High performance liquid chromatographic determination of triclosan, triclocarban and methyl-triclosan in wastewater using mini-bar micro-solid phase extraction

Abstract

An analytical method for the determination of the antibacterial agents (triclosan, triclocarban and methyl-triclosan) in wastewater is described. Attention was paid to sample pre-treatment where a new device, the mini-bar micro-solid phase extraction (mini-bar μ-SPE) was introduced. As in conventional micro-solid phase extraction (μ-SPE) device, sorbent (graphene, 20 mg) was introduced into a porous polypropylene (PP) bag (1.5 cm × 0.8 cm). It was next inserted into another slightly bigger PP bag (2.0 cm × 0.8 cm) together with a small metal rod (diameter, 1 mm; length, 1.5 cm). The open end of the outer bag was heat-sealed to secure the contents. After the extraction, the extracts were analysed by liquid chromatography on a pentafluorophenyl column (250 mm × 4.6 mm × 5 μm) with ultraviolet detection. Various experimental conditions influencing the mini-bar μ-SPE such as the effects of membrane type, preconditioning solvent, stirring speed, sorbent type and amount, sample volume and pH on the extraction were optimized. The desorption parameters (sonication time, solvent type and volume) were also studied. The method was validated, and calibration curves were linear with r2 > 0.99 over the range of 0.2–1000 μg L−1. The limits of detection were in the range 0.04–0.07 μg L−1. Recoveries were in the range between 80.8 and 103% for the target analytes. The relative standard deviation for inter- and intra -day precision was in the range of 3.6–27% for all analytes. The validated method was applied to the determination of the antibacterial agents in a campus wastewater treatment plant. Advantages of the mini- bar μ-SPE over the conventional μ-SPE are also highlighted.