Stereoselective separation of omeprazole and 5-hydroxy-omeprazole using dried plasma spots and a heart-cutting 2D-LC approach for accurate CYP2C19 phenotyping

•Two dimensional LC-MS/MS method for precise omeprazole and metabolites enantiomers quantification in human plasma.•Fast and efficient separation, with a total runtime of less than 8 min.•Innovative 2D-LC minimizes carryover, extending chiral column lifetime.•Successfully applied to clinical samples, demonstrating its clinical utility.