Abstract

In this report a study is described on the application of automated sample clean up by column switching in the quantitative determination of lorazepam in rat serum. Extraction of lorazepam from serum is by using a solid-phase extraction procedure with an "High-Hydrophobic" octadecylsilane sorbent. Determination of lorazepam is with high- performance liquid chromatography. The solid-phase extract is separated over a precolumn from serum components by "on line" column switching. Detection is by UV-detection at 230 nm. The extraction recovery (+- standard deviation) is (91 +- 0.7)%. The precision is 2.4% at 1.12 mug/l. The method is adapted to a concentration range from 0.05 to 4.2 mug/l.