Ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) for the sensitive determination of folates in rice

High-performance liquid chromatography, coupled to tandem mass spectrometry (HPLC–MS/MS) has been established as the method of choice for the sensitive and simultaneous determination of different folates in a particular matrix, especially when only minute quantities of material are available. Using a previously developed and validated HPLC–MS/MS method as a starting point, we here report on the development and validation of an ultra-performance liquid chromatography (UPLC–MS/MS) method for analysis of folates in rice, which allows higher throughput and better resolution. UPLC was performed under gradient conditions on an Acquity HSS T3 column, followed by tandem mass spectrometry detection. The method was validated based on linearity, sensitivity, precision, accuracy and matrix effects. The limits of detection and the lower limits of quantification varied between 0.06 and 0.45 μg/100 g and 0.12 and 0.91 μg/100 g, respectively. Two linear calibration curves were established, one for the low and the other for the high concentration range. Analysis of the distribution and levels of folates in wild-type and folate-biofortified rice showed up to 50-fold enrichment in biofortified rice, with total folate levels of up to 900 μg/100 g rice. This is the first successful implementation of a UPLC method for the rapid and sensitive quantitative determination of folates in plant material.