superimposed on the separated M1 spot. The plate is kept in the dark 3 min, heated to 75 degrees C for 5 min, and developed with chloroform-methanol-acetic acid-water (92 + 8 + 2 + 0.8). The Rf value of the blue-fluorescent derivative is compared with that for the M1 standard. The method was used successfully on extracts of milk, cheese, and liver. M1 quantities on the plate as low as 0.5 ng can be confirmed by this method. The method is also suitable for simultaneous confirmation of aflatoxin B1.
TL;DR: A spectrophotometric method for determining vitamin A based on interaction with 50% trichloroacetic acid solution in dichloromethane showed excellent agreement with the Carr-Price method.
Abstract: A spectrophotometric method for determining vitamin A based on interaction with 50% trichloroacetic acid solution in dichloromethane was developed. The blue reaction product had a maximum absorption at 620 nm and obeyed Beer's law over the concentration range of 0.5-5.0 microgram retinol/ml solution. The molar absorptivity of the reaction product was 1.58 X 10(5). As much as 100 microgram vitamin D2, and beta-carotene up to 12 times the vitamin A concentration, did not interfere with the determination. The results obtained from the determination of vitamin A in cod liver oil and butter showed excellent agreement with the Carr-Price method, 43.013(d).
TL;DR: The sulfuric acid extraction step affords a simple method for isolating benzo(a)pyrene from various kinds of interfering substances which could not be separated by existing methods.
Abstract: An analytical method was developed for determining benzo(a)pyrene in foods, suitable for routine use. The method consists of 4 cleanup steps: (1) alkali cleavage of sample, (2) preliminary silica gel column chromatography, (3) selective extraction with concentrated sulfuric acid, and (4) further silica gel column chromatography. Recoveries of benzo(a)pyrene added to 50 g (or 10 g) food at levels of 0.4 ppb (or 2 ppb) ranged from 70% for short-necked clam and mackeral to 85% for chicken meat. The sulfuric acid extraction step affords a simple method for isolating benzo(a)pyrene from various kinds of interfering substances which could not be separated by existing methods.
TL;DR: The analyses performed on 14 bald eagle carcasses and livers, 3 bald eagle eggs, and 14 osprey eggs show measurable levels which indicate that Kepone accumulates in the tissues of fish-eating birds.
Abstract: A procedure is described for determining Kepone (decachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene-2-one) residues in avian egg, liver, and tissue. Samples were extracted with benzene-isopropanol, and the extract was cleaned up with fuming H2SO4-concentrated H2SO4. Kepone was separated from organochlorine pesticides and polychlorinated biphenyls on a Florisil column and analyzed by electron capture gas-liquid chromatography (GLC). The average recovery from spiked tissues was 86%. The analyses performed on 14 bald eagle carcasses and livers, 3 bald eagle eggs, and 14 osprey eggs show measurable levels which indicate that Kepone accumulates in the tissues of fish-eating birds. Residues were confirmed by GLC-mass spectrometry.
Journal Article•
TL;DR: Three of the diagnostic kits have been adopted as official first action as alternatives to the AOAC biochemical tube system for presumptive generic identification of foodborne Salmonella and for screening and eliminating non-Salmonella isolates.
Abstract: The comparative accuracy of 4 biochemical diagnostic kits (API, Enterotube, Minitek, and Pathotec) and the conventional (AOAC) tube system for identifying primarily Salmonella and other enteric isolates was collaboratively studied. Each of 11 participating analysts received 40 foodborne isolates (25 Salmonella and 15 non-Salmonella cultures), representing a total of 440 cultures examined by each identification system. In decreasing order of accuracy, the overall number of correctly identified cultures with each of the systems was as follows: AOAC, 423 (96.1%), Minitek, 403 (91.6%), Enterotube, 395 (89.8%), API, 394 (89.5%), and Pathotec, 373 (84.8%). A cost analysis showed that all 4 diagnostic kit systems were less expensive than the conventional AOAC tube system for a single culture identification. Three of the diagnostic kits have been adopted as official first action as alternatives to the AOAC biochemical tube system for presumptive generic identification of foodborne Salmonella and for screening and eliminating non-Salmonella isolates. Routine incorporation of any one of the 3 diagnostic kits, however, should be preceded by the demonstration in the analyst's own laboratory of adequate correlation between the kit and the AOAC system.
TL;DR: The chloride ion selective electrode is used for a rapid, simple, and reliable determination of chloride ion in biological materials, food products, soils, and waste water.
Abstract: The chloride ion selective electrode is used for a rapid, simple, and reliable determination of chloride ion in biological materials (blood serum, urine, fish, and plant tissues), food products (milk, beef extract, nutrient broth and orange, tomato, and grapefruit juices), soils, and waste water (industrial and municipal). The method consists of treating the samples with perchloric acid (pH 1) and potassium peroxydisulfate and determining the chloride content either by a calibration curve or by known addition or analyte addition, using the chloride ion selective electrode. Such sample treatment eliminates most of the interferences occurring in the samples, including iodide, complexing and reducing compounds, and macromolecular and surface-active species. The method is suitable for a wide range of chloride concentration, e.g., 5010 ppm Cl- in nutrient broth and 4890 ppm in beef extract and as low as 12 and 80 ppm in soil extracts.
TL;DR: The determination of lead isotope ratios in 14 bullets, and in material taken from 9 hand swabs and 5 primers shows that there are potentially valuable forensic uses for such a method, and gunshot residue from a test-fired weapon was detectable even after washing the hands.
Abstract: The determination of lead isotope ratios in 14 bullets, and in material taken from 9 hand swabs and 5 primers shows that there are potentially valuable forensic uses for such a method. While a more complete study is required, this method could possibly be used to prove (or disprove) relatiohships between bullets and manufacturers, weapons, or persons firing the weapons. Sample size requirements (1 microgram or less) are such that damaged or fragmented bullets, or minute particles therefrom, may be used for the required analyses. An experiment showed that gunshot residue from a test-fired weapon was detectable even after washing the hands. Language: en