Spectrophotometric determination of N-acetyl-L-cysteine and N-(2-mercaptopropionyl)-glycine in pharmaceutical preparations

Lea Kukoc-Modun; Njegomir Radić

doi:10.1155/2011/140756

Spectrophotometric determination of N-acetyl-L-cysteine and N-(2-mercaptopropionyl)-glycine in pharmaceutical preparations

Int J Anal Chem. 2011:2011:140756. doi: 10.1155/2011/140756. Epub 2011 May 23.

Authors

Lea Kukoc-Modun¹, Njegomir Radić

Affiliation

¹ Department of Analytical Chemistry, Faculty of Chemistry and Technology, University of Split, Teslina 10/V, 21000 Split, Croatia.

Abstract

A simple spectrophotometric method for the determination of N-acetyl-L-cysteine (NAC) and N-(2-mercaptopropionyl)glycine (MPG) in pharmaceutical preparations was developed, validated, and used. The proposed equilibrium method is based on a coupled two-step redox and complexation reaction. In the first step, Fe(III) is reduced to Fe(II) by NAC or MPG. Subsequently, Fe(II) is complexed with 2,4,6-tripyridyl-s-triazine (TPTZ). Several analytical parameters of the method were optimized for NAC and MPG analysis in the concentration range from 1.0 μM to 100.0 μM. Regression analysis of the calibration data showed a good correlation coefficient (0.9999). The detection limit of the method was 0.14 μM for NAC and 0.13 μM for MPG. The method was successfully applied to quantify NAC and MPG in pharmaceutical preparations. No interferences were observed from common pharmaceutical excipients.