Automation of Atrazine and Alachlor Extraction from Soil Using a Laboratory Robotic System

Abstract

Abstract In order to analyze our ever‐increasing number of samples, we developed an automated multistep procedure for the extraction of atrazine (6‐chloro‐ N ‐ethyl‐ N ′‐[1‐methyl ethyl]‐1,3,5‐triazine‐2,4‐diamine) and alachlor (2‐chloro‐ N ‐[2,6‐diethylphenyl]‐ N ‐[methoxymethyl] acetamide) from soil using a commercially available laboratory robotic system. The robotic system shakes the soil‐extraction solvent mixture, separates solvent from soil, evaporates methanol from the solvent, performs a liquid‐solid extraction on the remaining herbicide‐water solution, transfers the eluate containing the herbicides and internal standard to a gas chromatograph (GC) vial, and caps the vial. Serial robotic processing of samples, compared with manual batch processing, increased sample throughput by a factor of three and decreased labor by 50%. Efficiency and precision of extraction of atrazine and alachlor increased to 89 ± 2% (robotic) from 79 ± 17% (manual). At present, the soil weight of 10 g results in a minimum detectable amount of 10 µg herbicide kg −1 soil.