Gold nanoparticles as a colorimetric probe for the determination of N-acetyl-l-cysteine in biological samples and pharmaceutical formulations

Abstract

In this study, gold nanoparticles (AuNPs) have been synthesised using ascorbic acid as a reducing agent and employed in the design of an in situ colorimetric probe for the spectrophotometric detection of N-acetyl-L-cysteine (NAC). The analyte induced an intensity decrease in the plasmon resonance absorbance of the AuNPs, and this represents a simple and reliable colorimetric assay for the quantification of NAC. The proposed approach allows the determination of NAC ranging from 3.0 to 100.0 μmol L⁻¹ with a limit of detection of 2.7 μmol L⁻¹. The relative standard deviations for eight replicate measurements of NAC at concentration levels of 5.0 and 30.0 μmol L⁻¹ were calculated to be 3.8 and 0.6%, respectively. This probe was successfully applied for the rapid determination of NAC in human urine samples and tablet formulations.