Measurement of sulfite at oxide-coated copper electrodes.
The amperometric determination of sulfite was performed using copper electrodes in alkaline media. A mechanism for the oxidation of sulfite at these electrodes is suggested, based on the formation of superficial CuO(.OH), which acted as an electron transfer mediator to the analyte. At 0.5 V versus SCE in 1 M NaOH, sulfite could be calibrated at a sensitivity of 0.2 A l mol-1 cm-2, with a response time for the steady state of 30 s. The limit of detection (three times the signal-to-noise ratio) was 2.5 x 10(-6) M and the response was linear up to 5 x 10(-4) M (r2 = 0.9996, n = 15). The standard deviation (n = 10) at 1 x 10(-5) and 1 x 10(-4) M was 3.27 x 10(-7) A cm-2 (mean = 3.62 x 10(-6) A cm-2) and 1.07 x 10(-13) A cm-2 (mean = 2.25 x 10(-5) A cm-2), respectively.
Kiattipoomchai
M
M
School of Bioresources, King Mongkut's Institute of Technology, Thonburi, Bangkok, Thailand. imitdrum@cc.kmitt.ac.th
Somasundrum
M
M
Tanticharoen
M
M
Kirtikara
K
K
D000975:Antioxidants / Q000032:analysis*; D003300:Copper; D004563:Electrochemistry; D004566:Electrodes; D005504:Food Analysis; D006801:Humans; D013447:Sulfites / Q000032:analysis*
D000975:Antioxidants; D013447:Sulfites; D003300:Copper