On-Line Derivatization of N-acetylcysteine Using Ethyl-Propiolate as a Novel Advantageous Reagent and Sequential Injection Analysis

Abstract

This study reports a novel automated assay for the determination of N-acetylcysteine (NAC). The method is based upon the on-line derivatization of the analyte with a new reagent, ethyl-propiolate (EPL), to form a UV-absorbing derivative. The reaction is fast, proceeds in aqueous solutions under mild conditions and is, therefore, ideal for automation using sequential injection analysis. All major chemical and instrumental variables were examined thoroughly. The assay was validated for linearity, range, LOD-LOQ, within and day-to-day precision, selectivity, and accuracy. The experiments confirmed its suitability for the reliable quality control of NAC-containing formulations at a sampling rate of 80 h^−1.

Keywords:

• N-Acetylcysteine
• Determination
• Ethyl propiolate
• Sequential injection
• Spectrophotometry

Ms. Aspasia Verdoukas and Mr. Aris Kazantzis (Cosmopharm Ltd, Greece) are kindly acknowledged for providing the samples and the HPLC analysis results.

Notes

^a Mean of three replicates.

^b HPLC: HPLC method recommended by the USP (U.S. Pharmacopoeia 2005).

^a Mean of three replicates.

^b VB: Validation batch.

^c HPLC: HPLC method recommended by the USP.