Determination of vitamin D3 (cholecalciferol) in wheat flour using a solid-liquid extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Abstract

Vitamin D helps absorb calcium and preserve healthy bones. In several countries, vitamin D intake comes mainly from fortified foods. Fortification of wheat flour is a way to improve the low intake of vitamin D in low- and middle-income countries. At the same time, reliable analytical methods are required to perform quality controls to certify the vitamin D content in this matrix. This work presents an analytical method to determine vitamin D3 (cholecalciferol) in white wheat flour, based on a very simple solid-liquid extraction (SLE) and quantification by liquid chromatography-tandem mass spectrometry (LC-MS/MS). SLE involves 5 g of sample and 15 mL of extractant solution (16 % ethyl acetate in ethanol), shaking for 12 min (in a vortex) and repeating the process. Evaporation of the extract at 1.5 mL complete the sample treatment. The LC-MS/MS determination use atmospheric pressure chemical ionization (APCI) source in positive mode and monitoring the m/z 385.4 to 259.1 transition. The average recovery was 84 % at the limit of quantification of the method (0.9 μg/100 g of vitamin D3). The coefficients of variation for repeatability and intermediate precision were 11 and 9 %, respectively. The proposed method compares favorably with those few reported in the literature. Due to the delay in the application of the Food Sanitary Regulations that indicate the fortification of flours with vitamin D3 at the national level in Chile, real samples were not available for the application of the method. However, this will allow adequate control when mandatory fortification comes into force.