Lorne A. Kerr

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.

Use of an automated thermal desorption system for gas chromatographic analysis of the herbicides trifluralin and triallate in air samples

An automated solid particulate adsorption-based air sampling and thermal desorption gas chromatographic system has been evaluated for monitoring trifluralin and triallate vapours in air. Utilizing mini-tubes packed with Tenax-TA resin, capillary gas chromatographic separations of these herbicides with electron-capture detection were equivalent to those obtained with autosampler on-column injection. Linear detector responses and precision exhibiting standard deviations of < 1% with respect to retention time and < 2% with respect to peak area were obtained following thermal desorption of mini-tubes fortified with 0.1 to 50 ng of both compounds. Relative humidity (0–100%) of the air being sampled had little effect on mini-tube breakthrough, with < 1% breakthrough of either herbicide following 28-h sampling periods with a flow-rate of 100 ml min−1. Recoveries of trifluralin and triallate from fortified tubes maintained at room temperature for up to 168 h was quantitative with insignificant cross-contamination between mini-tubes stored in the sampling carousel over this time frame.

Field comparison of polyurethane foam plugs and mini-tubes containing Tenax-TA resin as trapping media for the aerodynamic gradient measurement of trifluralin vapour fluxes

Abstract The effectiveness of a low-volume (0.3 l min −1 ) mini-tube (MT) sampler packed with Tenax-TA resin was compared in a field study with that of a polyurethane foam (PUF) sampler (25 l min −1 ) for measurement of herbicide vapour concentrations in air following fall soil-incorporation of trifluralin at 690 g ha −1 . Based on a paired comparison, no significant difference was observed in trifluralin concentrations (ng m −3 ) determined by gas chromatographic (GC) analysis of air samples collected using the MT and PUF samplers. As a consequence, fluxes determined using the aerodynamic gradient method of measurement for either sampler type were also similar. Because the entire air sample collected by the MT sampler was transferred onto the GC column, greater sensitivity was achieved using the MT sampler.