bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Evaluation of the Globulin Proteins of Cottonseed Meals
Authors: Marshall Henry F , Conkerton Edith J
Published: February 2020

A method for the analytical evaluation of the globulin (saltsoluble) fraction of cottonseed meals has been developed. Cottonseed of 14% moisture content is stored for 6 and 9 weeks at 50°C. Meals obtained after seeds are defatted with pet ether are analyzed for nitrogen content, and then extracted with water. Residues are then extracted with 10% NaCI to isolate the globulin fraction. This fraction is characterized by liquid chromatography (LC) and gel electrophoresis (LDS-PAGE). Kjeldahl analyses showed no loss of nitrogen in meals from stored seed compared with those from unstored seeds. However, a large decrease in NaCI extractable nitrogen was noted in meals from stored cottonseed. LC and LDS-PAGE showed that an alteration of the globulin proteins occurred during storage, and the method demonstrated a progressive change in the 11S and 7S components of the globulin fraction.
Analysis of Trypsin Inhibitors and Lectins in White Kidney Beans (Phaseolus vulgaris, var. Processor) in a Combined Method
Authors: Roozen Jacques P , de Groot Jolan
Published: February 2020

Buffered saline extraction, affinity chromatography, and Folin-BSA protein assay were used consecutively to provide a combined method for analysis of trypsin inhibitors and lectins in white kidney beans (Phaseolus vulgaris, var. Processor). The method was tested by following the decrease of both antinutritional factors by germination of the beans for 7 days at 20°. Repeatability coefficients of variation were 2-7.4% for the trypsin inhibitors and 2.2-10% for the lectins. After 7 days of germination, trypsin inhibitors and lectins were reduced by 72 and 92%, respectively.
Evaluation of Methods for Detection of Listeria monocytogenes in Foods: NMKL Collaborative Study
Authors: Westöö Anna , Peterz Mats
Published: February 2020

Eleven Nordic laboratories participated in a collaborative study on qualitative methods for the detection of Listeria monocytogenes in foods. Two enrichment methods (U.S. Department of Agriculture, Food Safety and Inspection Service method for meat, and modified U.S. Food and Drug Administration/International Dairy Federation method for dairy products) and 2 agar media (lithium chloride-phenylethanol-moxalactam (LPM) and Oxford agar) were compared. The effect of treatment of the enriched culture with KOH before plating was also studied. Food samples, blue and white mold cheese and canned corned beef, were Inoculated with 3 levels of L. monocytogenes. Beef was also Inoculated with a microbial flora derived from raw meat. The recoveries of L. monocytogenes using the 2 enrichment methods did not differ significantly. The Oxford agar was superior to the LPM agar. KOH treatment of the enriched culture did not significantly increase the detection rate of the organism. For cheese, the detection level of the methods was below 0.2 cfu L. monocytogenes/g and for meat, the detection level was below 5 cfu L monocytogenes/g.
Simultaneous Liquid Chromatographic Determination of Fenamiphos and Its Metabolites in Soil
Authors: Khazanchi R , Walia S , Handa S K
Published: February 2020

A reversed-phase liquid chromatographic method has been developed for the determination of fenamiphos and the metabolites fenamiphos sulfoxide, fenamiphos sulfone, 3-methyl-4-(methylthlo)- phenol, and 3-methyl-4-(methylsulflnyl)phenol. Trace quantities of the nematlclde and Its metabolites In soil can be determined simultaneously. The limit of detection of the method was 5 ppm. Recoveries of fenamiphos and Its degradation products at fortification levels of 25,50, and 100 ppm ranged from 99.2 to 100.8%. Standard deviations ranged from 0.29 to 0.70 ppm.
Batching Oils on Sisal Bags Used for Packaging Foods:
Analysis by Coupled LC/GC
Authors: Grob Konrad , Artho Anna , Biedermann Maurus , Caramaschi Adrian , Mikle Heinz
Published: February 2020

Sisal fibers are treated with a batching oil before spinning. Such oils usually consist of mineral oil products and cause considerable contamination of the packed foods (typically 10-100 mg/kg). Batching oils recovered from sisal bags previously used for transporting cocoa and coffee beans were analyzed for total concentrations on the bag as well as the composition of the paraffins and aromatics. Concentrations of total hydrocarbons ranged between 0.3 and 39 g/kg sisal bag; concentrations of aromatics ranged between <0.1 and 2.7 g/kg. The applied batching oils varied between raw mineral oil fractions, somewhat purified fractions, and a crystallized product.
Evaluation of Method for Enumeration of Brochothrix thermosphacta in Foods
Authors: Peterz Mats
Published: February 2020

A method for enumeration of Brochothrix thermosphacta In foods was evaluated in a collaborative study. Freeze-dried mixtures of bacteria were used as simulated food samples. Fifteen laboratories analyzed 2 negative control samples and 4 blind duplicate samples containing different levels of B. thermosphacta. The freeze-dried samples were reconstituted and spread on the surface of streptomycin sulphate-thallous acetate-actidlone agar and Incubated 2-3 days at 20-25°C. The method shows good repeatability (0.13) and reproducibility (0.21). Reproducibility might be Improved by specifying a more exact Incubation temperature. The number of false-positive results was rather high, but could be diminished if a catalase test was Included and the oxidase test performed by using commercial strips instead of by allowing a solution of an oxidase reagent (tetramethyl-p-phenylenedlamlne dlhydrochloride) to flow over the agar surface.
Liquid Chromatographic Determination of Cyclopiazonic Acid in Corn and Peanuts
Authors: Urano, Takashi , Trucksess, Mary W , Matusik Jean , Dorner Joe W
Published: February 2020

A liquid chromatographic (LC) method Is described for the determination of cyclopiazonic acid (CPA) in corn and peanuts. CPA was extracted from the test portion with methanol-2% NaHC03 solution (7 + 3); the extract was defatted with hexane and then acidified. CPA was partitioned into chloroform and applied to a Sep-Pak silica cartridge. CPA was eluted with chloroform-methanol (3 + 1), the solvent was evaporated, and the residue was dissolved In methanol- water (60 + 40). CPA was quantitated by reversed- phase LC with a linear gradient of 0-4mM ZnS04 In methanol-water (85 + 15) and UV measurement at 279 nm. Recoveries of CPA from corn spiked over the range of 50-500 ng/g and peanuts spiked over the range of 100-500 ng/g were 72-84% and 74-80%, respectively. The limits of quantitation for CPA in corn and peanuts were about 50 and 100 ng/g, respectively. CPA (820 ng/g) was found In corn naturally contaminated with anatoxin Bi, and CPA Identity was confirmed by tandem mass spectrometry.
Determination of Mono- and Disaccharides in Foods by Interlaboratory Study: Quantitation of Bias Components for Liquid Chromatography
Authors: Bugner Emmanuel , Feinberg Max
Published: February 2020

In 1988, a group of French food manufacturers decided to validate the methods used to determine mono- and disaccharides in foods (fructose, glucose, sucrose, maltose, and lactose) based on liquid chromatography with refractive Index detection. Twenty laboratories analyzed 12 products. The reproducibilities obtained exceeded Horwltz's criteria but were still acceptable because laboratories used different equipment and the sample matrixes were complex. Six different sources of variation were characterized because of a more complex experimental design. The method for calculating concentration, In particular, had considerable impact on the final precision; the choice between peak area and peak height must be strictly considered.
Gas Chromatographic Determination of Dimethoate Residues in Chrysanthemums and Soil
Authors: Wu Jia-Lun , Fan De-Fang
Published: February 2020

A gas chromatographic (GC) method was developed for determination of dimethoate residues In chrysanthemums and soil. Dry flowers, fresh flowers, and leaves of chrysanthemum and soil samples are extracted with acetone, cleaned up by coagulation, and partitioned with dlchloromethane. Dimethoate is determined by GC with nitrogenphosphorus detection. Recovery ranges of dimethoate from samples of dry flowers, fresh flowers, and leaves of chrysanthemums are 86.7-91.0% (fortified at 0.5-2.0 ppm), 88.1-93.6% (fortified at 0.036- 0.721 ppm), and 83.3-96.9% (fortified at 0.5-1.31 ppm), respectively. Recovery ranges of dimethoate from soil samples are 93.0-104% (fortified at 0.125- 0.327 ppm). Average recoveries of the 4 kinds of samples (n = 9) are 88.4 ± 8.94%, 91.5 ± 4.18%, 91.1 ± 4.69%, and 97.3 ± 5.1 %, respectively
Matrix Solid-Phase Dispersion Extraction and Liquid Chromatographic Determination of Ivermectin in Bovine Liver Tissue
Authors: Schenck Frank J , Barker Steven A , Long Austin R
Published: February 2020

A method for the isolation and liquid chromatographic (LC) determination of the antiparasitic drug ivermectin in bovine liver is presented. Liver samples (0.5 g) are blended with 2 g C18 (octadecylsilylderivatized silica packing material). A column made from the C18liver matrix is washed with 3 mL hexane, then the ivermectin is eluted with methylene chloride-ethyl acetate (3 + 1). After purification by alumina solid-phase extraction, the ivermectin is derivatized and analyzed by LC with fluorescence detection. The overall recovery of ivermectin added to liver was 74.6%. The lowest level validated in tissue by the method was 10 ppb, and the limit of detection was 1 ppb. This method and a classical extraction method gave comparable results for a liver sample that contained incurred ivermectin residues. The method uses small volumes of solvents, has a limited number of sample manipulations, and does not require solvent partitioning or backwashing of extracts. These characteristics make this method attractive when compared to classical isolation procedures for ivermectin.
Liquid Chromatographic Assay of Dimetridazole, Ipronidazole, and Ronidazole in Feeds and Premixes
Authors: Tollomelli B , Laffi R , Rossato S , Colpo G
Published: February 2020

A rapid method has been developed for the determination of dimetridazole (DMZ), ipronidazole (IPZ), and ronidazole (RNZ) in turkey feeds, swine feeds, and premix. The compounds are extracted from samples with warm methanol, the extract is purified over a short alumina column, and an aliquot of the eluate is analyzed by reversed-phase liquid chromatography and UV detection at 309 nm. Alumina cleanup of premixes is not essential, although the resulting chromatograms are cleaner. Recoveries of DMZ from feed formulations ranged from 97 to 103% at the 10.0,50.0, and 100.0 ppm levels, with a standard deviation (SD) of 0.62-3.2%. Recoveries of IPZ ranged from 94.4 to 101.2% at the 5.0,50.0, and 100.0 ppm levels (SD, 0.42-4.4%). RNZ recoveries ranged from 95 to 100.7% at the 6.0,60.0, and 120.0 ppm levels (SD, 1.2-5.33%).
Determination of Total Aflatoxin Levels in Peanut Butter by Enzyme-Linked Immunosorbent Assay: Collaborative Study
Authors: Patey Alan L , Sharman Matthew , Gilbert John
Published: February 2020

Laboratories in Australia, Japan, Spain, the United Kingdom, and the United States participated in a collaborative study to evaluate a commercial enzyme- linked immunosorbent assay for the determination of total aflatoxin. Collaborators were sent 10 randomly numbered samples (5 blind duplicates) of roasted peanut butter. Two pairs were "blank" peanut butters to which aflatoxin B1, B2, G1, and G2 standards had been added. The other 3 pairs of peanut butters were 1 low aflatoxin level sample and 2 naturally contaminated samples. The assay is based on indirect competition. Test samples containing (free) aflatoxin, added to aflatoxin-coated microwells, compete for specific monoclonal rat anti-aflatoxin. As the concentration of aflatoxin in the test samples increases, the amount of rat antiaflatoxin binding to the aflatoxin attached to the well decreases. After a wash step to remove unbound material, the amount of rat anti-aflatoxin bound to the well is determined by its reaction with peroxidase conjugated rabbit anti-rat globulin. Bound peroxidase activity is then determined by the addition of a substrate, whose color development is inversely proportional to the aflatoxin concentration and is measured by absorbance. Coefficients of variation (CV) for total aflatoxin concentrations, for mean levels of 9,30, and 89µg/kg, were between 28 and 37% for the low level and 2 naturally contaminated samples, which contained mainly aflatoxin B1. CVs for the spiked samples were lower (24-25%) for mean levels of 11 and 20 µg/kg; recoveries were 84 and 89%, respectively. Ranges for relative standard deviations for repeatabilty and reproducibility were 9-30% and 25-37%, respectively. The method has been adopted first action by AOAC International.
Stable Carbon Isotope Ratio Method For Detection Of Corn-Derived Acetic Acid In Apple Cider Vinegar: Collaborative Study
Authors: Krueger Dana A
Published: February 2020

The stable carbon isotope ratio analysis method for determining the presence of corn-derived acetic acid in cider vinegar has been collaboratively studied. The method is based upon natural differences in the 13C /12C ratio; pure cider vinegars yield δ13C results near -25 %o, while corn vinegar yields results near -10 %o. Samples are combusted at 500 C in sealed glass tubes over CuO. The purified CO2 is analyzed by isotope ratio mass spectrometry relative to the Pee Dee belemnite limestone (PDB) standard. The precision of this method was observed to be similar to that of other isotope ratio methods that have been collaboratively studied: SR ranged from 0.6 to 1.2, while sr ranged from 0.1 to 1.1. The results indicate that as little as 10% added corn vinegar may be detected in cider vinegar. On the basis of published data of the natural variability of cider vinegar 13C /12C ratios, it is recommended that samples yielding results more positive than -22.0 %o be classified as not pure cider vinegar using this method. This method has been adopted first action by AOAC International.
Liquid Chromatographic Determination of Sucralfate in Dental Cream
Authors: Gargiullo Robert J
Published: February 2020

A simple, rapid liquid chromatographic method is described for quantitative determination of sucralfate in dental cream. Analyses were performed on a weak anion exchange column with 0.6M ammonium sulfate-0.005M tetrabutylammonium hydrogen sulfate as the mobile phase and refractive index detection. The method was linear over a range of 0.0 to 20.0% sucralfate in dental cream. The coefficient of variation was 3.2%. Standard recoveries were concentration dependent and ranged from 97.2 to 104.9%.
Pesticide Residue Survey of Produce from 1989 to 1991
Authors: Schattenberg Herbert J , Hsu Jong-Pyng
Published: February 2020

A pesticide residue screening program for 111 pesticides was performed on 6970 produce samples. Of the 81 varieties of samples, 2.4% contained illegal levels of pesticide residues (that is, higher than U.S. Environmental Protection Agency [EPA] tolerance or no tolerance specified), and 13.3% contained levels within tolerable limits established by EPA. Pesticide results are presented both by commodity and category type. The nature of violative residues is discussed.
Determination of Total Mercury in Seafood and Other
Protein-Rich Products
Authors: Landi Silvio , Fagioli Francesco , Locatelli Clinio
Published: February 2020

A previously developed wet-digestion method for the determination of total mercury in plants by cold vapor atomic absorption spectroscopy (CVAAS) was extended to the analysis of seafood and other products rich in proteins. Oxidation of matrixes is accomplished by K2Cr2O7 in the presence of diluted H2SO4; a simple air condenser is used to reflux vapors released from the boiling mixture. The original procedure (A) and 2 modifications (B and C), which differ with respect to the mode of acidification and/or digestion time and the types of condensers used, were compared for precision and accuracy by means of National Institute of Standards and Technology Research Material 50 Albacore Tuna and proved to be reliable (Hg present, 0.95 ± 0.1 μg/g; Hg found, 0.97 ± 0.029 μg/g [A], 0.98 ± 0.018 μg/g [B], and 0.94 ± 0.025 μg/g [C]). The modified procedures were tested further in Hg recovery experiments on a variety of biological matrixes with different spiking substances and again showed good analytical characteristics (overall average recoveries = 98 ± 5.1 % for seafood and 100 ± 3.6% for protein-rich baby foods)
Interlaboratory Study on the Analysis of Chlorobiphenyl
Congeners
Authors: De Boer Jacob , Duinker Jan C , Calder John A , Van Der Meer Jaap
Published: February 2020

An intercompanson exercise on the determination of individual chlorobiphenyls (CBs) in marine media was organized by the International Council for Exploration of the Sea, the Intergovernmental Oceanographic Commission, and the Oslo and Paris Commissions. Sixty-two laboratories from 16 countries participated in the first part of this exercise, which consisted of determining 10 CBs in a standard solution. Considerable emphasis was placed on optimization of the gas chromatographic analysis, which has led to better agreement than former intercalibration exercises on CB analysis. Standard errors of 1.10-1.12 for the reproducibility were obtained for all CBs, except CB 52 for a group of 47 laboratories. It was demonstrated that the linear range of the electron capture detector was restricted to a factor of 5 in the concentration range 15-750 pg. About half of the participants used calibration solutions with CB concentrations outside the linear range. More than half of the participants had difficulties in separating the peaks of CB 28 and CB 31. Results based on peak heights showed better reproducibility than results based on peak areas
Determination of N-Methylcarbamate Insecticides in Vegetables, Fruits, and Feeds Using Solid-Phase Extraction Cleanup in the Normal Phase
Authors: Page Michael J , French Mark
Published: February 2020

A liquid chromatographic (LC) method is described for the simultaneous determination of 8 carbamate pesticides in vegetable, fruit, and feed crops. Carbamates are extracted and then partitioned from vegetable, fruit, and feed crop samples using procedures previously developed. An aliquot is taken from the sample partitioning, evaporated by a nitrogen stream, and reconstituted in 5 mL 5% methylene chloride-hexane. Sample cleanup is accomplished by aspirating through an aminopropyl Bond Elut (NH2) solid-phase extraction column. Following aspiration, the sample is eluted with 10 mL 2% methanol-methylene chloride. The eluate is evaporated, again under nitrogen, and reconstituted in methanol for fluorometric LC analysis. The method provides an excellent cleanup for all matrixes studied. Initial recoveries of 98,90, and 91% were obtained for fortifications of 0.05,0.5, and 5.0 ppm, respectively. Linear range recovery studies demonstrated results that agreed with the initial recovery study. An intralaboratory study of the method was conducted in quadruplicate, using 10 assorted vegetable, fruit, and feed crops. With no exceptions, the overall average pesticide recovery for this study was 92%, with a standard deviation of 7.1 (n = 253). Carbamate recoveries varied from 80 to 105%, with coefficients of variation (CVs) that compared favorably to the intralaboratory Horwitz CV. Detection limits of less than 0.01 ppm are obtainable with the described method
Determination of Eight Organochlorine Pesticides at Low
Nanogram/Liter Concentrations in Groundwater Using Filter
Disk Extraction and Gas Chromatography
Authors: Tomkins Bruce A , Merriweather Roosevelt , Jenkins Roger A , Bayne Charles K
Published: February 2020

Eight organochlorine pesticides may be quantitated routinely at levels below 10 parts per trillion (ng/L) in natural groundwaters. Analytes are extracted rapidly from 1 L groundwater samples by using conditioned Teflon filter disks impregnated with silica containing bonded octadecyl phase. Filter is dried briefly under vacuum, and pesticides are eluted with 10 mL ethyl acetate. The extract is dried with about 1 g anhydrous sodium sulfate and then concentrated to exactly 1 mL. Pesticides are separated in a gas chromatograph equipped with a capillary column, detected by a high-sensitivity electron capture detector, and quantitated by the method of external standards. Certified reporting limit (CRL) values for the 8 pesticides ranged between 2 and 7 ng/L. Preliminary data demonstrated that the organochlorine pesticides could be collected on the filter disks and stored up to 4 weeks in the dark at either refrigerated or ambient temperature without obvious degradation of the sample. Calculated CRL values are comparable (within a factor of 2) to method detection limit values defined by the U.S. Environmental Protection Agency.
Gas Chromatographic/Mass Spectrometric Determination
of Oxolinic, Nalidixic, and Piromidic Acid in Fish
Authors: Takatsuki Keigo
Published: February 2020

A gas chromatographic/mass spectrometric (GC/MS) method using selected ion monitoring (SIM) mode has been developed for determination of oxolinic, nalidixic, and piromidic acid in fish. Drugs are extracted with ethyl acetate from a sample homogenized with phosphate buffer (pH 6.0). The extract is partitioned into 3% sodium bicarbonate solution, and the aqueous phase is re-extracted with ethyl acetate after neutralization. After evaporation, the residue is dissolved in methanol and reduced with sodium tetrahydroborate. The reaction mixture is treated with acid, extracted with ethyl acetate, and re-extracted with ethyl acetate after alkalinization. The combined ethyl acetate extract is passed through an alumina cartridge column, concentrated, and analyzed by GC/MS in SIM mode. Percent recoveries and coefficients of variation (CV%) from silver salmon fortified at the 0.1 ppm level were 92.2 (4.4) for oxolinic, 100.6 (12.8) for nalidixic, and 92.1 (3.8) for piromidic; at the 0.01 ppm level, they were 80.5 (6.2) for oxolinic, 81.5 (8.2) for nalidixic, and 69.6 (8.5) for piromidic. The detection limit is 0.003 ppm
Quantitation of Sulfamethazine in Pork Tissue by Thin-Layer Chromatography
Authors: Unruh Joseph , Schwartz Daniel P , Barford Robert A
Published: February 2020

Our earlier method to detect and quantitate sulfamethazine (SMZ) in milk at the 10 ppb level was modified to quantitate SMZ in pork tissue. Sulfabromomethazine (SBZ) is added to the tissue as an internal standard. SMZ and SBZ are extracted from the tissue into water as the supernatant of a centrifuged, aqueous homogenate and are cleaned up and concentrated by a series of solid-phase extractions. The sulfonamide-containing eluate is then separated on a silica gel thin-layer chromatographic plate. SBZ and SMZ are derivatized with fluorescamine, and their fluorescence is quantitated with a scanning densitometer. The limit of detection was estimated at 0.25 ppb (signal-to-noise ratio, 3:1). The average accuracy over the analysis range (0.54-21.8 ppb [μg/kg]) was 95.6% (standard deviation = 29.4%, n = 54).
Liquid Chromatographic Detection of a Variety of Inexpensive Sweeteners Added to Pure Orange Juice
Authors: Wudrich Gerald G , McSheffrey Sandra , Low Nicholas H
Published: February 2020

Liquid chromatography with pulsed amperometric detection was used to analyze pure orange juice adulterated with a variety of inexpensive sweeteners. This method can be used to detect low levels (5-10%) of high fructose com syrup (42 and 55), cane sugar hydrolysates (50 and 80%), and beet sugar hydrolysates (chemically or enzymatically prepared).
Spectrophotometric Determination of Boron in Dates of Some Cultivars Grown in Saudi Arabia
Authors: Al-Warthan A A , Al-Showiman S S , Al-Tamrah S A , BaOsman A A
Published: February 2020

The formation of a red complex between boron and the quinalizarin reagent was investigated and used as the basis for a simple and sensitive spectrophotometric method for boron in date cultivars. At 620 nm, the absorbance was linear (r= 0.999) over the 0.25-2.5 μg/mL concentration range. The molar absorptivity was found to be 2.23 x 103mol-1cm-1 and the relative standard deviation for 10 replicates (1.0 μg/mL) was 0.97%.
Rapid Determination of Listeria monocytogenes in Foods Using a Resuscitation/Selection/Kit System Detection
Authors: Martin Alain , Katz Stanley E
Published: February 2020

A resuscitation medium consisting of a trypticase soy broth base supplemented with 0.5% yeast extract, 0.25% sodium pyruvate, 0.01 % sodium thiogly col late, and 0.1 % chicken fat was used in the resuscitation of heat-injured and freeze-injured cells of Listeria monocytogenes. After a resuscitation period of 4-h, the medium was made selective through the addition of nalidixic acid, acriflavin, and cycloheximide. The organisms were incubated in the selectivized medium at 35°C for an additional 16 h. The numbers of resuscitated Listeria monocytogenes cells rose from 101 to 107 cells/mL in 20 h. Similar numbers of Staphylococcus aureus, Escherichia coli, and Salmonella bonn were grown together with Listeria monocytogenes; these organisms did not inhibit the growth of Listeria monocytogenes nor interfere with its detection by the Listeria-Tek kit system. The resuscitation/selection/ kit system (RSK) was compared with the methodology in the Bacteriological Analytical Manual (BAM) for the detection of Listeria monocytogenes in 22 naturally contaminated cheese samples: 8 of these were positive by the BAM system and 12 were positive by the RSK system. The 8 Listeria positives found by the BAM system were positive by the RSK system. All 12 Listeria-presumptive positive samples by the RSK system were confirmed to be Listeria monocytogenes. The use of the RSK system enhanced the recovery of the pathogen, and detection was accomplished within 24 h.
Simultaneous Determination of Linuron and Trifluralin Residues in Carrots and Their Pulp by Liquid Chromatography and Gas Chromatography
Authors: Amato Angela D' , Semeraro Isabella , Bicchi Carlo
Published: February 2020

A simple method is described for determining trifluralin and linuron in carrots and their pulp. Samples are extracted with hexane-ethyl ether (1+1), cleaned up with a disposable Florisil cartridge, and eluted first with hexane-ethyl ether (99 + 1) (for trifluralin), and then with hexane-ethyl ether (3 + 7) (for linuron). Trifluralin is then analyzed by electron capture gas chromatography (GC/ECD), and linuron by GC/ECD and liquid chromatography with ultraviolet detection (LC/UV). Recoveries were determined by spiking untreated carrot and carrot pulp homogenates with trifluralin and linuron at 0.04, 0.16, and 0.32 μg/g. Six determinations were performed at each level for both compounds. GC/ECD average recoveries were 87.1% for trifluralin and 93.6% for linuron in carrots and 89.9% for trifluralin and 94.2% for linuron in carrot pulp. LC/UV recoveries for linuron were 91.5% for carrots and 92.8% for carrot pulp.
Polyclonal Enzyme Immunoassay Method for Detection of Motile and Non-Motile Salmonella in Foods: Comparative Study
Authors: Feldsine Philip T , Falbo-Nelson Maria T , Hustead David L
Published: February 2020

A new enzyme immunoassay (EIA) method for detection of motile and non-motile Salmonella was examined in a comparative study. This method uses a proprietary formulation of polyclonal antibodies to Salmonella and is controlled to maintain specificity. Sensitivity is enhanced with an additional antibody reaction designed to minimize false-negative reactions attributable to steric interference that can occur during conjugate binding in immunoassay procedures. Twenty food types representative of a wide variety of food products were analyzed by both the EIA method and the AOAC/Bacteriological Analytical Manual (BAM) method, 967.26. Of the 1000 samples analyzed, there was a 95.6% agreement rate between the EIA method and the AOAC/BAM method. False-negative rates for the 2 methods were comparable for all foods and all Salmonella levels except ground poultry, where the EIA method detected significantly more confirmed positive samples than did the AOAC/BAM method. Twenty-seven samples were positive by EIA but negative by the culture method, and 17 samples were negative by EIA but positive by the culture method. There were no false-positive isolates detected in the comparative study.
Pararosaniline as a New Chromogen for the Extractive Spectrophotometric Determination of Trace Amounts of Hydrogen Sulfide in Air
Authors: Kumar B S M , Balasubramanian N
Published: February 2020

A sensitive spectrophotometric method for the determination of trace amounts of hydrogen sulfide H2S) in air, after fixing in a zinc acetate–disodium ethylenediaminetetraacetate–sodium hydroxide solution, is described. The reaction of iodate with the fixed H2S in the presence of acid and an excess of chloride leads to the formation of ICI2 ions. The resulting IC-2 species forms an ion par with pararosaniline cation, and the product is extracted into isopentyl alcohol. The color system obeys Beer’s law over the range of 0 to 5.0 μg H2S. The molar absorption coefficient of the color system is 1.8 × 104 L mol-1 cm-1 . The coefficient of variation is 3.3% for 10 determinations at 3.0 μg H2S. The effect of interfering gases on the determination is discussed. The method was applied to the determination of residual amounts of H2S present in a laboratory fume cupboard, and results were compared to those obtained by the widely used methylene blue method. The current method can be used to determine residues as low as 0.2 μg H2S.
Rapid Determination of Cholesterol in Single and Multicomponent Prepared Foods
Authors: Al-Hasani Sami M , Hlavac Jan , Carpenter Mark W
Published: February 2020

A rapid method has been developed for cholesterol determination in single and multicomponent foods. The method involves alcoholic KOH saponification of the samples, extraction of the nonsaponif iable fraction with hexane, and injection of concentrated extract into the gas chromatograph without derivatizations. It has been applied to a wide variety of frozen and refrigerated foods. More than 300 samples were analyzed with a coefficient of variation (CV) ranging from 0.5 to 8.6%. The average recoveries of cholesterol from spiked oil and tomato vegetable soup samples were 100 ±1.5% and 99.7 ±1.6% and the CVs were 1.5 and 1.6%, respectively. This method reduces labor by >70%, eliminates dangerous chemicals, and minimizes solvent use, compared to the AOAC method and other methods cited in the manuscript. The method was used successfully on a wide variety of multicomponent foods. We recommend this method for collaborative study under the AOAC guidelines for method approval.
Extension of a Liquid Chromatographic Method for N-Methylcarbamate Pesticides in Cattle, Swine, and Poultry Liver
Authors: Sher Ali M , White Jerry D , Bakowski Ralph S , Stapleton Nancy K , Williams Kay A , Johnson Robyn C , Phillippo Evan T , Woods Robert W , Ellis Richard L
Published: February 2020

Liver samples of bovine, swine, and poultry were fortified with 0,5,10, and 20 ppb mixed standards of an additional 6 carbamates as part of a method extension study. Each of the 3 species in this study was analyzed 4 times at 0,5,10, and 20 ppb fortification levels. The average of 12 recoveries of 6 carbamates at all 3 fortification levels was greater than 90%, with a maximum coefficient of variation less than 18%.
Discriminating Between Adult Mandibles of Oryzaephilus surinamensis and Oryzaephilus mercator Using Setal Brush Length
Authors: Wheeler Mark M
Published: February 2020

The setal brush was identified as a diagnostic characteristic which can be used to distinguish between the mandibles of adult Oryzaephilus surinamensis and O. mercator. The right and left setal brushes of 50 specimens from each species were measured. Statistical analysis showed that the mean brush lengths of the 2 species were significantly different (ρ = 0.0001). A demarcation value was established to distinguish between the mandibles. By using this value it is possible to reliably classify the mandibles of O. surinamensis and O. mercator. A mandible with setal brush >0.0296 mm would be classified as O. mercator, a mandible with a setal brush <0.0296 mm would be classified as O. surinamensis.
Indirect Fluorometric Determination of Lactic Acid in Wine
Authors: Burini Giovanni
Published: February 2020

A sensitive, specific, and reliable fluorometric method for the determination of lactic acid in wine is described. After the wine sample was boiled and diluted, lactic acid was fluorometrically determined by evaluating the concentration of fluorophore derived from the reaction between acetaldehyde, a product of the oxidation of lactic acid, and 1,3-cyclohexanedione. The best oxidation conditions were a temperature of 90°C for 2 min and a Ce(SO4)2 concentration of 2 mg/mL in 0.5M H2S04. These values are not strictly critical, because the time value ranged from 1 to 2.6 min, temperature from 82 to 93.6°C, Ce(SO4)2 concentration from 1 to 2.6 mg/mL, and H2SO4 concentration from 0.125 to 0.72M; the values yielded fluorescence intensity decrements of <5% relative to the optimum. Six wine samples (3 red and 3 white) as well as those spiked with 1 and 2 g lactic acid/L were analyzed. The average recoveries ranged from 98.3 to 100.1%, with the relative standard deviation ranging from 1.3 to 3.4. The results of the fluorometric analyses compared with those obtained from the known liquid chromatographic method gave good agreement. The proposed method appears to be sensitive, specific, and reliable but not advantageous for routine analysis.
Development of a Multispecies Identification Field Test by Modified Agar-Gel Immunodiffusion
Authors: Cutrufelli Mark E , Mageau Richard P , Schwab Bernard , Johnston Ralph W
Published: February 2020

A multispecies identification field test (MULTI-SIFT) was developed for detection of beef, poultry, pork, sheep, horse, and deer in a wide variety of raw meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for detection of single species. MULTI-SIFT was demonstrated to be specific, relatively sensitive, and accurate in the complete speciation of 100 meat samples.
Determination of Biogenic Amines in Beers and Their Raw Materials by Ion-Pair Liquid Chromatography with Postcolumn Derivatization
Authors: Izquierdo-Pulido M L , Vidal-Carou M C , Marine-Font A
Published: February 2020

A liquid chromatographic method is described for the determination in one run of the following 10 biogenic amines in beers: histamine, tyramine, serotonin, (β-phenylethylamine, tryptamine, cadaverine, putrescine, agmatine, spermine, and spermidine. The method is based on ion-pair chromatographic partition on a reversed-phase column and involves a postcolumn reaction with o-phthalaldehyde (OPT) to form fluorescent derivatives with amines. Treatment of beer samples before injection requires only a filtration through a 0.45 μm filter. It is necessary to obtain a perchloric extract for analysis of raw materials (malt and hops). The method was tested for lack of interference from amino acids and other amines. Linearity, precision, recovery, and sensitivity were satisfactory. Detection limits ranged from 0.30 to 0.40 mg/L, and determination limits ranged from 0.40 to 0.50 mg/L, except for serotonin and spermine, which were slightly higher. The simple preparation of sample and the automatic accomplishment of derivatization steps considerably reduce analysis time and effort.
Gas Chromatographic Determination of Cyclohexanone Leached from Hemodialysis Tubing
Authors: Snell Robert P
Published: February 2020

A capillary gas chromatographic procedure is described for the determination of cyclohexanone leached from hemodialysis tubing by water. Recoveries were 100% at 2.0 mg/100 mL (20 ppm), 99.0% at 500 μg/100 mL (5 ppm), and 106% at 1.0 μg/100 mL (10 ppb). Reproducibility of the system was 0.152% for 3.0 μL injections of a solution containing cyclohexanone at 5.58 μg/mL. Correlation coefficients were 0.9983 for 0.3672-3.672 ng and 1.0000 for 3.672-367.2 ng. Twenty hemodialysis tubing sets from 4 manufacturers were examined. The leachable cyclohexanone ranged from 1.02 to 43.7 ppm per set. Rinsing the tubing with 1 L 0.9% sodium chloride solution did not remove significant amounts (P = 0.05) of leachable cyclohexanone.
Rapid Thin-Layer Chromatographic Microestimation of Elemental Sulfur: Application to Complex Sulfur Ointments
Authors: Sanyal Asis K , Chowdhury Bhabadeb , Banerjee Arun B
Published: February 2020

Because of its nonpolar character, elemental sulfur can be separated easily from the components of complex samples and quantitated by thin-layer chromatography. Sulfur was separated by petroleum ether on silica gel G layers. The sulfur band on the chromatogram was scraped off and eluted with chloroform, and sulfur was estimated by its absorbance at 265 nm. The present method allows rapid, simple, but highly sensitive detection of sulfur down to 1 μg on the plate. The method was applied with high accuracy and precision to the analysis of complex sulfur ointments. No interference was encountered from other active components usually present in such complex formulations.
Evaluation of Current AOAC Fertilizer Sample Preparation Requirements
Authors: Newlon Natalie , Cox-Trout Candace , Kane Peter
Published: February 2020

The official AOAC fertilizer sample preparation requires that all dry mixtures be ground to pass a U.S. No. 40 sieve. With current fertilizers and mechanical grinders, these criteria may no longer be appropriate. Blended fertilizers were ground and sieved, and the fractions were analyzed separately to show potential variability in results. In general, potassium was heavily concentrated in the smaller particles of the ground sample, whereas phosphorus tended to be concentrated in the coarser particles. A representative set of fertilizers was subjected to 7 grinding treatments designed to produce samples with a wide distribution of particle size. N, P, and K were determined in the samples by traditional methods. Analysis of the results demonstrated that precise, accurate results could be obtained from samples that did not technically meet current sample preparation requirements. The relationship between fineness of grind and size of the analytical sample portion was examined. With proper sample grinding, sample sizes of ≤20 mg could give representative results for nitrogen analysis, with precision equal to or better than traditional Kjeldahl analysis using 1 g samples. This is of particular interest, because various combustion instruments now becoming popular for nitrogen analysis are limited in sample size.
Effectiveness of the Bacteriological Analytical Manual Culture Method for the Recovery of Shigella sonnei from Selected Foods
Authors: June Geraldine A , Sherrod Patricia S , Miguel Amaguana R , Andrews Wallace H , Hammack Thomas S
Published: February 2020

The relative retention of the indigenous morphological, biochemical, and serological characteristics by Shigella sonnei was tested under various storage conditions (room temperature, refrigeration, freezing at −20°C and at −70°C, and lyophilization). The use of a selective (desoxycholate citrate) agar rather than a nonselective (brain heart infusion) agar gave a lower conversion rate of smooth to rough colonies, and the percentage of rough colonies derived from cultures stored for prolonged periods increased under all conditions. With respect to biochemical characteristics, there were no major differences in the reactions of smooth vs rough variants. For serological characteristics, smooth variants agglutinated more readily in homologous antisera than did rough variants. S. sonnei populations maintained at −70°C with glycerol remained reasonably stable and were used in recovery studies. Up to six foods (potato salad, chicken salad, cooked salad shrimp, lettuce, raw ground beef, and raw oysters) were inoculated with unstressed, chill-stressed, or freeze-stressed S. sonnei cells. Test portions (25 g) were inoculated with serial 10-fold dilutions of culture and subsequently analyzed by the culture method described in the U.S. Food and Drug Administration’s Bacteriological Analytical Manual. It was found that the method was relatively ineffective for the recovery of S. sonnei from raw ground beef and raw oysters.
Speciation Analysis of Organolead Compounds in Wine by Capillary Gas Chromatography/Microwave-Induced-Plasma Atomic Emission Spectrometry
Authors: Lobinski Ryszard , Szpunar-Lobinska Joanna , C. Adams Freddy , Teissedre Pierre-Louis , Cabanis Jean-Claude
Published: February 2020

A method was developed for the speciation analysis of ionic organolead compounds in wine. The analytes were extracted as diethyldithiocarbamate complexes into hexane and propylated with a Grignard reagent. The derivatized extract was analyzed by capillary gas chromatography/microwave-induced-plasma atomic emission spectrometry. The method of standard additions was used for calibration to correct for variable recoveries and signal en hancements. Red, rosé, and white wines from southern France were analyzed. Trimethyllead was the ubiquitous species. The wines made from grapes grown close to industrial zones showed elevated concentrations of ethyllead species. The con centrations of methyllead and ethyllead found in wines were compared with the concentrations of organolead found in rain water and plant sap collected in the viticultural regions. The ratio of methyllead to ethyllead in wines greatly exceeded the same ratio found in atmospheric deposits.
Determination of Volatile Chemicals Released from Microwave-Heat-Susceptor Food Packaging
Authors: Mcneal Timothy P , Hollifield Henry C
Published: February 2020

Microwave heat susceptors that convert electromagnetic energy to heat attain high temperatures that make it possible to cook some foods to golden crispness in a microwave oven. Susceptors are typically packaged with foods intended for microwave use, e.g., waffles, pizzas, and french fries. The high temperatures >302°F used to cook some foods release trace levels of volatile chemicals from metalized polyester film, adhesive, and paper packaging materials; these volatile chemicals may be absorbed by the food. We simulated microwave susceptor cooking conditions and developed protocols by using headspace concentration capillary gas chromatography and mass spectrometry to identify volatile chemicals released from heated susceptors. We purchased a limited, cross-sectional sample of local retail microwave food products packaged with susceptors and used our protocol to analyze 10 different susceptor products. Although more than 140 unique chromatographic peaks were tabulated, only 44 volatile chemicals were identified, including 1,1,1-trichloroethane, benzene, and 2-(2-butoxyethoxy)ethanol, which were derived primarily from the paper and adhesive susceptor components. No one susceptor contained all the identified substances. The standard additions technique was the preferred method for quantitation. Trichloroethane and 2-(2-butoxyethoxy)ethanol were present in several products at 75-122 μg/in.2 of susceptor surface area. Benzene was found in 3 susceptors at ≤0.22 μg/in.2 levels. Examination indicates that adhesives used in more recent susceptor products were reformulated to remove even this trace level of benzene.
Method Modification for Liquid Chromatographic Determination of Thiamine, Riboflavin, and Pyridoxine in Medical Foods
Authors: Chase G William , Landen William O , Soliman Abdel-Gawad M , Eitenmiller Ronald R
Published: February 2020

A reversed-phase ion pair liquid chromatographic method developed for the simultaneous determination of thiamine (B1), riboflavin (B2), and pyridoxine (B6) in perchloric acid extracts of infant formulas was modified to include medical foods. UV detection of B1 and B2 was replaced by fluorescence detection, which resulted in improved sensitivity and specificity. B1 was detected by fluorescence after conversion to thiochrome by a postcolumn reaction with sodium hydroxide and potassium ferricyanide. The method uses a mobile phase of water, acetonitrile, hexanesulfonic acid sodium salt, ammonium hydroxide, and phosphoric acid adjusted to pH 3.6. The column is a 300 × 3.9 mm Nova Pak C18. Limits of detection were 0.05 μg/mL for B1 and B2 and 0.01 μg/mL for B6 by fluorescence detection. The system reproducibility was evaluated by completing 10 repetitive determinations on a medical food that gave a coefficient of variation of 5.9, 6.0, and 10.7% for B1, B2, and B6, respectively. Mean recoveries (n = 10) were 111,96.3, and 113% for B1, B2, and B6, respectively. The results compared favorably with those by AOAC Official Methods 942.23, 940.33, and 961.15 for B1, B2, and B6, respectively.
Partial Automation of Microbiological Assays for Vitamins
Authors: Haggett T O Richard , Matheson Alan R , Harnett Michelle
Published: February 2020

The dispensing and turbidity measurement steps used in microbiological assays of B group vitamins were automated by the use of a Gilson hardware package, a specially constructed turbidimeter, an IBM PC-AT or compatible computer, and software written in-house to facilitate data entry, control the hardware, and calculate the results. Considerable improvement in the speed and precision of the turbidity measurement was achieved (1% compared to 3-12%). The precision of the dispensing operation was better than that of manual dispensing (0.02-0.8% compared to 0.4-2%), although the speed was not improved. However, results and errors obtained from the automated system did not significantly differ from those obtained by former procedures. This was attributed to growth response variations not related to the automated procedure. The automation process facilitated detection of errors and halved the operator time per assay.
Analyte Stability Study of N-Methylcarbamate Pesticides in Beef and Poultry Liver Tissues by Liquid Chromatography
Authors: Ali M Sher , White Jerry D , Bakowski Ralph S , Phillippo Evan T , Ellis Richard L
Published: February 2020

To optimize conditions for sample collection, preparation, storage, and analysis and to assure the validity of our previously published liquid chromatographic (LC) method for carbamate analysis in tissue, stabilities of 16 N-methylcarbamates in beef, duck, and chicken liver tissues were studied by using 2 sampling protocols. Tissue samples were fortified at room temperature to a concentration 5 to 10 times greater than either the Environmental Protection Agency tolerance level for each compound (if established) or the concentration used in the previously published method. Thereafter, samples were continuously frozen at -4°C for varying time intervals. In the first study, samples were analyzed one day (initial) and 0.5, 1, 1.5, 2, 3, 4, 5, and 6 months after fortification. In the second study, samples were analyzed one day (initial) and 0.5, 1,2,3, and 6 months after fortification. For each residue and species, a minimum of 4 samples were analyzed by LC at each point in time, and the mean represented analyte concentration at the end of each time interval. Rates of residue depletion varied among analytes and among species. Depletion rates were greater in duck livers than in beef livers. Methomyl and oxamyl were depleted completely within 2 weeks. Between 2 and 6 months after sample fortification, residue depletions to levels below detection limits were observed for aldicarb, aldicarb sulfoxide, aldicarb sulfone, dioxacarb, promecarb, propoxur, and bendiocarb. The initial loss of certain carbamates during sample preparation in tissues exposed to room temperature for up to 8 h was greater than the subsequent rate of loss. Results indicate that cryogenic conditions are required for sample preparation and storage. Results also provide information on how long a violative evidentiary sample can be stored for potential litigation.