Rapid on-site detection of zinc pyrithione in real-life samples with unprecedented selectivity and sensitivity

Zinc pyrithione (ZPT) has been widely applied in anti-dandruff cosmetics and anti-fouling coatings/paints. Recently, the European Union has announced a ban on further ZPT use in cosmetic products due to its potential health risk, raising the needs for its detection in a reliable and convenient way. This study reports a highly sensitive (down to ng/L level) method for rapid on-site one-step (no need for any pretreatments) detection of ZPT in real-life samples with exceptional selectivity, using the surface-enhanced Raman spectroscopy (SERS) technique. The SERS sensor with significant Raman enhancement is mass-produced by electrochemically treating commercial Ag needle, enabling insertable probes for easy sampling. Applying thus-obtained SERS sensor, the ZPT in shampoos can be readily identified on a portable Raman spectrometer within one minute. Mechanistic studies reveal that the formation of the Ag-Zn and Ag-S bonds bestows Ag probe with a strong affinity toward ZPT, enabling unprecedented selectivity. To the best of our knowledge, it is for the first time that ZPT is detected using the SERS technique, which is potentially valuable for the market regulation of its usage and the investigation of its ecological impacts.