bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colorimetric Determination of Poly(N-Vinyl-2-Pyrrolidone) in Contact Lens Solutions
Authors: Riedhammer Thomas M 
Published: February 2020

Abstract
A rapid colorimetric method is presented for the quantitative determination of poly(N-vinyl-2-pyrrolidone) in contact lens solutions. The method is simple, requires no sample pretreatment, and uses only a small volume of sample. The procedure is based on the measurement of the net absorbance of a poly(N-vinyl-2-pyrrolidone)-Congo red complex at 545 nm. An accuracy of greater than ± 4% was obtained for the concentration ranges usually found in contact lens solutions with a minimum detection level of 10 ppm. The method is useful as a screening procedure for solutions of unknown composition and as a quality assurance procedure for routine determinations.
Gas-Liquid Chromatographic Determination of Morphine, Heroin, and Cocaine
Authors: Prager Manfred J , Harrington Shirley M , Governo Thomas F 
Published: February 2020

Abstract
Morphine, heroin, and cocaine are quantitatively determined with the same gas-liquid chromatographic system. The compounds are separated on a 6 ft × 2 mm id glass column packed with a 1:1 mixture of 5% SE-30 on 80-100 mesh Chromosorb W and 3% OV-17 on 80-100 mesh Varaport 30. The column is temperatureprogrammed. Flame ionization detector responses are measured with a computer-based data system. Heroin and cocaine are chromatographed directly; morphine is derivatized first. The procedure was evaluated with previously analyzed commercial and forensic samples. Accuracy and precision were 5 and 3%, respectively.
Automated Fluorometric Determination of Vitamin C in Foods
Authors: Dunmire David L , Reese John D , Bryan Ralph , Seegers Mary 
Published: February 2020

Abstract
Two automated fluorometric methods were compared with the official AOAC methods for determining vitamin C in fortified ready-to-eat cereals, fruits, vegetables, baby foods, flour products, pet foods, meats, frozen dinners, juices, and nutritional health bars. Each sample was analyzed in duplicate on 2 days and included a recovery study on all products. Egberg's semiautomated method (Method 1) and Roy's automated method (Method 2) were compared with the manual AOAC tritrimetric and fluorometric methods. The correlation factor for Methods 1 and 2 were 0.999 and 0.979, respectively, when compared with the AOAC methods. The recovery study showed average recoveries of 97.8% for Method 1, 99.3% for Method 2, and 100.6% for the AOAC methods. The results suggest that Method 1 is the method of choice for the majority of the products analyzed.
Sensitive Thin Layer Chromatographic Detection of High Fructose Corn Sirup and Other Adulterants in Honey
Authors: Kushnir Irene 
Published: February 2020

Abstract
A highly sensitive procedure has been developed to detect the undeclared addition of high fructose corn sirup (HFCS) to honey. Carbohydrates must be separated first to achieve the requisite degree of sensitivity: charcoal-Celite chromatography was used to isolate a fraction containing oligo- and polysaccharides. The fraction was then concentrated and examined by thin layer chromatography on silica gel. Pure honeys yielded only 1 or 2 blue-grey or bluebrown spots at Rf values &gt;0.35; a series of spots or blue streaks extending from the origin characterized adulterated samples. The method detects HFCS and conventional honey adulterants at levels as low as 10% or less of the total mixture. In addition, the procedure detects the presence in honey of all starch-derived sugar sirups tested thus far, regardless of the plant source.
Stability of Three Forms of Vitamin B6 to Laboratory Light Conditions
Authors: Ang Catharina Y W 
Published: February 2020

Abstract
Pyridoxine.HCl, pyridoxal.HCl, and pyridoxamine. 2HCl solutions were exposed to several laboratory light treatments, and the resulting vitamin retentions were determined by the AOAC microbiological method. The 5 treatments compared were total darkness, regular laboratory light, low actinic glass protection, yellow incandescent light, and golden fluorescent light. All treatments were imposed for 8 and 15 hr, and with the vitamin solutions at both a low and a high pH. Regular laboratory light was the most destructive to the vitamins, with greater destruction at higher pH and longer exposure time in all cases. Pyridoxine retentions ranged from 97 (pH 4.5, 8 hr) to 66% (pH 7, 15 hr); pyridoxal from 97 (pH 4.5, 8 hr) to 55% (pH 6, 15 hr); and pyridoxamine from 81 (pH 4.5, 8 hr) to 47% (pH 8, 15 hr). Retentions in low actinic glassware or in clear glassware under yellow or golden fluorescent light were essentially complete, ranging from 94 to 106% over all treatments and all 3 forms. Results showed that either of the 2 subdued light conditions, yellow or golden fluorescent light, is suitable in vitamin B6 assays and that low actinic glassware is suitable for storing sample solutions.
Semiautomated Method for the Analysis of Chlorpheniramine Maleate Tablets: Collaborative Study
Authors: Kirchhoefer Ross D ,   Collaborators:, Brown R L , Gleason J P , Hauser S , Kling R E , Moore E S , Savage T S 
Published: February 2020

Abstract
A semiautomated method for the analysis of chlorpheniramine maleate tablets, which is based on the USP XIX general assay for salts of organic nitrogenous bases, was collaboratively studied by 6 laboratories. Collaborators were supplied with 4 composites from 4 manufacturers. In the method, the active ingredient is dissolved in dilute HC1, sampled, made basic with dilute NaOH, and extracted with isooctane. The isooctane phase is resampled and the drug is re-extracted into dilute HCL. The absorbance of the acidic aqueous solution is measured at 265 nm. The Associate Referee assayed the collaborative samples to compare the semiautomated and USP XIX methods, and found close agreement in the results from the 2 methods. In the collaborative study of the semiautomated method, there was excellent agreement of the results obtained by the collaborators. The coefficients of variation ranged from 0.46 to 2.24%. The method has been adopted as official first action.
High Pressure Liquid Chromatographic Determination of Carbohydrates in Food Products: Evaluation of Method
Authors: Vries Jonathan W De , Heroff John C , Egberg David C 
Published: February 2020

Abstract
A high pressure liquid chromatographic (HFLC) method for determining 5 common carbohydrates in food products was evaluated. Reproducibility data were generated showing a relative standard deviation of 2.8%. Recovery studies on a variety of foods gave an average recovery of 98.8%. The HPLC data for 3 varieties of ready-to-eat cereals were compared with data from 4 independent laboratories using current AOAC chemical methods. The HPLC mean values differed from the chemical mean values by 3.2%.
Colorimetric Determination of Uric Acid in Poultry Excreta and in Mixed Feeds
Authors: Alumot Eugenia , Bielorai Rachel 
Published: February 2020

Abstract
Uric acid was determined in samples of poultry excreta and animal feeds to which poultry excreta were added. The rapid colorimetric method used by Van Handel was adapted for this purpose. The method is simple, accurate, and gives reproducible results.
Detection of Honey Adulteration By Carbohydrate Analysis
Authors: White Jonathan W 
Published: February 2020

Abstract
Thirteen market samples of falsified honey containing invert sirups or conventional corn sirup and 2 labeled mixtures have been analyzed. Results are interpreted in relation to literature values for various carbohydrate constituents of honey and their vulnerability. Published data on composition of United States honey have been refined for this purpose by eliminating samples containing a major portion of honeydew, thus narrowing the compositional ranges for known honey.
Gas-Liquid Chromatographic Method for Determining Bolstar Insecticide in Formulations: Collaborative Study
Authors: Boyd Willard G ,   Collaborators:, Antles H D , Audino J B , Bishop R , Campbell D L , Evans R T , Gale G T , Gentry G M , Grypa R , Guthery M D , Johnson H S , Launer J E , Meinen V J , Minyard J P , Noel R J , Roberts J R , Tannahill G O , Ullrich L , Linde D C Vande , Ware W C , Wayne R S , Winstead III G R 
Published: February 2020

Abstract
A gas-liquid chromatographic (GLC) method for determining Bolstar insecticide in liquid technical material and emulsifiable concentrate formulations was collaboratively studied using Youden’s matched pair scheme. Three matched sample pairs were analyzed by 21 laboratories using integrator area measurements and/or peak height measurements. Samples of a technical material containing about 78% active ingredient, a commercial 6 lb/ gal. emulsifiable concentrate containing about 64% active ingredient, and a synthetic emulsifiable concentrate containing about 64% active ingredient were dissolved in a measured amount of internal standard solution, tetracosane in toluene, and were subjected to gas-liquid chromatography on a column of 1.5% SE-30 + 1.5% OV-210. Bolstar was detected using flame ionization. The mean coefficient of variation by integrator area measurement for the 6 samples was 1.22%, and the mean coefficient of variation by peak height measurement for the 6 samples was 1.65%. The method was adopted as official first action.
Gas-Liquid Chromatographic Determination of N-Octylbicycloheptene Dicarboximide: Collaborative Study
Authors: Meinen Vernon J ,   Collaborators:, Allen J L , Audino J B , Boyd W G , Carlson D J , Carlstrom A A , Chang W L , Daubert J P , Dawson V , Gentry G M , Korger P , Launer J E , Lim B M , Looker J , Miller W K , Minyard J P , Partipilo T , Poulsen H H , Tannabull M , Winstead G R 
Published: February 2020

Abstract
A gas-liquid chromatographic method for the quantitative determination of N-octylbicycloheptene dicarboximide (MGK® 264 Synergist) was collaboratively studied with technical material and 2 formulations. The samples are diluted with acetone and determined after gas chromatography on an OV-1 column by a flame ionization detector. A statistical evaluation of the matched pair technical samples indicates good agreement among collaborators. An evaluation of the F-factor did not indicate significant systematic error contributions. A statistical evaluation of results for the 2 formulations showed coefficients of variation of 1.25 and 0.97. An examination of the t-values showed no contribution to systematic error. The method has been adopted as official first action.
Differential Pulse Polarographic Determination of Saccharin in Foods: Collaborative Study
Authors: Holak Walter , Krinitz Benjamin ,   Collaborators:, Carr R L , Gajan R J , Haberger L , Heusen C A , James T , Jasinski J , McNerney F Y , Tepedino N , Williamson J R 
Published: February 2020

Abstract
An improved differential pulse polarographic method for the determination of saccharin in foods has been developed. The sample (if solid) is blended with water; an aliquot is acidified with HC1, mixed with Celite, transferred to a chromatographic column, and eluted with chloroform. After chloroform is evaporated with a current of air, the residue is dissolved in 0.1N NaOH, and an aliquot is polarographed in a supporting electrolyte composed of 0.1N HC1, 0.1N KC1, and 0.1% tetrabutylammonium bromide. The method is sensitive, relatively precise, and applicable to a wide variety of foods. A collaborative study has been conducted and the results indicate average recoveries of 101.5, 99.8, 96.9, 91.9, and 95.3%, respectively, for samples containing saccharin from 0.028 to 1.4%. The method has been adopted as official first action.
Ripper Procedure for Determining Sulfur Dioxide in Wine: Collaborative Study
Authors: Vahl James M , Converse Jean E ,   Collaborators:, Andreasen A A , Barnett J H , Bence J G , Caputi A , Cherolis J A , Cofran D , Dowrie R , Dyer R H , Fike S A , Finley R G , Grorud R B , Hanson R , Jacobs D , Johnson A , Jones J C , Kipp W H , Kutschinski J L , Mattick L R , Peterson R , Pike R , Quinsland D , Rehn B W , Rice A C 
Published: February 2020

Abstract
Twenty-three laboratories analyzed 5 replicate wine samples according to a specified version of the Ripper direct iodometric titration for sulfur dioxide. Each sample was analyzed for (A) free S02, (B) total S02, and (C) iodine-reactive substances other than S02. Although variations of A with temperature and of A and B with time of analysis were anticipated, analysis of covariance showed no significant reduction in error when these variables were taken into account. Error did vary with S02 level and wine type, red vs white. Pooled estimates of precision (withinlaboratory error) in mg S02/L wine were, for white wine: (A) 3.3, (B) 10.4, (C) 1.9; for red wine: (A) 3.8, (B) 7.3, (C) 1.9. Pooled estimates of systematic (between-laboratory) error in mg SO2/L wine were, for white wine: (A) 2.7, (B) 16.6, (C) 2.1; for red wine: (A) 4.3, (B) 15.1, (C) 3.0. Although rapid and convenient, the Ripper method is severely limited by poor precision and large systematic error. The Ripper method is not recommended for adoption by the AOAC.
High Pressure Liquid Chromatographic Determination of Difenzoquat in Formulations
Authors: Barry Carla , Pike Richard K 
Published: February 2020

Abstract
Difenzoquat (l,2-dimethyl-3,5-diphenylpyrazolium ion) as its methyl sulfate is extracted from commercial pesticide formulations with acetonitrile-water (1+), with acetophenone added as internal standard. The sample is chromatographed by reverse phase high pressure liquid chromatography with ultraviolet detection at 280 nm. Peak area ratios are used for quantitative measurement. The method is simple, rapid, and direct, and its applicability to other quaternary ammonium herbicides is discussed.
New Spectrophotometric Assay for Pilocarpine
Authors: El-Masry Sawsan , Soliman Raafat 
Published: February 2020

Abstract
A quick method for the determination of pilocarpine in eye drops in the presence of decomposition products is described. The method involves complexation of the alkaloid with bromocresol purple at pH 6. After treatment with 0.1N NaOH, the liberated dye is measured at 580 nm. The method has a relative standard deviation of 1.99%, and has been successfully applied to the analysis of 2 batches of pilocarpine eye drops. The recommended method was also used to monitor the stability of a pilocarpine nitrate solution in 0.05N NaOH at 65°C. The BPC method failed to detect any significant decomposition after 2 h incubation, but the recommended method revealed 87.5% decomposition.
Simple, Sensitive, and Selective Thin Layer Chromatographic Technique for Detecting Some Photosynthesis Inhibiting Herbicides
Authors: Lawrence James F 
Published: February 2020

Abstract
Photosynthesis inhibiting herbicides such as triazines, phenylureas, phenylcarbamates, uracils, and acyl anilides are detected after thin layer chromatography (TLC) by spraying the plate with a mixture of spinach or bean leaf chloroplasts and the redox indicator 2,6-dichloroindophenol. The chloroplasts are isolated by homogenizing the fresh leaves with 0.5M sucrose solution. The filtrate is centrifuged, and the chloroplast plug is resuspended in glycerol–water (1+9) for preparation of the TLC spray. Minimum detectable levels of most ureas, triazines, and anilides are about 100–500 pg/spot. The selectivity of the reaction is such that the bipyridilium, phenoxyacid, and wild oat herbicides are negative. AH insecticides tested (carbamates, organophosphates, organochlorines) were negative. In samples such as potatoes, carrots, and corn, detection limits with no cleanup were 1 ppb or less for linuron or 5–10 ppb for atrazine.
High Performance Liquid Chromatographic Determination of Chloramphenicol in Milk
Authors: Wal Jean-Michel , Peleran Jean-Claude , Bories Georges F 
Published: February 2020

Abstract
A rapid and sensitive high performance liquid chromatographic method for the determination of trace amounts of chloramphenicol (CP) in milk has been developed. The antibiotic can be quantitated at a 10 ppb level with a limit of detectability estimated at 5 ppb. Recoveries ranged from 72 to 99.5%. Milking studies have been carried out on goats that received CP either by intramuscular injection or by intramammary administration. CP was measured in milk samples collected 1, 2, 3, 4, 5, 6, 7, 8, 24, 32 h after treatments. No residue could be detected 32 h after treatment. No interfering peaks appeared on control milk chromatograms.
High-Fructose Corn Syrup Adulteration of Honey: Confirmatory Testing Required with Certain Isotope Ratio Values
Authors: White Jonathan W 
Published: February 2020

Abstract
Misinterpretation of some analytical results obtained by using the carbon isotope ratio method for determining adulteration in honey has resulted in misclassification as adulterated some honeys falling in the grey area (–23.4 to –21.5 per mil). Samples having isotope ratios in that range must be confirmed by a positive TLC test.
High Pressure Liquid Chromatography of Captan in Formulations: Collaborative Study
Authors: Carlstrom A Aner ,   Collaborators:, Bryant M Akerblom , Allochuku G C , Audino J B , Coppi E L , Day E W , Grorud R B , Haye E H , Jenning F A , Kawan Y , Eachern G Mac , Martijn A , McDermott W H , Meier J , Meinen V J , Minyard J P , Pavel K , Povlsen H H , Skelly N E , Suter R 
Published: February 2020

Abstract
A simple method for measuring captan was tested by 18 collaborators. Formulations are extracted with methylene chloride which contains diethyl phthalate as an internal standard, and detected at 254 nm after high pressure liquid chromatographic separation in a 25 cm × 4 mm column packed with 10 µm silica gel. After inert materials are removed, the supernate is added directly to the column with methylene chloride as the mobile phase; peak height ratios are used for quantitation. Most pesticides commonly formulated with captan do not interfere. Retention times and UV response factors relative to captan are listed for 34 pesticides formulated with captan. The collaborators made single determinations on 6 samples (3 pairs of duplicates). The coefficients of variation were 0.67% for the technical, 1.16% for the 50% wettable powder, and 1.71% for the 5% dust. Several collaborators were unable to separate carbaryl and diethyl phthalate on a combination dust containing captan, dicofol and carbaryl; therefore, the method has been adopted as official first action only for captan formulations containing no other active ingredients.
Chemical Test for Mammalian Feces: Collaborative Study
Authors: Thrasher Joel J , Gecan John S ,   Collaborators:, Bradicich R , Chaput M , Grimmet J , Jessop J , Kaminski J , Loges M , Palmer W , Schaefer P 
Published: February 2020

Abstract
A chemical method was developed to determine the presence of mammalian feces in food. The method consisted of the colorimetric determination of alkaline phosphatase and involved the splitting of the phosphate radical from phenolphthalein diphosphate and the resultant color development of phenolphthalein in a basic medium. A collaborative study testing the feces of 22 animals resulted in a 95% correct identification of samples as mammalian feces. The method has been adopted official first action.
Analysis of Fat-Soluble Vitamins. XXV. High Performance Liquid Chromatographic Determination of Vitamin D in Multivitamin Preparations: Collaborative Study1
Authors: Vries Ellen J De , Mulder Frits J , Borsje Ben ,   Collaborators:, Ameika L , Anderssen E , Bagnall K W , Baillies T , Bjorholm H , Boufford C E , Bruno J V , Chadde F , Delano N , Vries E J De , Egtberts W , Fine B G , Gillingham P J , Grady L T , Jekabsons E , Johansson S , Jordi H C , Knapstein H , Kobayashi T , Kring P , Kurtz G W , Lotfy P A , Mahn F P , May E M , Monard A , Minister J V , Nedelkovitch G , Nicolaux G , Oelrich E , Öhrner B , Okano T , Phillips G F , Richter E F , Schwarze P , Steuerle H , Thakker K D , Theivagt J , Townley E , Antwerp J Van , Riper E S Van , Vuht G , Whall P J , Woodby J A , Zygmunt L 
Published: February 2020

Abstract
The HPLC method for determining vitamin D in multivitamin preparations was studied collaboratively. Samples were distributed to 43 laboratories in 10 countries. Twenty-four laboratories gave their results. The method specifies a reverse phase system for the cleanup and a straight phase system for the determination. Difficulties arise when laboratories are equipped with HPLC apparatus with a single column. Laboratories experienced in vitamin D analysis reported good results, even if they were equipped with a single column HPLC apparatus. Eleven of the 24 laboratories reported satisfactory results. For this rather complicated method, the coefficient of variation for a single assay is acceptable. The method has been adopted official first action as an alternative procedure to the chemical method for determining vitamin D in multivitamins.
Novel Cleanup Method for Quantitative Gas Chromatographic Determination of Trace Amounts of Di-2-Ethylhexyl Phthalate in Fish Lipid
Authors: Burns B Garth , Musial Charles J , Uthe John F 
Published: February 2020

Abstract
A new, simple, and rapid cleanup procedure is described for di-2-ethylhexyl phthalate (DEHP) residues in fish lipids. Extracts are chromatographed on small alumina:sulfuric acid-impregnated alumina (layered) columns after gel permeation chromatography of the fish lipid extracts on BioBeads SX-3. Quantitative analyses were carried out by electron capture gas chromatography using 2 columns. Spiked DEHP recoveries varied from 79.3% in mackerel to 86.1% in herring. DEHP concentrations were determined in plaice, eel, redfish, herring, cod, and mackerel tissues and ranged from trace (&lt;0.001 µ/g) to approximately 10 µ/g (wet wt basis). Ethanolic KOH saponification of the purified DEHP fraction, resulting in the disappearance of the DEHP peak, was used as a confirmatory test. Limited studies with dibutyl, di-n-heptyl, and diethyl phthalates suggest that the method can be made more versatile.
Colorimetric Determination of Disulfiram in Tablets: Collaborative Study
Authors: Wojtowicz Edward J ,   Collaborators:, Harms J P , Johnson R H , Lazar A , Olsen R E , Newton J M , Petzinger G , Ristich R , Robinette M L 
Published: February 2020

Abstract
The colorimetric reaction of cuprous iodide and disulfiram has been collaboratively studied in 8 laboratories to determine the drug in tablet form at 2 dosage levels. The disulfiram was extracted from the tablet matrix with methylene chloride. After a basic wash with 1 M NaOH, an aliquot of the methylene chloride solution was reacted with solid cuprous iodide, and the absorbance of the resulting color was measured. Single assays on 2 synthetic preparations of known disulfiram content were performed with average recoveries of 98.4 and 99.2% for 93.3 and 105.3mg, respectively. Duplicate determinations on 2 commercial tablet preparations declared at 250 and 500 mg gave mean and standard deviation values of 246.6 ± 6.40 and 493.6 ± 12.0 mg, respectively. The results agreed closely with those obtained by the author using the NF iodometric titration procedure. The method has been adopted official first action.
High Pressure Liquid Chromatographic Analysis of Chlorpyrifos Containing Insecticidal Formulations: Collaborative Study
Authors: Skelly Norman E , Jackson David J , Anderson Phyllis K ,   Collaborators:, Audino J B , Bushway R J , Chang W , Hageman L , Hanks A R , Hodgins W E , Kawano Y , Magnenant R , Mcdaniels S , Rivera L , Rowe N W , Turley R 
Published: February 2020

Abstract
A high pressure liquid chromatographic method for determining chlorpyrifos was collaboratively studied. Three liquid and 2 solid formulations were analyzed by 12 collaborators. Samples were weighed and diluted with acetonitrile containing the internal standard, 1,4-dibromonaphthalene. Chlorpyriphos is separated on a Zorbax ODS column with acetonitrile- water-acetic acid (82 ± 17.5 ± 0.5) at 2 mL/min and monitored at 300 nm. Clay samples are extracted with the internal standard solution by agitation for 5 min. Coefficients of variation ranged from 1.28 to 2.40%. Results of all 12 collaborators fell within the 5% two-tail limits. The method has been adopted official first action.