Preparation of single-walled carbon nanotube fiber coating for solid-phase microextraction of organochlorine pesticides in lake water and wastewater

The feasibility of single-walled carbon nanotubes (SWCNTs) as adsorbents for solid-phase microextraction was investigated by using organochlorine pesticides (OCPs) as model compounds. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method has a linear range of 2 - 800 ng/L for most analytes, with coefficients of correlation ranging from 0.9911 to 0.9996, LODs ranged from 0.19 to 3.77 ng/L (S/N = 3), and RSDs in the range of 3.5 - 13.9% (n = 5). Compared with the commercial PDMS fiber, the SWCNT fiber has better thermal stability (over 350 degrees C) and longer life span (over 150 times). The developed method was applied to determine trace OCPs in lake water and wastewater samples with external standard calibration. Results showed that OCP contamination was very low in these samples, and HCHs were detected in almost all water samples while DDT concentrations were almost under detection limits in these samples. Recoveries obtained at 20 ng/L spiking level were in the range of 88.4-111 % for OCPs in lake water. For wastewater samples, however, the recoveries were satisfactory for HCHs (63.6-97.1%) but relatively low for DDTs (44.7-116%) due to the high content of organic matter in wastewater.