Immersed solvent microextraction and gas chromatography-mass spectrometric detection of s-triazine herbicides in aquatic media

An immersed solvent microextraction (SME) method was successfully developed for the trace enrichment of s-triazine herbicides from aquatic media. A microdrop of butyl acetate was applied as the extraction solvent. After extraction, the microdrop was introduced directly into a gas chromatography-mass spectrometry (GC-MS) injection port. Some important extraction parameters such as type of solvent, extraction time, stirring rate, and temperature were investigated and optimized. The highest possible microdrop volume of 3 μl, a sampling temperature of 60 °C, and use of butyl acetate are major parameters to obtain high enrichment factors. The enrichment factor and linearity was studied by preconcentration of 1 ml of HPLC-grade, rice farm water and river water, spiked with a standard solution of triazines at a concentration range of 0.1-100 μg l−1 (R.S.D. < 11%). The correlation coefficient was satisfactory (r2 > 0.98) for all the studied triazines. Detection limits were obtained using HPLC-grade and river water, i.e. 0.015-0.4 μg l−1. The effect of matrix on extraction efficiency was, also, studied using some real-life water samples.