bluuebunny/crossref_metadata_2025 huggingface dataset:
Coupled-Column System for Quantitating Low Levels of Aflatoxins
Authors: Bicking Merlin K L , Kniseley Richard N , Svec Harry J
Published: February 2020

The combination of Styragel and Florisil columns allows recovery of aflatoxins at low levels. Two switching valves between the columns reduce the analysis time and exposure to solvents. Florisil is modified with oxalic acid, allowing recovery of aflatoxins at levels below 500 pg. The method is useful for contaminated corn and peanut meal samples.
Critical Re-appraisal of Fluorometric Method for Determination of Selenium in Biological Materials
Authors: Koh Tee-Siaw , Benson T H
Published: February 2020

The reaction of 2,3-diaminonaphthalene (DAN) with Se(IV) to form a fluorescent Se-DAN complex is the basis of a fluorometric method for determination of Se. With the aid of metabolically incorporated 75Se the method was critically re-examined. The study showed that loss of 75Se was negligible when liver or blood was microwave-dried or thermally dried at temperatures up to 120°C; during HC1 reduction of Se(VI) to Se(IV), a temperature up to 210°C could be used with no loss of 75Se; it was unnecessary to perform pH adjustment of solution for formation of Se-DAN complex before solvent extraction; it was unnecessary to carry out the chelation/extraction step in diffuse light; solvent phase containing Se-DAN complex could be left in contact with aqueous phase up to one week under fluorescent light with no effect on analytical results. From this study we were able to dispute or overcome a number of criticisms and myths which have been laid against the fluorometric method for many years. As a result, an improved single tube method was developed. The withinbatch variation of the improved method was about 2%, while the between-batch variation over a period of 2 years was less than 10%. The method can handle 200 samples per batch and is applicable to a wide range of biological samples including liver, orchard leaves, barley, wheat, lucerne (alfalfa), poultry feed, fish, hair, blood, urine, and milk.
Identification of Pacific Rockfish (Sebastes) Species by Isoelectric Focusing
Authors: Lundstrom Ronald C
Published: February 2020

Isoelectric focusing (IEF) is currently the most reliable method available for the identification of fish species. The high resolution of this method usually allows discrimination between even closely related species. One genus, the Sebastes, does present a problem however. Using both low and high resolution, IEF is unable to differentiate several species. Disc electrophoresis, used in an AOAC official final action method, does not differentiate the rockfish reliably. Using IEF, identical protein patterns were obtained for Pacific Ocean perch (Sebastes alutus), Bocaccio rockfish (S. paucispinis), and yelloweye rockfish (S. ruberrimus). A second group, comprised of silvergray rockfish (S. brevispinis), yellowtail rockfish (S. flavidus), black rockfish (S. melanops), and canary rockfish (S. pinniger), also has identical protein patterns. Widow rockfish (S. entomelas) and chilipepper rockfish (S. goodei) each had a unique pattern, different from the above 2 groups and from each other. The actual taxonomic relationships of these rockfish species are not clear and further work with IEF may help in this regard. Users of IEF and disc electrophoresis for identification purposes should be aware of this problem when working with the Sebastes.
Reverse Phase High Pressure Liquid Chromatographic Determination of Vitamin K1 in Infant Formulas
Authors: Bueno Martin P , Villalobos Melina C
Published: February 2020

A reverse phase high pressure liquid chromatographic (HPLC) method for quantitating vitamin K1 in enzymatic hydrolysates of infant formula is described. The vitamin is extracted with n-pentane before determination by isocratic and isothermal reverse phase HPLC. Recovery of vitamin Ki added io 5 infant formulas ranged from 84 to 103%
Improved Apparatus for Rapid Mercury Determination by Cold Vapor Atomic Absorption Spectrometry
Authors: Kupchella Lawrence , Syty Augusta , Mahfood John J
Published: February 2020

A glass reaction vessel is described and the convenience and simplicity of its use in cold vapor atomic absorption spectrometric determination of mercury are pointed out. The vessel is easy to construct and requires only 15 s for collection of the analytical signal. It provides for continuous flow of carrier gas, and contains a septum-covered sample injection port, a buret for rapid introduction of reagent, and a drain stopcock. Using this apparatus, the relative standard deviation is 2.9% at the 40 ng Hg/mL level. The detection limit is 1 ng/mL. Applicability of the apparatus is proved by analysis of 3 commercial waste water quality control samples.
Reverse Phase High Pressure Liquid Chromatography and Fluorescence Detection of Ethoxyquin in Milk
Authors: Perfetti Gragia A , Joe Frank L , Fazio Thomas
Published: February 2020

A high pressure liquid chromatographic (HPLC) method has been developed for the determination of ethoxyquin (l,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline) in milk. Milk solids are precipitated by adding acetonitrile, and the water-acetonitrile supernate is washed with hexane to remove fat. Addition of sodium chloride causes the water-acetonitrile solution to separate into an aqueous phase and an acetonitrile phase, thus separating ethoxyquin from most water-soluble impurities. A large volume of water is then added to the acetonitrile layer and ethoxyquin is partitioned into hexane, which is removed at reduced pressure. The residue is dissolved in the mobile phase and analyzed on a 4.6 mm id × 250 mm Ultrasphere ODS column using fluorescence detection (excitation 230 nm; 418 nm cutoff filter). Water-acetonitrile with a diethylamine-acetic acid buffer is the mobile phase. Recoveries from samples fortified at 1, 5, and 10 ppb averaged 78% with a coefficient of variation of 5.0%. Low levels (<1 ppb) of apparent ethoxyquin were found in commercial milk samples that were analyzed by using the method.
Detection and Determination of Error in Analytical Methodology. Part I. In the Method Verification Program
Authors: Cardone Mario J
Published: February 2020

A total method verification program is presented, composed of the initial developing laboratory’s method validation process and the end user’s method evaluation studies. Both processes escalate in a cyclic fashion and the communicative pathway is the method transfer process. The participating laboratories acquire data by the intralaboratory procedures described and the cross-over studies entail the interlaboratory (collaborative) procedures described. During the entire process, the diagnostic techniques described result in the detection and determination of error in the methodology.
Effects of Grinding and Storage for One Month on Retention of Vitamin A in Premixes and Mineral Supplements
Authors: Parrish Donald B , Patterson Karen
Published: February 2020

Tested standardized procedures for handling premixes and mineral supplements from time of sampling to time of analysis for vitamin A have not been developed, which could account for some unexplained inconsistent and low analytical results. Grinding premix samples and storing them in a freezer for one month had little effect on amount of vitamin A found, but there was a significant loss (about 10%) after storage for one month at room temperature. Results on replicated determinations of vitamin A in unground and ground mineral supplements and on effect of storage were somewhat more variable than for premixes, but only the loss (about 12%) during storage for one month at room temperature was significant.
Liquid Chromatographic Determination of 2,4-Dinitro-l-Naphthol and 1-Naphthol in External D&C Yellow No. 7
Authors: Goldberg Allen L , Calvey Robert J
Published: February 2020

A sensitive, reproducible method that uses liquid chromatography in the reverse phase mode with a C-18 column is described for determining 2,4-dinitro- 1-naphthol and 1-naphthol in Ext. D&C Yellow No. 7. With this method, these 2 compounds are eluted in a reproducible pattern by increasing the organic nature of a buffered mobile phase. Average recoveries of 2,4-dinitro-l-naphthol and 1-naphthol added to samples of Ext. D&C Yellow No. 7 at levels ranging from 0.003 to 0.20% were 103.9 and 94.7%, respectively.
Gas Chromatographic Determination of Glucono-δ-Lactone in Foods
Authors: Tsuda Taizo , Nakanishi Hiroshi
Published: February 2020

A method is described for the gas chromatographic (GC) determination of glucono-δ-lactone in foods. A sample was homogenized with 60-70°C water and filtered. The filtrate was buffered with NH4OHNH4CI pH 10 solution, and was passed through a QAE-Sephadex A25 column. The column was washed with water and glucono-δ-lactone was eluted with 0.1N HC1. An aliquot of the eluate was evaporated to dryness and derivatized with pyridine, N,O-bis(trimethylsilyl)trifluoroacetamide, and trimethylchlorosilane at room temperature. GC separation of glucono-δ-lactone as the TMS derivative was performed on a 2% OV-17 column at 180°C. Recoveries from bread, jelly, soybean curd, and other foods fortified with 0.1% glucono-δ-lactone ranged from 92 to 106%, with standard deviations from 2.2 to 9.8%. The detection limit was approximately 0.025%.
Retention Indexes for Electron Capture Gas Chromatography on Programmed Temperature High Resolution Capillary Column
Authors: Nakamura Akio , Tanaka Ryoichi , Takashi Kashimoto
Published: February 2020

A simple method and a series of compounds for a retention indexing study on a linear programmed capillary gas chromatograph are described. References are chlorobenzenes and decachlorobiphenyl, which show the same behavior in this system as Kovat's references (n-alkanes). This retention index system and gas chromatograph with cryogenic coolant apparatus and electron capture detection, is suitable for measuring the retention index of various compounds with characteristic detection ranging from low volatility to high molecular weight.
Simple Colorimetric Method for Determination of Metaproterenol Sulfate in Pharmaceuticals
Authors: Sane Ramesh T , Sawant Satish V , Doshi Vipul J , Mhalas Jagannath G , Paarikh Ajay K , Gijare Ashok S , Deshpande Deepak S
Published: February 2020

A simple coiorimetric method is described for the determination of metaproterenol sulfate (orciprenaline sulfate). The method is based on measurement of a colored species formed when metaproterenol sulfate is treated with diazotized dapsone, p-nitroaniline, or benzocaine at room temperature, followed by treatment with an aqueous solution of trimethylamine in the case of benzocaine. Compounds such as starch, talc, and common excipients do not interfere in the reaction. Statistical validation showed that the method was precise and accurate. The results agree well with those obtained by other methods reported in the literature.
First Derivative Spectrophotometric Determination of Strychnine and Brucine in Nux Vomica Liquid Extract
Authors: Korany Mohamed A , Seif El-Din Ahmed A
Published: February 2020

A simple, rapid, and accurate method is presented for determining strychnine and brucine in nux vomica liquid extract. The 2 alkaloids are directly extracted from the alkaline liquid extract with 0.1N H2S04, and the liberated alkaloids are determined separately using first derivative spectrophotometry. The minimum strychnine and brucine concentrations detectable by means of this method are 3.0 μg/mL. The method has been successfully applied to the analysis of 3 batches of nux vomica liquid extract.
Confirmatory Method for Sulfamethazine Residues in Cattle and Swine Tissues, Using Gas Chromatography-Chemical Ionization Mass Spectrometry
Authors: Stout Steven J , Steller William A , Manuel Arthur J , Poeppel Manfred O , Dacunha Andrian R
Published: February 2020

A gas chromatographic (GC) method has been reported for the determination of sulfamethazine residues in cattle and swine tissues. The extracts from this procedure were found to be directly amenable to examination by gas chromatography–mass spectrometry (GC-MS), allowing positive confirmation of an apparent residue of sulfamethazine. Chemical ionization mass spectrometry (CIMS) was chosen as the MS technique because it generated an ion indicative of intact sulfamethazine and fragment ions indicative of the amine functionality and sulfanil moiety. Positive ion (PI) chemical ionization mass spectrometry was adequate by itself for a confirmatory technique. Negative ion (NI) chemical ionization mass spectrometry alone could not be used for the confirmatory analysis of sulfamethazine, but it did offer a means to check the quantitative data from the positive ion analyses and provided complementary confirmatory data. Satisfactory recoveries were obtained for sulfamethazine in swine and cattle tissues at the tolerance level of 0.1 ppm. Apparent sulfamethazine residues in control tissues were less than 0.01 ppm.
Determination of Citrinin in Corn and Barley on Thin Layer Chromatographic Plates Impregnated with Glycolic Acid
Authors: Gimeno Alberto
Published: February 2020

A method is described for the determination of citrinin in corn and barley. The mycotoxin is extracted with a mixture of acetonitrile-10% glycolic acid in water, defatted with isooctane, and transferred to chloroform according to published methods. The mycotoxin is separated by thin layer chromatography (TLC) on plates previously impregnated with 10% glycolic acid solution in ethanol; identity is confirmed by chemical tests. Citrinin is then quantitated by the limit detection method. Recoveries of citrinin from corn and barley samples spiked at levels of 50, 80, 150, 300, 500, and 1000 μg/kg were in the range 91-98%. The minimum detectable concentration is 15-20 μg/ kg. Recoveries obtained with and without glycolic acid in the extraction solvent were compared. Sensitivities on TLC plates (limits of detection, μg/spot) impregnated with glycolic acid were compared with those on plates impregnated with oxalic acid.
Improved Reverse Phase Liquid Chromatographic Determination of Vitamins A and D in Fortified Milk
Authors: Wickroski Alphonse F , Mclean Lucia A
Published: February 2020

A method for determination of vitamins A, D2, and D3 on the same 6 mL sample of fortified milk is described. A special indicator permits selection from the cleanup column of a fraction that contains all vitamin D and is free of cholesterol interference for final measurement by reverse phase liquid chromatography. Conservation of analyst's time and expensive solvents results from the relatively small sample processed. The average recoveries and standard deviations were, respectively, 94.1% and 4.8 for vitamin D2, 91.1% and 5.2 for vitamin D3, and 92.2% and 2.6 for vitamin A in nonfat skim milk; 86.5% and 9.4 for vitamin D2, and 83.7% and 4.9 for vitamin D3 in homogenized whole milk. Detectable minima are about 100 IU vitamin A/qt and 50 IU vitamin D2 or D3/qt.
Protein Efficiency Ratio: AACC/ASTM Collaborative Study
Authors: Hackler L Ross , Bodwell Clarence E , Happich Muriel L , Phillips John G , Derse Phillip H , Elliott James G , Hartnagel Ralph E , Hopkins Daniel T , Kapiszka Eugene L , Mitchell Geraldine V , Parsons Grace F , Prescher Elmer E , Robaidek Eugene S , Womack Madelyn
Published: February 2020

Eight laboratories (7 of the laboratories conducted animal experiments) participated in a collaborative study to standardize some of the methodology associated with animal bioassays for determining protein efficiency ratios and to suggest improvements which would reduce the variation among laboratories. One-, 2-, 3-, and 4-week protein efficiency ratios (PER) with 0-, 2-, or 4-day adaptation periods were obtained from each laboratory, respectively, for 6 protein sources: casein, lean beef, lactalbumin, textured vegetable protein, peanut flour, and wheat flour. Analyses were computed for PER and adjusted PER (APER). From the analysis of variance for PER and APER, significant (P < 0.05) effects were observed due to laboratories, adaptation length, protein sources, and/or interactions among these variables. In general, APER values show much less variation among laboratories than PER values. The reproducibility and repeatability variances were significantly (P < 0.05) greater for an assay length of 2 weeks than they were for 3- or 4-week assays. Two protein sources, casein and textured vegetable protein, were fed at both high (10%) and low (6%) levels of protein. Analysis of variance of PER values shows a significant (P < 0.05) laboratory by protein level by assay length interaction.
Method for Determination of Organohalogen Pesticide Residues in Vegetable Oil Refinery By-Products
Authors: Young Susan , Marion Clower , Roach John A G
Published: February 2020

A method using gel permeation and Florisil column chromatographic cleanup techniques is described for determination of residues of nonpolar organohalogen pesticides and pesticide alteration products in vegetable oils and their refinery by-products. Supplemental Florisil separation and alkali cleanup techniques are used to facilitate determinations. Residues are determined with a 63Ni electron capture gas chromatographic detection system used in conjunction with 3 different gas chromatographic columns. Residue identities are confirmed by gas chromatography-mass spectrometry. Recoveries of 7 organohalogen pesticides, ranging from 90 to 103%, were determined by the supplemental Florisil separation technique to augment previously reported recovery data determined for initial GPC and Florisil cleanup steps. Soybean, peanut, and cottonseed deodorizer distillates and crude and refined oil, as well as additional refinery by-products, were analyzed. Nine to 13 organohalogen residues ranging from 0.5 to 6.3 ppm were determined in the 2 soybean deodorizer distillate samples used to develop and test the method. Identities of residues present at ≥0.3 ppm were confirmed by gas chromatography-mass spectrometry. An intralaboratory trial of the method provided additional recovery and residue determination data as follows: Recoveries ranging from 102 to 116% were obtained for 4 pesticides added to peanut oil deodorizer distillate. Residues determined in 1 soybean deodorizer distillate sample supported previously obtained data for this sample.
Reverse Phase Liquid Chromatographic Screening Procedure for Parts-Per-Million Levels of/P-ToIuidine in D&C Red No. 6 and D&C Red No. 7
Authors: Bailey John E
Published: February 2020

A reverse phase liquid chromatographic method is described for the determination of p-toluidine in D&C Red No. 6 and D&C Red No. 7. The procedure employs octylsilanized silica gel as the stationary phase and gradient elution with a mobile phase of aqueous acetonitrile solutions containing ammonium sulfate-sulfuric acid electrolytes (pH 2). The dye is first mixed with an aqueous extraction solution containing tetrabutyl ammonium sulfate and sulfuric acid and is then extracted with chloroform. The dye migrates to the organic layer, leaving theptoluidine in the aqueous layer as the protonated amine. The limit of determination for the method is 1.9 ppm. Recoveries of p-toluidine averaged 91.8% from samples of D&C Red No. 6 and 94.6% from samples of D&C Red No. 7
Atomic Absorption Spectrometric Determination of Arsenite in Water Samples by Graphite Furnace After Extraction with Ammonium sec-Butyldithiophosphate
Authors: Chakraborti Dipankar , Irgolic Kurt J , Adams F
Published: February 2020

Arsenite—but not arsenate, methylarsonic acid, or dimethylarsinic acid—is extracted from water samples by 5 mL of a 0.01M hexane solution of rec-dibutylthiophosphate. A 10 μL aliquot of the extract is injected into an atomic absorption spectrometer with a graphic furnace for the determination of arsenic. The calibration curve is linear to 1500 Dg As. Quantities of arsenic as low as 100 ng As (0.2 ppb As when contained in 500 mL) can be confidently determined. The method was tested with natural river water and synthetic river water. The relative standard deviations associated with the recoveries of arsenite from natural water and synthetic river water spiked with arsenite range from 4.8 to 8.0%. Ten to 15 arsenite determinations can be completed in 1h.
Alumina Blending Technique for Separation of Pesticides from Lipids
Authors: Gillespie Allesia M , Walters Stephen M
Published: February 2020

An evaluation of an extraction technique for elimination of lipids during pesticide residue analysis was undertaken, which included a study of the parameters involved in an attempt to optimize the separation and recovery of selected pesticides from lipid samples. The choice of alumina, the degree of water deactivation of alumina, the amount of alumina relative to the weight of sample taken, the volume and composition of extraction solvent, the blending time, and the filtration procedure were all significant factors. Optimization of these factors resulted in >90% recoveries of selected chlorinated pesticides from fortified fatty samples. In addition, the amount of co-extracted lipid material was about one-third of that obtained with the official method (AOAC 29.014), and less analytical time was required for the extraction by the proposed technique. The formation of troublesome emulsions sometimes encountered with the official method was also eliminated.
Aflatoxin Levels in Airborne Dust Generated from Contaminated Corn During Harvest and at an Elevator in 1980
Authors: Burg William R , Shotwell Odette L
Published: February 2020

Bulk corn samples and airborne samples generated therefrom were collected on a Georgia farm during the 1980 harvest and while the 1980 corn was being ground and fed to swine. The bulk corn harvested had 1640 ng total aflatoxin/g. Airborne dust samples collected at the front of the combine had an average of 3850 ng total aflatoxin/g; at the side of the combine, the average aflatoxin level was 2550 ng/g of dust. At one time, the operator was exposed to airborne dust containing 1360 ng/g while inside the combine cab. An airborne dust sample taken with a personal sampler during transfer of the corn to a truck had 52 000 ng/g. Airborne dusts collected while corn containing aflatoxin (1240- 1850 ng/g) was being ground and fed had total aflatoxin levels ranging from nondetected to 43 700 ng/g. Airborne dust, bulk corn, and settled dust samples were collected at a grain elevator. Airborne dust samples collected during the delivery of corn in farm trucks to the elevator had an average of 1240 ng total aflatoxin/g. The airborne dust samples taken while corn was being unloaded from the elevator into trucks and railroad cars had lower average aflatoxin levels than those in dusts collected during delivery. Settled dusts in the elevator had 173-669 ng total aflatoxin/g. The highest aflatoxin level in the air in the elevator was 13 000 ng/cu. m near the conveyor belt. Airborne dust samples collected by personal samplers on elevator workers contained aflatoxin levels of 429-1300 ng/g; aflatoxin levels in the air were .9-1120 ng/cu. m.
Comparison of Liquid Chromatography and High Performance Thin Layer Chromatography for Determination of Aflatoxin in Peanut Products
Authors: Tosch Donna , Waltking Arthur E , Schlesier John F
Published: February 2020

Recent research studies concerning aflatoxin in peanut products have involved the use of new instrumental methods for greater detection sensitivity. A comparison of 2 such techniques, liquid chromatography (LC) and high performance thin layer chromatography (HPTLC), is reported here. With respect to precision, accuracy, sensitivity, recovery, and linearity of response, HPTLC appears to be equivalent to LC. These points illustrate the viability of HPTLC as an alternative technique in the determination of aflatoxin.
Reverse Phase Liquid Chromatographic Determination of Aspartame in Beverages and Beverage Mixes
Authors: Webb Norma G , Beckman Darrell D
Published: February 2020

A method is described for determining the artificial sweetener aspartame in beverages and beverage mixes by liquid chromatography. Aspartame is separated on a μC18 column, using a mobile phase of acetic acid, water, and isopropyl alcohol at pH 3.0 and UV detection at 254 nm. Beverages are filtered through 0.45 μm filters and injected directly into the chromatograph. Aspartame is eluted in approximately 7 min. Detection of aspartame is confirmed by a UV scan of the trapped peak. Aspartame is quantitated in the presence of other beverage additives such as saccharin, caffeine, sodium benzoate, artificial colors, and artificial flavors. Results are presented for spiked soda beverages, beverages from fruit-flavored mixes, instant tea, reconstituted presweetened drink mixes, and a powdered tabletop sweetener.
Practical Screening Procedure for Chloramphenicol in Milk at Low Parts per Billion Level
Authors: Schwartz Daniel P , McDonough Frank E
Published: February 2020

A relatively simple screening procedure for the detection of chloramphenicol in cow’s milk is detailed. The drug in 50 mL skim milk is adsorbed onto Chromosorb 102 and subsequently eluted; interfering impurities are removed by passing the effluent directly over one column containing small beds of alumina and cation exchange resin in the H+ form. After solvent is removed, the nitro group of the drug is reduced with zinc dust in HCI, and the drug is detected by diazotization and coupling to N-1-(naphthyl)ethylenediamine. Milk containing ≥4 ppb chloramphenicol can be detected. A number of antibiotics and sulfa drugs permitted for use with dairy cows do not interfere with chloramphenicol detection, nor do some naturally occurring aromatic amino compounds. Nitromide (3,5-dinitrobenzamide) will interfere. It is estimated that approximately 50 samples of skimmed milk can be screened by one person during the working day. Cows secreted the drug into their milk for approximately 3 days following injection of chloramphenicol either intramuscularly or via infusion into the udder.
Gas Chromatographic-Mass Spectrometric Detection and Quantitation of Lincomycin in Animal Feedingstuffs
Authors: McMurray Cecil H , Blanchflower W John , Rice Desmond A
Published: February 2020

A substantially Improved assay was developed for lincomycin A in animal feedingstuffs. The assay allows unambiguous quantitation of at least 0.1 ppm in feed. Lincomycin B did not interfere because of differences in both retention time and mass of the main fragment ion in electron impact (EI) spectra. The assay using single ion monitoring with EI detection would not discriminate between lincomycin A and clindamycin. The presence of the latter was easily confirmed by using gas chromatography-mass spectrometry in the chemical ionization mode. The assay for lincomycin A was linear in the range 0–40 ng applied to the gas chromatographic column. The recovery was 93.4 ± 4.2% at 1 and 5 ppm and 86.2 ± 5.5% at 0.1 ppm in feed. The coefficient of variation of the assay was 4.8% at both 1 and 5 ppm, and was 6.43% at 0.1 ppm.
Available Amino Acid Score for Evaluating Protein Quality of Foods
Authors: Sarwar Ghulam
Published: February 2020

Amino acid scores corrected for true digestibility of individual amino acids (as determined by rat balance method) were termed “available amino acid scores” in the present investigation. Available amino acid scores were calculated for 7 protein sources and their 10 supplementary or complementary mixtures which have been tested in collaborative amino acid and rat growth assays for evaluating protein quality. The available amino acid scores were as follows: casein + methionine (100); egg white (100); rapeseed protein concentrate, RPC (94); casein (93); beef (89); soya assay protein, SAP (62); pea flour (61); whole wheat flour, WW (38); SAP + methionine (88); pea flour + methionine (72); WW + lysine (67); WW + casein (84); WW + egg white (79); WW + RPC (65); WW + beef (77); WW + SAP (70); and WW + pea flour (75). These scores were similar to the collaborative relative NPR values; the differences were less than 10 units (2–9 units) in most cases. The positive correlation (r = 0.92) between available amino acid scores and relative net protein ratio (RNPR, a rat growth method) values was highly significant (P < 0.01) and the origin of the regression line (y = 0.92x + 1.88) was not significantly different from zero. Amino acid bioavailability has previously been a problem, preventing widespread acceptance of amino acid score. Available amino acid score solves this problem.
Stored Wheat Insect Infestation Related to Uric Acid as Determined by Liquid Chromatography
Authors: Wehling Randy L , Wetzel David L , Pedersen John R
Published: February 2020

Liquid chromatography is used to measure the uric acid content of wheat internally infested by various growth stages of granary weevil (Sitophilus granarius), rice weevil (Sitophilus oryzae), and lesser grain borer (Ryzopertha dominica). Good correlation exists between numbers of insects and uric acid content of grain infested by a given stage of an internally infesting stored product insect, with correlation coefficients ranging from 0.970 to 0.998. Uric acid content of infested grain increases as the insect life cycle progresses, with granary weevil producing the greatest quantities of uric acid followed in order by rice weevil and lesser grain borer. A detection limit for the analytical procedure of less than 1.0 ppm uric acid allows detection of infestation levels as low as one kernel per 100 g grain for late instar granary weevil larvae. This limit is sufficiently sensitive to detect levels of infestation that may be commonly encountered in commerce.
Semiautomated Determination of Tridihexethyl Chloride in Meprobamate Tablets
Authors: Kirchhoefer Ross D
Published: February 2020

A semiautomated method has been developed for the analysis of tablets containing tridihexethyl chloride in combination with meprobamate. The method is based on the USP assay for tridihexethyl chloride in tablets. The active ingredient is dissolved in water, the aqueous solution is mixed with buffer and dye solution, and the dye complex is extracted into chloroform. The absorbance of the chloroform solution is monitored at 408 nm. Results from the semiautomated method agree with I results for the USP method. Recoveries from authentic formulations I show no interference from the excipients tested.
Liquid Chromatographic Determination of Oxfendazole in Swine Feeds
Authors: Shah Gaman , Bradley Dorothy , Shek Efraim
Published: February 2020

A relatively simple analytical method is presented for determination of oxfendazole (2-(methoxycarbonylamino)-5-phenylsulfinyl-benzimidazole) at levels as low as 0.012% in swine feeds, using cation exchange liquid chromatography (LC). The sample was extracted with a solvent mixture of methanol-glacial acetic acid (90 + 10) at 45°C, using a gyrorotory shaker. Plant pigments and other feed excipients were removed using zinc acetate treatment and pH-controlled extraction. Oxfendazole was further separated from the remaining interferences and quantitatively determined by LC on a Partisil SCX column with acetonitrile-1.01M phosphate buffer as mobile phase. The method is stability-specific, linear, precise, and accurate at 80-120% labeled strength (relative standard deviation 0.9-1.7 with mean recovery of 98-99%). Supporting data at a level of 0.0135% oxfendazole in swine feed indicated that this method is capable of complete recovery of oxfendazole from medicated swine feeds.
Liquid Chromatographic Analysis of Sugars, Acids, and Ethanol in Lactic Acid Vegetable Fermentations
Authors: Mcfeeters Roger F , Thompson Roger L , Fleming Henry P
Published: February 2020

Routine analysis of all the major substrates and products of homolactic or heterolactic acid vegetable fermentations was made possible by the use of 2 liquid chromatographic procedures. Sucrose, glucose, fructose, and mannitol were determined on a cation exchange column in the lead form. The coefficient of variation of the added compounds (2 to 30mM) in fermented cucumber juice with salt concentrations of 0-1.5% ranged from 2.0 to 3.1%. Sucrose (l-12.5mM), malic acid, lactic acid, acetic acid, and ethanol (2-25mM) added to cucumber juice containing 0- 6.0% NaCl were separated on a reverse phase column; coefficients of variation ranged between 4.3 and 5.9%. Sample preparation requires only blending and filtration prior to injection.
Liquid Chromatographic Determination of Flavor Enhancers and Chloride in Food
Authors: Nguyen Thanh T , Sporns Peter
Published: February 2020

A liquid chromatographic method is described for the simultaneous determination of flavor enhancers (glutamate, inosine-5'-monophosphate, and guanosine-5'-monophosphate) and chloride (salt) added to food. This rapid method exhibits excellent recoveries, and does not require derivatization or gradient elution by refractive index and UV detection in series.
Improved Storherr lube for Assisted and Sweep Co-Distillation Cleanup of Pesticides, Poly chlorinated Biphenyls, and Pentachlorophenol from Animal Fats
Authors: Neidert Eli , Saschenbrecker Peter W
Published: February 2020

A procedure is presented for the simultaneous extraction from animal fat and quantitation of 15 pesticide residues, 4 polychlorinated biphenyl (PCB) formulations, and pentachlorophenol (PCP). Silanization of the Storherr tube packing reduces thermal decomposition and allows for residue recoveries in excess of 88% from pork, beef, chicken, sheep, and rabbit fat. This Storherr tube performs well in either the assisted distillation or sweep co-distillation mode of operation. Detection limits of 2-5 ppb for the pesticides and 10 ppb for the PCBs are readily attained.
Chemical Derivatization Analysis of Pesticide Residues. VIII. Analysis of 15 Chlorophenols in Natural Water by In Situ Acetylation
Authors: Lee Hing-Biu , Weng Li-Da , Chau Alfred S Y
Published: February 2020

A rapid analytical method is presented for quantitative analysis of 15 chlorophenols in natural waters by in situ acetylation. In the presence of KHC03, phenols in water are acetylated by acetic anhydride directly without pre-extraction. The resultant acetates are extracted by petroleum ether and analyzed by electron capture gas chromatography. The investigation to optimize the conditions for in situ acetylation of these phenols is also described. This method has been validated and shown to be applicable over a range from 100 to 0.01 ppb with a 1 L water sample.
Gas Chromatographic Method for Analysis of 2,4-D in Wheat: Interlaboratory Study
Authors: Smith Allan E
Published: February 2020

A procedure is described for the determination of 2,4-D (2,4-dichlorophenoxyacetic acid) in dried green plant material. Samples are first extracted with dilute sodium hydroxide, and then after acidification and solvent extraction, the residues are methylated using boron trifluoride-methanol reagent. The methyl ester of 2,4-D is cleaned up on a Florisil column and quantitated using a gas chromatograph equipped with an electron capture detector. Six laboratories made quadruplicate determinations on control, dried green wheat check samples, on 4 similar samples fortified at the 0.50 ppm level, and on 4 samples fortified at the 1.00 ppm level with 2,4-D. Based on the data from 5 laboratories, the plant fortifications of 0.50 and 1.00 ppm yielded average interlaboratory recoveries of 2,4-D of 83.3 and 88.2%, respectively. The procedure also has potential for the determination of 2,4-D in wheat straw and wheat grain.
Simple Analytical Method for Organophosphorus Pesticide Determination in Unpolished Rice, Using Removal of Fats by Zinc Acetate
Authors: Adachi Kazuhiko , Ohokuni Nobuyuki , Mitsuhashi Takao
Published: February 2020

A rapid and simple method is developed for the determination of organophosphorus pesticides in unpolished rice. The new method incorporated acetonitrile-water (1 + 1) extraction, removal of fats by zinc acetate, and further cleanup on an activated charcoal chromatographic column. The higher fatty acids in the extract react rapidly with zinc acetate to form insoluble zinc carboxylates, which precipitate. Additional interferences were cleaned up on an activated charcoal chromatographic column, and organophosphorus pesticides adsorbed on the activated charcoal were eluted with acetone-hexane. Dimethoate is not retained on the activated charcoal and must be extracted with dichloromethane from the first acetonitrile-water eluate. Pesticides are measured by flame photometric gas chromatography. Recoveries from 50 g unpolished rice samples fortified with 5-50 μg diazinon, 6-30 μg parathion, 8-40 μg fenitrothion and IBP, 10-50 μg dimethoate and fenthoate, 20-100 μg malathion, or 40-200 μg EPN ranged from 75.7 to 95.8%.
Enumeration of Total Coliforms, Fecal Coliforms, and Escherichia coli in Foods by Hydrophobic Grid Membrane Filter: Supplementary Report
Authors: Entis Phyllis
Published: February 2020

Raw, comminuted poultry meat was used to determine the specificity of the media and incubation conditions used in the hydrophobic grid membrane filter method. Confirmation rates for target colonies were 100% for total coliforms, 98% for fecal coliforms, and 97-99% for Escherichia coli. The results of total coliform enumeration in 30 pasteurized milk samples by both the hydrophobic grid membrane filter method and AOAC method 46.013-46.016 are also reported.
Liquid Chromatographic Determination of Glucosinolates in Rapeseed as Desulfoglucosinolates
Authors: Sang Joseph P , Truscott Roger J W
Published: February 2020

A method was developed for the quantitative determination of rapeseed glucosinolates as the desulfo derivatives, using liquid chromatography. Glucosinolates were desulfated at 37°C with the enzyme aryl sulfatase in Tris buffer, pH 8.0. All glucosinolates present in rapeseed were separated in 30 min on a Waters C18 Z-module using an acetonitrile gradient at 4 mL/min. Recoveries of benzyl, 4-hydroxybenzyl, and allylglucosinolates added to plant extracts were quantitative.
Simultaneous Determination of Thiamine and Riboflavin in Foods by Liquid Chromatography
Authors: Augustin Jorg
Published: February 2020

Recent methods for determination of thiamine (thiochrome) and riboflavin by liquid chromatography (LC) are outlined and discussed, and a new method allowing the simultaneous determination of these 2 vitamins by using a single fluorescence detector is described. This system involves an ODS 5 μm ultrasphere column and a pH 7.5 mobile phase composed of 0.005M tetrabutyl ammonium phosphate in methanol-water (20 + 80).
Determination of Folacin m Foods and Other Biological Materials
Authors: Gregory III Jesse F
Published: February 2020

The objective of most methods for determination of folates in foods and other biological materials is to estimate the total folacin content of the sample. Because folacin comprises a diverse group of related compounds exhibiting similar biological activity, the analytical method must be capable of measuring all of the folates. Methods have been developed for separation of folates in their monoglutamy 1 form by using anion-exchange, paired-ion reverse phase, or conventional reverse phase liquid chromatography (LC). The application of these separations to determination of folates in foods and other biological materials has been limited largely by the need for development of adequate preparative methods and sufficiently sensitive and specific detection procedures. Although LC with ultraviolet absorption detection has been successful in certain limited applications, the development of fluorometric detection methods has permitted LC determination of folates in a wide range of materials. Tetrahydrofolic acid and its substituted derivatives are detected by monitoring their native fluorescence in an acid mobile phase, while folic acid and certain other folates are measured by using an oxidative post-column fluorogenic derivatization system. Methods also have been developed for determination of the polyglutamyl chain length distribution of folates in biological materials. In total, these procedures permit a direct determination and characi terization of folacin compounds.
Forage Nitrate Analysis: Laboratory Performance Study
Authors: McMahon Terence L , Casper Howard H
Published: February 2020

Four forage samples were analyzed by 16 laboratories for KNO3 content. Individual reported KNO3 values varied widely for each sample; coefficients of variation for the 4 samples were 36.0, 51.0, 12.8, and 55.0%. Recovery of KNO3 from the spiked sample averaged 105%. The analytical results, as a group, were unacceptable both statistically and for use in feeding recommendations. Three values reported could have resulted in feeding potentially toxic forage to livestock.
Microbiological Determination of Neomycin in Feeds and Formulated Products
Authors: Stahl Gerald L , Kratzer Dal D
Published: February 2020

An AOAC modified method is described for the microbiological assay of neomycin, which has been adapted to include complete feeds, supplements, premixes, liquids, oil suspensions, boluses, and antibiotic-impregnated paper. The method features a more sensitive standard response line with a monolayer plating system. The use of a buffered plating medium in place of the water-prepared medium results in a curve with less degree of slope, which allows for more accurate interpretation of the standard response. The feed extract diluent used for standard response line dilution, which is prepared from exposure of the feed extract fluid to pH changes, heat, and sodium hypochlorite, has been eliminated. The constant salt concentration diluent used for the preparation of standards is the same as the salt concentration of the sample extract solution to be tested. Results for 50 commercial complete feeds and 50 commercial premixes received over the last 5 years produced an overall mean recovery of 101% with a mean percent recovery range of 80-112%. A statistical analysis of these 100 commercial, complete feeds and premixes, ranging in concentration from 47 g/ton to 70 g/lb, indicates the assay has little, if any, concentration-related bias. Precision and accuracy of the method was supported by laboratory studies of 20 assays that produced a mean recovery of 101 % and standard deviation of 3.
Gas Chromatographic Determination of Residues of Bromopropylate and Two of Its Degradation Products in Honey
Authors: Formica Giuseppe
Published: February 2020

An analytical procedure is described for determination of residues of bromopropylate (BP) and its main degradation product 4,4'-dibromobenzophenone (BBP) in honey. The method also allows the determination of 4,4'-dibromobenzilic acid (BBA), a potential intermediate to BBP. The method involves dissolution of the honey in water and separation of BP and BBP from BBA on a partition column. BP and BBP are further cleaned up and separated on a silica gel column and determined by gas chromatography (GC) with electron capture (EC) detection. BBA is oxidized with potassium dichromate to BBP, which is partitioned into dichloromethane and further cleaned up on a silica gel column before determination by GC with EC detection. The method is sensitive to 0.02 mg BP or BBP/kg and 0.023 mg BBA/kg honey.
Liquid Chromatographic Determination of Phenol and Cresols in Total Particulate Matter of Cigarette Smoke
Authors: Tomkins Bruce A , Jenkins Roger A , Griest Wayne H , Reagan Roberta R , Reagan Roberta R , Holladay Susan K
Published: February 2020

The phenol and cresol contents of the total particulate matter of tobacco smoke can be conveniently determined. A simple extraction procedure using IN base is followed by partial neutralization with glacial acetic acid and elution of hydroxy benzenes from an end-capped reverse phase liquid chromatographic column. The procedure is rapid (20 min/sample after the initial extraction), precise (± 10% relative standard deviation), accurate, and convenient. Normally, 12 or fewer cigarettes are needed for a single measurement.
Reduction in Variability of Instrumental Methods
Authors: Horwitz William
Published: February 2020

The largest contribution to experimental error in most analyses is systematic, resulting from preparation of standards and calibration procedures. By their very nature, systematic errors are difficult to detect and measure, particularly without interlaboratory comparisons. It is suggested that systematic errors can be reduced by incorporating reference physical constants (such as molar absorptivity) and certified standards to verify the correctness of the calibration curve and the standard solutions from which they were constructed.
Rapid Determination of Organochlorine Pesticides and Poly chlorinated Biphenyls, Using Selected Ion Monitoring Mass Spectrometry
Authors: Hargesheimer Erika E
Published: February 2020

Methane chemical ionization (CI)-selected ion monitoring (SIM) mass spectrometry was used to identify and conclusively distinguish 19 organochlorine pesticides from polychlorinated biphenyls (PCBs) at parts-per-trillion to parts-per-billion levels in environmental water sample extracts with minimal sample cleanup. Two CI-SIM screens were developed. One set of ions scanned specifically for the presence of 4 classes of pesticides: diphenylmethane derivatives, bridged polycyclic chlorinated hydrocarbons, chlorinated benzenes, and acetanilide pesticides. The second set of ions responded exclusively to PCBs with biphenyl moieties containing from 1 to 8 chlorine atoms. Eight commercial Aroclor mixtures were analyzed and distinguished from the pesticide groups. The detection limit for pesticides and PCBs by CISIM screening was 0.005 and 0.1 ppb, respectively. CI-SIM can be used as an alternative method for the analysis of biological or environmental samples containing interferences that complicate the detection of PCBs and chlorinated pesticides.
Liquid Chromatographic Determination of Trace Residues of Polynuclear Aromatic Hydrocarbons in Smoked Foods
Authors: Joe Frank L , Salemme Jean , Fazio Thomas
Published: February 2020

A liquid chromatographic (LC) method was developed and applied to the determination of polynuclear aromatic hydrocarbons (PAHs) in a variety of smoked, market basket commodities. The PAHs are extracted with l,l,2-trichIoro-l,2,2-trifluoroethane (Freon 113) from alcoholic KOH digests of the commodities. The extracts are purified by column chromatography through a deactivated silica gel/alumina column and by liquid-liquid partitioning between dimethyl sulfoxide and cyclohexane before separation of the PAHs by LC. Both fluorescence and UV detectors are used to monitor the LC column effluent to detect nanogram quantities of PAHs. Trace levels of carcinogenic and noncarcinogenic PAHs were found in all samples analyzed, although generally at <1 ppb levels.
Direct Enzyme-Linked Immunosorbent Assay for Determining Aflatoxin M1 at Picogram Levels in Dairy Products
Authors: Fremy J Marc , Fun Sun Chu
Published: February 2020

Protocols for detecting picogram quantities of aflatoxin M1 in dairy products were established. Milk samples were subjected to a reverse phase Sep-Pak C18 cartridge treatment before analysis by an enzymelinked immunosorbent assay (ELISA) according to previously published procedures. M, in yogurt, brick cheddar, and ripened Brie cheese was extracted by a modified Pons method, subjected to a normal phase silica cartridge treatment, and analyzed by ELISA. The detection limits for M1 in milk, yogurt, cheddar, and Brie were 10, 10, 50, and 25 ppt (ng/kg), respectively. Recovery for M1 added to these products was in the range 70-110%. Good agreement was found for M1 levels in several naturally contaminated milk samples analyzed by both ELISA and liquid chromatography.
Reverse Phase Liquid Chromatographic Determination of Edifenphos in Technical and Emulsifiable Concentrate Formulations
Authors: Khazanchi Rajesh , Roy Nripendra K
Published: February 2020

A convenient reverse phase liquid chromatographic method has been developed for determination of edifenphos in its technical product and emulsifiable concentrate. The method allows determination of the active ingredient of the formulation directly, without any solvent extraction. In addition, reference standard edifenphos has been obtained by preparative liquid chromatography.