An Ultra-Performance Liquid Chromatoghraphy-Tandem Mass Spectrometry (UPLC-MS/MS) Method for the Rapid and Sensitive Determination of Sulforaphane and Sulforaphane Nitrile in Brassica Vegetables

Abstract

A rapid UPLC-MS/MS method has been developed and validated for the simultaneous analysis of sulforaphane and sulforaphane nitrile from Brassica Oleracea L. This method was developed utilising an Acquity BEH C8 column with gradient elution combined with tandem mass spectrometry detection, using positive ion electrospray ionisation in multiple reaction monitoring (MRM) mode. The method was validated for linearity, sensitivity, precision, accuracy, matrix effects and recovery. The retention times for sulforaphane and sulforaphane nitrile were 0.4 and 0.6 min, respectively. The limits of detection and lower limits of quantification were 0.005 μM and 0.01 μM respectively for sulforaphane, and 0.06 μM and 0.16 μM for sulforaphane nitrile respectively. Intraand inter-day precision ranged, respectively, from 5.07 to 8.93 % RSD and from 3.44 to 9.31 % RSD, for sulforaphane and from 0.95 to 6.69 % RSD and 6.84 to 9.94 % RSD, respectively, for sulforaphane nitrile. The accuracy varied from 12.55 to 10.34 % bias for sulforaphane and from -8.67 to 8.06 % bias for sulforaphane nitrile. Matrix effects were also investigated and were found to be in the range of 92.5 to 105.7 %, and 99.2 to 102.9 %, for sulforaphane and sulforaphane nitrile respectively. This method is the first validated UPLC-MS/MS method for the rapid and sensitive determination of sulforaphane and sulforaphane nitrile in cruciferous sources such as broccoli plants.