Abstract: In this study, inositol contents in infant formula and milk were determined using ion chromatography-tandem triple quadrupole mass spectrometry. The sample pretreatment procedure included extracted by dissolution, extraction, pH adjustment, centrifugation and filtration. The analysis was performed on a Dionex CarboPac MA1 column (2.0 mm × 250 mm, 7.5 μm) using gradient elution with KOH generated online with an automatic eluent generator as eluent. Electrospray ionization was operated in the negative ion mode to detect the analyte. The results showed that good linearity with correlation coefficient (r) ≥ 0.999 was observed for inositol in infant formula and milk within the concentration range of 0.01–3.00 μg/mL. The limit of detection (LOD) and limit of quantitation (LOQ) of the method were 0.023 and 0.076 mg/100 g, respectively, both lower than those specified in the national standard of China. The recoveries of spiked samples were between 90.3% and 109.5% with relative standard deviations (RSDs) of 0.7%–9.1% (n = 6). The method was simple to operate, stable and sensitive and could be suitable for the determination of inositol in infant formula and milk.

Key words: ion chromatography-tandem triple quadrupole mass spectrometry; infant formula; milk; inositol