bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Validated Liquid Chromatographic Method for Determining Folates in Vegetables, Milk Powder, Liver, and Flour
Authors: Konings Erik J M 
Published: February 2020

Abstract
A liquid chronoat (LG) method was elaborated for determining folates in foods. Folates were extracted by homogenizing in buffer and heat treatment. A portion was incubated with an enzyme preparation containing conjugase, amylase, and protease. After purification by affinity chromatography, folate monoglutamates were determined by reversed-phase LG with fluorescence and diede array detection. Gradient elution with phosphate buffer and acetonitrile was used to separate vitamers. The most abundant folate forms naturally present in foods were detected, including tetrahy-drofolic acid, 5-methyltetrahydrofolic acid, and 5-formyltetrahydrofolic acid. 10-Formylffolic acid could be detected by applying a second fluorescence detector. Folic acid, used for fortification, might also be quantitated with this system. The difference between folate concentrations in sample extracts, with and without treatment of conjugase, is a measure of the quantity Of polyglutamates in the food matrixes. An additional treatment with conjugase, amylase, and protease reflects the arnount of matrix-bound folates. The LC system gave a linear response over the range 0–100 ng/mL. Detection limit for these compounds were 7 pg/mL for tetrahydrofolic acid and 5-methyltetrahydrofolic acid and folic acid were 1ng/ml. Repetability relative standard deviation values for separate folates in 3 candidate Certified Reference Materials (CRMs)—mixed vegetables (CRM 485), pig liver (CRM 487), and whole-meal flour (CRM 121)—and a Certified Reference Material milk powder (CRM 421) varied from 3.3 to 21.0% for the concentration range 1.8–1440 μg/100 g. Recoveries ranged from 73 to 109%. Use of amylase and protease was advantageous. Use of a comercially available folate-binding protein for cleanup saved time and money and was effective. Results for 5-methyltetrahydrofolioc acid were in good agreement with results obtained with other LC methods. Results for total folates were lower than results obtained with microbiological methods.
Multiresidue Gas Chromatographic Method for Determining Synthetic Pyrethroid Pesticides in Agricultural Products: Collaborative Study
Authors: Guo-Fang Pang , Yan-Zhong Cao , Chun-Lin Fan , Jin-Jie Zhang , Xue-Min Li ,   Collaborators:, Chu X-G , Duan W-Z , Gao X-M , Hu X-Z , Kamel A , Kubinec R , Lin A Q , Lin L-Y , Liu S-M , Papadopoulou-Mourkidou E , Mu J , Pan J W , Pardue J R , Parfitt C H , Pavoni G , Saleh M A , Shao J J , Song W B , Tahotna S , Tekel J , Tsai M-C , Wang D N , Wang K-O , Wong S S , Yu J X , Zhou Y , Zhu G-N 
Published: February 2020

Abstract
Fourteen laboratories from 6 countries and regions participated in an international collaborative study to evaluate a multiresidue gas chromatographic (GC) method for determining 8 synthetic pyrethroid pesticides in grains, fruits, and vegetables. The study design was based on Youden’s matched-pairs principle for collaborative tests of analytical methods. Each laboratory analyzed 12 collaborative samples of wheat, oranges, and tomatoes as blind samples. Wheat samples were extracted with acetonitrile–water (2 + 1), while orange and tomato samples were extracted with acetone. Residues were partitioned into hexane, evaporated to dryness with a rotary evaporator, and then dissolved in hexane. The hexane extract was partitioned with acetonitrile and cleaned up on a 5% water-deactivated Florisil column with 6% ethyl ether in hexane as eluant. Residue concentrations were determined by GC with electron capture detection with split-less injection by comparison with single-point calibration standards. The appropriate standard concentration was determined by screening sample extracts before analysis. The multiresidue method was tested over the concentration range of 0.0951.909 mg/kg depending on the 8 different of pesticides and agricultural products analyzed in the collaborative study. Statistical analysis of data from 13 laboratories showed weighted average recoveries for 8 pyrethroids in wheat, oranges, and tomatoes at 0.105–1.909,0.095–1.909, and 0.105–0.954 mg/kg, respectively, ranging from 91.8 to 100.2%, from 88.1 to 100.6%, and from 88.2 to 101.5%, respectively. Reproducibility relative standard deviation values ranged from 6.46 to 17.74%, from 5.94 to 18.13%, and from 5.59 to 10.48%, respectively. Repeatability relative standard deviation values ranged from 6.34 to 10.84%, from 5.19 to 11.72%, and from 3.20 to 8.09%, respectively. The multiresidue GC method for determining synthetic pyrethroid pesticides in agricultural products has been adopted first action by AOAC INTERNATIONAL.
Determination of Benzoylurea Insecticides in Apples and Pears by Solid-Phase Extraction Cleanup and Liquid Chromatography with UV Detection
Authors: Tsiropoulos Nicholas G , Aplada-Sarlis Pipina G , Miliadis George E 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed and statistically validated for simultaneous determination of 5 benzoylurea insecticides (di-flubenzuron, triflumuron, teflubenzuron, flufenoxuron, and lufenuron) in apples and pears. It involves preliminary extraction with ethyl acetate–sodium sulfate and cleanup on silica solid-phase extraction cartridges using dichloromethane–2-propanol (9 + 1) as eluant. The eluate is dried under nitrogen and redissolved in methanol. Benzoylurea insecticides are determined by reversed-phase LC with gradient elution at 42°C and UV diode array detection. Recoveries from samples fortified with the 5 insecticides at 0.02–0.5 mg/kg ranged from 83 to 102% for apples and from 75 to 99% for pears. Relative standard deviations were 0–12%. Limits of detection were 0.01 mg/kg for apples and 0.02 mg/kg for pears.
Screening Nitrate in Forages with a Test Strip: Collaborative Study
Authors: Jain Anant V , Ross P Frank , Carlson Michael P ,   Collaborators:, Barger T , Barr C , Booth M , Brown W , Buckley C , Coatuey C , Colvin B , Everson R , Holt K , Kinker J , Landgraf W , Lecrone E , Medlin M , Ross S , Rumbler P , Sanchez D , Short A , Shockley M , Tahara J , Warner D , Weiband L 
Published: February 2020

Abstract
A collaborative study was conducted for screening nitrate in forages with a commercially available test strip. The method involves extracting a finely ground sample with deionized water. The test strip is dipped in the sample extract. The color of the reaction zone on the test strip changes from white to pink or purple depending on the nitrate concentration in sample extract. The nitrate present in the extract is determined by comparing the color of the test strip to the color scale on the test strip container. Six blind quintuplicates of forage samples were analyzed by 20 collaborators. Nitrate concentrations in forage samples tested ranged from &lt;1000 ppm nitrate to &gt;10 000 ppm nitrate on dry matter basis. Each collaborator was asked to assign each sample to one of the 4 following nitrate concentration ranges: (1) &lt;1000 ppm, (2) 1000 to 5000 ppm, (3)&gt;5000 ppm to 10 000 ppm, and (4) &gt;10 000 ppm. Nineteen of 20 collaborators reported results. Results from 2 laboratories were rejected as outliers by inspection and χ2 test. Sensitivity rates (p+) ranged from 0.965 to 0.998, with standard errors of 0.006 to 0.16. Specificity rates (p−) ranged from 0.991 to 0.997 for the 4 ranges, with standard errors of 0.003 to 0.006. False-positive rates (pf+) ranged from 0.006 to 0.046, with standard errors of 0.006 to 0.025. False-negative rates (pf−) ranged from 0.003 to 0.007, with standard errors of 0.003 to 0.006. Screening nitrate in forages with a test strip has been adopted first action by AOAC INTERNATIONAL.
Molar Absorptivities of Aflatoxins B1, B2, G1, and G2 in Acetonitrile, Methanol, and Toluene-Acetonitrile (9 + 1) (Modification of AOAC Official Method 971.22): Collaborative Study
Authors: Nesheim Stanley , Trucksess Mary W , Page Samuel W ,   Collaborators:, Greer J , Hurley J M , Suggs F S , Wilson D M 
Published: February 2020

Abstract
Four laboratories participated in a mini-collaborative study of AOAC Official Method 971.22, Standards for Aflatoxins, Thin-Layer Chromatographic Method, to extend the method to 3 replacement solvents for benzene for calibration of standard afla- toxin solutions. Triplicate test sample vials, each containing 25 μg of the respective aflatoxin for each of the 4 aflatoxins and for each of the solvents, were prepared and sent to each collaborator. The collaborators dissolved the aflatoxin in each vial in 2 mL solvent, measured the UV spectrum, and reported the absorptivity maxima near 350 nm. The concentrations of the aflatoxins in the test samples were determined by dissolving identical test samples in benzene-acetonitrile (98 + 2) and following the procedure described in AOAC Official Method 971.22. These concentrations were, in turn, used to determine the molar absorptivities in the other 3 solvents (see Table 1). AOAC Official Method 971.22 has been modified to extend its applicability to 3 replacement solvents for benzene for calibration of standard aflatoxin solutions.
Laboratory Proficiency Testing of Aflatoxins in Corn and Peanuts—A Cooperative Project between Thailand and the United States
Authors: Vongbuddhapitak Amara , Trucksess Mary W , Atisook Kanoporn , Suprasert Duangchan , Horwitz William 
Published: February 2020

Abstract
The objective of this project was to conduct an aflatoxin proficiency test program in government, academia, and industry laboratories in Thailand. Aflatoxin-free corn and peanuts and corn and peanuts naturally contaminated with aflatoxins diluted to approximately 25 μg/kg were analyzed. Homogeneity of prepared, naturally contaminated test samples was checked on multiple replicates. The test was conducted according to the ISO/IUPAC/AOAC INTERNATIONAL Harmonized Protocol with z scores indicating laboratory performance. The participants used 3 methods: enzyme-linked immunosorbent assay, thin-layer chromatography, and the minicolumn. Of 19 laboratories that reported results for aflatoxins in naturally contaminated corn, 13 (68%) performed satisfactorily, on the basis of the mean obtained by an expert laboratory, a calculated target value for standard deviation, and the z score. Of 21 laboratories that reported results for aflatoxins in naturally contaminated peanuts, 10 (48%) performed satisfactorily. For aflatoxin-free corn, 6 laboratories reported finding aflatoxins at ≥10 ng/g, chiefly by the minicolumn method; for aflatoxin-free peanuts, 1 laboratory reported finding aflatoxins at &gt;10 ng/g. Subsequently, a workshop of lectures and laboratory sessions was conducted to improve performance. A new and simple successive outlier removal procedure applied to the same data removed the same laboratories as did the use of z scores.
Microbial Ranking of Porous Packaging Materials (Exposure Chamber Method), ASTM Method: Collaborative Study
Authors: Placencia Ana M ,   Collaborators:, Cogdill Phil , Bauman Linda , Patterson Tim , Taylor Julie , Martin Lynn , Lampe Carol , Hesler George , Anderson Helen , Goff Caroline , Oxborrow Gordon , Domeyer Tina , Jones Lois , Thornburg Robert , Reich Robert , Imburgia Richard , O’Dell Gerry , Scholia Michael , Spitz Joe , Tallentire Allan , Schwab Albert , Duran Anthony , Twohy Christine , May Ramona , Chamberlain Virginia Ross 
Published: February 2020

Abstract
A collaborative study involving 11 laboratories was conducted to measure the microbial barrier effectiveness of porous medical packaging. Two randomly cut samples from each of 6 commercially available porous materials and one positive and one negative control were tested by one operator in each of 11 laboratories. Microbial barrier effectiveness was measured in terms of logarithm reduction value (LRV), which reflects the log10 microbial penetration of the material being tested. The logarithm of the final concentration is subtracted from that of the initial concentration to obtain the LRV. Thus the higher the LRV, the better the barrier. Repeatability standard deviations ranged from 6.42 to 16.40; reproducibility standard deviations ranged from 15.50 to 22.70. Materials B(53), C(50), D(CT), and E(45MF) differ significantly from the positive control. The microbial ranking of porous packaging materials (exposure chamber method), ASTM method, has been adopted First Action by AOAC INTERNATIONAL.
Dietary Intake and Residues of Organochlorine Pesticides in Foods from Hsinchu, Taiwan
Authors: Doong Ruey-An , Lee Chen-Yu , Sun Yuh-Chang 
Published: February 2020

Abstract
The levels of contamination with various organochlorine pesticides (such as total HCH, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endosulfan, and total DDT) of different foods from 3 traditional markets were determined to estimate Taiwanese daily intake of organochlorine pesticides. Of the 18 organochlorine pesticides investigated, α-HCH, β-HCH, lindane, δ-HCH, heptachlor, heptachlor epoxide, dieldrin, endrin, α-endosulfan, p,p′-DDE, and p,p′-DDT were detected at concentrations ranging from 0.26 to 10.2 ng/g wet weight. Contamination with organochlorine pesticides followed the order heptachlor &gt; dieldrin &gt; α-endosulfan &gt; HCH isomers &gt; heptachlor epoxide &gt; DDT. Frequencies of detection of organochlorine pesticide residues ranged from 2.0 to 52.3%. α-Endosulfan was the most frequently detected organochlorine pesticide in the foods analyzed, followed by heptachlor epoxide (47.6%) and α-HCH (38.9%). Estimated daily intakes (EDIs) of organochlorine pesticides from foods were 1.137 μg for total HCH, 2.147 μg for heptachlor, 0.702 μg for heptachlor epoxide, 0.624 μg for endosulfan, 0.098 μg for cyclodiene, and 0.541 μg for total DDT. These EDIs were only 0.075% of the acceptable daily intake (ADI) for lindane, 47.5% of ADI for heptachlor and heptachlor epoxide, 0.045% of ADI for total DDT, and 1.01% of ADI for aldrin and dieldrin. Therefore, consumption of the foods analyzed does not pose a risk to consumer health.
Determination of Haloacetic Acids in Water by Ion Chromatography—Method Development
Authors: Lopez-Avila Viorica , Liu Yan , Charan Chatan 
Published: February 2020

Abstract
The microextraction/ion chromatographic (IC) method developed in this study involves extraction of 9 haloacetic acids (HAAs) from aqueous samples (acidified with sulfuric acid to a pH of &lt;0.5 and amended with copper sulfate pentahydrate and sodium sulfate) with methyl tert-butyl ether (MTBE), back extraction into reagent water, and analysis by IC with conductivity detection. The separation column consists of an Ion Pac AG-11 (2 mm id × 50 mm length) guard column and an Ion Pac AS-11 (2 mm id × 250 mm length) analytical column, and the concentration column is a 4 mm id × 35 mm length Dionex TAC-LP column. Use of the 2 mm id Dionex AS-11 column improved detection limits especially for trichloracetic acid (TCAA), bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), and tribromoacetic acid (TBAA). The peak interfering with BCAA elutes at the same retention time as nitrate; however, we have not confirmed the presence of nitrate. Stability studies indicate that HAAs are stable in water for at least 8 days when preserved with ammonium chloride at 100 mg/L and stored at 4°C in the dark. At day 30, recoveries were still high (e.g., 92.1–106%) for dichloroacetic acid (DCAA), BCAA, dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), BDCAA, and DBCAA. However, recoveries ofmono chloroacetic acid (MCAA), monobromoacetic acid (MBAA), and TBAA were only 54.6,56.8, and 66.8%, respectively. Stability studies of HAAs in H2SO4-saturated MTBE indicate that all compounds except TBAA are stable for 48 h when stored at 4°C in the dark. TBAA recoveriesdropped to 47.1% after 6 h of storage and no TBAA was detected after 48 h of storage. The method described here is only preliminary and was tested in only one laboratory. Additional research is needed to improve method performance.
UV Spectrophotometry and Nonaqueous Determination of Terbinafine Hydrochloride in Dosage Forms
Authors: Cardoso Simone Gonçalves , Schapoval Elfrides E S 
Published: February 2020

Abstract
An ultraviolet spectrophotometric and a nonaqueous volumetric method for determining terbinafine hydrochloride (TH) in pharmaceutical formulations are presented. The UV spectrophotometric procedure was developed for assay of TH in raw materials, tablets, and creams. The method was tested for linearity (0.8–2.8 μg/mL, r = 0.9997), recovery (102.00% for creams and 99.90% for tablets) and precision (101.3%, CV = 0.96%, n = 9, for creams; 100.25%, CV = 1.08%, n = 9, for tablets). The volumetric method involves titration of TH with 0.05M perchloric acid with crystal violet as indicator. This method was used for quantitative determination of TH in raw materials and tablets. Mean recovery and precision were, respectively, 100.41 and 101.18% (CV = 1.64%, n = 9) for TH in tablets. There were no significant differences between the proposed methods and a previously described high-performance liquid chromatographic method. The UV spectrophotometric and titrimetric methods are potentially useful for a routine laboratory because of their simplicity, rapidity, and accuracy.
Sterol and Triterpene Diol Contents of Vegetable Oils by High-Resolution Capillary Gas Chromatography
Authors: Reina Robert J , White Kevin D , Firestone David 
Published: February 2020

Abstract
An in-laboratory validated method for identification and quantitation of sterols and triterpene diols was used to determine the relative composition of identifiable sterols and triterpene diols in 13 vegetable oils and quantitate these components in multiple samples of 6 vegetable oils: extra virgin olive, pomace olive, corn, cottonseed, canola, and evening primrose oils. Erythrodiol, a triterpene diol present in all olive oils, was also found in cottonseed oil.
Determination of Choline in Infant Formula by Ion Chromatography
Authors: Laikhtman Mark , Rohrer Jeffrey S 
Published: February 2020

Abstract
Choline was determined in infant formula by ion chromatography with suppressed conductivity detection. Samples were digested with 1M hydrochloric acid, filtered, diluted, and injected into the chromatographic system. Choline and the alkali and alkaline earth metals were separated on a high-resolution cation-exchange column and detected by suppressed conductivity. The method was linear between 2 and 200 mg/L (r2 = 0.9999), the concentration range of the diluted samples. This method accurately determined choline in powdered, concentrated, and ready-to-feed infant formulas. Recoveries of choline spikes into powdered infant formula at approximately 1, 0.8, 0.5, and 0.2 times the labeled value ranged from 85 to 114%. This method had good agreement for 8 blind duplicates. The values determined for these samples, which were used in an AOAC collaborative study of an enzymatic method, were consistent with the values determined by the enzymatic method.
Determination of Organochlorine Pesticide Residues in Medicinal Plants Sold in Coimbra, Portugal
Authors: Lino M Celeste , Guarda Lúcia M C , M Irene N Silveira 
Published: February 2020

Abstract
Levels of 14 organochlorine pesticide residues—1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) group (p,p'-DDT, p,p'-DDT, p,&-DDD, and p,&-DDE), HCH isomers (α-, ß-, and γ-HCH), hexachlorobenzene (HCB), aldrin, dieldrin, endrin, heptachlor, α-endosulfan, and endosulfan sulfate—were evaluated in 127 samples of medicinal plants collected in pharmacies (78 samples) and herb stores (49 samples) in 1996. Samples were divided between 15 national brands and 7 foreign brands. Most samples sold in pharmacies contained residues of γ-HCH (51.3%). All residues were detected in analyzed samples, with exception of endrin in herb store samples. Detection frequency varied between 51.3% for γ-HCH and 1.3% for endrin in pharmacy samples, and between 34.7% for HCB and 4.1 % for endosulfan sulfate in herb store samples. Maximum residue levels were exceeded in 38 (48.7%) pharmacy samples and in 26 (53.1 %) medicinal herb store samples.
Multiresidue Determination of 19 Fungicides in Processed Fruits and Vegetables by Capillary Gas Chromatography after Gel Permeation Chromatography
Authors: Sannino Anna , Bandini Mirella , Bolzoni Luciana 
Published: February 2020

Abstract
A gas chromatographic (GC) method was developed for simultaneous determination of 19 fungicides (chlorothalonil, vinclozolin, dichlofuanid, triadimefon, penconazole, chlozolinate, captan, procymidone, triadimenol, folpet, hexaconazole, myclobutanil, cyproconazole, propiconazole, nuarimol, captafol, iprodione, fenarimol, and bitertanol) and the acaricide tetradifon in tomato puree, peach nectar, orange juice, and canned peas. Samples were extracted with acetone, partitioned with ethyl acetate-cyclohexane (50 + 50, v/v), and cleaned using gel permeation chromatography with ethyl acetate-cyclohexane (50 + 50, v/v) as eluant. The final extract was analyzed by GC with ion trap mass spectrometry (ITMS) using a DB5 capillary column. Recoveries from fortified samples ranged from 74.6 to 99.3%, except for triadimenol and bitertanol. Quantitation limits for most anlytes were between 0.005 and 0.050 mg/kg. The purified extracts were analyzed further by GC with electron capture and nitrogen phosphorus detection, and the results were compared with those obtained by ITMS.
Determination of Sulfamethazine in Milk by Biosensor Immunoassay
Authors: Gaudin Valérie , Pavy Marie-Laure 
Published: February 2020

Abstract
A biosensor based on surface plasmon resonance (SPR) measurement was developed for use in an immunoassay for detection of sulfamethazine (SMZ) in milk. The biospecific surface was a carboxymethyl dextran¯modified gold-surface sensor chip to which SMZ was covalently bound. The assay was based on inhibition of the binding of polyclonal antibodies to immobilized SMZ by SMZ in the sample. The SPR response changed inversely in relation to the antibiotic concentration in the sample. Calibration curves were constructed for SMZ in buffer and in milk at a concentration which included the maximum residue limit (0 to 200 μg/kg). The analysis time per sample varied from 8 to 30 min. Different flow rates and antibodies were modified alternatively during the study to assess their influence on the performance of the assay. The active antibody concentration was calculated at approximately 1880 and 180 nM for the antibody anti-SMZ 1 and the antibody anti-SMZ 2, respectively. No cross-reactivity of antibodies with other antibiotics was found. Under optimal conditions, the detection limits in milk for SMZ were 8 and 1.7 μg/kg, respectively, for antibody 1 and antibody 2, at a flow rate of 20 μL/min.
Determination of Oxytetracyciine in Bovine Kidney and Medicated Milk Replacer by Liquid Chromatography
Authors: Kijak Philip James , Cope Carol V , Pedersoli Waldir M 
Published: February 2020

Abstract
Improvements and optimization of AOAC INTERNATIONAL Official Method 995.09 for the detection of oxytetracyciine in bovine kidney at the new U.S. tolerance of 12 ppm are reported. Recoveries from kidney fortified at 4 concentrations over the range of 3-40 ppm averaged 84-98%. Results from the kidney of a calf fed medicated milk replacer containing oxytetracyciine are also reported. Additionally, adaptation of this method to the detection of oxytetracyciine in medicated milk replacer is discussed.