bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Chromatographic Determination of Thiamine, Riboflavin, and Pyridoxine in Infant Formula
Authors: Chase George W , Landen William O , Eitenmiller Ronald R , Soliman Abdel-Gawad M 
Published: February 2020

Abstract
An Ion pairing reversed-phase liquid chromatographic method developed for multivitamin supplements and premlxes was applied to the simultaneous determination of thiamine, riboflavin, and pyridoxine In perchloric acid extracts of milkand soy-based Infant formulas. The method uses m-hydroxy benzoic acid as Internal standard and a mobile phase consisting of water, acetonltrile, hexanesulfonlc acid sodium salt, and ammonium hydroxide solution, adjusted to pH 3.6 with phosphoric acid. The column Is a 15 cm x 3.9 mm id Nova Pak C18. Limits of detection were 0.15 μg/mL for thiamine and 0.09 μg/mL for riboflavin by UV detection at 254 nm, and 0.010 μg/mL for pyridoxine by fluorescence detection. Mean percent recoveries based on triplicate determinations were 102 ± 1.8,102 ± 3.3, and 101 ± 3.1 for thiamine, riboflavin, and pyridoxine, respectively. The results compared favorably with the AOAC methods for thiamine, riboflavin, and pyridoxine.
An FDA Laboratory Approach to Uncovering Potential Fraud in the Generic Drug Industry
Authors: Kirchhoefer Ross D 
Published: February 2020

Abstract
The Division of Drug Analysis of the U.S. Food and Drug Administration In St. Louis, MO, has screened more than 1400 drug samples for potential generic drug fraud by a combination of physical, instrumental, and chemical techniques. The approach to fraud centered around the analysis of exciplents as opposed to the normal approach of analysis of active Ingredients. Approximately 80% of the drug formulation pairs (Innovator and generic) submitted for bloequlvalence testing could be differentiated by a combination of physical and instrumental analysis, mainly thermogravimetrlc analysis (TGA) and Fourier-transform Infrared (FTIR) spectrometry. TGA proved to be the single most useful instrumental technique to determine differences In formulations. Liquid chromatography, gas chromatography, chemical tests, and polarizing microscopy were found to be the most useful tools to differentiate formulations that could not be resolved by FTIR, TGA, or physical comparisons. Xray powder diffraction and nuclear magnetic resonance spectroscopy were found not to be useful techniques to differentiate formulations. No clear-cut evidence of direct fraud was found, but Inconsistencies and suspicious samples were noted. Follow-up inspections based on the laboratory findings will probably occur. The procedures discussed In this article could be streamlined and made more efficient for examining large numbers of potential problem formulations.
C18 Extraction of Atrazine from Small Water Sample Volumes
Authors: Shepherd Timothy R , Carr James D , Duncan Diana , Pederson Darryll T 
Published: February 2020

Abstract
A method was developed to detect atrazine at a 0.05 ppb detection limit with a 10 ml_ sample volume. The herbicide Is extracted from 10 mL water with C18 solid-phase extraction and eluted into a reduction vessel with ethyl acetate. The sample is then evaporated to dryness under a stream of nitrogen and redlssolved for Injection Into a gas chromatograph/ mass spectrometer. Terbuthylazlne is used as Internal standard to compensate for extraction process variables. Standard curves have consistently shown correlation coefficients of 0.99 or better. Duplicate samples show a variance of 5% or less. Twelve samples can be extracted In about 1.5 h with &lt;10 mL organic solvent and minimum glassware.
Determination of Leucogentian Violet in Chicken Fat by Liquid Chromatography with UV Detection
Authors: Heller David N 
Published: February 2020

Abstract
UV detection is proposed as an alternative to electrochemical detection for the determination of leucogentian violet (LGV) in chicken fat by liquid chromatography. UV detection was combined with a previously reported extraction technique and new chromatographic conditions to yield a method that was evaluated at the target level of 10 ppb. Baseline separation of LGV from matrix interferences was achieved with a Cia bonded silica column and a mobile phase of methanol-pH 4 ammonium acetate (90 +10). Average recovery for samples fortified at 5,10, and 20 ppb was 76.4%, with a coefficient of variation (CV) of 4.8%. Fat from chickens raised on feed medicated with 30 ppm gentian violet was found to contain 17.6 ppb LGV, with a CV of 7.9%, after a 3-day withdrawal period. The detection limit for the system used was estimated to be 0.4 ng, and the limit of quantitation for the method was estimated to be 2 ppb.
Determination of Lanthanum, Europium, and Ytterbium in Food Samples by Electrothermal Atomic Absorption Spectrometry
Authors: Miaokang Shen , Yinyu Shi 
Published: February 2020

Abstract
A method had been developed for the determination of lanthanum, europium, and ytterbium in food samples by using electrothermal atomic absorption spectrometry with a graphite furnace lined with tungsten foil. The proposed method provides higher sensitivity than inductively coupled plasma/atomic emission spectrometry (ICP/AES); the characteristic masses are 8.1 x 10-9 g for lanthanum, 3.9 x 10-11 g for europium, and 4.27 x 10,-12 g for ytterbium. The precision, accuracy, and interferences of the method were also investigated. The method can be used for the analysis of trace amounts of lanthanum, europium, and ytterbium in various foods without predissociation of the matrixes of the digested solutions. The results obtained by the method are in good agreement with those from ICP/AES.
Headspace Method for Rapid Determination of Methyl Bromide in Assorted Nut Samples
Authors: Daft James L 
Published: February 2020

Abstract
A headspace method has been developed for the rapid, safe determination of methyl bromide (MeBr) in raw and processed nuts. Fifty grams of frozen nut meats is blended 3 min at high speed in 200-250 mL aqueous solution in a sealed 1 L blender cup fitted with a septum port on its cover. The cup is equilibrated 10 min in a 25C water bath. Two 250 ±150 μL aliquots of the sample headspace gas are sequentially removed with a gas-tight syringe and injected into a dual column/ dual detector gas chromatograph. One determination is made with a GS-Q wide-bore capillary column and a Hall electrolytic conductivity detector, the other with a packed column, 20% OV-101 on Chromosorb W(HP), and a 63Ni electron capture detector. The average variation for the manual injections is about 5% for both column/detector systems. To prevent random emission of MeBr during the determination, dated standards, headspace wastes, and electron capture detection effluent are passed through liquid traps. The overall recovery of MeBr from fortified samples is about 40%; the coefficient of variation is 29%. Eighteen assorted nut samples were analyzed on both systems at a quantitation limit of ᑉ100 ng/g; no detectable MeBr was found.
Assessment of Fourier Transform Infrared Analysis of Milk
Authors: Van De Voort Frederick R , Sedman Jacqueline , Emo Gary , Ismail Ashraf A 
Published: February 2020

Abstract
A Nicolet 510 Fourier transform infrared (FTIR) spectrometer was modified to perform IR milk analyses by incorporating a temperature-controlled 37 µm CaF2 flow cell and a homogenizer into the analytical system. The unit was evaluated for its ability to predict the chemical values of calibration milks, and its performance was compared with that of a commercial filter-based IR milk analyzer (Multispec MK1). Conventional dual-wavelength multiple regression methods and whole-spectrum multivariate analysis techniques (classical least squares and partial least squares) were also compared for their predictive capabilities. We found that the prototype FTIR unit met AOAC standards for milk analyses and performed as well as or better than the filter instrument. The macro-programming capability of the FTIR software, which enables the user to combine strings of FTIR commands and parameters into a single command, allowed automation of data processing. The whole-spectrum multivariate analysis methods were able to provide total solids data directly in addition to fat, protein, and lactose. On the basis of this evaluation, FTIR appears to be a viable alternative means for performing milk analyses.
Determination of Nitroimidazole Metabolites in Swine and Turkey Muscle by Liquid Chromatography
Authors: Mallinson Edward T , Henry A Carolyn , Rowe Loyd 
Published: February 2020

Abstract
The method described can determine hydroxy dimetridazole and hydroxy ipronidazole in turkey and swine muscle tissue at levels of 2 ppb. After an initial extraction with ethyl acetate and subsequent evaporation, the samples are solvated in acid and back-extracted. A C18 solid-phase extraction is performed after neutralization of the acidic extract. The basis for quantitation was an external standard containing both analytes. After performing 10 recovery curves with blank control tissue spiked at 0, 1,2, and 4 ppb, the mean recoveries of hydroxy dimetridazole and hydroxy ipronidazole were 61.8 and 64.6%, respectively. Recovery variation was less than 20% for both analytes over all 10 curves. The performance of the extraction method was verified in tissues incurred through the dosing of live animals.
Liquid Chromatographic Determination of Vitamin D in Animal Feeds and Premixes
Authors: Agarwal Vipin K 
Published: February 2020

Abstract
A liquid chromatographic (LC) method has been developed for the determination of vitamin D (D2 + D3) in animal feeds and premixes. The sample is saponified with potassium hydroxide, and vitamin D is extracted with hexane and isomerized to isotachysterol with 10M HCI in 2-butanol. LC determination of isotachysterol to quantitate vitamin D is carried out on a reversed-phase column with acetonitrilemethanol (90 +10) as the mobile phase and ultraviolet detection at 301 nm. The detection limit of the method is 1 lU/g. This method can also be used for the determination of vitamin D2 and D3 separately.
Effect of the Limit of Detection on Exposure Assessment
Authors: Loftus Michele L , Barraj Leila M , Tomerliv J Robert 
Published: February 2020

Abstract
An important component in evaluating the risk from pesticides in our foods is estimating the dietary exposure from the pesticide. This paper examines the effect of the limit of detection (LOD) on dietary exposure assessment. When designing food surveys for the purpose of estimating exposure from residues in foods as eaten, the effect of the LOD on exposure assessment should be evaluated before commencement of the analytical phase of the food survey. The purpose of the evaluation is to determine the LOD required to adequately quantify human exposure. The evaluation entails either determining the level at which the LOD is low enough to obtain exposure estimates that fall in the acceptable range or the level at which further reduction of the LOD will not result in additional observable reduction in estimates of exposure. Models describing exposure as the product of consumption and the magnitude of the residue in food are presented. Residue data from controlled field studies are used as examples to determine the optimum LOD to use in a food survey for assessment of exposure from a chronic adverse health effect. A computer program, EXPOSURE 1®, based on the U.S. Department of Agriculture Nationwide Food Consumption Survey, is used to estimate dietary exposure.
Extractive Spectrophotometric Determination of Trace Amounts
of Sulfur Dioxide in Air
Authors: Kumar B S M , Balasubramanian N 
Published: February 2020

Abstract
A sensitive spectrophotometric method was developed for the determination of trace amounts of sulfur dioxide (SO2) in air after SO2 has been fixed in a buffered formaldehyde solution. The reaction of iodate with the fixed SO2 in the presence of an acid and an excess of chloride leads to the formation of ICI2 ions. The resulting ICI2 species forms an ionpair with pararosaniline cation; the product is extracted into isopentyl alcohol and measured spectrophotometrically at 560 nm. The color system obeys Beer's law over the range 0-40 μg SO2. The color is stable for 72 h from the time of extraction. The molar absorption coefficient of the color system is 4.5 x 103Lmol"1cm"1. The coefficient of variation is 3.6% for 10 determinations at 20 μg SO2. The effect of interfering gases on the determination is discussed. The method was applied to the determination of SO2 at low concentrations, and the results obtained were compared with the widely used West and Gaeke method. The method can be used to determine as low as 2 μg S02
Polyclonal Enzyme Immunoassay Method for Detection of Motile
and Non-Motile Salmonella in Foods: Collaborative Study
Authors: Feldsine Philip T , Falbo-Nelson Maria T , Hustead David L 
Published: February 2020

Abstract
A new enzyme immunoassay (EIA) method for detection of motile and non-motile Salmonella was examined in a multilaboratory collaborative study. This method uses a proprietary formulation of polyclonal antibodies to Salmonella and is controlled to maintain specificity. Sensitivity is enhanced with an additional antibody reaction designed to minimize false-negative reactions attributable to steric interference that can occur during conjugate binding in immunoassay procedures. Thirty-two laboratories participated in this evaluation, which included 6 food types: nonfat dry milk, dry egg, black pepper, soy flour, chocolate, and ground poultry. Of the 1020 samples analyzed, there was a 97.2% agreement rate between the EIA method and the AOAC/Bacteriological Analytical Manual(BAM) culture method, 967.26. False-negative rates for the 2 methods were comparable for all foods and all Salmonella levels except ground poultry, where the EIA method detected significantly more confirmed positive samples than did the AOAC/BAM method. Nineteen samples were positive by EIA but negative by the culture method, and 10 samples were negative by EIA but positive by the culture method
Gas Chromatographic Determination of Acaricide Danjiami
in Citrus and Soil
Authors: Yitong Lu , Yuzhong Xue , Jin Xu , Wei Yan 
Published: February 2020

Abstract
A method is described for determining total danjiami residues in citrus and soil. Danjiami and its metabolites are hydrolyzed to 2,4-dimethylaniline by ref luxing with acid/base, re-extracted with petroleum ether, and cleaned up with acid/base partition. Sample is then derivatized to the heptafluorobutyranilide and quantitated by electron capture gas chromatography. Theoretical detectable limits are 5 ppb for citrus pulp and soil and 1 ppb for citrus peel. Recoveries for control samples fortified with danjiami at 0.25-2.0 ppm averaged 82.4% for citrus and 82.8% for soil
Survey of Butyltin, Cyclohexyltin, and Phenyltin Compounds
in Canadian Wines
Authors: Forsyth Donald S , Weber Dorcas , Dalglish Karen 
Published: February 2020

Abstract
Butyltin, cyclohexyltin, and phenyltin compounds were extracted with 0.05% tropolone in pentane from enzymatically hydrolyzed wine samples. Methyl derivatives made by Grignard reaction were quantitated by gas chromatography (GC)/atomic absorption spectrometry (AAS). Wine samples contained &lt;0.1-138 ng dibutyltin/mL. Lower levels of monobutyl- and tributyltin were also detected by GC/AAS. Polyvinyl chloride) (PVC) liner material used in some commercial transport tanks contained extractable butyltins. Imported wines sampled from these containers and Canadian wines blended with wine imported in PVC-lined tanks had considerably higher butyltin levels than did wines shipped in stainless steel. Analysis by GC/mass spectrometry confirmed the presence of butyltins in wine and PVC liner samples and, in addition, detected monophenyl- and monocyclohexyltin compounds at levels below the GC/AAS method detection limits of 0.04-0.05 ng Sn/mL
Simplified Method to Measure Suspensibility of Water-Dispersible Powder: Use of Microanalytical Techniques to Reduce Wastewater
Authors: Ogawa Masao , Ohtsubo Toshiro , Tsuda Shigenori , Tsuji Kozo 
Published: February 2020

Abstract
A method was developed for suspensibility of pesticides in the form of water-dispersible powders (WPs) as an alternative to CIPAC method MT 15.1. After the suspensibility study, the methods, along with several variations, were compared on the basis of reduction of waste, simplicity of the procedures used, and time required to measure suspensibility. WPs in this study were prepared by using fenitrothion and procymidone as representatives of liquid and solid active ingredients. The best method was obtained by modifying CIPAC MT 15.1 as follows: (a) A100 mL measuring cylinder was used instead of a 250 mL cylinder, (b) the process for preparing a suspension in a beaker was deleted, (c) the content of the active ingredient in the top 90% was analyzed instead of the bottom 10%, and (d) the process for evaporating water from a suspension removed by pipet from the top 90% was deleted. Suspensibility determined by this method showed good consistency with that determined by the original CIPAC method, and results were reproducible. Time required for determination of suspensibility and the amount of waste produced by this method was about 40% of that for the original CIPAC method. Furthermore, this method is suitable for WPs made with both liquid and solid active ingredients.
Organochlorine Pesticide Residues in Dairy Milk in and around Delhi
Authors: Mukherjee Irani , Gopal Madhuban 
Published: February 2020

Abstract
A survey of dairy milk and milk products in and around Delhi, India, was undertaken to monitor the levels of DDT and HCH. The survey revealed that pesticide residue levels in milk often exceeded the limits recommended by the Food and Agriculture Organization/World Health Organization Expert Committee. Maximum residue levels of total HCH in milk (fat/whole milk basis) has not yet been prescribed. The 15 samples of dairy milk and 4 samples of milk products analyzed had residue levels ranging from 0.022 to 0.166 μg/g for HCH and from 0.042 to 0.382 μg/g for DDT.
Specific Determination of Ethylene Oxide and Ethylene Chlorohydrin in Cosmetics and Polyoxyethylated Surfactants by Gas Chromatography with Electron Capture Detection
Authors: Sasaki Kumiko , Kijima Keiji , Takeda Mitsuharu , Kojima Shigeo 
Published: February 2020

Abstract
A simple specific determination method was developed for ethylene oxide (EO) and ethylene chlorohydrin (ECH) in cosmetics and surfactants. EO is desorbed from samples by using a nitrogen stream and absorbed into acidic potassium iodide solution, where it is converted to ethylene iodohydrin (EIH). Any remaining ECH in the samples is converted to EO by the addition of sodium hydroxide, and the desorption procedure is repeated with a fresh acidic potassium iodide absorbing solution. EIH is extracted with benzene and determined by gas chromatography with electron capture detection. EO and ECH contents in the samples are calculated from EIH results. Recoveries from water and shampoo samples were 70.3 ± 5.4 and 58.9 ± 1.2%, respectively, for EO and 66.3 ± 4.0 and 64.5 ± 4.6%, respectively, for ECH. Detection limits in 0.2-2.0 g samples were in the 0.005-0.03 μg/g range for EO and 0.01-0.07 μg/g for ECH. High levels of EO (30-394 μg/g as ECH) were found in 5 of 18 polyoxyethylated surfactant samples, but only small amounts (0.07-4.0 μg/g) of ECH were detected in the samples. EO was not detected in cosmetic samples tested, but ECH was present in small quantities (≤1.11 μg/g).
Liquid Chromatographic Determination of Aflatoxins in Animal Feeds and Feed Components
Authors: Yen Ivan Chang , Bidasee Keshore R 
Published: February 2020

Abstract
A method is described for the determination of af latoxins B1, B2, G1, and G2 in animal feeds and feed components by liquid chromatography (LC) with fluorescence detection. In this modified procedure, the aflatoxins are extracted from the samples with methanol-water (75 + 25), and the solution is vacuum- filtered through Whatman No. 541 filter paper. An aliquot of the extract is first defatted with petroleum ether, and then the aflatoxins are partitioned into chloroform. The chloroform extract is purified on a silica gel chromatographic column, aflatoxins B1 and G1 are derivatized by trif luoroacetic acid to their hemiacetals, and the aflatoxins are determined by reversed-phase liquid chromatography. Recoveries from 11 samples ranged from 90 to 98% for aflatoxins B1 and G1 (spiking range 2-25 ng/g) and B2 and G2 (spiking range 0.2-2.5 ng/g).
Gas Chromatographic Determination of Hydrocarbons in Crude Palm Kernel Oil
Authors: Tan Yew Ai , Kuntom Ainie 
Published: February 2020

Abstract
A method for the determination of hydrocarbons (HCs) in crude palm kernel oil (CPKO) is described. HCs are extracted from CPKO by passing through a silica gel column by using n-hexane as the eluting agent. The eluate is collected for analysis. Identification and confirmation of the HCs in the eluate are performed with the aid of a gas chromatograph equipped with a mass selective detector, and the HCs in CPKO are quantitated by comparison of peak areas with reference to an external standard, eicosane (C20H42). Recoveries and coefficients of variation for 5 samples of oil spiked with 1 - 300 μg/g eicosane were 70.0-86.6% and 3.5-13.2%, respectively. The method was used for the analysis of CPKO suspected of being contaminated with mineral oil.
Determination of Residual Imazethapyr in Soybeans by Gas Chromatography/Nitrogen-Phosphorus Detection
Authors: Mortimer Richard D , Weber Dorcas F 
Published: February 2020

Abstract
Imazethapyr, a recently introduced imidazolinone herbicide, is registered for use on soybeans and other legumes in the United States and Canada. Its maximum allowed residue level in soybeans is 0.1 ppm. A method was developed to allow the measurement of ≥0.01 ppm imazethapyr on soybeans. The method exploits the ready cyclization of the nonvolatile acid to the volatile imidazoisoindol-3,5-dione by using an excess of easily removed, watersoluble carbodiimide and the selectivity of gas chromatography with nitrogen-phosphorus detection. A simple cleanup on a diol-bonded silica minicolumn reduces the complexity of the soybean extract. The derivatization works equally well for other imidazolinone herbicide acids. Because imidazoisoindolediones have characteristic fragmentation patterns, they are useful for mass spectroscopic confirmation of suspected residues.
U.S. Food and Drug Administration Monitoring of Pesticide Residues in Infant Foods and Adult Foods Eaten by Infants/Children
Authors: Yess Norma J , Gunderson Ellis L , Roy Ronald R 
Published: February 2020

Abstract
The U.S. Food and Drug Administration uses 3 approaches to monitor pesticide residues in foods: regulatory monitoring, incidence/level monitoring, and the Total Diet Study. The results of monitoring infant foods and adult foods that may be eaten by infants/children under these 3 approaches are presented. Under regulatory monitoring, which is performed to enforce tolerances set by the U.S. Environmental Protection Agency (EPA), during fiscal years 1985-1991, over 10 000 such domestic and imported food samples were collected and analyzed, and under the Total Diet Study, in which pesticide residue intakes are estimated in foods prepared for consumption, the food items in 27 market baskets were analyzed. Under incidence/level monitoring, which is complementary to regulatory monitoring, over 4000 analyses were performed on infant foods and adult foods eaten by children. Fewer than 50 of the 10 000 regulatory samples had violative residues; nearly all of those were residues for which there was no tolerance for the particular commodity/pesticide combination. Under incidence/ level monitoring and the Total Diet Study, the levels of pesticide residues found in infant foods and adult foods eaten by children were well below tolerances set by EPA.