Calibration and field application of Chemcatcher® passive samplers for detecting amitrole residues in agricultural drain waters.

A passive sampler device suitable for monitoring of residues of the hydrophilic ionic herbicide amitrole in irrigation waterways was developed. Uptake of amitrole on styrenedivinylbenzene-reverse phase sulfonated Empore™ disks was linear and proportional to its water concentration over the range of 1-10 μg/L with a sampling rate of 23.1 mL/day under laboratory flow-through conditions. Performance of the sampler was evaluated by deployment in an agricultural irrigation drain for 10 days. The amount of amitrole adsorbed by the passive samplers compared well with the cumulative mean water concentrations calculated from daily spot samplings of the drain water.