Electrochemical preparation of poly(p-phenylenediamine-co-aniline) composite coating on a stainless steel wire for the headspace solid-phase microextraction and gas chromatographic determination of some derivatives of benzene

A poly(p-phenylenediamine-co-aniline) composite coating was prepared on a stainless steel wire through electrochemical method. The coating was characterized by scanning electron microscopy, Fourier transform infrared spectrophotometry and thermogravimetry. It showed thin slice shape and netlike microstructure, and thus it had large surface area and large extraction capacity. When the resulting fiber was used for the headspace solid-phase microextraction of some derivatives of benzene (i.e. chlorobenzene, 1,3-dimethylbenzene, 1,2-dimethylbenzene, 2-chlorotoluene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene), followed by gas chromatographic (GC) analysis, it presented better performance than the polyaniline coated stainless steel wire. Under the optimized conditions, the GC peak areas were linear to their concentration in the ranges of about 0.5–500 μg L−1, with correlation coefficients of 0.9911–0.9989; the detection limits were 0.2–0.88 μg L−1(S/N=3). The run-to-run RSD was smaller than 5.5% (n=5), and the fiber-to-fiber RSD was 3.5%–12.7% (n=3). The fiber was quite stable and durable; after it was used for about 140 times, its extraction efficiency kept almost unchanged. The developed method was successfully applied to the determination of the derivatives of benzene in waste water, and the recoveries were 86.9%–107.7%.