Multiple strategies can be used to derivatize opiates prior to analysis on GC-MS.  A variety of both silylation and acylation reagents can be used to best accomplish this, including either BSTFA (with 1% TMCS) or Propionic Anhydride (PIA).  When using BSTFA, a hydroxylamine solution can be added to the sample following hydrolysis if the oxime derivative is desired.  This additional step allows for single derivatives of hydromophone and hydrocodone to be observed, in addition to increased retention times.  This provides better separation from morphine and codeine, respectively.  Both ultra-pure BSTFA and PIA are available in UCT’s line of Selectra-Sil®  derivatization reagents.