Fast and sensitive determination of aluminium with RP-HPLC using an ultra-short monolithic column

Abstract

A fast and sensitive reversed-phase high-performance liquid-chromatographic method for determination of aluminium in aqueous samples has been developed. The fluorescent aluminium-lumogallion complex (λ_ex 505 nm, λ_em 574 nm), was formed with a pre-column reagent and then separated on a Chromolith® RP-18e Guard column using a two-tiered, stepped gradient program, with matrix elimination (5/95 (v/v) methanol/water), followed by elution (90/10 (v/v) methanol/water). This method achieved a run time of 2.5 min without compromising sensitivity (limit of detection = 5.6 × 10⁻¹⁰ M, limit of quantification = 7.2 × 10⁻⁷ M), precision (3.5% at 3.71 × 10⁻⁶ M) or accuracy (recovery = 97.5% ± 3.2%, n = 5, P = 0.95). This represents an improvement in run time by >50% compared to the fastest previously published method [Lee et al., Clin. Chem., 1996, 42, 1405–1411]. This method uses MES buffer (2-(N-morpholino)ethanesulfonic acid), which compared to other buffers is more easily purified, does not complex with aluminium, and can be used in lower concentrations. This method was applied to analysis of: deionised water for column comparison; seawater for matrix interference effects; and tea-infusion for calibration and recovery studies.