Handheld paper spray ionization mass spectrometry for direct analysis of Ningxia goji berry.

Authentication of geographical origin is important for ensuring the quality and traceability of high-value botanical products such as goji berries (Lycium barbarum L.). While paper spray ionization (PSI) has been explored for rapid analysis, its broader application has been limited by reliance on high-voltage supplies integrated within specific mass spectrometers. In this study, we developed a compact handheld direct-current (DC) high-voltage power supply as an independent module for PSI, enabling flexible coupling with both benchtop and portable mass spectrometers. This design allows the same ionization source to be applied across different platforms, facilitating consistent comparison between portable and laboratory-scale instruments. Using this platform, we profiled the metabolomes of eight goji berry samples-seven from Ningxia and one from Xinjiang. A total of 156 distinct features were detected, including amino acids, sugars, alkaloids, and organic acids. Neural network-based classification achieved robust discrimination between Ningxia and Xinjiang samples, while the minimal variation among Ningxia cultivars suggests that the geographical environment exerts a stronger influence than varietal differences on metabolite composition. The handheld PSI-MS system also demonstrated reliable analytical performance, with a detection limit of 10 pg/mL for sucrose, stable signal reproducibility (RSD = 7.47%), and high classification accuracy (AUC = 0.992 on the Orbitrap; AUC = 0.978 on the portable MS). These results highlight the significance of a modular, handheld high-voltage supply for extending PSI beyond instrument-integrated solutions, providing a practical and versatile approach for rapid, on-site authentication of functional foods and other agricultural products.