The development of a sample preparation method and optimization of the analytical instrumentation conditions were performed for the determination of the vitamin B12 content in emulsified baby foods sold on the Korea market. After removal of the milk protein and fats by chloroform extraction and centrifugation, the vitamin B12 was water extracted from the sample. Following filtration of the solution through a nylon filter, the water-soluble extract was purified by solid-phase extraction using a Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). The solution eluted from the cartridge was dried under a stream of nitrogen gas and reconstituted with 1 mL of water. The sample solution was injected into an LC-MS/MS system after optimizing the mobile phase for vitamin B12 detection. The calibration curve showed good linearity with the coefficient of correlation (r2) value of 0.9999. The limit of detection was 0.03 µg/L and the limit of quantitation was 0.1 µg/L. The method of detection limit was 0.02 µg/kg. The vitamin B12 recovery from a spiking test was 99.62% for infant formula and 99.46% for cereal-based baby food. The sample preparation method developed in this study would be appropriate for the rapid determination of the vitamin B12 content in infant formula and baby foods with emulsified milk characteristics. The ability to obtain stable results more quickly and efficiently would also allow governments to exercise a more extensive quality control inspection and monitoring of products expected to contain vitamin B12. This method could be implemented in laboratories that require time and labor saving.

This study was carried out to develop an analytical method for the determination of vitamin D in infant formula. Vitamin D was determined by column-switching high-performance liquid chromatography (HPLC) equipped with a reversed phase column and UV detector after saponification and extraction of the formula with an organic solvent. A preseparation column (C 8 ), focusing column (C 18 ), analytical column (C 18 ) and UV-Vis detector (254 nm) were used. The limits of detection (LOD) and the limits of quantification (LOQ) for vitamin D were estimated to be 1.51 µg/kg and 4.95 µg/kg, respectively. The linearity, recovery, precision and accuracy of the analytical method for vitamin D were evaluated through the application of a SRM (Standard Reference Material) 1846 (National Institute of Standard & Technology, USA). The linearity of this method was calculated with a value of the coefficient of determination (r 2 ) ≥0.9999. The recovery of vitamin D was 85.20±3.00%. The intra-assay precision for vitamin D was between 1.68±0.03% and 5.75±0.33%, and the inter-assay precision for vitamin D ranged from 1.73±0.03% to 2.96±0.09%. The intra-assay accuracy for vitamin D was between 100.03±2.77% and 102.01±0.59%, and the inter-assay accuracy for vitamin D ranged from 99.00±1.53% to 102.01±3.04%. The proposed method is optimal for the separation and quantification of vitamin D from infant formula.