Development of a coupled dispersive liquid-liquid micro-extraction with supported liquid phase micro-extraction for triclosan determination in wastewater

Abstract

As attention is drawn towards the monitoring of the so-called emerging pollutants, some common household chemicals are not well researched. Household antimicrobials can also present wastewater treatment challenges if not taken cognisance of. Herein we report the application of a recently reported coupled dispersive liquid-liquid micro-extraction (DLLME) with supported liquid phase micro-extraction (LPME) for the extraction of triclosan from wastewater. A univariate approach was used to investigate various parameters amenable to DLLME while no attempt was made to optimise the LPME, achieving the following optimum conditions: 25 μL of a 1:1 toluene-chloroform mixture with 10% sodium chloride into 1 mL aqueous triclosan solutions and extraction time of 15 min achieving an enrichment efficiency 167 times the reference solution prepared with distilled water, good linearity (R² = 0.9946) with the estimated limit of detection at 0.013 μg/mL and good repeatability (%RSD ≤ 10). The method showed considerable ruggedness with a similar linearity (R² = 0.9957) and repeatability (%RSD < 10), with only the limit of detection being compromised (0.31 μg/mL) when applied to a wastewater sample using a matrix-matched standard addition approach. Although the GC-FID method detected triclosan in the wastewater sample, the results were negated by those from the GC-MS; as such it therefore could not be concluded with confidence whether the water contained any triclosan or not. However, the results demonstrated the potential of this method in determination of triclosan in water-based samples when the extraction was coupled to a more rugged system such as a GC-MS.

Keywords: dispersive liquid-liquid microextraction, liquid phase microextraction, coupling, mixed-solvents, triclosan, wastewater