Analytical Sciences

Surface Improvement of Glassy Carbon Electrode Anodizedin Triethylene Glycol and Its Application to Electrochemical HPLC Analysis of Protein-Containing Samples

Hatsuo MAEDA, Kazunori KATAYAMA, Rie MATSUI, Yuji YAMAUCHI, and Hidenobu OHMORI

Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-Oka, Suita, Osaka 565-0871, Japan

In order to improve electrochemical performance of a glassy carbon (GC) electrode anodized in triethylene glycol (TEG),a GC electrode was anodized in H₂O prior to TEG anodization. The effect of this pretreatment was evaluated bycomparing electrochemical responses of acetaminophen on HPLC using the following electrodes: a GC electrodeanodized in both H₂O and TEG (double modified GC electrode); an unmodified GC electrode; GC electrodes anodized ineither H₂O or TEG. HPLC was carried out for samples containing uric acid and acetaminophen with or without variousproteins. The results reveal that the double modified GC electrode has satisfactory sensitivity, reproducibility, anddurability in electrochemical detection of acetaminophen by HPLC, compared with other electrodes. In order todemonstrate the advantage of the double modified GC electrode, analysis of acetaminophen from a urine sample wasperformed by HPLC without carrying out any tedious procedures such as the removal of proteins. In addition,electrochemical analyses of various compounds were performed using the double modified GC electrode in a near-flowinjection mode, suggesting that the electrode has potential applications for HPLC analysis of biologically importantcationic and neutral compounds.

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