A liquid chromatographic method for any liquid mixture of the 3 herbicides 2,4-D, MCPP, and dicamba, found in commercial formulations, has been collaboratively studied. Each collaborator received 4 samples, 3 of which were ternary formulations and one a binary formulation of amine salts. Concentrations in the formulations range from 0.02 to 2.32% for dicamba, 0.32 to 21.7% for 2,4-D, and 0.22 to 11.6% for MCPP. A binary solvent system and the use of a specified 25 cm column of RP 10 μm in the reverse phase ion suppression mode will selectively quantitate each herbicide, separating many impurities found in the technical products. Standard deviations in each of 11 columns of results obtained indicate good precision. The method has been adopted official first action.
A high pressure liquid chromatographic method has been developed for liquid herbicide combinations that contain different combinations of 3 active ingredients including 2,4-dichlorophenoxyacetic acid (2,4-D), 2-(2-methyl-4-chlorophenoxy)propionic acid (MCPP), and dicamba. A reverse phase column in the ion suppression mode and a binary solvent system separate all 3 herbicides quantitatively on a single chromatogram. The internal standard solution may contain 2 internal standards, salicylic acid and butyrophenone, for use with certain combinations of the herbicides. The solvent system resolves the compounds of interest from all significant impurities.
A high pressure liquid chromatographic (HPLC) assay of amine salt and ester formulations of MCPA has been collaboratively studied. The AOAC 2,4-D HPLC method has been modified for application to MCPA products. The MCPA methodology is identical to that of 2,4-D except in strength of mobile solvent, pH of mobile solvent, heating of ester formulations to 50°C to ensure complete saponification, and the use of glass microfiber filters. The method is specific and separates all known impurities. Examination of chromatograms and percentage results from 8 collaborators indicate that selection of a practical internal standard would improve precision in the procedure and a second collaborative study is recommended.
An infrared method was developed for the analysis of Probe 75% wettable powder formulation for methazole content. The procedure involves an extraction of the powder by agitation with acetone. The suspension is centrifuged, and the clear supernatant liquid is measured for absorbance at 755 cm−1. A collaborative study was conducted with 10 laboratories participating. One laboratory omitted the centrifugation, which resulted in a low assay. Statistical analysis of the data showed no significant variances. The coefficient of variation for 10 laboratories analyzing 2 samples in duplicate was 1.29%. The method has been adopted interim official first action.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.