Multichannel amperometric detection system for liquid chromatography to assay the thiols in human whole blood using the platinum microelectrodes chemically modified by copper tetraaminophthalocyanine

The fabrication and application of a novel multichannel amperometric detect ion system (MADS) with chemically modified microelectrodes (CMEs) for liqui d chromatography (LC) are described. These CMEs are based on the immobiliza tion of copper tetraaminophthalocyanine(CuTAPc) on platinum (Pt) microelect rodes by cyclic voltammetry (CV). The CMEs show good catalytic activity oxi dation of several analytes including thiocompounds. With the multichannel a mperometric detection system (MADS) coupled to LC, a three-dimensional hydr odynamic voltammogram (3D HDV) (i.e. current as a function of time and pote ntial) is obtained. The optimum detection potentials of thiocompounds and o ther analytes at the CMEs are easy to find. The novel multichannel amperome tric detector with CMEs shows good stability and reproducibility in detecti ng the thiocompounds and other analytes in LC. The linear ranges cover over three orders of magnitude and the limits of detection are 10 pmol for cyst eine, 16 pmol for glutathione, 16 pmol for N-acetylcysteine, 10 pmol for as corbic acid and 16 pmol for uric acid. The application of this method with microdialysis sampling and normal sampling in human whole blood assay is su ccessful, The method of LC-MADS with microdialysis sampling is more useful to assay the compounds in the biological matrix. (C) 1999 Elsevier Science B.V. All rights reserved.