A simple method for the determination of methyl-triclosan in water samples

Abstract

Triclosan (TCS) is a bactericide widely used in personal care products such as shampoo, deodorants, and toothpaste. Along with its metabolite, methyl-triclosan (MeTCS), they can reach surface water through wastewaters, as they are not removed in traditional wastewater treatment plants. Although TCS is easily degraded by photolysis, MeTCS is much more persistent. While TCS can be directly analyzed by LC-ESI-MS, MeTCS must be analyzed by GC-ECD/MS, given low ionization by ESI and thus undesirable limits of detection. A fast and simple extraction method was developed using low temperature partitioning for waste and bioassay water samples, the later where fish were exposed to TCS. A 1-mL aliquot was placed in a 2-mL vial, followed by 200 μL of a 10% NaCl solution and 100 μL of toluene. The vial was shaken in a vortex mixer for 30 seconds, allowed to stand for 2 minutes and placed in a freezer, here the organic solvent (top layer) did not freeze. A volume of 3 μL was injected in a GC-μECD. Recovery on spiked samples was 82% ± 2%. Method was linear in the range tested (1 to 500 μg.L-1), with a Relative Standard DeviationRSD <2% and a Relative Error-RE <15%. Sample extraction repeatability had a standard deviation <8%. Method limit of detection and quantification were 0.05 and 0.1 μg.L-1, respectively. The proposed method is simple – as little sample preparation is required, and fast – less than 5 minutes for sample, and achieving low limit of detection in the type of samples studied.