Flow-injection Spectrophotometric Determination of N-acetyl-L-cysteine Based on Coupled Redox-complexation Reaction

Abstract

A flow-injection spectrophotometric method is developed for determination of N-acetyl-L- cysteine (NAC) in pharmaceutical formulations. The method is based on coupled redox-complexation reaction, the first step of which is the reduction of Fe III by NAC; the second one includes the complexation of Fe II , resulting from the preceding redox reaction, with 2,4,6-tripyridyl-s-triazine (TPTZ). The stable Fe(TPTZ)2 2+ complex exhibits an absorption maximum at λ = 593 nm. Under experimental conditions, optimized by univariate method, a linear calibration curve is established in NAC concentration range from 6.0× 10 −6 mol L -1 to 2.0× 10 -4 mol L -1 with NAC detection limit of 2.0× 10 -6 mol L -1 . The analytical fre- quency was 60 h -1 . Usual excipients used as additives in pharmaceuticals do not interfere with the analysis of NAC. The proposed method is simple, rapid, sensitive, accurate and precise (repeatability RSD 0.29 %, n = 10), and can be applied for determination of NAC in pharmaceutical formulations up to nano- mole quantity. (doi: 10.5562/cca1753)