Preparation of polydimethylsiloxane/β-cyclodextrin/divinylbenzene coated “dumbbell-shaped” stir bar and its application to the analysis of polycyclic aromatic hydrocarbons and polycyclic aromatic sulfur heterocycles compounds in lake water and soil by high performance liquid chromatography

Abstract

A “dumbbell-shaped” stir bar was proposed to prevent the friction loss of coating during the stirring process, and thus prolonged the lifetime of stir bars. The effects of the coating components, including polydimethylsiloxane (PDMS), β-cyclodextrin (β-CD) and divinylbenzene (DVB) were investigated according to an orthogonal experimental design, using three polycyclic aromatic hydrocarbons (PAHs) and four polycyclic aromatic sulfur heterocycles (PASHs) as model analytes. Four kinds of stir bars coated with PDMS, PDMS/β-CD, PDMS/DVB and PDMS/β-CD/DVB were prepared and their extraction efficiencies for the target compounds were compared. It was demonstrated that PDMS/β-CD/DVB-coated stir bar showed the best affinity to the studied compounds. The preparation reproducibility of PDMS/β-CD/DVB-coated stir bar ranged from 3.2% to 15.2% ( n = 6) in one batch, and 5.2% to 13.4% ( n = 6) among batches. The “dumbbell-shaped” stir bar could be used for about 40 times, which were 10 extractions more than a normal stir bar. The prepared PDMS/β-CD/DVB-coated “dumbbell-shaped” stir bar was used for stir bar sorptive extraction (SBSE) of PAHs and PASHs and the desorbed solution was introduced into HPLC-UV for subsequent analysis. The limits of detection of the proposed method for seven target analytes ranged from 0.007 to 0.103 μg L −1, the relative standard deviations were in the range of 6.3–12.9% ( n = 6, c = 40 μg L −1), and the enrichment factors were 19–86. The proposed method was successfully applied to the analysis of seven target analytes in lake water and soil samples.