Electrochemiluminescence from Isoniazid Itself and Its Analytical Application

Abstract

A weak electrochemiluminescence (ECL) of isoniazid in NaOH solution was observed at a platinum wire anode. When cetyltrimethylammonium bromide (CTAB) was present, the weak ECL was enhanced. The stronger ECL mechanism of isoniazid in NaOH–CTAB solution could be described as follows: isoniazid was electrochemically oxidized via one-electron and one-proton transfer to isoniazid hydrazyl radical. Then the formed radical was further chemically oxidized by dissolved oxygen to the excited state isonicotinate that subsequently emitted light. Based on the stronger ECL phenomenon of isoniazid, a flow injection ECL method for the determination of isoniazid was proposed. The ECL intensity was linear with isoniazid concentration in the range of 4.0 × 10 −7 to 1.0 × 10 −5 mol l −1 and the limit of detection ( s / n = 3) was 1.9 × 10 −7 mol l −1 . The proposed method was simple and convenient operation, and has been applied to the determination of isoniazid in pharmaceutical preparations and human urine.