CE‐MS analysis of heroin and its basic impurities using a charged polymer‐protected gold nanoparticle‐coated capillary

The first application of charged polymer‐protected gold nanoparticles (Au NPs) as semi‐permanent capillary coating in CE‐MS was presented. Poly(diallyldimethylammonium chloride) (PDDA) was the only reducing and stabilizing agent for Au NPs preparation. Stable and repeatable coating with good tolerance to 0.1 M HCl, methanol, and ACN was obtained via a simple rinsing procedure. Au NPs enhanced the coating stability toward flushing by methanol, improved the run‐to‐run and capillary‐to‐capillary repeatabilities, and improved the separation efficiency of heroin and its basic impurities for tracing geographical origins of illicit samples. Baseline resolution of eight heroin‐related alkaloids was achieved on the PDDA‐protected Au NPs‐coated capillary under the optimum conditions: 120 mM ammonium acetate (pH 5.2) with addition of 13% methanol, separation temperature 20°C, applied voltage ?20 kV, and capillary effective length 60.0 cm. CE‐MS analysis with run‐to‐run RSDs (n=5) of migration time in the range of 0.43–0.62% and RSDs (n=5) of peak area in the range of 1.49–4.68% was obtained. The established CE‐MS method would offer sensitive detection and confident identification of heroin and related compounds and provide an alternative to LC‐MS and GC‐MS for illicit drug control.