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Kinetic Spectrophotometric Determination of N-Acetyl-L-cysteine Based on a Coupled Redox-Complexation Reaction

A novel simple kinetic spectrophotometric method for the determination of N-acetyl-L-cysteine (NAC) has been developed and validated. The proposed method is based on a coupled redox-complexation reaction, the first step of which is the reduction of Fe3+ by NAC ; the second one includes the complexation of Fe2+, resulting from the preceding redox reaction, with 2, 4, 6-trypyridyl-s-triazine (TPTZ). The stable Fe(TPTZ)2 2+ complex exhibits an absorption maximum at λ = 593 nm. The initial rate and fixed-time (at 5 min) methods were utilized for constructing calibration graphs. The graphs were linear in concentration ranges from 4.0 × 10–6 to 1.0 × 10–4 mol L–1 for the initial rate method and 1.0 × 10–6 to 1.0 × 10–4 mol L–1 for the fixed-time method, with detection limits of 1.0 × 10–6 mol L–1 and 1.7 × 10–7 mol L–1, respectively. The proposed methods were successfully applied for the determination of NAC in its commercial pharmaceutical formulations.

kinetic spectrophotometric determination; N-Acetyl-L-cysteine; pharmaceutical formulation

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