Determination of total choline by liquid chromatography-electrospray ionization-tandem mass spectrometry in infant formulas

Choline is a water-soluble nutrient important for infants' brain and neural development. In infant formulas, choline is one of the important fortified nutrients. A single-laboratory validation study conducted an LC-electrospray ionization-MS/MS to determine total choline in infant formulas. Sample preparation was adopted from AOAC Official Method 999.14, and instrumental running conditions were optimized. The LOQ was 0.2 microg/100 g, which is significant for measuring total choline in infant formulas. Average recoveries for milk-, rice-, soybean-, and hydrolyzed protein-based samples ranged from 86.45 +/- 6.04% to 108.98 +/- 3.68%, with RSD less than 7%. The repeatability RSD (RSD(r)) range was 0.24-3.59% in within-day evaluation and 1.16-3.24% in day-to-day evaluation. Matrix effect was also investigated, and can be effectively eliminated by using an internal standard. Therefore, this method has high credibility, and could be used as a routine method of quality control, or for clinical studies and other research areas.