Gold Nanoparticle Immunochromatography Assay for Identification of Acetaminophen Adulterant in Herbal Tea

Acetaminophen (APAP), a medicinal drug, is illegally added to herbal tea, which poses health risks. This study developed a rapid on-site detection method. Through rational hapten design and computational chemistry, a high-affinity monoclonal antibody with an IC₅₀ of 42.91 ng/mL was produced. Based on this antibody, a gold nanoparticle immunochromatography assay (AuNPs-ICA) was established. The assay showed a visual cut-off value of 250 ng/mL for qualitative judgment, with sensitive limits of detection and quantitation at 1.61 and 2.33 ng/mL, respectively. Method validation confirmed satisfactory accuracy, with recoveries ranging from 81.36 to 108.77%, and precision, reflected by an interbatch coefficient of variation between 1.56 and 4.69%. The results obtained by AuNPs-ICA showed good agreement with confirmatory ultrahigh-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. In conclusion, the established AuNPs-ICA is a portable, reliable tool for the rapid screening of APAP adulteration in herbal tea.