Raj Grover

Duplicate sampling reproducibility of atmospheric residues of herbicides for paired pan and high-volume air samplers.

The reproducibility of collection of atmospheric residues of the herbicides 2,4-D and triallate as bulk (wet plus dry) deposition samples by paired pan samplers and as particulate (filter) and vapour (PUF/XAD-2 resin cartridge) samples by paired high-volume air samplers was determined. Variability of herbicide concentrations in paired bulk deposition samples was within 25% for 65 and 80% of the samples for 2,4-D and triallate, respectively, with approximately 90% of the paired samples being within a factor of 2 for both herbicides. The vapour samples of 2,4-D and triallate showed similar reproducibilities. The highest reproducibility was observed for the filter samples with 92% of the paired data sets for 2,4-D being within 25% variability. No triallate was detected in the filter samples.

Environmental Fate of Triclopyr

Triclopyr is nonpersistent in surface water. It has limited mobility and low to medium persistence in soil. Considering its adsorptive characteristics and that it dissipates via multiple pathways, such as photolysis, plant metabolism, and microbial degradation, its potential to leach to depth in soil and to contaminate groundwater is low. This conclusion is corroborated by field leaching and groundwater monitoring data, both derived from use areas in several states in the U.S. and sites directly near handling/mixing facilities. Even when detected in the groundwater, e.g., five reported detections in two states in the U.S., the highest concentration was well below the estimated HAL of the USEPA.

Determination of the herbicide diclofop in human urine

A simple and sensitive method for the gas chromatographic determination of diclofop residues in human urine is described. Recoveries of diclofop, as its methyl ester, from fortified urine were greater than 85% at 100, 50, 10 and 1 micrograms kg-1, and were similar with and without the inclusion of a hydrolytic step in the analytical method. However, a hydrolytic step was necessary for analysis of 24-h urine samples collected from a male applicator following a single exposure to diclofop-methyl during application to wheat using a tractor-pulled sprayer. Diclofop residues determined with hydrolysis were approximately double those without hydrolysis, suggesting that a significant portion of diclofop was excreted in the conjugated form.