Synthesis of stable isotope labelled steroid bis(sulfate) conjugates and their behaviour in collision induced dissociation experiments

O] stable isotope label for sulfate metabolites is reported, which allows for the selective, late-stage and 'one-pot' synthesis of a variety of SIL-steroid conjugates suitable as MS probes and internal standards. The method is applied to more comprehensively study the MS behaviour of steroid bis(sulfate) compounds through collision-induced dissociation (CID) experiments.