Simultaneous determination of sulphoraphane and sulphoraphane nitrile in Brassica vegetables using ultra-performance liquid chromatography with tandem mass spectrometry

Introduction Several analytical methods exist for the determination of sulphoraphane or sulphoraphane nitrile from biological matrices and plant extracts. However, no UPLC-MS/MS method exists for the simultaneous detection of both. Objective To develop and validate an UPLC-MS/MS method for the simultaneous analysis of sulphoraphane and sulphoraphane nitrile from Brassica oleracea L. ssp. italica Methods This method was developed utilising an Acquity BEH C8 column with gradient elution combined with tandem mass spectrometry, using positive electrospray ionisation in multiple reaction monitoring mode. Results The retention times for sulphoraphane and sulphoraphane nitrile were 0.4 and 0.6 min respectively, and total run time was 3 min. The method was validated for linearity, sensitivity, precision, accuracy, matrix effects and recovery. The method was employed to determine glucoraphanin hydrolysis products in broccoli and the predominant product was found to vary depending on the variety tested. It was also applied to the accurate determination of sulphoraphane and sulphoraphane nitrile in broccoli samples hydrolysed under different conditions. It was observed that the formation of sulphoraphane and sulphoraphane nitrile was influenced by the temperature of the reaction. Conclusion The validated UPLC-MS/MS method for simultaneous detection of sulphoraphane and sulphoraphane nitrile was shown to be applicable to broccoli plants and is expected to be applicable to other cruciferous sources.