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

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 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)(2)(2+) 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.