Amperometric Determination of Sulfite by Gas Diffusion-Sequential Injection with Boron-Doped Diamond Electrode

Sensors

Chakorn Chinvongamorn¹  Kulwadee Pinwattana¹  Narong Praphairaksit¹  Toshihiko Imato² 

[1] Materials Chemistry and Catalysis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok, 10330, Thailand;Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan; E-mail:

关键词: Sequential injection;    sulfite;    gas diffusion unit;    boron-doped diamond electrode;   

DOI  :  10.3390/s8031846

来源: mdpi

【 摘 要 】

A gas diffusion sequential injection system with amperometric detection using a boron-doped diamond electrode was developed for the determination of sulfite. A gas diffusion unit (GDU) was used to prevent interference from sample matrices for the electrochemical measurement. The sample was mixed with an acid solution to generate gaseous sulfur dioxide prior to its passage through the donor channel of the GDU. The sulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution of 0.1M phosphate buffer (pH 8)/0.1% sodium dodecyl sulfate in the acceptor channel of the GDU and turned to sulfite. Then the sulfite was carried to the electrochemical flow cell and detected directly by amperometry using the boron-doped diamond electrode at 0.95 V (versus Ag/AgCl). Sodium dodecyl sulfate was added to the carrier solution to prevent electrode fouling. This method was applicable in the concentration range of 0.2-20 mg SO₃²⁻/L and a detection limit (S/N = 3) of 0.05 mg SO₃²⁻/L was achieved. This method was successfully applied to the determination of sulfite in wines and the analytical results agreed well with those obtained by iodimetric titration. The relative standard deviations for the analysis of sulfite in wines were in the range of 1.0-4.1 %. The sampling frequency was 65 h⁻¹.

【 授权许可】

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