Rapid detection of surface chemical residues by miniature mass spectrometry

The increasing demand for rapid, on-site screening of trace chemical residues on surfaces in security and forensic contexts necessitates the development of portable analytical technologies that extend beyond conventional laboratory instruments. This study addresses this critical gap through the creation of a thermal desorption atmospheric pressure chemical ionization (TD-APCI) source integrated with a miniature mass spectrometer (mini-MS). The TD-APCI module facilitates non-destructive, direct analysis of surfaces by employing hot-air blowing desorption combined with corona discharge ionization under ambient conditions. This integrated platform eliminates the need for extensive sample preparation while preserving substrate integrity. The performance of the system was rigorously validated by directly detecting illicit drugs on personal identity documents, including IDs and passports. Limits of detection (LODs) as low as 0.5 ng for caffeine and 1 ng for methamphetamine were achieved, demonstrating excellent linearity (R² > 0.995) using tandem MS techniques. Furthermore, the system was successfully utilized to rapidly detect pesticide residues on vegetables and traditional Chinese medicines, showcasing sub-nanogram sensitivity, minimal interference, and outstanding linearity. These findings underscore the potential of the TD-APCI-mini-MS platform as a transformative tool for real-time, on-site security screening. It offers uncompromised sensitivity, matrix tolerance, and operational simplicity. Its ability to deliver laboratory-grade analysis directly at points of need represents a significant advancement in portable chemical detection relevant to public safety, food security, and pharmaceutical quality control.