bluuebunny/crossref_metadata_2025 huggingface dataset:
Composition and Protein Efficiency Ratio of Meat Samples Partially Defatted with Petroleum Ether, Acetone, or Ethyl Ether
Authors: Happich Muriel L , Ackerman Stanley , Miller Arthur J , Swift Clifton E , Gumbmann Michael R
Published: February 2020

Freeze-dried beef samples were partially defatted with either petroleum ether, acetone, or ethyl ether before determination of protein efficiency ratio (PER) to study the extraction effects on the composition and protein nutritional quality of the extracted beef. Defatting a protein source, such as meat or a meat product, may often be necessary to produce a test diet that contains 10% protein and 8% fat. Amino acid, carnosine, anserine, creatine, creatinine, inosine, and proximate com- 5 positions%ere determined on the extracted samples. Resulting data were compared to the composition and PER data of the beef that had no solvent treatment. Although the chemical analysis data from the study showed some variation between the proteins and other nitrogenous components of the unextracted and the extracted beef, these variations were too small to affect the protein nutritional quality of the beef as measured by PER.
Liquid Chromatographic Cleanup and Determination of Low Levels of Vitamin D3 in Sheep Plasma
Authors: Cohen Huguette , Hidiroglou Michel , Keough Michael
Published: February 2020

A liquid chromatographic (LC) method is described for the determination of vitamin D3 in sheep plasma. Samples are extracted by one of 2 different methods, depending on the concentration of vitamin D> The samples are purified by using either a Sep-Pak silica cartridge or a small alumina column, followed by additional cleanup on a Metalsorb LC column. Final analysis was carried out on a 5 μm C18 column using a radial compression separation system with an acetonitrile-methanol solvent system. Vitamin D3 was completely resolved from any interfering compounds in the plasma; total run time was less than 15 min, using a variable wavelength detector set at 264 nm. The method was successfully applied to samples at levels of 1-10 ng added vitamin D3/mL sheep plasma, with recoveries in the range 90-97%.
Gas Chromatographic Determination of Pentachlorophenol in Gelatin
Authors: Borsetti Arnold P , Thurston Lee S
Published: February 2020

A method is described for the determination of pentachlorophenol (PCP) in gelatin. The method employs acid and heat to hydrolyze the gelatin matrix, a base partition and wash for separation and cleanup, and a reacidification and extraction with hexane for direct determination of PCP, without preparation of a derivative, using gas chromatography (GC) with a 1% SP-1240DA liquid phase and a 63Ni electron capture detector. Recoveries averaged 106% for fortifications between 0.02 and 1.0 ppm. The limit of quantitation is 20 ppb. The limit of detection is 4-6 ppb. The method, which has undergone a successful intralaboratory trial, is simple and rapid, and requires only general laboratory reagents and equipment. GC of the acetate derivative of PCP is used for confirmation of identity.
Determination of Aflatoxins in Peanut Butter, Using Two Liquid Chromatographic Methods: Collaborative Study
Authors: Campbell Alfred D , Francis Octave J , Beebe Roberta A , Stoloff Leonard ,   Collaborators:, Brown S , Cantafora A , Chang H L , Chin K S , Crosby N T , DeVries J W , Doeden W G , Duhart B T , Elliot L , Gorman L A , Gregory J F , Kronert W , Nesheim S , Routh J , Smiechowski R , Trantham A L , Webb N , Wilson D M
Published: February 2020

Two methods for determining aflatoxins in peanut butter, one using normal phase and the other reverse phase liquid chromatography (LC), were studied by 8 and 10 collaborators, respectively. Fluorescence detection was used for the determinative step in both methods. For reverse phase LC, aflatoxins B1 and G1 were converted to B2a and G2a; for normal phase LC, a silica gel-packed flow cell was placed in the irradiating light path of the detector. The samples included spiked and naturally contaminated peanut butter with total aflatoxin levels from about 5 to 20 ng/g and controls in a balanced pair design. For the normal phase LC method, recoveries of B1, B2, G1, and G2 from spiked samples averaged 79, 92, 74, and 88%, respectively; for the reverse phase method, the recoveries were 103, 104, 89, and 163%. For the normal phase LC method, pooled repeatabilities were 20, 23, 28, and 17% for B1, B2, G1, and G2, respectively; for the reverse phase method, the repeatabilities were 19, 22, 38, and 31%. For the normal phase method, pooled reproducibilities were 34, 33, 39, and 34% for B1, B2, G1, and G2, respectively; for the reverse phase method, the reproducibilities were 32, 46, 51, and 52%. Both methods show an improved limit of detection and better within-laboratory precision over current AOAC methods; however, between-laboratory precision is no better, and the reverse phase method shows evidence of interferences being measured. For these reasons and because of no benefits of present value, neither method was submitted for adoption as official first action.
Determination of Aflatoxicol and Aflatoxins B1 and M1 in Eggs
Authors: Trucksess Mary W , Stoloff Leonard
Published: February 2020

Procedures from 2 methods, one for aflatoxins B1 and M1 in eggs and one for aflatoxicol in milk, blood, and liver, have been combined to determine the 3 toxins in eggs. The sample is blended with sodium chloride-saturated water and this mixture is then blended with acetone. After separation from the solid residue, the aqueous acetone extract is defatted with petroleum ether. The toxins are next partitioned into chloroform and separated from interferences on a silica gel column. Aflatoxicol is determined by fluorescence measurement after separation on a C18 reverse phase liquid chromatographic column, and aflatoxins B1 and M1 are determined by fluorescence densitometry after separation on a silica gel thin layer chromatographic plate. In a recovery study with eggs, mean recoveries of aflatoxicol added at levels of 0.1, 0.05, and 0.025 ng/g were 87, 77, and 78%, respectively. Mean recoveries of aflatoxins B1 and M1 added at a level of 0.1 ng/g were 75 and 87%, respectively, and at an added level of 0.05 ng/g were 86 and 75%. The within-laboratory precision (repeatability) ranged from 2 to 13%.
Residues of Organochlorine Insecticides, Polychlorinated Biphenyls, and Heavy Metals in Biota from Apalachicola River, Florida, 1978
Authors: Winger Parley V , Sieckman Carol , May Thomas W , Johnson W Waynon
Published: February 2020

Seventy-seven composite samples composed of largemouth bass (Micropterus salmoides), channel catfish (Ictaluras punctatus), threadfin shad (Dorosoma petenense), Asiatic clam (Corbicula fluminea), burrowing mayfly (Hexagenia sp.), water snake (Natrix spp.), and little green heron (Butorides virescens) were collected from upper and lower reaches of the Apalachicola River, Florida, in 1978 for residue analysis of organochlorine insecticides, PCBs (polychlorinated biphenyls), and metals. Compared with data from the National Pesticide Monitoring Program and criteria recommended for the protection of aquatic life, residue concentrations were moderately high in the Apalachicola River. Biota from the upper river generally had higher organic and lower metal residues than those from the lower river. Highest residues in the biota were total DDT, total PCBs, and toxaphene. Although individual mean concentrations were below 2 μg/g and total organic contaminant residues never exceeded 5 μg/g, residue concentrations of DDT, PCBs, and toxaphene (particularly from the upper river) exceeded recommended permissible levels for the protection of aquatic life. Metal residues were generally below 1 μg/g. Exceptions were arsenic residues in threadfin shad (1.07 μg/g) and Asiatic clams (1.75 μg/g), and selenium in eggs of channel catfish (1.39 μg/g). The residues observed in the biota, particularly from the upper station, indicated moderate contamination of the Apalachicola River system at the time samples were collected.
ISO Working Group Studies on Filtration Problems in Crude Fiber Determinations
Authors: Holst David O ,   Members:, Crosby N T , Dordio A M , Harland B F , Hollman P , Kadijk F , Lutonska P , Martillott D F , Meer J M v d , Mudgal V D , Olah I , Pichl I , Rayner S E
Published: February 2020

A working group of individuals from International Organization for Standardization member nations studied the use of ceramic fiber to replace asbestos as a filter aid in crude fiber determinations in 8 samples: rolled oats, 48% solvent-extracted soybean meal, alfalfa meal, degermed corn meal, an all-bran cereal, hard red winter wheat, brussels sprouts, and soy fiber. Results obtained using ceramic fiber were accurate and precise, except for one laboratory which reported very high values. Results on 4 of these samples were compared with results obtained on the same 4 samples in an earlier collaborative study. There was good correlation between the studies. In addition, 2 laboratories reported data obtained using sea sand as filter aid, and 2 laboratories analyzed samples using no Alter aid.
Evolution of Analytical Methods for Fertilizers Through the AOAC Process
Authors: Johnson Frank J
Published: February 2020

A historical and scientific account is given of the evolution of chemical methods of analysis for fertilizers, as recorded in the annals of AOAC. Meetings that preceded the formation of AOAC are recalled with evidence of their domination by fertilizer chemists. The development, study, and adoption procedures of AOAC pertaining to primary, secondary, and micro plant nutrients are reported in chronological order. Only those changes in methods of analysis that had significant impact on future developments are noted. No attempt is made to present an exhaustive review of all AOAC analytical methods for fertilizer.
Liquid Chromatographic Determination of Chlorinated Phenol Impurities in Technical Pentachlorophenol Using Electrochemical Detection (Coulometric Mode)
Authors: Lanouette Monique , Cochrane William P , Singh Jojinder
Published: February 2020

Fourteen technical pentachlorophenol and 3 sodium pentachlorophenate samples were obtained from several manufacturers and analyzed for the presence of various chlorinated phenolic impurities. Reverse phase liquid chromatography with an electrochemical (coulometric mode) detector was used for qualitative and quantitative determinations. Nineteen chlorinated phenols were separated using a 50–70% methanol and 50–30% 0.02M KH2P04 (pH 4.0) 35 min gradient system on a Spheri-5 RP-18 column. 2,4-Dichlorophenol (average 0.07%); 3,5-dichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, 3,4,5-trichlorophenol (each <0.03%); 2,3,5,6-tetrachlorophenol (average 0.009%); 2,3,4,6-tetrachlorophenol (average 4.47%); 2,3,4,5-tetrachlorophenol (<0.025%) were detected as contaminants in the various samples. The minimum detectable amount ranged from 0.1 to 10 ng, depending on the chlorophenol.
Liquid Chromatographic Determination of Propoxur in Technical and Formulated Products: Collaborative Study
Authors: Slahck Stephen C ,   Collaborators:, Audino J B , Bennett O O , Folsom B D , Guenther P , Hodgins E , Jaworski J J , McDermott W H , Minyard J P , Noel R J , Polli R L , Teubert W E , Weisskopf C P
Published: February 2020

A liquid chromatographic method for the determination of propoxur in technical and formulated products has been subjected to a collaborative study with 8 participating collaborators. Formulations are extracted with acetonitrile and analyzed by reverse phase chromatography, with n-butyrophenone as an internal standard. Collaborators were furnished with samples of technical, 70% wettable powder, 1.5 emulsifiable, and 2% bait. Coefficient of variation values obtained on the 4 samples were 0.34, 0.68, 3.25, and 5.41%, respectively. The method has been adopted official first action.
Liquid Chromatographic Determination of Strychnine as Poison in Domestic Animals
Authors: Hunter R Tracy , Creekmur Robert E
Published: February 2020

A liquid chromatographic (LC) method is described, using a preliminary thin layer chromatographic (TLC) screen followed by LC quantitation of strychnine in biological specimens of domestic animals. The TLC solvent system is also used as the LC mobile phase. Samples are extracted using acidic acetone, followed by evaporation of the acetone. The aqueous residue is extracted with ethyl ether, made basic with ammonium carbonate, and back-extracted into methylene chloride before TLC-LC analysis. The method has been successfully applied to liver, kidney, and urine specimens, as well as stomach contents. Six replicates each of a 0.75 and 7.5 ppm strychnine standard were taken through the method; recoveries ranged from 94 to 104%. Six replicates of a naturally incurred canine liver sample had a mean value of 3.9 ppm strychnine, with a standard deviation of 0.138 and a coefficient of variation of 3.58 %.
Rapid Thin Layer Chromatographic Method for Determination of Zearalenone and Zearalenol in Grains and Animal Feeds
Authors: Swanson Steven P , Corley Richard A , White Donald G , Buck William B
Published: February 2020

A rapid and inexpensive method has been developed for the analysis of zearalenone and zearalenol in grains and animal feeds. The method involves extraction with 75% methanol, precipitation of pigments with lead acetate, and defatting with petroleum ether. The mycotoxins are subsequently partitioned into toluene–ethyl acetate, chromatographed on high performance thin layer chromatographic plates, and detected after treatment with Fast Violet B salt solution. Sensitivity of the method is better than 80 ng/g for zearalenone and 200 ng/g for zearalenol. Ten samples can be completed in less than 2 h. The method is applicable for zearalenone in corn, wheat, barley, millet, and swine feeds.
Evaluation of Cryogenic Impact Grinding Technique for Powdering Whole Fish for Metal Determinations
Authors: May Thomas W , Kaiser Millie L
Published: February 2020

A cryogenic grinding technique, which involves brittle fracture of samples by impact pressure, was evaluated for the final reduction of whole-fish samples for subsequent metal determinations. The technique incorporated a number of desirable features: protection of heat-labile components; incorporation of lyophilization to facilitate handling and storage; requirement of few procedural steps; short grinding time per sample; and easy, rapid cleanup of equipment. Particle size in the ground powder was <100 μm. Problems associated with the technique were contamination of fish samples with Cr, Fe, Mo, and Ni; limited size of the grinding container; and powder clumping caused by the presence of lipids. Approaches to alleviate these problems are discussed.
Improved Liquid Chromatographic Method for Determination of Aflatoxins in Peanut Butter and Other Commodities
Authors: Tarter Edward J , Hanchay Jean-Pierre , Scott Peter M
Published: February 2020

A combination of the extraction and cleanup procedures of Pons and Franz with the liquid chromatographic (LC) derivatization technique of Beebe is proposed as an accurate, precise, and sensitive method for determination of aflatoxins B,, B2, G,, and G2 in various foodstuffs. Mean recoveries of total aflatoxins added in the range 15–34 ng/g to peanut butter were 86–94% in 2 laboratories. Recovery of total aflatoxins (30 ng/g) from shelled peanuts, shelled Brazil nuts, pistachios, cashews, walnuts, and filberts exceeded 86% and from pumpkin seeds was 80%. Coefficients of variation for total aflatoxins were less than 7% for spiked samples and 15% for peanuts naturally contaminated with 16.7 ng/g of total aflatoxin (B1 + B2). Analyses of peanut meal, yellow corn meal, and peanut butter check samples (AOCS Smalley Series 1980/81 and 1981/82, IARC Series 1982/83) by this method compared favorably with reported averages. The detection limit is about 0.3 ng/g for each aflatoxin.
Automated Determination of α-Tocopherol in Food and Feed. Part 2. Continuous Flow Technique
Authors: Bourgeois Claude F , George Philippe R , Cronenberger Lucien A
Published: February 2020

The proposed determination of α-tocopherol is a continuous flow method with fluorometric detection. The only cleanup necessary is the usual saponification. A solution of the unsaponifiable matter in isooctane is automatically assayed. Isooctane is the carrier solvent and extractions are inserted between steps. These steps are selective reactions which render the method very specific. The natural homologs of α-tocopherol (α-T) do not interfere in the determination. A procedure for blank assays allows selective inhibition of α-T conversions and measurement of interfering fluorescence. The method is highly sensitive, which allows the determination of α-T in very dilute solutions. This in turn suppresses matrix effects and renders the results reliable. The time interval between 2 peaks is 6 min, washing included, and it is possible to carry out 50 determinations per day (sample preparation not included). The system is robust and maintenance is easy. Parallel determinations of foods and feeds have been carried out with a conventional thin layer chromatographic method.
Liquid Chromatographic Determination of Prednisolone in Tablets and Bulk Drugs: Interlaboratory Study
Authors: Brower James F
Published: February 2020

A normal phase liquid chromatographic (LC) method for the determination of prednisolone in tablets and bulk drugs was studied by 7 analysts. An LC system, consisting of a methanol-water-ethylene dichloride- acetic acid mobile phase and a silica column, was used to analyze bulk drugs, individual tablets, and composite samples. Analysts were supplied with 16 samples, including simulated formulations, composites of commercial tablets, intact tablets, and bulk drug substances. Results agreed with those obtained by the author. The coefficients of variation of the analysts' results ranged from 1.34% for bulk drugs to 2.14% for tablet composites. The LC method is suggested as an alternative to the official AOAC and USP XX blue tetrazolium colorimetric methods.
Liquid Chromatographic Determination of Sodium Salinomycin in Feeds, with Post-Column Reaction
Authors: Goras John T , Lacourse William R
Published: February 2020

A method for the detection and quantitation of sodium salinomycin in feeds by a liquid chromatographic, post-column reaction system is presented. Sodium salinomycin is leached from feed with hexane, isolated as a dried residue, and dissolved in mobile phase for analysis. The drug is separated from interfering substances on a silica LC column, combined with vanillin reagent in a mixing tee, reacted with vanillin at elevated temperature in a coil, and detected in the effluent stream at 527 nm. Response, as peak area, is linear with concentration. Feed components, other common veterinary drugs, and closely related compounds do not interfere. Average recovery and coefficient of variation (CV) values for liquid spiked feeds and supplements were 101 ± 3.5% and 100 ± 0.3%, respectively. Results for laboratory blends and commercial scale feeds were within 6% of intent with CV values ranging from 0.4 to 5.1%.
Confirmation of N-Nitrosodimethylamine and N-Nitrosopyrrolidine in Foods By Conversion to their Nitramines with Pentafluoroperoxybenzoic Acid
Authors: Kimoto Walter I , Silbert Leonard S , Fiddler Walter
Published: February 2020

Amethod is presented, wherein concentrated dichloromethane extracts from malt, beer, and nonfat dried milk powder containing N-nitrosodimethylamine (NDMA), and fried dry-cured and pump-cured bacon containing NDMA and iV-nitrosopyrrolidine (NPYR) undergo 3N HC104- Celite microcolumn cleanup followed by peroxidation with pentafluoroperoxybenzoic acid, a stable solid peroxyacid, to N-nitrodimethylamine and N-nitropyrroIidine, as an aid to nitrosamine confirmation. The nitramine-containing solution underwent further cleanup with 6N HC104-Celite and acid alumina-6 % H2O microcolumns for subsequent analysis by gas chromatography interfaced with thermal energy analyzer and 63Ni electron capture detectors. With a 20 g sample, 1 ppb NDMA and 2.5 ppb NPYR could be confirmed by this method. The extract can be concentrated further before analysis, so the detection level can be reduced to <1 ppb NDMA and 1 ppb NPYR.
Headspace Gas Chromatographic Determination of Methylene Chloride in Decaffeinated Tea and Coffee, with Electrolytic Conductivity Detection
Authors: Page B Denis , Charbonneau Claudette F
Published: February 2020

A headspace gas chromatographic procedure is described for the determination of methylene chloride (MC) in decaffeinated tea and coffee. The tea or coffee sample, with added methylene bromide (MB) internal standard, is equilibrated for 1.5 h at 100°C in aqueous sodium sulfate before manual headspace sampling. MC and MB are separated on a Porasil A column at 160°C and detected by using a Coulson electrolytic conductivity detector. For coffee and tea samples spiked at 1.3 ppm MC, as well as commercially decaffeinated teas and coffees containing up to 8 ppm MC, coefficients of variation were 10% or less. For decaffeinated teas, problems involving sample homogeneity and loss of MC before sealing the headspace vial had to be overcome. Similar problems with decaffeinated instant and ground coffees were minimal. The headspace procedure was superior to a previously reported distillation technique. MC was readily detected at 0.05 ppm. Fourteen decaffeinated teas and 15 decaffeinated coffees were analyzed; MC was detected at levels that ranged up to 15.9 and 4.0 ppm, respectively.
Thin Layer Chromatographic Detection and Spectrophotometric Determination of the Trisodium Salt of 1,3,6-PyrenetrisuIfonic Acid in D&C Green No. 8
Authors: Richfield-Fratz Naomi
Published: February 2020

A thin layer chromatographic method is presented for separating the reaction by-product 1,3,6-pyrenetrisuIfonic acid (trisodium salt) (PTS) from D&C Green No. 8 (8-hydroxy-l,3,6-pyrenetrisulfonic acid). PTS is detected visually, extracted from the adsorbent, and determined spectrophotometrically. Recoveries of PTS added at 0.75-6.73% levels to 8-hydroxy-l,3,6-pyrenetrisuIfonic acid ranged from 80.0 to 94.8%.
Liquid Chromatographic Determination of Nitrogen Derived from Urea and Water-Soluble Methylene Ureas in Urea Formaldehyde Fertilizers: Collaborative Study II
Authors: Davidson Allan D ,   Collaborators:, Barry C , Carmany J , Grigor A F , Hastings R E , Hendricks T A , Morris H F , Thorpe V A
Published: February 2020

A second collaborative study with 6 collaborators was conducted on the AOAC official first action method for measuring nitrogen derived from urea, methylenediurea (MDU), and dimethylenetriurea (DMTU). No variations were made. The collaborators made single determinations on 2 separate days on 5 sets of paired samples. The mean coefficients of variation for the completed study were 4.22% for urea, 5.08% for MDU, and 5.48% for DMTU, which are only slightly higher than the values reported in the first study: urea, 3.24%; MDU, 3.48%; and DMTU, 6.56%. The method has been adopted official final action.
Gas Chromatographic Methods for Determination of γ-BHC in Technical Emulsifiable Concentrates and Water-Dispersible Powder Formulations and in Lindane Shampoo and Lotion: Collaborative Study
Authors: Miles James W , Mount Dwight L ,   Collaborators:, Beckmann T J , Carrigan S K , Galoux I M , Hitos P , Hodge M C , Kissler K , Martijn A , Sanchez-Rasero F , Weeren R D , Zi-Hou Z
Published: February 2020

Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.
Liquid Chromatographic Assay of Ascorbic Acid, Niacinamide, Pyridoxine, Thiamine, and Riboflavin in Multivitamin-Mineral Preparations
Authors: Lam Fuk-Luen , Holcomb Ira J , Fusari Salvatore A
Published: February 2020

A simple and rapid method is presented for the liquid chromatographic assay of ascorbic acid, niacinamide, pyridoxine, thiamine, and riboflavin from a single chromatogram. Ion-pair chromatography with a reverse phase C18 cartridge in a radial compression system is used. Quantitation is excellent with a total analysis time of less than 20 min. A mobile phase of methanol-water (15 + 85) (0.005M heptanesulfonic acid) with 0.5% triethylamine at pH 3.6 and a flow rate of 2.0 mL/min gives the most satisfactory separation of the 5 water-soluble vitamins. By using 2 detectors in series set at different wavelengths and sensitivities, all 5 vitamins, with peak heights on scale, can be measured from a single injection; peak elution order is ascorbic acid, niacinamide, pyridoxine, thiamine, and riboflavin. Ascorbic acid is measured at 254 nm and the other vitamins, at 280 nm. The amount of amine modifier in the mobile phase is critical to the separation of niacinamide and pyridoxine. Recoveries of 5 water-soluble vitamins from spiked placebos were in the range of 98.2-102.0%. Confidence limits, ± 3 SD, were in the range of 1.0-5.4%. Overall, the results obtained using the liquid chromatographic method show excellent agreement with manual methods and automated analysis.
Liquid Chromatographic Determination of Zoalene in Medicated Feeds
Authors: Morawski John , Kyle Glenn
Published: February 2020

A rapid, reliable separation and quantitation of zoalene (3,5-dinitroo-toluamide) from feeds is accomplished by using reverse phase liquid chromatography (LC) and ultraviolet detection. An extraction technique which is similar to the present AOAC official colorimetric method is used before chromatographic analysis. This extraction is followed by an activated alumina cleanup and LC to separate zoalene from feed matrix. The methodology was applied to a variety of spiked feed matrices, and yielded good recoveries. Liquid chromatographic results were shown to correlate with colorimetric determinations.
Determination of Alkalinity and Acidity of Water by Conductometric Acid-Base Titration
Authors: Sekerka Ivan , Lechner Josef F
Published: February 2020

The alkalinity and acidity of water are parameters of great importance for studies of aquatic ecosystems. This paper describes the determination of total alkalinity by using acid-base titration with trichloroacetic acid solution as titrant. Total acidity is determined by titration with ammonium hydroxide solution. Both titrations are monitored conductometrically. Performance is evaluated and compared with performance of the potentiometric titration. Automated conductometric titration is simple, fast (30 s/titration), sensitive (detection limit 0.1 ppm CaC03), and accurate. Relative error of the determination increased from about 1% at high levels to about 10% at 1 ppm CaC03. The relative standard deviation of alkalinity measurements ranged from to 5%; for acidity, these values ranged from 1.5 to 17%. Relative standard deviation reached 33% at lower detection limits. Samples containing noncarbonate contributory components of alkalinity (borate, silicate, phosphate, organic acids) can be reproducibly analyzed.
Determination of Captan, Folpet, and Captafol in Fruits and Vegetables, Using Two Multiresidue Methods
Authors: Gilvydis Dalia M , Walters Stephen M
Published: February 2020

Two multiresidue methods, the Mills method and the Luke et al. method, are widely used for the determination of pesticides in foods. These methods were evaluated for the determination of the fungicides captan, folpet, and captafol in selected fruits and vegetables. The analytical behavior of standards through these methods was investigated first. Recoveries from apples, strawberries, lettuce, and tomatoes fortified with these compounds at levels of 0.2-5.9 ppm were then obtained. The analytes were quantitated by gas chromatography with electron capture detection, using a column of 5% SP-2401 on 100-120 mesh Supelcoport. Recoveries of captan, folpet, and captafol from fortified crops ranged from 69 to 78, 90 to 93, and 67 to 83%, respectively, by the Mills procedure and from 87 to 102, 81 to 106, and 91 to 109%, respectively, by the Luke et al. method modified to include additional solvent elution of the optional Florisil column.
Improved Cleanup for Liquid Chromatographic Analysis and Fluorescence Detection of Aflatoxins M1 and M2 in Fluid Milk Products
Authors: Ferguson-Foos Jane , Warren J D
Published: February 2020

A rapid method is described for extraction and cleanup of raw and processed milk for determination of anatoxins M1 and M2 by using a C18 Sep-Pak/silica gel cleanup column combination. Anatoxins are separated by normal phase liquid chromatography and their concentrations are determined by fluorescence detection in a silica gel-packed flow cell. Recoveries ranged from 99 to 103% with coefficients of variation less than 2% for Mi levels of 0.117-1.17 ng/mL added to raw milk. Similar recoveries were obtained for M2. The coefficient of variation for analysis of 5 subsamples of naturally contaminated milk was Jess than 1%. Agreement with the official method is satisfactory. Each sample requires less than 25 mL solvent and 10 min actual handling time. Sample chromatograms show no interferences in the M1-M2 elution region and no late-eluting peaks, which permits spacing injections at 13-20 min intervals. Anatoxin levels as low as 0.03 ppb may be determined by this procedure. Extracts have also been analyzed by thin layer chromatography.
Liquid Chromatographic Determination of Nicarbazin in Feeds and Premixes
Authors: Macy Thomas D , Loh Andrew
Published: February 2020

A liquid chromatographic (LC) method has been developed for the determination of nicarbazin in premixes and poultry feed. Liquid chromatography of the 4,4'-dinitrocarbanilide (DNC) portion of nicarbazin is performed isocratically with a reverse phase octadecylsilica column and a UV detector set at 340 nm. The 2-hydroxy-4,6-dimethylpyrimidine (HDP) portion of nicarbazin is chromatographed isocratically with a reverse phase octylsilica column and a UV detector set at 305 nm. Nicarbazin concentration can be calculated by assaying both DNC and HDP, or by assaying DNC or HDP and assuming that nicarbazin is a 1:1 molar ratio of the two. Average recoveries of DNC and HDP added to poultry feed were 101% and 87%, respectively. This procedure provides an alternative to existing colorimetric procedures for determining nicarbazin in premixes and poultry feeds.
Liquid Chromatographic Determination of Methyldopa and Methyldopa-Thiazide Combinations in Tablets: Collaborative Study
Authors: Susan Ting ,   Collaborators:, Brown R L , Dougherty L A , Schepman J B , Doucette Y H , Schneider P J , Perry P J , Rihbany L A , Gordon K
Published: February 2020

A reverse phase liquid chromatographic method for the determination of methyldopa, methyldopa-hydrochlorothiazide, and methyldopachlorothiazide in tablets was collaboratively studied by 8 laboratories. Each collaborator received 20 samples that included drug substance, synthetic and commercial tablet compositions. The overall repeatability and reproducibility standard deviations for commercial tablets were 1.11 and 1.75% for methyldopa, 0.96 and 1.62% for chlorothiazide, and 1.21 and 2.15% for hydrochlorothiazide, respectively. The overall recoveries of methyldopa, chlorothiazide, and hydrochlorothiazide added to synthetic tablets were 100.78, 100.70, and 101.34%, respectively. The method has been adopted official first action.
Gas Chromatographic Determination of Nonvolatile Organic Acids in Sap of Sugar Maple (Acer saccharum Marsh.)
Authors: Mollica Joseph N , Morselli Maria Franca
Published: February 2020

Qualitative analysis of organic acids has never been reported for sugar maple sap, but only for its products, "sugar sand" and maple syrup. A gas chromatographic (GC) method is described for the simultaneous determination of up to 13 nonvolatile organic acids in sugar maple sap. Sap is filtered through Celite, and acids are isolated via cation- and anion-exchange chromatography. Reaction of dried acids with BSA [N,O-bis(trimethylsilyl)acetamide] in the presence of pyridine and methoxyamine hydrochloride yields the more volatile TMS (trimethylsilyl) esters. Oxalic, succinic, fumaric, L-malic, tartaric, cis-aconitic, citric, and/or shikimic acids were found in maple sap at concentrations ranging from less than 50 ppb to more than 45 ppm, depending on the particular acid and the date of sap flow. Percent recoveries and coefficients of variation for the acids at the 500 ppm level were 46.0 (3.2), 92.0 (2.9), 73.0 (0.77), 94.0 (2.0), 95.0 (−), 72.0 (−), and 97.0 (0.38), respectively. Various amounts of nonvolatile organic acids are reported in the sap of one sugar maple tree throughout a sap season, and of 3 individual maples during an early sap flow. Quantitation limits were as low as 15 ppb for individual acids in the analysis of a 100 mL sap sample. Esters were separated on a mixed liquid phase column of 4% SE-52/2% SE-30 on Chromosorb W-HP. They were identified by relative retention time, using a dual flame ionization detector. Naphthalene was used as the internal standard. Concurrent identification of pyruvic, malonic, glutaric, α-ketoglutaric, cis-aconitic, and isocitric acids with those previously mentioned is also possible.
Liquid Chromatographic Determination of Tetracycline Residues in Meat and Fish
Authors: Onji Yoshiki , Uno Masakiyo , Kaoru Tanigawa
Published: February 2020

A simple and rapid method was developed for quantitative determination of common tetracyclines, such as oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC), in meat and fish. Tetracyclines were extracted with aqueous HCI, and then centrifuged. The supernate was applied to an Amberlite XAD-2 column, which was washed with water and eluted with methanol. The eluate was concentrated to about 0.5 mL under vacuum at 35°C, and then measured by liquid chromatography and UV detection. Two analytical columns were used for confirmation. The average recoveries of OTC, TC, and CTC from meat and fish fortified at 1, 1, and 3 ppm were 82.6, 81.5, and 67.0% respectively.
Determination of Aflatoxins in Vegetable Oils
Authors: Miller Noah , Pretorius Helena E , Trinder Donald W
Published: February 2020

A simple method is proposed for determination of aflatoxins in vegetable oils. The method was successfully applied to both crude and degummed oils. The oil sample, dissolved in hexane, was applied to a silica column and washed with ether, toluene, and chloroform; aflatoxins were eluted from the column with chloroform-methanol (97 + 3). As quantitated by thin layer chromatography and liquid chromatography, the oils analyzed contained aflatoxin Bx at levels of 5-200 αg/kg. Recoveries of aflatoxin Bi standards added to aflatoxin-free oils were between 89.5 and 93.5%, with coefficients of variation of 6.3- 8.0%.
Detection and Determination of Error in Analytical Methodology Part IIB. Direct Calculational Technique for Making Corrigible Systematic Error Corrections
Authors: Cardone Mario J , Lehman Jay G
Published: February 2020

The direct calculational technique described allows extrapolation to an infinite-size sample. The relationship between conventional calibration curve-based concentration values and reciprocal sample weights over the linear dynamic range of interest is obtained by linear regression. The intercept is shown to be the concentration result for the sample which has been corrected for the systematic corrigible constant error bias. In an analogous procedure described, the concentration result, corrected for both the corrigible systematic bias proportional and constant errors, may also be directly determined. The theoretical basis of the fundamental relationship is presented as well as theoretical derivations for the conventional calculation in calibration curve-based analyses and for the calculation used in the method of standard additions
Gas Chromatographic Determination of Ethylene Dibromide in Flour Products
Authors: Mckay Gordon
Published: February 2020

A method based on gas chromatography with electron capture detection was developed for the determination of ethylene dibromide (EDB) extracted from flour products. The procedure relies on the organic extraction of flour/water mixtures and uses an internal standard, 1- bromo-3-chloropropane. Recoveries of EDB at 10 and 100 ppb were 80.1 ± 2.8% (SD) and 84.4 ± 4.3%, respectively; recovery of the internal standard at the working concentration 500 ppb was 98.3 ± 6.7%. Calibration curves were linear over the range 5-400 ppb, with a mean overall coefficient of variation of <5%. The reliability of the procedure was assessed by using gas chromatography combined with mass spectrometry. Results are shown for determination of EDB in locally milled flour products.
Fractionation Of Radioactivity In The Milk Of Goats Administered 14c-Aflatoxin B1
Authors: Goto Tetsuhisa , Hsieh Dennis P H
Published: February 2020

A detailed fractionation of radioactivity in the milk of goats administered 14C-aflatoxin Bx at low doses was performed. The milk collected in the first 24 h following dosing contained radioactivity equivalent to 0.45-1.1% of the dose given. The radioactivity in each sample was partitioned into 4 fractions: ether, protein, dichloromethane, and wateralcohol. Over 80% of the radioactivity was detected in the dichloromethane fraction, of which over 95% was attributable to aflatoxin M1. No aflatoxin B, or other known aflatoxin metabolites were detected in any fraction. The results indicate that the major metabolite of aflatoxin B, in goat milk is aflatoxin M] and that other metabolites, including conjugates, are of minor significance.
Rapid Gas Chromatographic Determination of Ethylene Oxide, Ethylene Chlorohydrin, and Ethylene Glycol Residues in Rubber Catheters
Authors: Muzeni Richard J
Published: February 2020

Isothermal gas chromatography with flame ionization detection was used to determine residual ethylene oxide (EtO), ethylene chlorohydrin, and ethylene glycol in soft rubber catheters that had been sterilized with EtO. Catheter samples were extracted by shaking with carbon disulflde, and the extract was analyzed on a 3% Carbowax 20M on 80- 100 mesh Chromosorb 101 column, using nitrogen as the carrier gas. Ten replicate injections of a mixed standards solution gave coefficients of variation of 1.91, 1.23, and 4.74% for EtO, ethylene chlorohydrin, and ethylene glycol, respectively. A linear response was obtained with concentrations ranging from 1.0 to 7.9 μg EtO, 14.0 to 88.0 μg ethylene chlorohydrin, and 31.0 to 98.5 μg ethylene glycol. The proposed method detected as little as 0.5, 5.0, and 16.5 ng EtO, ethylene chlorohydrin, and ethylene glycol, respectively.
Rapid Hydrophobic Grid Membrane Filter Method for Salmonella Detection in Selected Foods: Collaborative Study
Authors: Entis Phyllis
Published: February 2020

A collaborative study was carried out in 36 laboratories to validate a hydrophobic grid membrane filter method for rapid (2-3 days) Salmonella detection by comparing its performance against the AOAC/ BAM reference method. Six products were included in the study: semisweet chocolate, raw ground poultry meat, ground black pepper, cheese powder, egg powder, and nonfat dry milk. With the exception of the naturally contaminated poultry, all products were inoculated in advance with low concentrations of a variety of Salmonella serotypes. The hydrophobic grid membrane filter method detected the following numbers of positive samples (results of the AOAC/BAM reference method are shown in parentheses): chocolate, 67(68); raw ground poultry, 133(131); ground black pepper, 57(56); cheese powder, 81(80); egg powder, 51(45); and nonfat dry milk, 68(72). The 2 methods did not differ significantly at the 95% confidence level in any of the 6 foods. The hydrophobic grid membrane filter method has been adopted official first action for detection of Salmonella in selected foods.
Improved Procedure for Determination of Acrylonitrile in Foods and Its Application to Meat
Authors: Page Denis B , Charbonneau Claudette F
Published: February 2020

The previously described headspace-gas chromatographic procedure for the determination of acrylonitrile (AN) in several foods, with N/P selective detection, has been modified to include packaged luncheon meats. The loss of AN during equilibration at 100°C in meat samples as well as the previously described loss in cold pack cheese and peanut butter has been studied. The loss of AN could be prevented by the addition of 10% phosphoric acid, which increases the acidity of the food-acid-salt slurry to pH 1.2-1.5. This acidification permits detection of AN at 2 ppb (5% FSD at 16 x 102 amp/mV) in all foods studied. AN was not detected in 10 samples of luncheon meat packaged in AN-based plastic which contained up to 2.6 ppm AN.
Liquid Chromatographic Determination of Vitamin K1 Trans- and Cis-Isomers in Infant Formula
Authors: Hwang Shie-Ming
Published: February 2020

The normal phase liquid chromatographic (LC) method for determination of trans- and c/s-isomers of vitamin K1 (phylloquinone) in infant formula described here uses an Apex silica column, isocratic elution, and UV absorption detection at 254 nm. Vitamin Kt is extracted quantitatively from the product matrix by pretreating the as-fed liquid with concentrated ammonium hydroxide and methanol, and then extracting it with a 2:1 mixture of dichloromethane and isooctane. The extract is cleaned up by silica open-column chromatography and concentrated for LC analysis. For trans-vitamin K1, the method precision is ≤3% RSD (relative standard deviation), and the spike recovery is 98 ± 4%. For cis-vitamin K1,, the precision is <12% RSD, determined at levels near the detection limit, and the spike recovery is 95 ± 9%. The detection limit is 0.3 ng for both isomers at signal/noise = 3.
Liquid Chromatographic Determination of N-Methylcarbamate Insecticides and Metabolites in Crops. I. Collaborative Study
Authors: Krause Richard T
Published: February 2020

A liquid chromatographic (LC) multiresidue method for determining residues of iV-methylcarbamate insecticides in crops was collaboratively studied in 6 laboratories. Methanol and a mechanical ultrasonic homogenizer are used to extract the carbamates. Water-soluble plant coextractives and nonpolar plant lipid materials are removed from the carbamate residues by liquid-liquid partitioning. Additional crop coextractives (e.g., carotenes, chlorophylls) are removed with a Nuchar SN-silanized Celite column. The carbamate residues are then separated on a reverse phase LC column, using an acetonitrile-water gradient mobile phase. Eluted residues are detected by an in-line post-column fluorometric detection technique. Seven carbamates and 2 carbamate metabolites were included in the collaborative study. Each collaborator determined all the carbamates at 2 levels (approximately 0.05 ppm and United States tolerance) in blind duplicate samples of grapes and potatoes. Fortified and control samples were analyzed. Repeatability coefficients of variation for all the carbamates on the 2 crops averaged 4.7% and ranged from 2.4 to 7.1%. Reproducibility coefficients of variation for all the carbamates on the 2 crops averaged 8.7% and ranged from 5.3 to 12.4%. Accuracy, measured by comparison with fortification values, averaged 95% and ranged from 79 to 103%. The estimated limit of quantitation is 0.01 ppm. The method has been adopted official first action.
Liquid Chromatographic Determination of N-Methylcarbamate Insecticides and Metabolites in Crops. II. Analytical Characteristics and Residue Findings
Authors: Krause Richard T
Published: February 2020

Four laboratories obtained 177 carbamate recovery values using a liquid chromatographic method. The average recovery of 11 carbamates (aldicarb, aldicarb sulfone, bufencarb, carbaryl, carbofuran, 3- hydroxy carbofuran, 3-keto carbofuran, methiocarb, methiocarb sulfoxide, methomy 1, and oxamyl) from 14 crops was 99% with a coefficient of variation of 8% (0.03-1.8 ppm fortification levels). No statistical difference in recovery was found between oxime and phenyl carbamates, or between parent and metabolite carbamates. Average recovery of aldicarb sulfoxide was 59% due to loss in the liquid-liquid partitioning because of the polarity of this compound. A fifth laboratory contributed 34 carbamate recoveries (average 99%) on table-ready food products for 4 carbamates. Bendiocarb, dioxacarb, isoprocarb, and propoxur are also quantitatively recovered through the method. Previously reported carbamate and noncarbamate recovery data are also discussed. In the Food and Drug Administration's (FDA) analysis of 319 samples (mainly crops), 86 (27%) were found to contain residues of carbamate insecticides and/or toxic carbamate metabolites. Carbaryl and methomyl were the most common carbamate residues found on the food products excluding the aldicarb sulfone and sulfoxide residues found on potatoes. In one FDA Total Diet Program "market basket", 11 of 69 table-ready food commodities contained from 0.005 to 0.094 ppm carbamate residues. Carbaryl was the most prevalent residue. Several laboratories reported adverse effects on the determinative system when inadequately purified reagents were used.
Use of Microwave Oven and Nitric Acid-Hydrogen Peroxide Digestion to Prepare Botanical Materials for Elemental Analysis by Inductively Coupled Argon Plasma Emission Spectroscopy
Authors: White Thomas R , Douthit Garnett E
Published: February 2020

A sample preparation method has been developed that provides a nitric acid-hydrogen peroxide digestion of plant tissue when it is heated internally by the oscillating electromagnetic field generated in a microwave oven. The total elemental concentration for barium, calcium, magnesium, manganese, phosphorus, potassium, sodium, sulfur, and zinc can be determined by inductively coupled argon plasma emission spectroscopy after sample preparation in a microwave oven. The method is rapid and provides quantitative results that agree with certified values for 4 National Bureau of Standards Standard Reference Materials: 1570 Spinach, 1572 Citrus Leaves, 1573 Tomato Leaves, and 1575 Pine Needles.
Identification and Quantitation of Sulfamethazine Metabolites by Liquid Chromatography and Gas Chromatography-Mass Spectrometry
Authors: Paulson Gaylord D , Mitchell Alva D , Zaylskie Richard G
Published: February 2020

Methods for the identification and quantitation of carbon-14 labeled sulfamethazine [4-amino-iV-(4,6-dimethyl-2-pyrimidinyl)benzenesulfonamide], W-acetylsulfamethazine, the N4-glucose conjugate of sulfamethazine, and desaminosulfamethazine in swine tissue are described. Tissues are ground and extracted with methanol, and the 14C-labeled compounds are purified by XAD-2 column chromatography and C-18 reverse phase liquid chromatography (LC) and the relabeled compounds are then methylated and identified by gas chromatography- mass spectrometry analysis. Quantitation is accomplished by measuring the amount of 14C-activity that cochromatographs (C-18 reverse phase LC) with reference compounds.