Flow Injection Spectrophotometric Determination of?N-Acetyl-L-cysteine as a Complex with Palladium(II)

摘要

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd2+ ions in the concentration range from 1.0 × 10?5 mol L?1 to 6.0 × 10?5 mol L?1. The detection limit NAC was 5.84 × 10?6 mol L?1 and the recorded relative standard deviation of the method is in the range from 1.67 to 4.11%. NAC and Pd2+ form complexes of Pd2+:NAC molar ratios of 1:1 and 1:2, depending on the ratio of their analytical concentrations. The cumulative conditional stability constant for the Pd(NAC)₂2+ complex is β₁₂' = 2.69 × 109 L2 mol?2. The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl₂, and had shown certain advantages: a) shorter analysis time; b) the use of smaller volumes of sample and reagents, which make the proposed method cheaper and faster for NAC determination in real samples without sample pretreatment.