Determination of alkylphenols in water by solid-phase extraction with on-column derivatization coupled with gas chromatography-mass spectrometry

Abstract

An analytical methods based on solid-phase extraction (SPE) with in situ derivatization followed by gas chromatography-mass spectrometry has been developed for the determination of alkylphenols (APs) in water samples. Two important APs, 4-n-nonylphenol and 4-t-octylphenol, were selected as the target compounds for method development. The SPE extraction was conducted on a C-18 extraction cartridges with on column silylation by bis (trimethylsilyl) trifluoroacetamide. Operationasl parameters including silylation reagent silylation time, pH value, concentration of salts, elulent which are expected to impact on the recoveries of analytes were optimized by orthogonal experimental design. It is shown that the acetone is the best silylation reagent while DCM was efficient in eluting AN from SPE cartridges. The recovery of APs increases slightly with increasing concnetration of NaCl in the range of 0 - 1. 5 % of NaCl, beyond the concentration of 1.5%, the recovery of Al's starts to decrease. But the recovery of AN reduced by the increase in pH value. The optimised method was further verified by performing spiking experiments in ultrapure water and seawater matrices, with good recovery and reproducibility for all the selected compounds. The method showed better performance than the reported liquid liquid extraction-derivatization method in terms of analytical speed, procedural simplicity and recovery.