Optimizacija metod za hitro določanje vodotopnih vitaminov v sadnih ekstraktih s tekočinsko kromatografijo sklopljeno z masno spektrometrijo

The dissertation presents the development and validation of two HPLC-MS/MS methods for analyzing water-soluble vitamins in fruit extracts. First method is a multivitamin analysis method for nine major B vitamins: thiamine (B1), riboflavin (B2), nicotinamide (B3-M), nicotinic acid (B3-A), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folic acid (B9), and cyanocobalamin (B12). A HILIC-based HPLC-MS/MS method was developed to simultaneously analyze ascorbic acid (AA) and dehydroascorbic acid (DHA) as the combined amount of AA and DHA reflects the true total vitamin C content. The developed methods were validated according to ISO 21748 guidelines. The use of ammonium fluoride as an eluent modifier was investigated and was found to improve the MS sensitivity for the majority of vitamins significantly. The most profound increase was seen for B5, with a 15-fold increase in signal intensity. The effect was found to be non-additive as it did not improve with the increasing concentration of ammonium fluoride. The developed methods were also used to assess differences in vitamin retention in differently treated strawberry nectar with processing undertaken using pilot plants: conventional thermal processing (TT), high-pressure processing (HP), ohmic heating (OH), and pulse-electric field (PF). All processing techniques but HP were found to significantly increase total vitamin C content after processing, with the highest increases witnessed for TT-treated samples. The content of B vitamins remained largely unchanged after processing.