Use of disposable gold working electrodes for cation chromatography–integrated pulsed amperometric detection of sulfur-containing amino acids

We have prepared disposable thin-film gold working electrodes on polymeric substrates. Our microfabrication process allows for inexpensive and reproducible mass production of such electrodes. We utilize this new type of electrode in flow-through electrochemical cells to replace the conventional non-disposable gold working electrodes for integrated pulsed amperometric detection (IPAD) of compounds separated by high-performance cation-exchange chromatography. Using two S-containing amino acids (homocysteine and cysteine) as test compounds, we have modified a previously reported waveform for optimum performance with disposable gold electrodes. With the help of the same two test substances we have characterized the analytical performance of disposable gold electrodes under the new conditions. Compared to non-disposable working electrodes, the disposable working electrodes generated equal or better results in the limit of detection, linearity of calibration and reproducibility. When used with a new IPAD waveform, the disposable electrodes functioned reproducibly for 3 days. At the end of the specified usage period of 3 days, the disposable electrodes are simply replaced. Reconditioning by polishing is thus no longer required.