bluuebunny/crossref_metadata_2025 huggingface dataset:
Residue Level Determination of the Aquatic Herbicide Fluridone and a Potential
Photoproduct (N-Methylformamide) in Water
Authors: West Sheldon D , Turner Larry G
Published: February 2020

Methods are presented for the determination of the aquatic herbicide fluridone and /V-methylformamide (NMF), a potential photoproduct of fluridone which has thus far been observed only in a laboratory aqueous photolysis study. Water samples are passed through a Sep- Pak C,8 cartridge to extract fluridone while NMF passes unretained through the cartridge with the water. Fluridone is eluted from the cartridge with methanol, which is then concentrated for analysis by liquid chromatography with UV detection at 313 nm. The water eluate containing NMF is concentrated for analysis by rotary vacuum evaporation at 40-46°C. Methanol is added to help evaporate the water, and glycerol is added as a keeper solvent to retain NMF during the evaporation. The residual NMF is dissolved in methanol for analysis by gas chromatography with a Hall electrolytic conductivity detector operated in the nitrogen mode. The assay limits of detection are 1 and 2 ppb for fluridone and NMF, respectively. Recoveries averaged 98% for fluridone at 1-400 ppb and 87% for NMF at 2- 50 ppb.
Reverse-Phase Liquid Chromatographic Determination of Benzoic and Sorbic Acids in
Fresh Cheese
Authors: Kuppers Frans J. E. M , Jans Jan A
Published: February 2020

The sorbate and benzoate contents of commercial fresh cheese (quarg) samples are determined by reverse-phase liquid chromatography following extraction with a methanol-acetate buffer pH 4.5 mixture (37 + 63). The mobile phase is acetonitrile-acetate buffer pH 4.5 (20 + 80), the effluent flow rate is maintained at 1.0 mL/min, and the detector is set at 232 nm. Recoveries from quarg spiked at the 5-50 mg/kg level ranged from 95 to 99%, which compares favorably with methods previously published. Precision averaged 2-5% RSD, whereas the limit of detection was 0.3 mg/kg (sorbic acid) and 1.0 mg/kg (benzoic acid).
Aflatoxin, A Human Carcinogen: Determination in Foods and Biological Samples by Monoclonal Antibody Affinity Chromatography
Authors: Groopman John D , Donahue Kevin F
Published: February 2020

We have used monoclonal antibody technology to produce antibodies that recognize aflatoxins in order to develop noninvasive methods in conjunction with other chemical analytical techniques to monitor human exposure to environmental carcinogens. These methods require the ability to quantitate aflatoxins and their metabolites, including DNA and protein adducts, in readily accessible compartments such as serum and urine. The techniques permit efficient analysis of many samples in a relatively short time. Also, these monoclonal antibody affinity columns have been extremely useful for rapid isolation of aflatoxins from food and grain samples, as well as aflatoxin M, from milk. Monoclonal antibody affinity methods are nondestructive to the aflatoxin molecule, so the sample aliquot can be used for confirmation. The use of monoclonal antibody preparative affinity columns represents a major, substantive breakthrough for analytical chemists and will be a generally applicable technology for isolation of many different substances.
Quantitative Evaluation of Bacteria Washed from Stainless Steel Penicylinders During AOAC Use-Dilution Method
Authors: Alfano Edith M , Cole Eugene C , Rut Ala William A
Published: February 2020

Stainless steel penicylinders inoculated separately with test bacteria {Salmonella choleraesuis, Pseudomonas aeruginosa, or Staphylococcus aureus) are used in the AOAC use-dilution method (UDM) for disinfectant efficacy testing. Numbers of bacteria remaining on penicylinders were quantitatively assessed to determine if cells are washed from the penicylinders after a 10 min exposure to phosphate buffer dilution water (PBDW). Inoculated penicylinders were also examined by scanning electron microscopy (SEM) to determine the presence of cells remaining attached to the penicylinders after a 10 min exposure to a quaternary ammonium disinfectant and separately to PBDW. The percentage of cells washed from inoculated penicylinders exposed to PBDW was 89.9 for Salmonella choleraesuis, 48.8 for Pseudomonas aeruginosa, and 38.8 for Staphylococcus aureus. Qualitative examination of penicylinders by scanning electron microscopy confirmed the attachment of S. aureus and P. aeruginosa cells to penicylinders exposed separately to PBDW and a quaternary ammonium disinfectant. Few S. choleraesuis cells were observed on penicylinders exposed to PBDW and no cells were observed after disinfectant exposure. The variability of the numbers of viable cells entering the recovery media among the 3 UDM test bacteria due to cell detachment could be a significant factor in the recognized variability of the use-dilution method.
Comparison of Babcock and Ether Extraction Methods for Determination of Fat Content of Milk: Collaborative Study
Authors: Barbano David M , Clark Jenny L , Dunham Chapman E
Published: February 2020

Eleven collaborating laboratories analyzed 18 blind duplicate pairs of raw milk samples for fat by the Babcock method and by a modified Mojonnier ether extraction method in 7 round robins conducted over a 14 month period. Ten laboratories used the Babcock method and 10 used the modified Mojonnier method. Fat content of samples ranged from approximately 2.7 to 5.6%. Mean test value of samples analyzed was approximately 3.9% fat. Average standard deviations of within-laboratory repeatability (Sr) of the Babcock and ether extraction methods were 0.029 and 0.015% fat, respectively. Average standard deviations of between-laboratory reproducibility (SR) of the Babcock and ether extraction methods were 0.039 and 0.020% fat, respectively. Average repeatability relative standard deviations (RSDr) for the Babcock and ether extraction methods were 0.742 and 0.396%; average reproducibility relative standard deviations (RSDR) were 1.014 and 0.512%, respectively. Mean repeatability values (r) and reproducibility values (R) were 0.081 and 0.111% for Babcock and 0.044 and 0.056% for ether extraction, respectively. The ether extraction method demonstrated consistently better within- and between-laboratory agreement. The overall mean test value for the Babcock method was significantly higher (0.021% fat) than that for ether extraction. The difference between Babcock and ether extraction fat test results was different for different farms. In addition, the mean difference between percent fat determined by the Babcock and ether extraction methods was different in different months. There was no correlation in the difference between Babcock and ether extraction methods with the absolute level of fat in the samples in the range of 2.7 to 5.6% fat. The modifications of the AOAC Babcock method and the modified Mojonnier ether extraction method have been approved interim official first action.
Liquid Chromatographic Determination of the Estrogens Daidzein, Formononetin, Coumestrol, and Equol in Bovine Blood Plasma and Urine
Authors: Lundh Torbjorn J O , Pettersson Hans , Kiessling Karl-Heinz
Published: February 2020

A liquid chromatographic (LC) method is described for the determination of the plant estrogens daidzein, formononetin, and coumestrol and the estrogenically active metabolite equol in bovine blood plasma and urine. The blood and urine samples are incubated overnight with and without β3-glucuronidase/sulfatase for analysis of both free and conjugated forms of estrogens. Samples are applied to Extrelut ® columns, extracted with ethyl acetate, and evaporated to dryness. Residues from urine samples are dissolved in methanol, diluted with water, acidified with HCl, and purified by injection through a Sep-Pak® C,8 cartridge. This eluate is used for LC analysis. Residues from blood samples are dissolved in benzene-petroleum ether (1 + 1), extracted with ammonium hydroxide, acidified with glacial acetic acid, and extracted with ethyl acetate. The ethyl acetate extract is evaporated, dissolved in 80% methanol, injected onto a LC reversephase column, and separated in a linear gradient system between 40 and 80% methanol in phosphate buffer. Quantitation is performed by means of UV and fluorescence responses. The method was sensitive enough to determine 0.4 μg/mL of daidzein and formononetin and 0.1 and 13 ng/mL of coumestrol and equol, respectively, in blood, and 130,80, and 7 ®g/mL of daidzein, formononetin, and coumestrol, respectively, and 4 Mg/mL of equol in urine. The applicability of the method was checked by the determination of total and free plant estrogens in blood samples from a dairy cow fed a normal diet.
Liquid Chromatographic Method for Determination of Azinphos-Methyl in Formulated Products: Collaborative Study
Authors: Slahck Stephen C
Published: February 2020

A liquid chromatographic method for determination of azinphosmethyl (Guthion®) in formulated products has been developed. Samples are dissolved in acetonitrile and analyzed by reverse-phase chromatography using n-butyrophenone as an internal standard. The method was subjected to a collaborative study involving 15 participating laboratories. Each collaborator was furnished with reference standard, internal standard, and blind duplicate samples of Guthion 50% wettable powder (50WP), 3 flowable (3F), and emulsifiable concentrate (2L and 2S) formulations. Collaborators were instructed to evaluate the method by peak height measurements only. Relative standard deviations for reproducibility (RSDR) were 1.11, 6.28, 2.47, and 1.17% for the 50WP, 3F, 2L, and 2S formulations, respectively. The method has been approved interim official first action for determination of azinphos-methyl in the 50WP, 2L, and 2S formulations.
Liquid Chromatographic Determination of Rotenone in Fish, Crayfish, Mussels, and
Sediments
Authors: Dawson Verdel K , Allen John L
Published: February 2020

An analytical procedure is described for determining residues of rotenone in fish muscle, fish offal, crayfish, freshwater mussels, and bottom sediments. Tissue samples were extracted with ethyl ether and extracts were cleaned up by gel permeation chromatography and silica gel chromatography. Sediment samples were extracted with methanol, acidified, partitioned into hexane, and cleaned up on a silica gel column. Rotenone residues were quantitated by liquid chromatography, using ultraviolet (295 nm) detection. Recoveries from sediment samples fortified with rotenone at 0.3 μg/g were 80.8%, whereas recoveries from tissue samples fortified with 0.1 μg/g ranged from 87.7 to 96.8%. Samples fortified with 0.3 μg/g and stored at - 10°C for 6 months before analysis had recoveries ranging from 83.2 to 90.5%. Limits of detection were 0.025 μg/g for sediments and 0.005 μg/g for tissue samples
Liquid Chromatographic Determination of Olaquindox in Medicated Feeds and in Contents of
Porcine Gastrointestinal Tract
Authors: Spierenburg Theo J , Van Lenthe Henk , De Graaf Gertjan , Jager Lowie P
Published: February 2020

A liquid chromatographic method for the determination of olaquindox in both medicated feeds and porcine gastrointestinal tract is described. Samples are extracted with water and cleaned on a disposable reverse-phase column. The eluate is chromatographed on a reverse-phase column under isocratic conditions. Olaquindox is detected by UV absorption at 260 nm. The minimum amount detected by this method was 0.075 ng. The corresponding minimum detectable concentration in a 1 g sample was 0.3 mg/kg. The detector response was linear within the interval of 0-500 ng. Mean recovery of olaquindox in spiked gastrointestinal samples was 89 ± 5% (mean ± standard deviation, n = 43). Concentration profiles of olaquindox in the gastrointestinal tract of pigs fed medicated feed were used to evaluate the preventive potency against Treponema hyodysenteriae. The presence of some N-O reduced metabolites of olaquindox in the gastrointestinal tract was assessed
Liquid Chromatographic Determination of Propyl Paraben in Cigarette Filler
Authors: CastaÑo Jorge I , Palacio Francisco J , Vargas Luis R
Published: February 2020

A liquid chromatographic method for the quantitative determination of propyl paraben in cigarette tobacco filler has been developed. Propyl paraben is extracted from cigarette tobacco filler with acetonitrile and further purified using a silica Sep-Pak® cartridge and ethyl acetate-petroleum ether (1 + 4) as eluting solvent. The purified extracts are analyzed by reverse-phase liquid chromatography using buffered water (pH 4)-acetonitrile (65 + 35) as mobile phase, with UV detection at 254 nm. Cut tobacco samples were fortified with 100 and 200 ppm propyl paraben. Average recoveries (N = 5) of propyl paraben were 98 and 94%, respectively, with coefficients of variation less than 4%.
Competitive Direct Enzyme-Linked Immunosorbent Assay for Detection of
Sulfamethazine Residues in Swine Urine and Muscle Tissue
Authors: Dixon-Holland Deborah E , Katz Stanley E
Published: February 2020

A sensitive assay for the detection of sulfamethazine in swine urine and muscle tissue using a direct competitive enzyme-linked immunosorbent assay (ELISA) has been developed. Undiluted urine or a phosphate-buffered saline extract of pork muscle tissue is mixed with an enzyme-labeled conjugate of sulfamethazine and horseradish peroxidase. The mixture is added to wells of a microtiter plate coated with antibody to sulfamethazine. After the test system is incubated, washed, and re-incubated with substrate and the reaction is stopped, the absorbance is measured at 405 nm. Levels of sulfamethazine as low as 20 ng sulfamethazine/g muscle tissue and 10 ng sulfamethazine/ mL swine urine were detected and estimated
Liquid Chromatographic Determination of L-Ascorbate 2-Polyphosphate in Fish Feeds by
Enzymatic Release of L-Ascorbate
Authors: Wang Xiao-Ying , Liao Ming-Long , Hung Tsui-Hwa , Seib Paul A
Published: February 2020

An accurate method was devised to assay L-ascorbic 2-polyphosphate esters (AsPP) in fish feed by phosphatase digestion followed by determination of the released L-ascorbic acid (AsA). Compressed yeast and dithiothreitol are added to the phosphatase reaction mixture to give 95-100% recovery of AsA, which is quantitated by reverse-phase liquid chromatography (LC) with electrochemical detection. Chromatograms of all feed digests showed baseline resolution of AsA. In 3 feeds, to which 75-125 ppm AsA equivalents in the form of AsPP were added, the assay procedure gave 98-100% recovery of AsA
Liquid Chromatographic Determination of Zearalenone and a- and 0-Zearalenols in Milk
Authors: Scott Peter M , Lawrence Guillaume A
Published: February 2020

Previous research has demonstrated transmission of zearalenone and α- and β-zearalenols into the milk of cows and other animals. Since human intake of zearalenone and its metabolites via milk is an unknown factor in risk assessment of zearalenone and because appropriate methodology for their determination in milk is not available, a rapid and sensitive analytical method has been developed. Essentially, the method includes extraction with basic acetonitrile, acidification, partition into methylene chloride on a hydrophilic matrix, cleanup on an aminopropyl solid phase extraction column, and reverse- phase liquid chromatography with fluorescence detection. Recoveries from milk averaged 84% for zearalenone, 93% for α-zearalenol, and 90% for β-zearalenol at spiking levels of 0.5 to 20 ng/ mL. As little as 0.2 ng/mL of zearalenone and a-zearalenol and 2 ng/mL of 0-zearalenol can be detected in milk. These 3 compounds are stable in refrigerated milk for at least 2 weeks and in milk brought to boiling. Enzymes (β-glucuronidase and aryl sulfatase) may be added to milk prior to extraction to hydrolyze any conjugates
Evaluation of APHA and AOAC Methods for Phosphatase in Cheese
Authors: Murthy Gopala K , Cox Samuel
Published: February 2020

Varieties of market cheese were analyzed for alkaline phosphatase by the modified rapid colorimetric method of the American Public Health Association (APHA) and the official AOAC method, 16.304- 16.306. In the APHA method, 5 g cheese (pH <7.0) is macerated with 2 mL 1:1 carbonate buffer, or 2 mL water (for cheese with pH >7.0). Addition of 0.1 mL magnesium acetate (1 mg magnesium) to test portions of cheese extracts yielded reproducible and quantitative recovery of added phosphatase. In the AOAC method, macerating 0.5 g cheese with 1 mL borate buffer before adding milk phosphatase improved recovery among cheeses. Addition of magnesium ion increased phosphatase activity in some cheeses. Phosphatases in blue mold-ripened and Swiss cheeses were inactivated by heat faster than was milk phosphatase, yet milk phosphatase added to various soft cheeses was completely inactivated at 60°C for 10 min. The lability of phosphatase was due to the heat-denaturing effect of NaCl present in finished cheeses. Some Mexican style soft cheeses contained both heat-labile and heat-stable phosphatases. These data suggest that the phosphatase test to differentiate milk and microbial phosphatases on the basis of repasteurization and analysis of cheese is no longer valid
Liquid Chromatographic Determination of Saccharin in Beverages and Desserts:
Complementary Collaborative Study
Authors: SjÖberg Anna-Maija K
Published: February 2020

A complementary collaborative study was conducted on a liquid chromatographic method for determination of saccharin in accordance with the latest international recommendations. One industrial and 6 official food control laboratories analyzed 3 samples of a juice, a soft drink, and a dessert at concentration levels of 26-90 mg/L, 33-73 mg/L, and 56-147 mg/kg, respectively. Blind duplicates and a blank were supplied for each type of material at each concentration level. The beverage was chromatographed directly and the dessert was extracted with ethanol before chromatography. Average recoveries were 95-107%. The reproducibility relative standard deviations were 6.4-7.3% for the juice, 9.2-20.6% for the soft drink, and 13.4-16.2% for the dessert. The outlier percentage was 14.3%. The results were compared with those of an earlier collaborative study by Nordic laboratories and with general collaborative results obtained by AOAC
Radionuclides in Domestic and Imported Foods in the United States, 1983—1986
Authors: Cunningham William C , Stroube William B , Baratta Edmond J
Published: February 2020

Findings in the Food and Drug Administration's Radionuclides in Foods program are summarized for samples collected between October 1,1982, and September 30,1986. All radionuclide findings for Total Diet and reactor samples were either in Action Range I or low in Range II of the surveillance and control recommendations given by the Federal Radiation Council. The only long-range trend noted was a continuation of the general decline in dietary intake of "Sr since 1961. Imported food samples were analyzed for contamination after the Chernobyl nuclear accident. The findings for imported foods indicate that the surveillance efforts successfully targeted contaminated foods, and that contamination levels were below levels of concern for all but one oregano and 3 cheese samples.
Experimental Designs for Interlaboratory Precision Experiments: Comparison of ISO 5725 with Draft NEN 6303
Authors: Zaalberg J
Published: February 2020

To determine the precision of standardized analytical methods, interlaboratory experiments are carried out in which several laboratories analyze identical samples from well homogenized batches of material. From the test results, estimates of the standard deviations under repeatability as well as under reproducibility conditions are calculated. In the present work, the experimental designs recommended in the International Standard ISO 5725 have been compared with a design proposed in the draft Netherlands Standard NEN 6303. This has been done by comparing their mathematical models as well as by applying them to the results of a recent collaborative study on the determination of heavy metals in edible oils and fats. The reproducibility standard deviation is estimated equally well with both Standards, but it appeared that the designs given in ISO 5725 can lead to serious underestimation (uniform-level design) or overestimation (split-level design) of the repeatability standard deviation. By using the design proposed in NEN 6303, these biases can be avoided. Hence, it is recommended that interlaboratory studies be organized according to the design of NEN 6303.
Limited Survey of Deoxynivalenol in Wheat and Corn in the United States
Authors: Wood Garnett E , Carter Lawrence
Published: February 2020

A limited survey was conducted over a 2-year period to determine the incidence and levels of deoxynivalenol (DON) in corn and wheat grown in selected areas of the United States. Samples of corn (198) and wheat (247) were collected and analyzed by a gas chromatographic method. Sixty-six percent of the corn samples collected in 1984 and 30% of the corn samples collected in 1985 contained DON. The average concentration of DON in corn, by state, ranged from 0.11 to 1.20 μg/g; the maximum concentration was 2.47 μg/g. Only 2 of the 247 samples of wheat contained DON at a concentration >2 μg/g, which is the level of concern suggested by the Food and Drug Administration for wheat entering the milling process for human consumption.
Liquid Chromatographic Determination of Acids and Sugars in Homolactic Cucumber Fermentations
Authors: Lázaro Maria Jesus , Carbonell Elvira , Aristoy Maria Concepcion , SafÓn Jose , Rodrigo Miguel
Published: February 2020

A rapid, high yield, and quantitative method for determination of sugars (glucose and fructose) and acids (malic, lactic, acetic, and citric) in fresh and fermented cucumber juices is described; the procedure solves the fructose and malic acid coelution problem. Samples are prepared by passing the juice directly through a disposable C18 cartridge. Compounds are separated by liquid chromatography on an Aminex HPX-87H chromatographic column, with 0.013N H2S04 as mobile phase in the isocratic mode at 0.6 mL/min flow rate and 60°C column temperature. Compounds are then detected and quantitated by using ultraviolet and refractive index detectors connected in series, and comparing with succinic acid as internal standard. Values for both fresh and fermented cucumber juices were in good agreement with literature data.
Food Directorate of Canada Contributions to the Association of Official Analytical Chemists
Authors: Coffin D Earle
Published: February 2020

The Food Directorate of the Health Protection Branch, Department of National Health and Welfare, Canada, is a committed supporter of the aims and operation of AOAC. The Directorate and its staff members have made significant contributions to AOAC over the past 40 years, presently contribute to many aspects of the operation of AOAC, and will continue their support for the betterment of both organizations. This support relies on an organizational policy of cooperation with AOAC in method development, on the coordination of individual work programs with AOAC activities, and on the voluntary commitment of time and effort by a group of individuals. The present paper is a record of the contributions of the Food Directorate and its predecessors to AOAC and its purpose of providing validated analytical methods for regulatory use.
Microbiological Determination of Neomycin in Feeds: Collaborative Study
Authors: Stahl Gerald L , Kratzer D Dal , Kasson Charles W
Published: February 2020

A modification of the AOAC microbiological determination of neomycin in feeds was collaboratively studied by 12 laboratories. The official method was modified by substituting a constant salt concentration diluent for the feed extract diluent, preparing the agar medium in tris buffer, and performing the test with a monolayer plating system. Each laboratory performed single assays on 8 samples in a randomized sequence. The samples included duplicates of a cattle and swine feed at 2 different marketed concentrations. The mean recovery across all laboratories was 110.7% of theory with a range of means of 69.4-128.6 across the 12 laboratories. The results of one laboratory and 2 additional values from different laboratories were deemed outliers and excluded from statistical analysis. The statistical analysis gave a confidence interval of ± 26% for individual assays.
Simultaneous Liquid Chromatographic Determination of Water-Soluble Vitamins, Caffeine, and Preservative in Oral Liquid Tonics
Authors: Maeda Yumie , Yamamoto Masatoshi , Owada Kazuhiro , Sato Shiro , Nakazawa Hiroyuki
Published: February 2020

A rapid, simple, and reliable liquid chromatographic method has been developed for the simultaneous determination of nicotinamide (niacinamide), thiamine, riboflavin, riboflavin sodium phosphate, pyridoxine, caffeine, and sodium benzoate in commercial oral liquid tonics. The 7 components are separated on a reverse phase C18 column using a mobile phase of acetonitrile-O.OlM potassium dihydrogen phosphate-triethylamine (8 + 91.5 + 0.5 v/v/v) containing 5mM sodium octanesulfonate and adjusted to pH 2.8 with phosphoric acid. Components are detected at 254 nm with attenuation 0.02 AUFS. Acetanilide is used as an internal standard. In addition to the 7 components mentioned, nicotinic acid (niacin), cyanocobalamin, and folic acid are also separated under the same conditions. Sample preparation involves only addition to internal standard solution and dilution with mobile phase and then filtration. Recoveries of the 7 components and cyanocobalamin from spiked preparations ranged from 97 to 104% with coefficients of variation of 0.9-4.2%.
Comparison Between Liquid and Paste Karl Fischer Extractions for NIRS Water Calibrations
Authors: Windham William R
Published: February 2020

The acceptance of near infrared reflectance spectroscopy (NIRS) for the routine analysis of water in forage was made possible by the application of Karl Fischer (KF) water analysis as the primary reference method during calibration. Water is extracted by ball milling the sample in the presence of methanol (1:50), and an aliquot of the liquid phase is sampled and titrated. An alternative extraction utilizes a 20 g sample with 20 mL methanol, and an aliquot of the paste is sampled and titrated. The objectives of this study were to compare extraction procedures (i.e., liquid vs paste) on the determination of water in 75 milled grains and concentrate rations, and to develop and compare NIRS calibrations for water on the basis of both extraction methods. The majority of the samples (N = 61) had a 1.05 percentage unit greater water content (P < 0.05) from the paste method than from the liquid method. Bias between the extraction procedures was positively correlated (r2 = 0.84) to starch content. The lowered extraction efficiency of the liquid method is explained by its inability to account for water bound to starch. NIRS calibration and equation validation statistics were superior with water data from the paste method. The increased calibration errors with the liquid method also appear to reflect the inability of the method to accurately measure the total water concentration of the samples in relation to the water measurement based on the NIRS signals. The study concludes that the KF paste method is a superior primary reference method for the determination of water in flour obtained from cereal grains and concentrate rations.
Rapid Headspace Gas Chromatographic Method for Assessment of Oxidative Stability of Cooked Chicken Meat
Authors: Ang Catharina Y W , Young Louis L
Published: February 2020

Experiments were conducted to determine the volatile compounds in cooked chicken meat using a static headspace gas chromatographic (GC) technique. Preheating conditions for samples in vials were tested at 70,80, and 90°C for 20-120 min at each temperature. The majority of the peaks increased in size as the temperature and time increased. Optimum conditions were established as preheating at 80°C for 30 min followed by analysis on a packed column of 8% Poly MPE on Tenax GC with the temperature programmed from 50 to 200°C at 10°/min. Coefficients of variation for major peaks ranged from 8.3 to 14.7%. These results were compared with those obtained with a capillary column analysis of samples preheated at the same conditions. Cooked and stored chicken patties, pretreated with different levels of sodium tripolyphosphate, were analyzed by the thiobarbituric acid (TBA) method and the headspace GC technique. Significant positive correlations were obtained between TBA numbers and the areas of 3 major peaks of the headspace profiles, indicating the applicability of the rapid headspace GC method for the determination of oxidative changes in chicken meat.
Temperature-Independent Pectin Gel Method for Coliform Determination in Dairy Products: Collaborative Study
Authors: Roth Jonathan N , Bontrager Gordon L
Published: February 2020

Ten laboratories participated in a collaborative study to compare a pectin-based violet red bile (VRB) method with the VRB agar-based standard method for estimation of coliform bacterial counts in 7 different dairy food groups: cream, cheddar cheese, cottage cheese, homogenized milk, raw milk, sour cream, and yogurt. Each laboratory analyzed 8 samples of each food group as sample pairs prepared at high, medium, and low inoculum levels, and an uninoculated control pair. Overall mean log counts were higher for the pectin gel method in 18 of 21 cases (7 samples at 3 inoculum levels); 12 results were significantly higher (P < 0.01) than those for the VRB agar method. Of the 3 higher VRB agar method means, 2 were not significant at P < 0.10, and one was of borderline significance (0.05 < P < 0.06). Repeatability variation (sr) favored the pectin gel method in 14 of 21 cases; 7 were highly significant differences (P < 0.01). None of the 7 results favoring the VRB agar method was statistically significant. Reproducibility variation (sR) favored the pectin gel method in 14 of 21 results. These data indicate that the pectin gel method gives higher recovery of coliforms with better precision than does the VRB agar method, and strongly support the suitability of the pectin gel method as an alternative to the agar-based VRB method for coliform counts in dairy products. The pectin gel method has been adopted official first action.
Fluorescent Enzyme Immunoassay for Rapid Screening of Salmonella in Foods: Collaborative Study
Authors: Flowers Russell S , Klatt Mary Joan , Keelan Susan L , Swaminathan B , Gehle Warren D , Chandonnet Heidi E
Published: February 2020

A collaborative study was performed in 13 laboratories to validate an enzyme immunoassay (EIA) procedure for rapid detection of Salmonella in foods. The EIA was compared with the standard culture procedure for detection of Salmonella in 6 food types: ground black pepper, soy flour, dried whole eggs, milk chocolate, nonfat dry milk, and raw deboned turkey. Uninoculated and inoculated samples were included in each food group analyzed. There was no significant difference in the proportion of samples positive by the EIA and culture procedures at the 5% level for any of the 6 foods. The enzyme immunoassay screening method has been adopted official first action as a rapid screening method for detection of Salmonella.
Simultaneous Gas Chromatographic Determination of Carbofuran, Metalaxyl, and Simazine in Soils
Authors: Getzin Louis W , Cogger Craig G , Bristow Peter R
Published: February 2020

A method for extraction, cleanup, and simultaneous gas chromatographic detection of carbofuran, metalaxyl, and simazine in soils has been developed. Pesticide residues were extracted from soil with acetone containing 10% 0.2M HCl-KCl buffer (pH 2.0), cleaned up with methylene chloride-carbonate buffer (pH 10.7) solvent partitioning and solid-phase extraction on disposable silica gel columns, and quantitated with gas chromatography using a Supelcowax 10 megabore capillary column and a nitrogen-selective detector. Method limits of detection were 0.02 μg/g for the 3 pesticides in surface soils (0-30 cm depths) and 0.02,0.02, and 0.005 μg/g in soils below 30 cm (subsoils) for carbofuran, metalaxyl, and simazine, respectively. Recoveries for carbofuran, metalaxyl, and simazine were 92.6 ± 5.5, 93.6 ± 5.0, and 88.4 ± 6.7%, respectively, when soil samples were spiked with pesticide concentrations ranging from 0.02 to 2.0 μg/g.
Application of Analytical Standards in Method Development: Selected Chlorinated Phenols and Herbicides
Authors: Fast Douglas M , Reddy V Vikram , Ashley David L , Holler James S
Published: February 2020

Pure analytical standards are key components in the successful development of accurate analytical methods. When such compounds are unavailable commercially, a laboratory synthesis activity can provide such materials for use in method development. An example of such an approach is the synthesis of ethyl ethers of chlorinated phenols and ethyl esters of several phenoxy herbicides. Individual synthesis steps and the characterization of such materials are described. The use of such analytical standards in method development is vital for defining method characteristics. In addition, such materials are helpful in diagnosing chromatographic and mass spectral problems in the course of this work. Key mass spectral information including parent and daughter scans obtained from these analytical standards by using tandem mass spectrometry provide the basis for a new analytical method with increased sensitivity and specificity.
Closed Vessel Sample Decomposition by Microprocessor Controlled High Temperature/ Pressure Asher for Elemental Analysis by Inductively Coupled Argon Plasma Emission Spectrometer
Authors: White R Thomas
Published: February 2020

A safe, reliable, and efficient method is described for automated acid decomposition of biological samples, agricultural food products, and environmental material under high temperature and pressure. A high temperature/pressure asher that provides temperatures up to 320°C and pressures up to 100 bars (1450 psi) is used to heat 5 mL of ultrapure acid 4 h for complete sample decomposition. The unit is microprocessor-controlled with up to 5 programmable temperature levels and ramp time intervals. These levels and intervals are displayed on a CRT screen. Both temperature and pressure program set points and actual readings inside the autoclave can be monitored by an analyst as the decomposition program progresses. Biological samples and agricultural food products of 1.0 g each are weighed into 70 mL closed quartz vessels for acid digestion. The digested samples are analyzed by using an inductively coupled argon plasma (ICP) emission spectrometer for aluminum, boron, calcium, iron, lead, magnesium, manganese, phosphorus, potassium, sodium, strontium, sulfur, and zinc. Environmental material of 0.2 g each is weighed into 20 mL glassy carbon vessels for digestion and ICP analysis for calcium, iron, lead, magnesium, manganese, nickel, phosphorus, potassium, sodium, strontium, sulfur, titanium, and zinc. The average recovery for 31 elemental standards evaluated by digestion in the high temperature/ pressure asher provided an average recovery of 98.7%.
Determination of Size Distribution of Fat Globules in Intravenous Fat Emulsions by Photon Correlation Spectroscopy
Authors: Cyr Terry D , Lawrence Robert C , Lovering Edward G
Published: February 2020

A photon correlation spectroscopy method has been developed to characterize the size distribution of fat globules in intravenous fat emulsions (IFE) in terms of mean diameter, standard deviation of the distribution, and percentage of large particles outside the distribution. Mean fat globule diameters of samples of all IFE products available in Canada were about 0.3 μm, similar to values reported in the literature. The methodology is sufficiently sensitive to detect the presence of 5% by weight of 2 μm polystyrene microspheres in an intravenous fat emulsion. The effect of changes in instrument settings and variables on the results has been evaluated.
Determination of Water-Insoluble Cell Walls in Feeds: Interlaboratory Study
Authors: Carré Bernard , Brillouet Jean-Marc
Published: February 2020

A collaborative study was conducted to test a new rapid procedure for determination of water-insoluble cell wall (WICW) content in feeds. In the method, starch is solubilized near boiling temperature with Termamyl, a heat-stable alpha-amylase, and proteins are solubilized at 40 °C with sodium dodecylsulfate and Pronase. Then, the organic matter of the residue is determined by incineration. Three hours were required to treat 12 different samples, including solubilization treatments, filtrations, and rinses. Eleven unknown products including 9 common feedstuffs of various origin and 2 mixed diets for poultry were analyzed by 7 analysts in France. Coefficients of variation ranged from 2.3 to 6.1%. The results were compared to those for water-insoluble dietary fiber (WIDF), total dietary fiber, and neutral detergent fiber. Agreement was best with the water-insoluble dietary fiber procedure. For most samples, the ratios of WIDF/WICW ranged from 0.981 to 0.842. The differences between WICW and WIDF values correspond to cell wall protein which is accounted for in WICW, but not in WIDF.
Determination of Arsenic and Selenium in Whole Fish by Continuous-Flow Hydride Generation Atomic Absorption Spectrophotometry
Authors: Brumbaugh William G , Walther Michael J
Published: February 2020

A combined wet chemical and dry ash digestion and use of a continuous- flow hydride generator coupled with a flame-heated quartz cell enabled the simple, precise, and highly automated atomic absorption determination of arsenic and selenium in tissues of whole fish. Percent relative standard deviation averaged 4% for each element; method detection limits (μg/g dry wt) were about 0.06 for arsenic and 0.04 for selenium. Digestion of samples proceeded with little operator attention and without perchloric acid. Analysis for arsenic as As(V) simplified sample preparation but care had to be exercised to avoid interferences from high concentrations of selenium.
Levels of Polychlorinated Biphenyls and Pesticides in Bluefish Before and After Cooking
Authors: Trotter William J , Corneliussen Paul E , Laski Ronald R , Vannelli Joseph J
Published: February 2020

Similar levels of polychlorinated biphenyls (PCBs), pesticides, and fat were found in 20 correlated uncooked and cooked (baked) bluefish fillets. Fillets averaged 2.5 ppm PCBs as Aroclor 1254 (whole basis) before cooking; after cooking, with the oil drippings and skin discarded, the average PCB level was 2.7 ppm. Although PCBs, lipophilic pesticides, and fat were lost along with oil drippings and skin that were discarded after cooking, the moisture loss in the fillets during cooking compensated for these weight losses almost completely. After the fillets were cooked and the oil drippings and skin were discarded, the PCB content of the fillets was 27% lower on the average.
Tolerance Setting Process in the U.S. Environmental Protection Agency
Authors: Trichilo Charles L , Schmitt Richard D
Published: February 2020

The U.S. Environmental Protection Agency (EPA) is responsible for setting tolerances for pesticide residues in food, under the authority of the Federal Food, Drug, and Cosmetic Act. The residue chemistry data required to set tolerances include metabolism in plants and animals, analytical methods, magnitude of the residue, and concentration in processed foods. A key aspect of tolerance-setting procedures is the identity of the residue in the matrix of concern; without knowledge of the chemical moieties that occur as residues, it is impossible to develop suitable methods or generate meaningful residue data. For new chemicals, EPA carries out a single-laboratory validation of the analytical method needed to generate residue data and to enforce tolerances. Tolerance enforcement methods need to be rapid and inexpensive and to use commercially available equipment and reagents. Methods are more complex for many newer pesticides, which are polar compounds that leave low levels of residue. EPA now requires that the registrants of older pesticides, for which methods are not acceptable by today's standards, must develop better methods.
Aflatoxins in Domestic and Imported Foods and Feeds
Authors: Wood Garnett E
Published: February 2020

Aflatoxins, metabolic products of the molds Aspergillus flams and A. parasiticus, may occur in foods and feeds. These toxins cannot be entirely avoided or eliminated from foods or feeds by current agronomic and manufacturing processes and are considered unavoidable contaminants. To limit aflatoxin exposure, the U.S. Food and Drug Administration (FDA) has set action levels for these toxins in foods and feeds involved in interstate commerce. FDA continually monitors food and feed industries through compliance programs. This report summarizes data generated from compliance programs on aflatoxins for the fiscal year 1986. Commodities sampled included peanuts and peanut products, corn and corn products, tree nuts, cottonseed, milk, spices, manufactured products, and miscellaneous foods and feeds. Correlations were highest between aflatoxin contamination and geographical areas for corn/corn products and cottonseed/cottonseed meal. Higher incidences of aflatoxin contamination in corn and corn products designated for human consumption were observed in samples collected in the southeastern states (32 and 28%, respectively). A higher incidence of contamination was observed in corn designated for animal feed from Arkansas-Texas (74%) than from the southeastern states (47%). Only 3% of feed corn from corn belt states contained detectable aflatoxins. All aflatoxin-contaminated cottonseed was collected in the Arizona-California area; 80% of cottonseed meal analyzed from this area also contained detectable levels of aflatoxins. No aflatoxin Mi was detected in any of the 182 samples of fluid milk and milk products examined. The percentage of samples that contain measurable levels of aflatoxins is expected to vary with commodities from year to year; thus, the 1986 information can be used as a baseline for comparison to determine the effectiveness of control efforts exerted by the food and feed industries.
Polarographic Determination of Famotidine in Dosage Forms
Authors: Squella Juan A , Valencia Gladys , Lemus Igor , Nunez-Vergara Luis J
Published: February 2020

Famotidine, which cannot be electrochemically reduced at the dropping mercury electrode, exhibits catalytic proton reduction waves. The peak obtained by in-phase ac polarography in neutral media is of analytical interest. Recovery studies and individual tablet assays are described. Results show adequate precision and accuracy. Sample preparation is not time consuming, and no excipient separation is required.
Determination of Enantiomeric Purity of Tranylcypromine Sulfate by Proton Magnetic Resonance Spectroscopy with Chiral Lanthanide Shift Reagent
Authors: Hanna George M , Lau-Cam Cesar A
Published: February 2020

Optimum experimental conditions were developed for determination of the optical purity of samples of tranylcypromine sulfate by proton magnetic resonance spectroscopy after complexation with the chiral lanthanide chelate Eu(hfc).3. At a substrate concentration of 0.25M (0.125M as sulfate) in CDC13 and an Eu(hfc)3 to substrate molar ratio of 1, the methine proton geminal to the amino group in the cyclopropane ring showed the largest induced shift and largest enantiomeric induced shift difference. From the relative intensities of the resolved (+)-CH-NH2 protons (15.77 ppm) and (-)-CH-NH2 proton (16.04 ppm), the enantiomeric purity and percentage compositions were readily calculated. The mean ± SD recovery of (+)- tranylcypromine sulfate from synthetic enantiomeric mixtures was 101.02 ± 2.59 (n = 6).
Determination of Nicarbazin in Chicken Tissues By Liquid Chromatography and Confirmation of Identity By Thermospray Liquid Chromatography/Mass Spectrometry
Authors: Lewis Jerry L , Macy Thomas D , Garteiz Daniel A
Published: February 2020

A liquid chromatographic method is described for the quantitative measurement of nicarbazin in chicken liver, fat, muscle, and skin tissues. The 4,4'-dinitrocarbanilide (DNC) portion of nicarbazin is extracted from tissues with ethyl acetate. After filtration and evaporation, the extract is purified by liquid-liquid partitioning with acetonitrile-hexane and alumina cartridge chromatography. DNC is separated and measured by reverse-phase liquid chromatography (RPLC) with an octadecylsilyl (ODS) column and a UV detector set at 340 nm. The overall average recovery of DNC added to tissues was 83.4 ±3.1%. The lowest level validated in tissues by this procedure was 0.10 ppm. The limit of detection was estimated to be 0.020 ppm. This method provides a sensitive, selective, rapid, and reproducible alternative to existing purification, separation, and detection techniques, such as differential pulse polarography and colorimetry, for determination of nicarbazin in chicken tissues. Identity of DNC is confirmed by subjecting the purified extracts to thermospray-LC/mass spectrometric analysis using negative-ion detection and selected ion monitoring. Three structural-indicating ions at m/z 302,272, and 164 are monitored in the thermospray-mass spectrum which are characteristic of the DNC molecule.
Liquid Chromatographic Determination and Gas Chromatographic-Mass Spectrometric Confirmation of Lasalocid Sodium in Bovine Liver: Interlaboratory Study
Authors: Frank Lesley R , Barnes Charlie J
Published: February 2020

The U.S. Food and Drug Administration (FDA) sponsored an interlaboratory study of a liquid chromatographic determinative procedure for lasalocid sodium in chicken skin with adhering fat. Four laboratories analyzed 35 dosed tissue samples and 82 fortified tissue samples containing lasalocid at levels ranging from 0.1 to 0.6 ppm. Samples were homogenized with acetonitrile, washed with hexane, and partitioned into the mobile phase prior to analysis liquid chromatography with fluorescence detection. The results of the interlaboratory study showed good reproducibility for fortified samples. Fortification levels, average recoveries, and interlaboratory percent coefficients of variation were as follows: 0.6 ppm, 0.57 ppm, and 9.7; 0.3 ppm, 0.25 ppm, and 9.1; and 0.15 ppm, 0.14 ppm, and 7.0, respectively. Data for analysis of the dosed tissue also showed good agreement among the laboratories.
Microscopic Detection and Identification of Various Substitute Vegetable Tissues in Ground Horseradish
Authors: Galacci Raymond R
Published: February 2020

Turnip root, parsnip root, potato tuber, and corn kernels have been used as adulterants in the preparation of horseradish sauce and horseradish powder. The diagnostic histological features of horseradish root and its known adulterants are described and illustrated as viewed through a polarizing microscope with cross polars and a first order red plate. A procedure which can be used to detect any of the known adulterants in horseradish is described. The adaptation of a previously reported semiquantitative method is also discussed.
Determination of Orotic Acid by Liquid Chromatography as a Criterion for Calculating Nonfat Milk Solids in Milk Bread
Authors: Bui Lap V
Published: February 2020

A sensitive and reproducible isocratic liquid chromatographic method is described for the determination of orotic acid levels in skim milk powder and milk bread. The results are used to calculate the nonfat milk solids content in milk bread. Sample preparation is simple and rapid and produces an extract which, after passing through an on-line cleanup system, has a minimum adverse effect on the performance and life of the analytical column. Mean recoveries of 96-105% were obtained with coefficients of variation in the range 1.0-8.5% and a detection limit of 5 mg/kg. The liquid chromatographic method was more sensitive than the standard colorimetric method, while results obtained by both methods agreed closely.