bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrocarbons m Crude Palm Kernel Oil
Authors: Tan Yew Ai , Kuntom Ainte
Published: February 2020

The sources of hydrocarbons in crude palm kernel oil were investigated by a series of laboratory-controlled oil extractions of kernels of varying quality. Site examinations of palm kernel-crushing plants were also conducted to determine possible sources of hydrocarbon contamination of palm kernels throughout the process of kernel extraction. Parallel to these studies, a random survey of crude palm kernel oil (CPKO) produced by different kernel crushers was also carried out to determine the range of hydrocarbon concentrations in locally produced CPKO. This study showed that hydrocarbons can be picked up from sources such as glassware, extracting apparatus, and plastic containers and stoppers. Extraction of oil from low-quality kernels that were both moldy and rancid, broken kernels, and kernels plus added shells also resulted in a higher hydrocarbon level in the final CPKO. Overheating and cooking of the kernels before extraction also contributed to the overall hydrocarbon content. The random survey of hydrocarbon level showed a range of 0.6–7.1 ppm.
Liquid Chromatographic Determination of Phosphamidon in Technical and Formulated Products: CIPAC Collaborative Study
Authors: Hanks Alan R
Published: February 2020

Phosphamidon is determined by reversed-phase liquid chromatography on a C18 column with a mobile phase of acetonitrile—methanol buffer solution, detected by a UV absorbance detector set at 218 nm, and quantitated by area measurements using an external standard. The method was adopted first action by AOAC INTERNATIONAL.
Wide-Bore Capillary Gas Chromatographic Determination of Organophosphorus Pesticide Residues in Foods: Interlaboratory Trial
Authors: Parfitt Charles H
Published: February 2020

Wide-Bore capillary columns are often used as alternatives to traditionally packed columns for gas chromatographic (GC) determination of pesticide residues in foods. Fused silica columns with cross-linked, bonded stationary phases are reproducible, rugged, and easy to use and are substantially more inert than their packed column equivalents. An interlaboratory trial was conducted in 5 U.S. Food and Drug Administration laboratories to determine the practicability of using isothermal wide-bore capillary GC as an alternative to the packed column GC systems used in AOAC Official Methods for determining pesticide residues in foods. Two wide-bore capillary columns with flame photometric detection were evaluated with respect to the following: linearity of detector response; repeatability of response for equal and unequal injection volumes of standard solutions; accuracy of quantitating pesticides in food extracts when the injection volumes or analyte concentrations of the standard solution and the food extract are different; recoveries of 23 pesticides from 5 fortified food extracts, calculated from both duplicate and single injections; and relative retention times. Before shipment, food extracts supplied to participants were fortified with pesticides after preparation and extraction of the foods by Official Method 985.22. The performance of wide-bore capillary columns with cross-linked bonded methyl silicone and methyl phenyl silicone stationary phases was equal or superior to that of the packed columns specified in the Official Method.
Effect of Infrared Analyzer Homogenization Efficiency on Linearity of Uncorrected Fat A and Fat B Signals
Authors: Smith Erika B , Barbano David M , Lynch Joanna M , Fleming J Richard
Published: February 2020

The objective of the survey was to determine if poor homogenizer performance causes nonlinear behavior of the uncorrected fat A or fat B signal that is not detected when an instrument’s residual nonlinearity is determined by using dilutions of homogenized milk instead of unhomogenized milk. Unhomogenized and homogenized (17238 kPa) portions of the same 6.1% fat milk were tested on 20 instruments to determine homogenization efficiency. Instruments with differences of ≥0.087% fat between homogenized and unhomogenized portions of the same milk had inefficient homogenization, on the basis of criteria established in a previous study. Four and 12 instruments out of 20 demonstrated inefficient homogenization for the fat A and fat B channels, respectively. Uncorrected signal linearity for the fat channels was evaluated quantitatively by using a series of dilutions of homogenized (17238 kPa) and unhomogenized milks. Most instruments passed the linearity evaluation for dilutions of either homogenized or unhomogenized milk, even though many of the same instruments failed the homogenization efficiency evaluation. Thus, using dilutions of homogenized milk is valid for linearity evaluation of instruments being used for testing unhomogenized milk in the range of fat concentrations used for payment testing.
Quantitative Detection of Whey Cream in Sweet Cream and Butter
Authors: Polak Pavel , Bradley Robert L
Published: February 2020

A simple and sensitive assay is described that can detect trace amounts of whey cream in sweet cream and in butter made from that cream. The method is based on the detection of sialic acid and involves a color reaction between Ehrlich’s reagent and sialic acid. The procedure is faster than other methods for detection of whey. The method could be termed semiquantitative because of the seasonal variability of sialic acid in cow’s milk. However, with a calibration curve, the method is quantitative and can easily detect as little as 1% whey cream in sweet cream and in the resulting butter. With 1% whey cream in sweet cream, the purple color indicating the presence of sialic acid is visible to the naked eye.
An Optimized MTT Bioassay for Determination of Cytotoxicity of Fumonisins in Turkey Lymphocytes
Authors: Dombrink-Kurtzman Mary A , Bennett Glenn A , Richard John L
Published: February 2020

In vitro cytotoxicity assays have been performed for detection and quantitation of fumonisins, as possible alternatives for whole animal testing. This study was undertaken to establish optimal in vitro conditions using turkey lymphocytes. Turkey lymphocytes were isolated from peripheral blood by Percoll gradient centrifugation. Cytotoxicity of fu-monisin B1 (FB1) and B2 (FB2) was determined by exposing lymphocytes to FB1 or FB2 at concentrations of 0.01–25 μg/mL for 24,48, or 72 h at 39°C. The MTT bioassay was used to measure cell viability and proliferation. In metabolically active cells, the tetrazolium salt, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide], was reduced to MTT formazan. Turkey lymphocytes that had been exposed in vitro to FB1 and FB2 for 48 and 72 h showed inhibition of cell proliferation that was dose-dependent. The 50% inhibitory dose for FB1 and FB2 was 0.4–5 μg/mL. Cells exposed to FB1 or FB2 exhibited high levels of cytoplasmic vacuolization and were unable to proliferate, whereas proliferation of control lymphocytes was observed at 48 and 72 h. FB2 was 3- to 4-fold more cytotoxic than FB1.
Niacin II: Identification of Isonicotinic Acid in Niacin by Liquid Chromatography with Diode Array Detection
Authors: Kirchhoefer Ross D
Published: February 2020

Isonicotinic acid impurity in bulk niacin was detected and identified by comparison with a reference material by liquid chromatography with a diode array detector. The niacin was dissolved in dilute hydrochloric acid and chromatographed on an amine column with a mobile phase of methanol and water acidified with formic acid. Isonicotinic acid has a relative retention time of 1.5 compared with niacin (nicotinic acid), and the wavelengths of maximum ultraviolet (UV) absorbance for isonicotinic acid and niacin are 270 and 260 nm, respectively. The amount of impurity found in the niacin sample was 0.3%. Twelve formulations, including sustained-release products, one bulk material, and the United States Pharmacopeia (USP) reference standard were tested. The impurity was detected in only the bulk and USP reference material samples.
Gas Chromatographic Determination of Chloramphenicol Residues in Shrimp: Interlaboratory Study
Authors: Munns Robert K , Holland David C , Roybal José E , Storey Joseph M , Long Austin R , Stehly Guy R , Plakas Steven M
Published: February 2020

An interlaboratory study of a gas chromatographic method for determining chloramphenicol (CAP) residues in shrimp was conducted. An internal standard (Istd), the meta isomer of CAP, was added to the shrimp, and the treated shrimp were homogenized with ethyl acetate. The ethyl acetate extract was defatted with hexane, and the CAP was partitioned into ethyl acetate from an aqueous salt solution. The ethyl acetate was evaporated, and the dried residue was treated with Sylon, a trimethyl-silyl derivatizing agent, to yield the trimethylsilyl derivative of CAP. A portion of the solution containing the derivative was injected into a gas chromatograph equipped with an electron capture detector. Levels of fortified and incurred CAP were calculated from the peak area ratio of standard CAP to Istd. Recoveries of CAP from tissue directly fortified at 5 ppb were 102% (within-laboratory relative standard deviation [RSDr] = 5.6%), 104% (RSDr = 5.5%), and 108% (RSDr = 6.3%) from Laboratories 1, 2, and 3, respectively. Incurred-CAP residues at 5 and 10 ppb levels were also determined, with the following results: Laboratory 1: composite A, 4.56 ppb (RSDr = 14.0%); composite B, 8.38 ppb (RSDr = 11.6%); Laboratory 2: composite A, 4.17 ppb (RSDr = 12.5%); composite B, 8.90 ppb (RSDr = 5.60%); Laboratory 3: composite A, 4.66 ppb (RSDr = 14.9%); composite B, 11.0 ppb (RSDr = 11.8%).
Determination of Volatile Organic Contaminants in Bulk Oils (Edible, Injectable, and Other Internal Medicinal) by Purge-and-Trap Gas Chromatography/Mass Spectrometry
Authors: Thompson Don W
Published: February 2020

Purge-and-trap gas chromatography/mass spectrometry is evaluated for the quantitation of part-per-billion levels of volatile organic contaminants in bulk vegetable oils. Results using 2 purge techniques (direct purging of the heated oil and purging after dispersing the oil on an aluminum oxide powder) and 2 quantitative methods (standard curve and deuterium-labeled internal standard addition) are reported. Twenty volatile compounds and 8 vegetable oils were investigated. Recovery data and estimated detection limits for each compound are reported for each purge technique. Generally acceptable recoveries (70-130% for more than 90% of the analyte spikes) and acceptable detection levels (approximately 4-10 ppb) were obtained for all compounds using either the external standard curve or the deuterium-isotope-labeled internal standard. The use of a dispersant (such as alumina) for sample purging resulted in poor recoveries of the highly volatile contaminants.
Enzyme-Linked Immunosorbent Assay of Total Aflatoxins B1, B2, and G1 in Corn: Follow-up Collaborative Study
Authors: Trucksess Mary W , Stack Michael E
Published: February 2020

A direct competitive enzyme-linked immunosorbent assay screening method for af latoxins at 20 ng/g in corn was studied by 15 collaborating laboratories. Test samples of corn were extracted by blending with methanol-water (8 + 2). The extracts were filtered and the filtrates were diluted with buffer to a final methanol concentration of <30%. Each diluted filtrate was applied to a test device containing a filter with immobilized polyclonal antibodies specific to aflatoxins B1, B2, and G1. Aflatoxin Bi-peroxidase conjugate was added, the test device was washed with water, and a mixture of hydrogen peroxide and tetramethylbenzidine was added. A test sample was judged to contain ≥20 ng af latoxins/g when, after exactly 1 min, no color was observed on the filter; if a blue or gray color developed, the test sample was judged to contain <20 ng aflatoxins/g. All laboratories correctly identified naturally contaminated corn test samples. Only one false positive was found for controls containing no aflatoxins. The correct responses for positive test samples spiked at levels of 10,20, and 30 ng aflatoxins/g (the ratio of B1:B2:G1 was 15:1:3) were 67,97, and 100%, respectively. This method was adopted first action by AOAC INTERNATIONAL as a change in method for 990.34 for screening for aflatoxins B1, B2, and G1 in corn at total aflatoxin concentrations of ≥20 ng/g.
Determination of Soluble Dietary Fiber in Foods and Food Products: Collaborative Study
Authors: Prosky Leon , Asp Nils-Georg , Schweizer Thomas F , Devries Jonathan W , Furda Ivan , Lee Sungsoo C
Published: February 2020

A collaborative study was conducted to determine the soluble dietary fiber (SDF) content of foods and food products by using a combination of enzymatic and gravimetric procedures. The method was basically the same as that employed for determining total dietary fiber (TDF), 985.29, and the method for insoluble dietary fiber (IDF), 991.42. Ten laboratories were each sent 13 test samples (6 blind duplicates and 1 standard [green beans] containing 29-33% TDF, 19-23% IDF, and 8-13% SDF) and were instructed to assay for IDF, SDF, and TDF independently. Included in the package were the 3 enzymes, namely alpha-amylase, amyloglucosidase, and protease, and the filter aid Celite, which was thought to be the major cause of high reproducibility relative standard deviation (RSDR) values for SDF obtained in a previous collaborative study. The foods to be analyzed were apricots, carrots, chickpeas, onions, raisins, and the sugar beet fiber Fibrex™. IDF, TDF, and SDF were calculated as the weight of residue minus the weight of protein and ash on a dry weight basis. RSDR values of the IDF results averaged 8.02%, with only 1 food having an RSDR >10%. The RSDR values for the TDF results averaged 4.97%, and all foods had an RSDR <7%. Although the RSDR values for SDF averaged 14.17%, 4 of the 6 foods had an RSDR <10%, and 1 of the 2 remaining foods that had a high RSDR had an SDF content of only 1.2%. In all cases, the RSDR values of the SDF content of the foods were less than the values for the same foods analyzed in a previous collaborative trial. The enzymatic-gravimetric method for the determination of SDF was adopted first action by AOAC INTERNATIONAL.
Accuracy and Precision of Fossomatic 250/300/360 Series of Somatic Cell Counters Compared to Fossomatic 215: Collaborative Study
Authors: Mckenna David
Published: February 2020

AOAC method 978.26, Somatic Cells in Milk—Optical Somatic Cell Counting Method (Fossomatic), using Fossomatic 215 was adopted first action in 1978 and final action in 1984. The method specifying a second-generation cell counter, the Fossomatic 90, was approved final action in 1989. This demonstrates that the method has been well tested and has satisfied all the requirements of the Association. Since then, the manufacturer, Foss Electric, has introduced a third generation of equipment, which is being distributed as 3 different models. These are the Fossomatic 250, Fossomatic 300, and Fossomatic 360. The models differ only in their packaging and the speed at which they perform analyses.
Gel-Permeation Liquid Chromatographic Method for Determination of Polymerized Triglycerides in Oils and Fats: Summary of Collaborative Study
Authors: Firestone David
Published: February 2020

The IUPAC Commission on Oils, Fats and Derivatives undertook development of a method and collaborative study for determination of polymerized triglycerides in oils and fats. Two collaborative studies were carried out by IUPAC in 1985 and 1986. Both studies consisted of 4 materials, including animal fat, frying oil with average content of polymers, and blends of frying oil containing varying amounts of polymers. Thirteen and 17 laboratories were included in the first and second IUPAC collaborative studies, respectively. Another collaborative study conducted by Inspectorate for Health Protection, Food Inspection Service, The Netherlands, included 13 laboratories. Six heat-processed fat samples (3 pairs of split samples) containing 14–28% (w/w) of polymerized triglycerides were studied. The method was adopted by AOAC INTERNATIONAL as an IUPAC–AOCS–AOAC method.
Normative Data for Commercial Pineapple Juice from Concentrate
Authors: Low Nicholas H , Brause Allan , Wilhelmsen Eric
Published: February 2020

Normative data for pineapple juice from concentrate were determined for 19 samples, including 5 that had been aseptically processed and representing 4 of the major pineapple growing regions of the world. Values are reported for sugars, organic acids, including isocitric acid, metals (specifically potassium, sodium calcium, and magnesium), δ13C, and oligosaccharides. Although geographical variation existed, the observed ranges and variances were small enough to be useful in describing authentic pineapple juice. Two concentrates (one aseptically and one nonaseptically processed) were intentionally adulterated (individually) with 3 commercially available inexpensive sweeteners (high fructose corn syrup, cane invert syrup, and beet medium invert syrup). Oligosaccharide analysis of these samples either by liquid chromatography or by capillary gas chromatography yielded oligosaccharide patterns that were useful for the detection of these sweeteners at 10% levels. Principal-component analysis (PCA) was used to represent graphically both the pure and adulterated samples based on their measured chemical parameters.
Determination of Bacitracin-MD in Complete Feed by Microbiological Plate Assay: Collaborative Study
Authors: Desai Anil D , Desai Anil D , Muir Larry A
Published: February 2020

Eleven laboratories evaluated the double extraction procedure for the determination of bacitracin methylene disalicylate in swine and poultry feeds at 22, 44, and 88 g/2000 lb. Bacitracin activity was determined on each of 2 days using blind duplicates in a random order. All collaborators submitted their data for statistical evaluation. No significant difference was found between the assay results and the label claim at 22,44, and 88 g/2000 lb for swine and poultry feed. For both feed types, reported ranges at 95% confidence limit for 22,44, and 88 g/2000 lb were 17-30 g/2000 lb, 29-61 g/2000 lb, and 64-112 g/2000 lb, respectively. The microbiological plate assay procedure for determination of BMD in complete feed was adopted first action by AOAC INTERNATIONAL.
Simultaneous Multiresidue Analysis of (β-Lactam Antibiotics in Bovine Milk by Liquid Chromatography with Ultraviolet Detection and Confirmation by Electrospray Mass Spectrometry
Authors: Tyczkowska Krystyna L , Voyksner Robert D , Straub Rolf F , Aronson Arthur L
Published: February 2020

A multiresidue analytical method was developed for the simultaneous determination of amoxicillin, cephapirin, procaine penicillin G, ampicil-lin, cloxacillin, and ceftiofur in bovine milk. The method involved ultrafiltration of milk diluted with an equal volume of 50% acetonitrile through a 10 000 dalton molecular mass cutoff filter. Separation of these β-lactam antibiotics from other milk components was performed by ion-paired (octane- and dodecanesulfonate) liquid chromatography using a phenyl column eluted with acetonitrile-water solution. Ultraviolet ab-sorbance of the column effluent was monitored in the 200-350 nm range of a photodiode-array detector. For quantitation, the chromatograms were acquired at λ210 nm for penicillin G, am-picillin, and cloxacillin; λ230 nm for amoxicillin; and λ290 for cephapirin, procaine, and ceftiofur. The limit of detection for the simultaneous determination of these antibiotics was estimated to be 100 ppb. Liquid chromatography/electrospray mass spectrometry could be used to confirm these antibiotics for quantities down to 100 pg entering the mass spectrometer.
Extraction of Light Filth from Bean Paste: Collaborative Study
Authors: Bryce John R , Glaze Larry E
Published: February 2020

Bean paste is a popular Asian food frequently imported to the United States. The main varieties are: hot bean and blackbean, which are used in pastry fillings; and soybean paste, which is usually used as a condiment. A new method was developed for the extraction of light filth from bean pastes containing beans and flour, and from hot bean paste containing red pepper. A100 g test portion is boiled in tap water containing Igepal DM-710 and CO-730 and washed with hot tap water on a No. 230 sieve. The residue is transferred to a beaker and boiled in isopropanol in a reflux apparatus. The mixture is transferred to a No. 230 sieve. The residue is washed again, transferred to a 2 L trap flask with 40% isopropanol, boiled with magnetic stirring, cooled, and trapped off with flotation liquid [mineral oil-heptane (85 + 15, v/v)]. Ten laboratories participated in a collaborative study validating the extraction method for the detection of light filth. Average recoveries were 94.9 and 82.8% for insect fragments and rat hairs, respectively. The method has been adopted first action by AOAC INTERNATIONAL.
Quantitation and Stability of Fumonisins B1 and B2 in Milk
Authors: Maragos Chris M , Richard John L
Published: February 2020

The well-documented presence of fumonisin myco-toxins B1 and B2 (FB1 and FB2) in corn raises the possibility that these toxins are carried over into the milk of animals fed with contaminated feed. The presence of FB1 and FB2 in milk has not been assessed because of the lack of sensitive analytical techniques for this matrix. Two methods, liquid chromatography (LC) and enzyme-linked immunosorbent assay (ELISA), were adapted for the analysis of milk. The ELISA, produced commercially for screening corn, required no sample preparation and was reproducible but was of low sensitivity [concentration that inhibits color development by 50% (IC50), 1200-1600 ng FB1/mL]. The more sensitive LC method involves serial extraction of milk with methanol-acetone and strong anion exchange followed by derivatization with naphthalene-2,3-dicarboxaldehyde. Recoveries of 50 ng FB1 and FB2/mL from unpasteurized and un-homogenized milk were 84 and 83%, respectively (limit of detection, 5 ng/mL). Recoveries of FB1 from whole homogenized milk (76%) were slightly lower. Heating milk for 30 min at 62°C, to mimic pasteurization, did not significantly reduce FB1 or FB2 recovery, nor did storing milk for 11 days at 4°C. The LC method was applied to 165 samples of milk, only 1 of which was positive. This finding suggests that exposure of humans to FB1 and FB2 from milk is low.
Determination of the Sum of Dimer and Polymer Triglycerides and of Acid Value of Used Frying Fats and Oils by Near Infrared Reflectance Spectroscopy
Authors: Boot Andries J , Speek Andrbes J
Published: February 2020

Near infrared reflectance spectroscopy (NIRS) in the transaction mode was applied to determine the sum of dimer and polymer triglycerides (DPTG) contents and acid value of used frying fats and oils. A filter instrument and a calibration sample set were used to determine DPTG content and acid value. For each parameter, a 7-wavelength calibration was developed using multiple linear regression analysis. For a validation set comprising 44 samples for the NIRS-DPTG determination in the range of 2.2 to 32.7% m/m, the correlation coefficient between NIRS and liquid chromatography (LC) was 0.976, with a standard error of prediction (SEP) of 1.8% m/m. For a validation set comprising 36 samples for the NIRS-acid value determination in the range of 0.30 to 18.8 mg potassium hydroxide per gram of sample (mg KOH/g), the correlation coefficient between NIRS and titration was 0.996, with a SEP of 0.33 mg KOH/g. Validation after routine operation for 1 year provided SEPs of 2.3% m/m and 0.44 mg KOH/g for DPTG and acid value determination, respectively. NIRS screening of 1400 samples collected during 1992 precluded the need for 1149 DPTG determinations by LC (82.1%) and 1033 acid value determinations by titration (73.8%), which are methods the judicature in The Netherlands accepted, because those samples appeared to comply with legislation.
Determination of Cholesterol by p-Nitrobenzoate Derivatization and Liquid Chromatography
Authors: Hamill Thomas W , Soliman Abdel M
Published: February 2020

The method involves direct saponification and formation of the sterol p-nitrobenzoate (PNB) derivatives or lipid extraction with methylene chloride and isopropyl alcohol, saponification, fatty acid methylation, and formation of the sterol PNB derivatives. The sterol PNB derivatives are separated on a C8 column with a mobile phase of acetonitrile-hexane-water (250 + 30 + 3) and quantitated by UV detection at 280 nm. The limit of detection for cholesterol is 2 ng. The response was linear over a range of 4 to 250 ng (r = 0.999). Assays of NIST SRM 1845 and 1563 by this method gave results that were closer to the certified values than were results obtained by the AOAC gas chromatographic method. Reproducibility was evaluated by using foods containing low, medium, and high levels of cholesterol. The % coefficient of variation ranged from 1.8 to 6.7. Studies on a wide variety of food products (using lipid extraction and saponification-methylation) gave a mean recovery of 87.5 ± 10.1%. Direct saponification of poultry and dairy products gave a mean recovery of 101.3 ± 15.8%. Peak purity was determined by diode array spectrophotometry.
Detection of Milk Fat Adulteration by Linear Discriminant Analysis of Fatty Acid Data
Authors: Ulberth Franz
Published: February 2020

Analysis of the fatty acid (FA) profile of milk fat (MF) by gas-liquid chromatography is widely used to detect adulteration with foreign fats. On the basis of the FA spectra of 352 genuine Austrian MF samples collected over a 4-year period, the effectiveness of concentration ranges of the major FA of MF and of certain FA ratios to identify non-MF/MF mixtures was tested. FA ratios proved useful for the detection of coconut fat in MF and admixture of vegetable oils rich in linoleic acid down to a level of 2%. This approach failed to identify non-MF/MF blends containing beef tallow, lard, olive oil, or palm oil at a level less than 10% commingling. Linear discriminant analysis applied to FA data was successful in distinguishing pure MFfrom adulterated MF. Computer-simulated data were used to derive the discriminant functions. Saturated and un-saturated FA with 18 C atoms were the most useful discriminating variables selected by a stepwise variable selection procedure. More than 95% of a data set composed of pure MF, and non-MF/MF blends containing 3% of either tallow, lard, olive oil, or palm oil were correctly classified. The validity of the classification rule was also tested by 206 gravimetrically prepared fat mixtures. Mixtures containing >3% foreign fat were detected in all cases.
Determination of Amino Acids in Feeds: Collaborative Study
Authors: Llames Cynthia R , Fontaine Johannes
Published: February 2020

A total of 28 laboratories (including authors’ laboratories) participated in a collaborative study for determination of amino acids in feeds using 3 complementary procedures. Each collaborator analyzed 5 blind duplicate samples of feed and ingredients used in the poultry industry. The amount of amino acids in these materials ranged from 0.10 to 8.50%. Twenty-three laboratories conducted analyses using performic acid oxidation with acid hydrolysis—sodium metabisulfite method, 16 laboratories performed analyses using performic acid oxidation with acid hydrolysis—hydrobromic acid method, and 15 laboratories used acid hydrolysis method. The repeatability relative standard deviation values for all amino acids for all 3 procedures ranged from 1.1 to 5.6% for broiler finisher feed, 1.1 to 4.73% for starter feed, 1.3 to 9.6% for corn, 0.8 to 3.96% for fishmeal, and 0.8 to 12.7% for poultry meal. The reproducibility relative standard deviation values for all amino acids ranged from 3.71 to 19.80% for broiler finisher feed, 4.1 to 16.93% for starter feed, 4.4 to 28.2% for corn, 3.46 to 18.96% for fishmeal, and 3.73 to 24.1% for poultry meal. The performic acid oxidation with acid hydrolysis—sodium metabisulfite and hydrobromic acid methods, and acid hydrolysis method for determination of amino acids in feeds have been adopted first action by AOAC INTERNATIONAL.
Determination of Antimony in Environmental Samples by Hydride Generation–Inductively Coupled Plasma Spectrometry
Authors: Anderson Kim A , Isaacs Brandon
Published: February 2020

Total antimony was determined by inductively coupled plasma atomic emission spectrometry (ICP AES) using hydride vapor generation. A1 g wet, 0.25 g dry, or 10 mL water sample was digested by one of 2 distinct methods in a 10 mL graduated Kimax culture tube on a programmed heating block by heating with nitric acid and then boiling in a mixture of sulfuric acid and perchloric acid. For soils, a 0.25 g sample was digested in a 10 mL volumetric culture tube with hydrochloric acid. After digestion, the samples were treated with hydrochloric acid and potassium iodide. The antimony was then reduced by sodium borohydride to stibine (SbH3) in a simplified, continuous-flow manifold. A standard pneumatic nebulizer effected the gas–liquid separation of SbH3, which was then quantified by ICP AES at 231.147 nm. The instrument detection limit was 0.41 μg/L. Recoveries from 10 matrixes were 80 to 100%, with a typical relative standard deviation of 5.3%. The digestion and analysis methods demonstrated statistical control for samples of environmental and biological interest and are especially well suited to analysis of small samples. This method requires no additional apparatus for hydride generation or sample introduction.
Determination of Organophosphorus Nematicide Residues in Banana-Field Soils by Gas Chromatography/Mass Spectrometry
Authors: Cooper Jean-François , Zheng Shan-Qiang , Wynn Nigel R , Palcy Louis
Published: February 2020

Gas chromatographic/mass spectrometric (GC/MS) methodology is presented for the determination, in banana-field soils, of the 4 most used organophosphorus nematicides in Martinique (French West Indies): cadusafos (Rugby), ethoprophos (Mocap), isazophos (Miral), and fenamiphos (Nemacur). After extraction with 2 successive solvent mixtures, ethyl acetate–dichloromethane (8 + 2, v/v) and ethyl acetate–acetone (7 + 3, v/v), cleanup was performed using solid-phase extraction cartridges (silica SPE). Fenamiphos and its metabolites were separated in the second eluate and then oxidized to sulfone. Analysis was performed by GC/MS in fragmentometric mode. Recoveries varied from about 75 to 90%. Limits of quantitation varied from 4 to 20 μg/kg fresh soil sample, depending on the nematicide.
Detection of 30 Acidic Herbicides and Related Compounds as Their Pentafluorobenzylic Derivatives Using Gas Chromatography/Mass Spectrometry
Authors: Heberer Thomas , Butz Susanne , Stan Hans-Juergen
Published: February 2020

Thirty phenoxyalkanoic acids, other acidic herbicides, and related compounds were derivatized with pentafluorobenzyl bromide to form their pentafluorobenzylic derivatives. Mass spectra are presented. Determination and detection of the derivatives was performed by capillary gas chromatography (GC)/mass spectrometry. With selected- ion monitoring, an optimized GC method, and appropriate time-window setting, the determination of all compounds could be achieved in a single GC run. The determination of ≤1 pg of the target compounds was achieved using electron-impact ionization in selected-ion monitoring mode. Most of the analytes were extracted from tap water, and recoveries were 80–100% when solid-phase extraction was applied with a carefully selected reversedphase-C18 adsorbent. The method enabled the detection of these contaminants from drinking water at the low nanogram-per-liter level when applying a concentration factor of 10 000.
Determination of Tin in Canned Fruits and Vegetables by Atomic Absorption Spectrometry and Liquid–Liquid Extraction
Authors: Martín Ana M , Sánchez Mercedes , Espinosa Pedro , Bagur Gracia
Published: February 2020

A method was developed for the determination of tin based on the extraction of its 5,5-methylenedisalicylohydroxamic acid complex with 1.09M isobutyl methyl ketone in tributyl phosphate. After the samples were treated with nitric and hydrochloric acid, the aqueous phase was made to 0.05M in perchloric acid. When the ratio of aqueous phase to organic phase was 4:1 (v/v), the detection limit and the relative standard deviation (n = 7,50 μg tin) were 0.20 μg/mL and 0.9%, respectively. The proposed method was applied to the analysis of tin in canned fruits and vegetables. The results were in good agreement with those obtained by the phenylfluorone method.
Cleanup with Two Florisil Columns for Gas Chromatographic Determination of Multiple Pyrethroid Insecticides in Products of Animal Origin
Authors: Pang Guo-Fang , Zhao Tie-Sheng , Chao Yan-Zhong , Fan Chun-Lin
Published: February 2020

A gas chromatographic method was developed for the simultaneous determination of 9 pyrethroid insecticides in products of animal origin. The multiresidues of the pyrethroids in different samples were extracted with acetone–petroleum ether (1+1), and extracts were cleaned up on a Florisil partition column and a Florisil adsorption column. Four animal tissue samples were examined at 0.05–0.25 ppm fortification levels. The average recoveries of all insecticides were 76.9–88.0%, and the coefficients of variation were <4.6% for all insecticides except permethrin. The detection limits of the method were ca 5 ppb for all insecticides but permethrin, which had a detection limit of ca 10 ppb.
Effects of Sample Size and Sample Acceptance Level on the Number of Aflatoxin-Contaminated Farmers’ Stock Lots Accepted and Rejected at the Buying Point
Authors: Whitaker Thomas B , Wu Jeremy , Dowell Floyd E , Hagler Winston M , Giesbrecht Francis G
Published: February 2020

Sixteen different aflatoxin sampling plan designs were evaluated using the negative-binomial distribution. Evaluations were used to predict the effects of 4 different sample sizes and 4 different sample acceptance levels on the classification of farmers’ stock lots according to the lot aflatoxin concentration. The 4 sample sizes evaluated were 2.27 kg (5 lb), 4.54 kg (10 lb), 9.08 kg (20 lb), and 18.16 kg (40 lb). The 4 sample acceptance levels evaluated were 5,50,100, and 180 ng/g. A decrease in the sample acceptance level from 180 to 5 ng/g decreased the number of lots accepted at all lot concentrations, increased the number of lots rejected at all lot concentrations, and decreased the average aflatoxin concentrations among all lots accepted. At the highest sample acceptance level, 180 ng/g, increase in sample size from 2.27 to 18.16 kg decreased the percent of lots accepted at concentrations above the sample acceptance level and increased the percent of lots accepted at concentrations below the sample acceptance level. At the lowest sample acceptance level investigated, 5 ng/g, an increase in sample size from 2.27 to 18.16 kg decreased the percent of lots accepted at all concentrations. The effect of using sampling designs with 2 sample acceptance levels to classify lots into 3 categories was investigated. The advantages of using dual sample acceptance levels over a single sample acceptance level was demonstrated for 2.27 and 9.08 kg samples.
Determination of 1,8-Cineole in Eucalyptus Essential Oils by Thin-Layer Chromatography and Densitometry
Authors: Rossini Carmen , Pandolfi Enrique , Dellacassa Eduardo , Moyna Patrick
Published: February 2020

A thin-layer chromatography (TLC) method with scanning is described for evaluation of the 1,8-cineole content of Eucalyptus essential oils. Samples were developed on silica gel G 60 with light petroleum–chloroform (70 + 30) as mobile phase. Color was developed with 4-dimethylaminobenzal-dehyde–sulfuric acid reagent. The absorbance of colored spots was measured at 460 nm. The response was linear between 15 to 75 μg of 1,8-cineole, with a correlation coefficient of 0.9997. The results of each assay were compared with those from gas–liquid chromatography (GLC). The TLC to GLC ratio was constant (0.92).
Capillary Electrophoresis: A New Tool in Food Analysis
Authors: Cancalon Paul F
Published: February 2020

The principle, equipment, and applications of capillary electrophoresis in food analysis are reviewed.
Liquid Chromatographic Procedure for the Determination of Novobiocin Residues in Bovine Milk: Interlaboratory Study
Authors: Reeves Valerie B
Published: February 2020

Novobiocin is used for the treatment of mastitis in dairy cattle. In 1982, the tolerance was set at 0.1 ppm in milk from dairy animals. A laboratory trial has been completed for a liquid chromatographic procedure that can quantitate novobiocin residues in bovine milk at tolerance level. In this procedure the milk is diluted with buffer, the proteins are precipitated with methanol, and the solution is filtered. Novobiocin is determined after separation of milk components using re-versed-phase chromatography with UV detection at 340 nm. The participating laboratories analyzed 2 concentrations of biologically incurred residues as well as control milk and control milk fortified at 0.05, 0.1, and 0.2 ppm. Recoveries of novobiocin reported by the participating laboratories were 89 to 99% at 0.05 ppm; 93 to 101% at 0.1 ppm; and 89 to 100% at 0.2 ppm. Coefficients of variation (CVs) ranged from 2.0 to 6.2%. The average concentrations for the low levels of incurred novobiocin in milk samples were 0.073, 0.072, and 0.081 ppm, with intralaboratory CVs of 3.3, 7.2, and 2.4%, respectively. The samples with high levels of incurred novobiocin averaged 0.139, 0.121, and 0.144 ppm, with CVs of 6.2, 0.7, and 4.7%, respectively.
An Interlaboratory Trial on the Identification of Irradiated Spices, Herbs, and Spice–Herb Mixtures by Thermolummescence Analysis
Authors: Schreiber Georg A , elle Norbert , Bögl Klaus W
Published: February 2020

Thermoluminescence analysis was used in an interlaboratory study to detect irradiation treatment of spices, herbs, and spice–herb mixtures in the dose range used for the reduction of microbial counts. About 3 and 9 months after irradiation, 14 participating laboratories determined the thermoluminescence of mineral contaminants that had been isolated from coded samples. A total of 18 different products (6 spices, 6 herbs, and 6 spice–herb mixtures) were examined. The method gave correct identifications as irradiated or nonirradiated in 99.1% of 317 samples. Only 3 irradiated samples were not correctly identified. This result was achieved by integration of whole glow curves. By glow curve analysis, a temperature range could be determined in which differentiation between irradiated and nonirradiated samples was even better than on the basis of the total integral values.
Gradient Multipeak Liquid Chromatographic Method for Determination of Ardacin in Bulk Chemical and Premix Formulations
Authors: Abdel-Kader Hafez , Kobylkevich Myriam M , Wigman Larry S , Menon Govind K
Published: February 2020

A liquid chromatographic (LC) method was developed for the determination of ardacin in bulk chemical (78 to 100%, w/w anhydrous) and premix formulations (3.3 to 26.4%, w/w). The method is based on reversed-phase LC resolution of ardacin components and detection by UV absorbance at 220 nm. Ardacin has 10 components, and each component can be quantitated separately. Total ardacin is determined by summing the areas of the 10 component peaks. Calculations are performed using an external standard approach. The method is linear for ardacin at 50 to 150 μ/mL. The method accuracy for a typical bulk chemical is ± 1.5%, w/w (relative standard deviation [RSD], 1.6%), and recovery from a typical pilot scale premix is 99.9% (RSD, 3.4%). The method is useful for monitoring stability during storage.
Generic Performance Tests for the Fertilizer Sample Preparation Laboratory
Authors: Beine Robert L , Tompkins David H , Ranta Kirk R , Puentes Julio
Published: February 2020

Good sample preparation is an essential first step to almost all laboratory analytical procedures. The procedures presented are intended to stimulate interest in generic methods for performance testing of various steps in fertilizer sample preparation, including initial reduction of unground sample, grinding, and mixing. Sample reduction quality is measured by 2 types of procedures, the first using 2 sizes of glass beads for a more theoretical approach, and the second using 2 common fertilizer materials for a more empirical method. Grinding performance is measured by recovery and carryover methods, followed by particle size and uniformity estimates of the ground material. Mixing after grinding is tested by measuring time-to-blend of a segregated mixture.
Aflatoxins in Foods Collected in Osaka, Japan, from 1988 to 1992
Authors: Taguchi Shuzo , Fukushima Shigehiko , Sumimoto Tatsuo , Yoshtoa Seisaku , Nisihmune Takahiro
Published: February 2020

A total of 195 samples of imported foods were analyzed for aflatoxins. Samples of nuts, spices, natural cheese, meats, cereals, and beans were collected in Osaka prefecture, Japan, from 1988 to 1992. Eight samples were contaminated with aflatoxins.Aflatoxins were detectd in 4 of 38 samples of peanut products, 2 of 3 samples of nutmeg, one of 13 samples of white pepper, and one of 2 samples of red pepper. Aflatoxins were not detected in almonds, cashews, macadamia nuts, pistachios, walnuts, black pepper, garlic, ginger, mustard, cheese, beef, corn, rice, buckwheat, Job’s tears, or bean products.
Glucoamylase Activity in Industrial Enzyme Preparations Using Colorimetric Enzymatic Method: Collaborative Study
Authors: Elder Michael T , Montgomery Rachel S
Published: February 2020

Fifteen laboratories participated in a collaborative study to validate a colorimetric assay for the determination of glucoamylase in industrial enzyme preparations. All laboratories received 12 samples as blind duplicates provided by 3 industrial producers. Each sample was analyzed once a day for 3 days. Results from one laboratory were excluded from the statistical analysis. Performance of the method was calculated according to the AOAC guidelines. For all 15 laboratories the repeatability relative standard deviation (RSDr) values ranged from 0.89 to 2.37%, and the reproducibility relative standard deviation (RSDR) values ranged from 7.92 to 9.86. After excluding outliers the RSDr values ranged from 0.74 to 2.24%, and RSDR values ranged from 3.46 to 8.92. The colorimetric enzymatic method for determination of glucoamylase activity in industrial enzyme preparations has been adopted first action by AOAC INTERNATIONAL.
Purge-and-Trap Gas Chromatographic-Mass Spectrometric Determination of Benzene in Denture Adhesives
Authors: Barry Thomas L , Petzinger Glenn , Lehr Gary , Specchio John J
Published: February 2020

A purge-and-trap gas chromatographic-mass spectrometric procedure is presented for determination of trace levels of benzene in denture adhesives and their raw materials. The limit of quantitation is 10 ppb, reproducibility is ± 10%, and recoveries of d6-benzene are 70–85%. Results of a nationwide survey of 109 finished products and their raw materials representing 32 brand name products from 17 manufacturers are reported.
Second-Derivative UV Spectrometric Microdetermination of Dithiocarbamate Residues as Methyl Xanthate
Authors: Schwack Wolfgang , Nyanzi Steven
Published: February 2020

The microdetermination of dithiocarbamate fungicide residues as methyl xanthate using second-derivative UV spectrometry is described. The residue analysis is based on a hot-acid decomposition, scrubbing the evolved CS2 with lead acetate and concentrated H2SO4, and absorbing the CS2 in methanolic KOH. The absorbance of the xanthate system (conventional method) and the height of the negative peak at 302 nm (second-derivative method) are used to quantitate the CS2. The molar absorptivity of the xanthate system within the range of 0.3–2.4 μg CS2/mL where Beer’s law is obeyed, was 1.70 × 104 L mol-1 cm-1. The derivative procedure was more selective and sensitive to CS2 than the classical method. The calibration graph of the derivative procedure was rectilinear from 0.1–1.1 μg/mL of CS2. The coefficient of variation for the determination (n = 10) of a 0.28 (μg/mL standard of CS2 was 2.6%. The detection limit for CS2 was 0.08 μg/mL. The second-derivative procedure was applied to the residue analysis of thiram on tomatoes.
Screening for Okadaic Acid by Immunoassay
Authors: Chin Julia D , Quilliam Michael A , Fremy J Marc , Mohapatra Sushil K , Skorska Hanna M
Published: February 2020

Increasing incidences of phytoplankton blooms with the potential danger of toxin release into the food chain have necessitated the search for new diagnostic methods that can detect toxins quickly and reliably. A competitive enzymelinked immunosorbent assay (ELISA) was developed to quantitate okadaic acid in shellfish and phytoplankton extracts. To determine the specificity of the assay, a number of toxins, such as calyculin A, brevetoxin-1, and dinophysistoxins-1, -2, and -3 were analyzed. Both dinophysistoxins-2 and -1 could be detected by the assay but in concentration ranges 10- and 20-fold higher than that for okadaic acid, respectively. Dinophysistoxin-3, calyculin A, or brevetoxin-1 could not be detected with this assay. To validate the accuracy of the method, 18 mussel and 7 phytoplankton extracts were analyzed in parallel for okadaic acid content by ELISA and liquid chromatography combined with either fluorescence or mass spectrometric detection. Very high correlation between the results was found.
Detection of Ciguatera and Diarrheic Shellfish Toxins in Finfish and Shellfish With Ciguatect Kit
Authors: Park Douglas L
Published: February 2020

The Ciguatect test kit for the detection of ciguatoxin, okadaic acid, and related polyether compounds, based on solid-phase immunobead assay technology, was developed for rapid screening of toxic fish and shellfish in harvesting areas and the marketplace. Earlier formats, based on radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) technology, were used successfully to identify and separate ciguatoxic fish harvested from Hawaiian waters. The new format utilizes a membrane attached to a plastic strip, immunobead solution, and a user-friendly readout. Multiple formats of the test kit, including a rapid extraction method (REM) and ELISA, were demonstrated to be more sensitive than the mouse assay for detection of ciguatera-related compounds. Depending on the format used, the level of detection can be as low as 50 pg okadaic acid per gram of tissue. The test kit has been used to map ciguatoxic and nontoxic fishing areas around the islands of Hawaii through the use of a biomarker and the monitoring of toxic fish obtained from Pacific and Caribbean regions. Ciguatera-related toxins can be detected directly on fish flesh or after extraction by traditional procedures or the newly developed REM. Initial applications of the test kit to monitor diarrheic shellfish poisoning (DSP)-related toxins in mussels before, during, and after Dinophysis sp. blooms and during depuration operations were successful. The Ciguatect methodology can be used to monitor reef fishing areas for ciguatera potential, shellfish beds for DSP toxins, and shellfish depuration operations for elimination of DSP toxins and to screen for toxic fish and shellfish in the marketplace.
Practical Assay of Feed Premixes for Selenite Adsorbed on Reduced Iron
Authors: Hulen Joele , Eisenberg Sylvan
Published: February 2020

This method assays feed premixes for added selenite in 5–10 min. It requires that selenite be added in a form easily isolated from the premix. Sodium selenite adsorbed on a reduced iron carrier serves this purpose since it can be retrieved magnetically from samples. The assay is done either indirectly by weighing the iron and calculating the amount of Se or directly by extracting the selenite from the iron carrier and determining it by titration. The indirect assay may be done any time after production of premix. The direct method requires retrieval of the additive from the premix soon after production. The actual assay may be done later. The indirect method gives high results with some matrixes unless adjusted for background ferromagnetic material. The direct method gives results with an accuracy and precision equal to those of the U.S. Food and Drug Administration’s Center for Veterinary Medicine regulatory enforcement method with all matrixes studied.