Determination of Phenoxy-acid Herbicides in Water with Solid Phase Microextraction Fiber Coated with Single-walled Carbon Nanotubes

By using solid phase microextraction (SPME) fiber coated with single-walled carbon nanotubes, an analytical method based on derivatization-SPME-GC-ECD method was established for the determination of 5 phenoxy-acid herbicides in water. The extraction parameters of the method were optimized, and the chemical stability of the SWCNTs fiber was investigated. The results showed that due to the inert nature of graphite, the SWCNTs fiber could be used at pH as low as 1 and the extraction efficiency of the fiber would not decline significantly after 160 extractions, showing excellent chemical stability. The linear range of the established method was 0.5-50.0 mu g/L for Dicamba, (+/-)-2-(2,4,5-trichlorophenoxy) propionic acid (2,4,5-TP) and trichlorophenoxy acetic acie (2,4,5-T), 1.0-100.0 mu g/L for 2,4-dichloraphenoxy acetic acid (2,4-D), and 5.0-500.0 mu g/L for 4-(2,4-dichlorophenoxy) bytyric acid (2, 4-DB). The LODs and LOQs were 0.03 - 0.25 mu g/L and 0.08-0.84 mu g/L, respectively