Use of alumina columns to prepare plasma samples for liquid-chromatographic determination of catecholamines

We describe an improved method of sample preparation for liquid chromatographic determination of plasma catecholamines. The catecholamines are extracted from plasma by using small, cheaply-made columns of alumina, with or without prior clean-up on commercially available ion-exchange columns. Advantages of this technique over the conventional batch-extraction method of using alumina are speed, convenience, and improved sample clean-up. In particular, the one-stage method we describe allows results to be reported within 20 min of receiving the sample.