Sensitive quantification of acetochlor and metolachlor in water using Taguchi-optimized DLLME coupled with high-performance liquid chromatography

Abstract

In this study, we developed a method that is sensitive, simple, and environmentally friendly for quantifying acetochlor and metolachlor. This method combines vortex-assisted dispersive liquid–liquid microextraction (DLLME) with high-performance liquid chromatography (HPLC). HPLC operating parameters and extraction parameters for direct and post-extraction analyses of acetochlor and metolachlor were optimized by employing the Taguchi experimental design method. The optimized HPLC parameters for acetochlor and metolachlor were 1.00 mL/min and 1.2 mL/min flow rate, 40 °C column temperature, and 70/30 (ACN/Water) and 80/20 (ACN/Water) at 210 and 230 nm wavelengths, respectively, for the direct injection method. For the DLLME procedure, 1,2-dichloroethane extraction solvent type, acetonitrile, and methanol dispersive solvent type, 400 µL and 300 µL extraction solvent volumes, and 1.0 mL dispersive solvent volume were the optimized DLLME extraction parameters, respectively. The developed and optimized methods for acetochlor and metolachlor analyses exhibited satisfactory validation results, with excellent linearity, indicated by R2 values greater than 0.99. The limit of detection (LOD) and the limit quantification (LOQ) levels of acetochlor and metolachlor were 28.96 to 31.25 µg/L, and 86.87 to 93.75 µg/L for direct injection, and 1.15 to 1.24 µg/L and 3.47 to 3.75 µg/L for post-extraction, respectively. The DLLME recovery values were within the range of 82.6–99.2 % (relative standard deviations-RSD: 4.47–10.13 %) for acetochlor and 91.1–103.4 % (4.31–7.96 %) for metolachlor. Repeatability and reproducibility results (n = 10) of direct injection and post-extraction methods for fortified acetochlor and metolachlor samples displayed very high precision lower than 2 % RSD.