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 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)2
2+ 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.