Sensitive and selective detection of 4-aminophenol in the presence of acetaminophen using gold–silver core–shell nanoparticles embedded in silica nanostructures

Abstract

Toxic 4-aminophenol (4-AP) can be considered as a primary impurity during the synthesis and/or storage of N-acetyl-para-aminophenol (APAP). In this study, 4-AP was sensitively and selectively detected in the presence of APAP using a gold–silver core–shell nanoparticle-embedded silica nanostructure (SiO2@Au@Ag). First, approximately 200nm of SiO2@Au@Ag were successfully prepared based on the Au-seed (3nm) mediated growth of Ag on the surface of SiO2 NP. Upon the incubation of 4-AP with SiO2@Au@Ag nanoparticles (NPs), the surface-enhanced Raman spectroscopy (SERS) intensity of 4-AP at 1591cm−1 increased proportionally in accordance with an increase in the concentration of 4-AP in the range of 0–800μM, with a detection limit of 3.5ppm. In addition, the APAP did not exhibit a significant Raman signal at high concentrations (5mM) and under the NP incubation condition. In the presence of 1mM, 3mM, and 5mM of APAP, 4-AP was detected using SiO2@Au@Ag NPs within the range of 200–1000μM, although the slopes decreased from 0.083cps/μM to 0.059cps/μM, 0.068cps/μM, and 0.035cps/μM, respectively. This study provides a method for the detection of 4-AP in the presence of APAP by using SiO2@Au@Ag for impurity detection in the pharmaceutical field.