Liquid Chromatographic Method for Determination of Anilazine in Formulated Products: Collaborative Study

A liquid chromatographic method for the determination of anilazine (DYRENE®) in formulated products has been developed and subjected to a collaborative study involving 15 participating laboratories. Each collaborator was furnished with reference standard, internal standard, and blind duplicate samples of DYRENE 80% concentrate, 75% wettable powder (75 WP), 50 WP, and 4 flowable formulation. Samples are dissolved in acetonitrile and analyzed by reverse phase chromatography using octanophenone as an internal standard. Collaborators were instructed to evaluate the method by either peak area or peak height measurements. Seven laboratories performed the analyses using peak areas; 8 laboratories used peak heights. Peak area measurements for the wettable powder samples resulted in statistically high bias vs peak height measurements. This was apparently due to inconsistent integration parameters among collaborators. Difficulties in establishing the correct integration parameters are illustrated along with t-test values for the 2 measurement techniques. Coefficients of variation of the peak height values obtained on the 80 concentrate, 75 WP, 50 WP, and 4 flowable were 1.68,1.29,1.74, 1.87%, respectively. The method has been adopted official first action.

Gas Chromatographic Determination of Propachlor in Pesticide Formulations: Collaborative Study

An isothermal gas chromatographic (GC) method for measuring propachlor in formulations was tested by 12 collaborators. Samples are prepared in acetone and determined using a GC column of 10% SP-2250 on 100-200 mesh Supelcoport, and diisobutyl phthalate as internal standard. Collaborators made single determinations on each of 2 similar materials (matched pairs) on 2 days for 3 pairs of samples. The study generated 62 matched pairs which were used in Youden’s matched pair calculations. The coefficients of variation (CV,) for flowable formulations were 0.84 and 1.48%; the CV, for the granular formulation was 1.28%. The method was simple to use and did not reveal any interferences in the samples tested. The method has been adopted official first action as an AOAC-CIPAC method.

Gas Chromatographic Determination of Butachlor in Formulations: Collaborative Study

An isothermal gas chromatographic (GC) method for measuring butachlor in formulations was tested by 15 laboratories. Samples were prepared in acetone and determined using a GC column of 10% SP-2250 on 100-120 mesh Supelcoport, and triphenyl phosphate as internal standard. Collaborators made single determinations on each of 2 similar materials (matched pairs) on 2 days for 2 pairs of samples. The study generated 56 matched pairs which were used in Youden’s matched pair calculations. Coefficients of variation (CV,) for liquid formulations were 1.06 and 0.98%. The method was simple to use and did not reveal any interferences in the samples tested. The method has been adopted official first action as an AOAC-CIPAC method.

Liquid Chromatographic Determination of Dicofol in Kelthane Formulations: Collaborative Study

A liquid chromatographic (LC) method was used to determine p,p'- and o,p'-isomers of dicofol AI (active ingredient) in Kelthane® EC and MF formulations. Samples are dissolved in methanol and AI components and impurities are separated on a high resolution C8 column in series with a short C18 guard column, with a methanol-water-acetic acid mobile phase. Cleaned samples are directly injected into the LC system and are monitored at 254 nm. Twelve collaborators submitted results on 5 samples. Using 95% confidence criteria, the average total standard deviation of the total AI across all samples was 2.82%. The method has been adopted official first action.

Gas Chromatographic Determination of Fensulfothion in Formulations: Collaborative Study

A collaborative study was conducted on a gas chromatographic method for determination of fensulfothion. Eleven laboratories analyzed 2 technical and two 6 lb/U.S. gal. spray concentrate samples. In the analysis, samples are dissolved in methylene chloride which contains 4-chlorophenyl sulfoxide as an internal standard, and solutions are injected into a gas chromatograph equipped with an OV-330 column. Withinlaboratory repeatability was 0.79% for technical product and 0.37% for the spray concentrate samples, with coefficients of variation of 0.88 and 0.58%, respectively. Among-laboratories reproducibility was 0.81% for technical product and 0.53% for the spray concentrate, with coefficients of variation of 0.91 and 0.84%, respectively. The method has been adopted official first action.

High Pressure Liquid Chromatographic Determination of Fensulfothion: Collaborative Study

A method for analyzing fensulfothion was tested by 10 collaborators. Formulations were dissolved, or extracted from inerts, in methanol. Benzophenone was used as an internal standard. The solution was diromatographed on a Partisil-10 ODS-2, or equivalent, reverse phase column, and detected at 230 nm. A mobile phase of methanol-water-phosphoric acid was used. The ratio of fensulfothion peak height to benzophenone peak height was calculated from the UV response and compared to the standard material for quantitation. A 15% granular formulation was analyzed as a matched pair. The results of one collaborator were outliers by the Dixon test. The coefficient of variation for the granular formulation was 1.6%. A matched pair of 63% spray concentrate samples was analyzed by 10 collaborators. The difference in results was an outlier for one collaborator; the coefficient of variation for the other collaborators was 1.5%. The method has been adopted official first action.

High Performance Liquid Chromatographic Analysis of Rotenone Formulations: Collaborative Study

A collaborative study was conducted on a high performance liquid chromatographic (HPLC) method for determining rotenone in formulations. One liquid and 4 dust samples, containing other rotenoids and pesticides, with rotenone guarantees ranging from 0.75% to 20% were analyzed by 16 laboratories. Peak height measurements were used by 14 laboratories while 8 laboratories used integrator area measurements. Samples were extracted on a rotary shaker for 1% h with dioxane. An aliquot was analyzed using reverse phase HPLC and UV detection at 280 nm. Coefficients of variation ranged from 2.47 to 3.19% for peak height determinations and from 2.56 to 6.00% for peak area determinations. One collaborator analyzed the samples by the official infrared method for a comparison. The HPLC method has been adopted official first action.

Gas-Liquid Chromatographic Determination of Pyrethrins and Piperonyl Butoxide: Collaborative Study

A gas-liquid chromatographic method is described for the quantitative determination of pyrethrins and piperonyl butoxide in various formulations. The samples are diluted in acetone and analyzed by gas chromatography, with a flame ionization detector and a column packed with OV-101 or OV-1 on Chromosorb W (HP). The method was collaboratively studied with technical piperonyl butoxide and 3 pyrethrin-piperonyl butoxide formulations. The coefficients of variation for piperonyl butoxide ranged from 1.36 to 3.41% for the 5 samples. For pyrethrins in 3 formulations, the coefficients of variation were 2.20, 4.73, and 2.22%. An examination of the t-values indicated little or no contribution to systematic error, with the exception of one formulation. The method has been adopted official first action.

High Pressure Liquid Chromatographic Analysis of Chlorpyrifos Containing Insecticidal Formulations: Collaborative Study

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.

Gas-Liquid Chromatographic Determination of Disulfoton in Formulations: Collaborative Study

A rapid method is described for the determination of disulfoton (0,0-diethyl S-[2-(ethylthio)-ethyl] phosphorodithioate) in formulations by gasliquid chromatography (GLC). Samples are dissolved in acetone, and, after an internal standard is added, the samples are diluted to volume with solvent. They are then injected into a gas chromatograph equipped with a flame ionization detector and quantitated by peak height or area measurements. Fourteen collaborators made duplicate determinations on 4 samples including the technical product, a liquid, and 2 granular formulations. The average coefficient of variation was 0.847% for the liquid samples and 1.90% for the granules. The method has been adopted as official first action.