Simultaneous liquid-chromatographic determination of 12 common sedatives and hypnotics

We present a method for simultaneously determining 12 hypnotics and sedatives (primidone, methyprylon, phe-nobarbital, butabarbital, butalbital,ethchlorvynol, pento-barbital, amobarbital, phenytoin, glutethimide,secobarbital and methaqualone) in 200 tl of serum. Serum proteins are precipitated with an acetonitrile solution containing 5-(4-methylphenyl)-5-phenylhydantoin, the internalstandard. The drugs are eluted from a reversed-phase column with a mobile phase consisting of an acetonitrile/phosphate buffer, at a flow rate of 3.0 mI/mm. The eluted drugs are detected by their absorption at 195 nm; their quantities are estimated from theirpeak heights. Each analysis requires no longer than 30 mm at the optimum column temperature of 50 #{176}C.The lower limit of detection for all of these drugs is less than 10 ng/sample for drug standard. A sensitivit