A validated method for quantitation of psilocin in plasma by LC–MS/MS and study of stability
After the immunisation of rabbits with a psilocin-specific immunogen, polyclonal antisera were obtained. With these antisera a competitive, heterogeneous radioimmunoassay for the detection of psilocin was developed. As tracer a derivative of psilocin was synthesised, which contained a tritiated CH3 group. The antisera showed a specific reaction with psilocin. The cross-reactivity of structurally related endogenous substances like serotonin, tryptophan and tyrosine was below 0.01%. Also common drugs of abuse (Δ9-tetrahydrocannabinol, cocaine, morphine, amphetamine) showed negligible cross-reactivity (0.01–2%). Only tricyclic neuroleptics with a (dimethylamino)ethyl side-chain showed some cross-reactivity (20%). Spiked serum and blood samples were analysed with this new immunoassay and the results obtained were compared with the values measured with a validated GC-MS method.