Online coupling of an electrochemically fabricated solid-phase microextraction probe and a miniature mass spectrometer for enrichment and analysis of chemical contaminants in infant drinks

A streamlined analytical workflow was developed for the analysis of infant drink samples using a miniature mass spectrometry system preceded by solid-phase microextraction (SPME) and extraction nano-electrospray ionization. Potential chemical contaminants in infant drinks (milk, lactic acid bacteria beverage, and fruit juice) were extracted and enriched using a custom-made stainless-steel SPME probe, which was coated with a thin layer of polyaniline and multi-walled carbon nanotubes nanocomposites (PANI/MWCNTs) by electrochemical deposition. The resulting porous microstructure has a larger surface area and enhanced microextraction efficiency, with enrichment factors ranging from 3055 to 8695 for exemplary analytes of antibiotics, bisphenol A, and perfluorinated compounds. The enriched analytes on the electrochemically fabricated SPME probe were simultaneously desorbed and ionized within a pulled glass capillary by extraction nano-electrospray ionization. The ionized species were subjected to instrumental analysis on a miniature ion trap mass spectrometer with adequate tandem mass spectrometry capability. The developed method was optimized and validated in terms of sensitivity, linearity, repeatability, and recovery. The integrated experimental protocol combining SPME, ambient ionization, and miniature mass spectrometry is promising for rapid, on-site screening of hazardous substances in food to ensure consumer health.