Contemporary capillary columns for gas chromatography

Preparation of novel, curable capillary gas chromatographic systems and their application to the analysis of underivatized barbiturates and other controlled drugs of forensic interest

Three novel stationary phases have been prepared for the analysis of underivatized barbiturates by incorporating different monomers, N,N'-di(but-3-enyl)amylobarbital, N,N'-di(pent-4-enyl)amylobarbital and N,N'-di(hex-5-enyl)amylobarbital into a standard SE-54 matrix. The chromatographic behaviour of these columns is compared with a standard immobilised SE-54 column. They are shown to be less polar than the previously reported N,N'-diallylamylobarbital incorporated column. Of the three new phases, the one incorporating the monomer N,N'-di(but-3-enyl)amylobarbital shows the best performance for the separation of a mixture containing 22 barbiturates but all are selective, very efficient, inert and can be used up to at least 300 degrees C. The versatility of these new phases is demonstrated further by the analysis of other drugs of abuse. They offer unique selectivities not previously available.

Drug level monitoring: sedative hypnotics

Barbiturates and other traditional non-barbiturate sedative hypnotics are still extensively prescribed for the treatment of insomnia. There are a number of situations where identification or quantitative determination of these agents in biological fluids is required. Gas-chromatography offers highly sensitive and specific procedures for the determination of these compounds. The use of a nitrogen-specific detector allows a relatively simple sample preparation for sensitive detection and the use of capillary columns with bonded liquid phase allows separation of barbiturates without derivatization. In recent years liquid chromatography has also been extensively applied to the determination of these compounds. Sensitivity and selectivity of detection of barbiturates have been improved with the use of an alkaline mobile phase. Immunoassays for the determination of therapeutic concentrations of phenobarbital are very popular as the assays can be rapidly performed automatically. Use of these techniques has been extended for emergency detection of barbiturate overdose and for monitoring high-dose pentobarbital therapy.