A screening method for the rapid detection of barbiturates in serum by means of tandem mass spectrometry.

A mass spectrometric screening method for barbiturates in serum was developed. Under electron impact conditions barbiturates fragment by loss of HNCO. A 'constant neutral loss' scan of 43 u provides, therefore, an indication of the presence of members of this toxicologically relevant class of compounds. Subsequent identification is possible either by 'daughter' or by 'parent ion' scans. The detection limit for propallylonal, buto- and phenobarbital was determined as better than 1 micrograms ml-1 serum.