Fabrication of polyaniline/silver composite coating as a dual-functional platform for microextraction and matrix-free laser desorption/ionization.

Polyaniline/silver (PANI/Ag) composites were prepared with a one-step synthesis method, and fabricated into solid-phase microextraction fiber coatings through three different means, i.e. in situ growth, gluing and chemical bonding. This work explored the utility of the as-fabricated PANI/Ag SPME fibers as dual-functional platforms for microextraction and matrix-free laser desorption/ionization (LDI) of the target analyte. The results showed that after incorporating Ag into the PANI polymer, the LDI efficiency was improved by over two times, which was 92.8% the LDI efficiency of the commercial LDI plate. In addition, the in situ grown fiber coatings were observed the most sensitive as dual platforms for the analysis of bifenthrin. The signal intensity was increased over twenty times by using in situ grown fiber, comparing to direct analysis with commercial LDI plate, which were attributed to the excellent extraction ability of PANI backbone, as well as the high LDI efficiency of the PANI/Ag composites. Low detection limit (lower than 10ngL) and good fiber-to-fiber repeatability (relative standard deviation 11.0%, n=3) were obtained by using the in situ grown coating for the analysis of bifenthrin, and bifenthrin in real water samples was successfully analyzed. The work successfully coupled SPME with matrix-free LDI, which greatly simplified the analytical process and improved the analytical sensitivity.