Fast simultaneous determination of multiple water-soluble vitamins and vitamin-like compounds in infant formula by UPLC-MS/MS

Fortification of infant formula provides the sole source of nutrition for bottle-fed baby; therefore, particular attention should be paid to ensure an adequate and balanced intake of vitamins, which cannot be synthesized by the body, but essential for the normal growth and functioning of human body. An Ultra Performance LC-Tandem Mass Spectrometry (UPLC-MS/MS) method was developed for fast simultaneous determination of 14 different water-soluble vitamins and vitamin-like compounds in infant formula, and methotrexate and nicotinamide (D4) were used as internal standards. To achieve a high sensitivity, selectivity and accuracy for the analyte, the most crucial factors, such as mass spectrometry parameter, column and mobile phase choosing were optimized. Identification and quantification were performed by using multiple reaction monitoring (MRM) with one parent ion, one daughter ion for each analyte, and electrospray ionization in positive ion scan mode. A chromatographic separation within 10 minutes was achieved by using a BEH Shield RP 18 (2.1 mm ×100 mm, 1.7 µm, Waters) column with a mobile phase program, consisting of methanol and 10 mM aqueous ammonium acetate. Recoveries were 81.8-106.1%, the limits of detection were 0.0042-28.872 ngml -1 (inject 10 µl), with Relative Standard Deviation (RSD) of 1.17-5.09% for intra-day and 2.61-7.43% for inter-day. Different water-soluble vitamins and vitamin-like compounds at a wide range of concentration level in 14 different commercial samples of infant formula, rice flour and wheat powder were tested using developed method and the results showed that it has offered certain advantages compared to previous reports and provided important and reliable information for government regulation, quality control and nutrition labeling.