Impurity Problems in Chromatographic Method Studies for Fenthion Formulations

1985 ◽  
Vol 68 (5) ◽  
pp. 925-929
Author(s):  
Willard G Boyd
Keyword(s):  
Mobile Phase ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Flame Ionization Detection ◽  
Private Communication ◽  
Flame Ionization ◽  
Glass Column ◽  
Liquid Chromatographic ◽  
Chromatographic Mass

Abstract Several gas chromatographic (GC) methods for analyzing fenthion were studied, and flame ionization detection, a glass column packed with SE-52 on Chromosorb GHP, and on-column injection were selected as parameters. No suitable internal standard was found because of coeluting, bias-producing impurities in fenthion. Several liquid chromatographic (LC) methods were also studied, and UV detection, a Zorbax ODS column, and a methanol-water-H3P04 mobile phase were finally selected as parameters. Dipentyl phthalate was selected as internal standard. After testing, this LC method was submitted for collaborative study. During the collaborative study, the manufacturer found an impurity, 3-methyl-4-(methylthio)anisole, co-eluting with fenthion in the collaborative method. The manufacturer's method was then evaluated as an alternative for collaborative study, but a significant unidentified impurity from the formulation blank, used for formulating emulsifiable concentrates, was also found co-eluting with fenthion. The anisole impurity was verified by LC, and the presence of the S-isomer and bis-methylthio-fenthion impurities was found by gas chromatographic- mass spectrometric (GC-MS) analyses. An anisole material obtained from Mobay was also verified by GC-MS analysis. Several other impurities were identified from literature references and from private communication with the manufacturer.

Collaborative Study of a Gas-Liquid Chromatographic Method for the Analysis of Chlorobenzilate and Chloropropylate

1975 ◽  
Vol 58 (3) ◽  
pp. 516-519
Author(s):  
Arthur H Hofberg ◽  
Lee C Heinrichs ◽  
Gene A Gentry
Keyword(s):  
Coefficient Of Variation ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Peak Height ◽  
Matched Pair ◽  
Flame Ionization ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatographic method for the determination of chlorobenzilate and chloropropylate in liquid formulations containing about 46 and 26% active ingredient, respectively, was collaboratively studied, using a matched pair scheme. The samples were dissolved in acetone containing dibenzyl succinate as an internal standard and chromatographed on Carbowax 20M, using a flame ionization detector. Analyses of 4 samples by 13 collaborators using peak height measurements showed the following results: chlorobenzilate—2.5% overall coefficient of variation, 1.0% coefficient of variation for the random error; and 0.7% systematic error; chloropropylate—2.0, 1.4, and 0.4%, respectively. The method has been adopted as official first action.

Collaborative Study of a Gas-Liquid Chromatographic Method for the Analysis of Propazine

1975 ◽  
Vol 58 (3) ◽  
pp. 513-515
Author(s):  
Arthur H Hofberg ◽  
Lee C Heinrichs ◽  
Gene A Gentry
Keyword(s):  
Coefficient Of Variation ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Peak Height ◽  
Matched Pair ◽  
Flame Ionization ◽  
Liquid Chromatographic Method ◽  
Two Samples ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatographic method for the determination of propazine in wettable powder formulations containing about 80% active ingredient was collaboratively studied, using a matched pair scheme. The propazine was extracted from the powder with chloroform, with dieldrin as an internal standard, and chromatographed on Carbowax 20M, using a flame ionization detector. Two samples were analyzed using peak height measurements with the following results (13 collaborators): 1.2% overall coefficient of variation and 1.2% coefficient of variation for the random error. Statistical evaluation of these factors reveals no evidence of systematic error contribution. The method has been adopted as official first action.

Gas-Liquid Chromatographic Determination of Paraldehyde in Paraldehyde Elixir

1972 ◽  
Vol 55 (1) ◽  
pp. 166-169
Author(s):  
William T Lampkin
Keyword(s):  
Collaborative Study ◽  
Internal Standard ◽  
Pharmaceutical Preparations ◽  
Standard Technique ◽  
Chromatographic Determination ◽  
Flame Ionization ◽  
Glass Column ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A collaborative study was conducted on a GLC method for determining paraldehyde in pharmaceutical preparations of paraldehyde elixirs. Eleven collaborating laboratories analyzed 2 unknown paraldehyde solutions and a solution of known paraldehyde concentration. Recoveries of 15–25% paraldehyde solutions averaged 98.5% with a coefficient of variation of about 2%. The method consists of diluting a sample aliquot to a definite volume and determining the paraldehyde content by GLC, using a flame ionization detector and a 6’ × 4 mm coiled glass column packed with 80–100 mesh Diatoport S coated with 2% HIEFF-8BP (cyclohexane dimethanol succinate) plus 20% Carbowax 20M. The internal standard technique was used for calculation. It is recommended that the method be adopted as official first action.

Gas-Liquid Chromatographic Method for the Analysis of Technical Dichlobenil and Its Formulations:1 Collaborative Study

1979 ◽  
Vol 62 (1) ◽  
pp. 8-10
Author(s):  
Pieter Van Bemmel ◽  
Bram Van Rossum ◽  
Albertus Martijn
Keyword(s):  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Flame Ionization ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Technical Material ◽  
Aoac Method ◽  
Liquid Chromatographic ◽  
Technical Sample

Abstract A gas-liquid chromatographic method for determining dichlobenil in technical material and formulations was collaboratively studied by 7 laboratories. Five samples were chromatographed on a 10% Carbowax 20M column with methyl myristate as the internal standard and flame ionization detection. The estimates of the repeatability (different analysts) and the reproducibility, expressed as coefficients of variation, were, respectively, 0.8 and 1.0% for the technical sample, 1.4 and 1.7% for the wettable powder, and 3.5 and 4.6% for the granular formulations. This method was adopted as a full CIPAC-AOAC method.

Modification of the AOAC Gas-Liquid Chromatographic Method for Indole in Shrimp: Collaborative Study

1982 ◽  
Vol 65 (4) ◽  
pp. 842-845
Author(s):  
Theodore L Chambers ◽  
◽  
E C Netz ◽  
K Ogger
Keyword(s):  
Silica Gel ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Current Method ◽  
Peak Height ◽  
Modified Method ◽  
Liquid Chromatographic Method ◽  
Gas Chromatographic Method ◽  
Liquid Chromatographic

Abstract Several changes were suggested for standardization of the AOAC official final action gas chromatographic method for the determination of indole in shrimp. In a collaborative study, 3 FDA laboratories compared the modified method with the current method. At a 95% confidence level, the same results were obtained for each respective sample by the AOAC or the modified method, which had the following changes. The cleanup column was standardized by drying the silica gel for 2 h at 125°C and equilibrating with 3 g of water/25 g of silica gel. Concentrated ethyl acetate shrimp extracts were treated with anhydrous sodium sulfate before column cleanup and indole was eluted from the column with 15% ethyl ether/hexane. A reduced amount of the internal standard, 2-methylindole, was used to improve peak height measurements at the 25 μg% indole level. The modified method has been adopted official first action to replace method 18.075.

Liquid Chromatographic Determination of Carbofuran in Technical and Formulated Products: Collaborative Study

1986 ◽  
Vol 69 (5) ◽  
pp. 915-918
Author(s):  
Edward J Kikta ◽  
◽  
E Bane ◽  
A Burns ◽  
A Christensen ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Data Sets ◽  
Matched Pairs ◽  
Reverse Phase ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method for the analysis of technical and formulated carbofuran samples was evaluated in a collaborative study. Carbofuran is determined by reverse phase LC, using a water-methanol mobile phase and acetophenone as internal standard, and detected at 280 nm. Twelve samples, 5 formulations and technical matched pairs, were analyzed by 17 collaborating laboratories. Accuracy and variability of results are typical of large LC data sets. The method has been adopted official first action.

Gas-Liquid Chromatographic Determination of Tetradif on Technical and Formulations: Collaborative Study

1981 ◽  
Vol 64 (4) ◽  
pp. 829-832
Author(s):  
Bram Van Rossum ◽  
Albertus Martijn ◽  
James E Launer ◽  
◽  
E C Calamita ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Flame Ionization ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract The gas-liquid chromatographic determination of tetradifon technical and formulations was collaboratively studied in duplicate with 12 laboratories. Six samples were dissolved in dichloroethane with n-hexacosane as the internal standard, chromatographed on a column of 3% SE-52, and detected by flame ionization. The average coefficients of variation were 1.2% for the 2 technical samples, 1.6% for the 2 wettable powders, and 1.5% for the 2 emulsifiable concentrates. The method has been adopted official first action.

Gas-Liquid Chromatographic Method for Analysis of Pentachloronitrobenzene Formulations: Collaborative Study

1982 ◽  
Vol 65 (1) ◽  
pp. 110-114
Author(s):  
Alan R Hanks
Keyword(s):  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Peak Height ◽  
Matched Pairs ◽  
Commercial Products ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Wettable Powder ◽  
Liquid Chromatographic

Abstract A collaborative study has been conducted on a gasliquid chromatographic (GLC) method for determining pentachloronitrobenzene (PCNB) in formulations. Wettable powder, liquid, and granular matched pairs of commercial products were analyzed by 17 laboratories using peak height measurements and by 12 laboratories using integrator area measurements. Samples were dissolved in chloroform and aliquots were mixed with internal standard before GLC analysis on a 5% SE-30 column. Mean coefficients of variation for the completed study were 1.54% for integrator area measurements and 1.35% for peak height measurements. The method has been adopted official first action.

Gas Chromatographic Method for Determination of Cypermethrin in Pesticide Formulations: Collaborative Study

1987 ◽  
Vol 70 (1) ◽  
pp. 51-53
Author(s):  
J F C Tyler
Keyword(s):  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Coefficients Of Variation ◽  
Pesticide Formulations ◽  
Glass Column ◽  
Technical Material ◽  
Gas Chromatographic Method ◽  
Ethylhexyl Phthalate

Abstract A gas chromatographic method for determination of total cypermethrin in technical and formulated products has been developed and subjected to a collaborative study involving IS participating laboratories. Each sample was dissolved in methyl isobutyl ketone containing di(2-ethylhexyl) phthalate as internal standard and analyzed by gas chromatography on a glass column with 3% OV-101 on Chromosorb W-HP. Each collaborator was furnished with reference stdard and 4 samples of technical material, 3 emulsifiable concentrates, one wettable powder, and one ultralow volume formulation for analysis. The coefficients of variation of the results obtained ranged from 0.955 to 1.7462%. The method has been adopted as official first action by AOAC.

Gas-Liquid Chromatographic Determination of p-Chloroacetanilide in Acetaminophen

1978 ◽  
Vol 61 (1) ◽  
pp. 68-71
Author(s):  
Dorothy K Wyatt ◽  
Lee T Grady
Keyword(s):  
Liquid Chromatography ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
Flame Ionization ◽  
Glass Column ◽  
Retention Characteristics ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Gas-liquid chromatography (GLC) coupled with column chromatography was used to accurately determine as little as 25 ppm p-chloroacetanilide in acetaminophen. p-Chloroacetanilide was eluted from a pH 8 phosphate-buffered diatomite partition column by using purified tetrachloroethylene (acetaminophen was retained). This solution was concentrated, internal standard (docosane) was added, and p-chloroacetanilide was determined by using a 0.9 m × 2 mm glass column packed with 3% Poly A 103 on Supelcoport and a flame ionization detector with electronic integration. Standard curves were linear for 10–100 ppm p-chloroacetanilide. Various chromatographic materials were investigated for optimal retention characteristics. High pressure liquid chromatography (HPLC) was also evaluated as an alternative; however, lack of reproducibility of the HPLC column favored the GLC procedure.

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