A modification of McKellar and Cholette's (1986) calorimetric method for determining lipase activity in reconstituted non-fat dry milk was develooed. The method uses the color reaction between Fast Blue BB and the S-naphthol (BN) enzymatically cleaved from f3-naphthyl cap@ate (BNC) as a measure of lipase activity. In the modified method, a solvent system is used to clarify the sample rather than extracting the colored product. This modification allows measurement of total sample lipase by excluding centrifugation. In addition, the modified method has greater sensitivity with equal ease of use.

Vitamin D is a fat-soluble vitamin with great nutritional interest. An HPLC/MS/MS method was developed to measure vitamin D with atmospheric pressure chemical ionization. Under the experimental parameters used, the LOQ was 0.018 IU/g or 0.45 ng/g, which greatly enhances the capability of measurement of vitamin D at low levels in foods and supplements. This method was validated with spike recovery of 100 15 and the RSD of less than 10 for most sample matrixes, including infant formula, cheese, cereal and cerealbased foods, multivitamin supplements, and pet foods. The results for vitamin D were compared with those obtained by other methods.

The increased focus on the accuracy of Trans fatty acid data generated using current methodologies has resulted in research initiatives to optimize the quality of these assays. In this study, scientists combined the established methodology from AOAC 996.06 and the American Oil Chemists Society method Ce 1h-05, as well as other independent research. As a result, method modifications are proposed that could allow for a more accurate determination of Trans fat than the current AOAC 996.06 method. Validation data from this study are presented. The authors encourage peer review and offer to facilitate a collaborative validation to update AOAC 996.06.

Ultra-performance liquid chromatography (UPLC)/MS/MS was applied to measure vitamin D in various foods and nutritional supplements. The run-time of the chromatographic separation was cut from 20 min in HPLC/MS/MS to 10 min in UPLC/MS/MS, while equal or better separation efficiency was achieved to deal with complex food matrixes. Under the optimized conditions, all the previtamins of vitamin D3, D2, and isotope-labeled vitamin D3 were baseline-separated from their corresponding vitamins. It was also demonstrated that many sterol isomers in complex food matrixes that interfere in the analysis could be well-separated from the analytes. Accuracy of this method was evaluated by analysis of NIST SRM 1849 infant formula reference material. With eight replicates, the average vitamin D3 concentration was 0.251 + 0.012 mg/kg, an excellent agreement with the certified value of 0.251 + 0.027 mg/kg. In addition, spike recovery from a commercial infant formula matrix was in the range of 100 to 108% for both vitamins D3 and D2 at three spike concentration levels. The spike recovery for an even more complex matrix, pet food, was 101–105%. LOQ values were 0.026 and 0.033 IU/g, or 0.086 and 0.11 IU/mL in solution, for vitamins D3 and D2, respectively. The dynamic range had three orders of magnitude, which made the method flexible and useful to deal with the wide concentration range of vitamin D in various samples. The method was robust based on the results of changing the parameters of LC separation and MS measurement. This accurate and reliable vitamin D method increased instrument efficiency and analysis productivity significantly.

In an effort to measure vitamin D, ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) was applied to samples. The use of UHPLC-MS/MS decreased the run time by 50%. The UHPLC-MS/MS achieved equal or better separation efficiency with complex food matrixes compared to HPLC-MS/MS. It was also observed that under the optimized conditions of UHPLC, all previtamins of vitamin D3, D2, and isotope-labeled vitamin D3 were baseline-separated from their corresponding vitamins. The sterol isomers found in complex food matrixes that interfere in the analysis were well separated from the analytes. The accuracy of the method was evaluated by analyzing National Institute of Standards and Technology Standard Reference Material 1849 infant reference material. The average vitamin D3 concentration was 0.251 +/- 0.012 microg/g. This showed excellent agreement with the certified value of 0.251 +/- 0.027 microg/g. The spike recovery study of a commercial infant formula matrix showed a range of recovery from 100 to 108%. The LOQ values determined were 0.0022 and 0.0028 microg/g for vitamins D3 and D2, respectively; LOD values were 0.00065 and 0.00083 microg/g for vitamins D3 and D2, respectively.