Auxins such as dicamba and 2,4-Dichlorophenoxyacetic acid (2,4-D) may volatilize when used as herbicides. In this work, a fast, straightforward method to determine the relative volatility of auxin formulations is presented. The method uses a sprayed soil substrate in a disposable closed dome system. For a 24-h period, air is drawn out of the closed dome and passed through a polyurethane foam (PUF) plug where any volatile auxin is trapped. The auxin is extracted from the PUF with methanol, and the resultant extract solution is analyzed for the auxin by liquid chromatography-mass spectrometry (either LC-MS or LC-MS\MS). The data are then used to determine the relative volatility of the formulations.

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An updated liquid chromatographic (LC) method for the determination of glyphosate in technical material and formulations was tested by 7 laboratories. Samples were dissolved in water and injected into an LC system with a C18 guard column, an anion exchange analytical column, and a phosphate buffer mobile phase with 12 to 15 methanol. Detection was by UV absorption at 195 nm or refractive index. Automated injections were made. Calculations were based on peak area comparisons with external standards. The interlaboratory study analyzed 6 matched pairs of 3 glyphosate technical materials and 3 glyphosate formulations. The matched pair results were analyzed by using the AOAC spreadsheet and Youden's matched pair calculations. Coefficients of variation for the 6 samples ranged from 0.46 to 0.85.

Automated headspace solid-phase microextraction (SPME) coupled with gas chromatography and flame ionization detection is used to determine the amounts of methanol and tetrahydrofuran (THF) in distillation residue samples from a proprietary chemical reaction. A 65-micron polydimethylsiloxane/divinylbenzene SPME fiber is used to perform the extractions. Optimized extraction conditions for each analyte are determined using a parts-per-million-level methanol in water standard and a parts-per-billion-level THF in water standard. The amount of methanol and THF in distillation residue samples is quantitated by both standard addition and external standard calibration curve. The two methods of quantitation are compared.

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