Determination of Thyreostats in Thyroid and Urine Using High-performance Liquid Chromatography–Atmospheric Pressure Chemical Ionisation Mass Spectrometry

Abstract

A method using liquid chromatography–atmospheric pressure ionisation mass spectrometry is described for the determination of five thyreostats in urine and thyroid tissue. Samples were extracted with ethyl acetate and the extracts were cleaned up on silica solid-phase cartridges. They were then concentrated and injected into the LC–MS system, monitoring the [M + H] ⁺ ions for each compound. Additional fragment ions for confirmation purposes could be obtained by increasing the cone voltage on the LC–MS system. Detection limits were in the region of 25 ng g ^{- 1} and recoveries ranged from 41% for the more hydrophilic compounds such as thiouracil to above 100% for the more hydrophobic compounds such as propyl- or phenylthiouracil.