A range of methods based on reverse-phase high-performance liquid chromatography is described for determining Al, Cu, Fe and Mn. The simplest method for determining Fe, Cu and Al involves direct formation and separation of the 8-quinolinol complexes on the column, with 1:l acetonitrile/water containing 5 X lOAs M 8-quinolinol, 0.4 M potassium nitrate and 0.02 M acetate buffer (pH 6.0) as the mobile phase, followed by electrochemical detection at -0.5 V vs. Ag/AgCl and/or spectropbotometric detection at 400 nm. Electrochemical detection enables <2 ng Cu and <l ng Fe to be quantified for injection volumes of 20 ~1. Spectrophotometric detection allows simultaneous deter minations of Al, Cu and Fe with lower sensitivity. The method is applied to the determination of Cu, Fe and Al in bovine liver and oyster tissue, Down to 1 ng of manganese (in the 20 ~1 injected) can be determined in biological samples by liquid chromatography with a mobile phase containing 1 mM Tris buffer (pH 8.8) after injection of an externally prepared 8-quinolinol complex. Preconcentration on SepPak cartridges after dichloromethane extraction is used for the determination of low concentrations of iron in water. A sensitive determination of aluminium based on detection at 254 nm is also reported.
Recently, considerable attention has been focused on the use of highperformance liquid chromatography
(h.p.1.c.) for the separation and sensitive multi-element determination of metals as chelated complexes formed externally or directly on the chromatographic column [l-3] . In particular, the reverse-phase h.p.1.c. method seems to offer excellent potential for the routine determination of heavy metals owing to its simplicity of operation and general convenience [4-231. The most extensively studied type of chelating agent in this branch of elemental analysis is probably dithiocarbamate [9, 11-141 although several papers have dealt with the h.p.1.c. of /3diketones [15, 161, nitrogen-oxygen-coordinated metal chelates [4, 51 and other metal complexes [l-3]. The study of the separation of 8-quinolinol metal chelates by reverse-phase h.p.1.c.