Kinetic Potentiometric Determination of some Thiols with Iodide Ion‐Sensitive Electrode

Abstract

This paper describes a kinetic potentiometric method for the determination of thiols (RSH): l‐cysteine (cys), N‐acetyl‐l‐cysteine (NAC), l‐glutathione (glu), and d‐penicillamine (pen). The proposed method is based on the reaction of formation the sparingly soluble salts, RSAg, between RSH and Ag⁺ ions. During this reaction potential‐time curves were recorded by using an electrochemical cell with commercial iodide selective electrode. The rectilinear calibration graphs are obtained in the RSH concentration range from 1.0×10⁻⁵ to 1.0×10⁻³ M. The applicability of the proposed method was demonstrated by determination of chosen compounds in pharmaceutical dosage forms.

Keywords:

• Kinetic potentiometry
• thiols
• l‐cysteine. N‐acetyl‐l‐cysteine
• d‐penicillamine
• l‐glutathione
• iodide ion selective electrode