Determination of testosterone concentrations in rat plasma using liquid chromatography–atmospheric pressure chemical ionization mass spectrometry combined with ethyl oxime and acetyl ester derivatization

A quantitative method for measuring testosterone (T) concentrations in rat plasma was developed using ethyl oxime and acetyl ester derivatization and liquid chromatography–atmosphere pressure chemical ionization tandem mass spectrometry (LC–APCI-MS/MS). The method utilizes a solid phase extraction with Varian Bond Elut C18, a derivatization process to form testosterone ethoxime acetate and LC–APCI-MS/MS with a reversed phase LC and a C8 column. This method is capable of detecting testosterone concentrations as low as 0.2 ng/ml in a 0.05 ml sample of rat plasma. This method can be used as a sensitive chromatography-based assay for small sample volumes of rat blood.