Determination of Free and Total Carnitine and Choline in Infant Formulas and Adult Nutritional Products by UPLC/MS/MS: Single-Laboratory Validation, First Action 2014.04.

A single-laboratory validation (SLV) has been performed for a method that simultaneously determines choline and carnitine in nutritional products by ultra performance LC (UPLC)/MS/MS. All 11 matrixes from the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) were tested. Depending on the sample preparation, either the added (free, with a water dilution and filtering) or total (after microwave digestion at 120°C in nitric acid and subsequent neutralization with ammonia) species can be detected. For nonmilk containing products, the total carnitine is almost always equal to the free carnitine. A substantial difference was noted between free and total choline in all products. All Standard Method Performance Requirements for carnitine and choline have been met. This report summarizes the material sent to the AOAC Expert Review Panel for SPIFAN nutrient methods for the review of this method, as well as some additional data from an internal validation. The method was granted AOAC First Action status for carnitine in 2014 (2014.04), but the choline data are also being presented. A comparison of choline results to those from other AOAC methods is given.