Flow-injection determination of cysteine in pharmaceuticals based on luminol–persulphate chemiluminescence detection

✍ Scribed by Amir Waseem; Mohammad Yaqoob; Abdul Nabi

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 216 KB
• Volume: 23
• Category: Article
• ISSN: 1522-7235
• DOI: 10.1002/bio.1024

✦ Synopsis

Abstract

A flow injection (FI) method is reported for the determination of l‐cysteine, based on its enhancement on chemiluminescence (CL) emission of luminol oxidized by sodium persulphate in alkaline solution. The calibration graph was linear over the range 1.0 × 10^–9^–5.0 × 10^–7^ mol/L (r^2^ = 0.9992), with relative standard deviations (RSDs) in the range 1.1–2.3% (n = 4). The limit of detection (3σ blank) was 5.0 × 10^–10^ mol/L with a sample throughput of 120/h. The method was applied to pharmaceuticals and the results obtained were in reasonable agreement with the amount labelled. The proposed method was also applied to cysteine in synthetic amino acid mixtures. Calibration graphs of N‐acetylcysteine and glutathione over the range 1.0–50 × 10^–8^ and 0.5–7.5 × 10^–7^ mol/L were also established (r^2^ = 0.998 and 0.9986) with RSDs in the range 1.0–2.0% (n = 4), and the limits of detection (3__σ__ blank) were 5.0 × 10^–9^ and 1.0 × 10^–8^ mol/L, respectively. Copyright © 2008 John Wiley & Sons, Ltd.