Flow injection spectrophotometric determination of N-acetyl-L-cysteine as a complex with palladium (II)

Abstract

We describe a new method using flow-injection analysis with spectrophotometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd 2+ 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 Pd 2+ form complexes of Pd 2+: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 β 12' = 2.69 × 10 9 L 2 mol -2. The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl 2, 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. © 2011 by The Authors.