Ambient ionization coupled with a miniature mass spectrometer for rapid identification of unauthorized adulterants in food

Considerably simplified workflows based on a miniature mass spectrometer combined with versatile ambient ionization methods were developed for rapid, on-site identification of illicit adulterants in select food (medicinal liquor, chili powder, hotpot seasoning and watermelon). The labor- and time-intensive procedures of sample pretreatment and chromatographic separation, traditionally required for mass spectrometry analysis, have been bypassed using capillary nano-electrospray ionization, paper spray ionization, or syringe spray ionization. A miniature ion trap mass spectrometer with a continuous atmospheric pressure interface and tandem mass spectrometry capability was employed for the analysis of adulterated additives. Key experimental parameters were carefully optimized in order to achieve the optimal performance of the integrated system. Maintaining the ease of analytical protocol, limits of detection as low as 30–40 μg/L for sex stimulants in medicinal liquor, 20–50 μg/kg for illegal dyes in chili powder and hotpot seasoning, and 15 μg/kg for plant growth regulator in watermelon were obtained. The capability of conducting quantitative analysis with an isotopic internal standard was demonstrated. The developed methodologies coupling ambient ionization and miniature mass spectrometry represent promising potential for fast and in situ screening of food adulteration.