High-throughput quantification of sodium saccharin in foods by ambient flame ionization mass spectrometry

Ambient flame ionization (AFI) coupled with triple quadrupole tandem mass spectrometry was developed for quantitative analysis of sodium saccharin (SAC) in various food samples. Typically, the micro-flame by the combustion of n-butane provided a heating zone for fast desorption and ionization of analytes in milliseconds. Then high ion abundance of analyte could be produced in a short time, which made AFI-MS possess a very high sensitivity for SAC detection and was particularly appropriate for the quantification in multiple reaction monitor (MRM) mode. Liquid samples were introduced into outer flame using dip-it tips in order to facilitate a rapid and high-throughput analysis. Saccharin-d4 was used as the internal standard to compensate for the variations of the ion intensities. With a minimal sample preparation, a linear range of 4-100 μg/mL was developed with all linear relationships of different matrices (including coke, juice, liquors, sunflower seeds and sweetmeats) greater than 0.992. Recoveries for coke and apple matrices were ranged from 88.4% to 108.9% at the concentration of 5, 20, 80 μg/mL and the limits of detection (LODs) were in the range of 0.12-0.21 μg/mL. Furthermore, the feasibility of this method was exhibited by the quantification analysis of SAC in seventeen real samples. These results indicated that AFI-MS was a valuable strategy for rapid screening detection and precise quantification analysis of SAC in food.