The determination of clioquinol in biological materials by extractive alkylation and gas-liquid chromatography.

Clioquinol, or 5-chloro-7-iodo-8-hydroxyquinoline (Vioform), and the internal standard, 5,7-dichloro-8-hydroxyquinoline are extracted from biological material in the form of their tetrahexylammonium salts into dichloromethane, where, in the presence of a methylating agent, both clioquinol and the standard are spontaneously transformed into their O-methyl derivatives. These derivatives can be purified by base-specific extraction and subsequently determined by gas chromatography; concentrations down to 10 ng per sample may be assayed. The method is compared with a previously reported procedure based on the O-acetyl derivatives.