Determination of serum and urinary aluminum by HPLC with fluorometric detection of Al-lumogallion complex

Abstract

We describe a simple and sensitive HPLC method for quantifying aluminum (Al) in biological fluids by measuring the fluorescence of the Al-lumogallion complex (excitation wavelength 500 nm, emission wavelength 575 nm). Serum samples are deproteinized with 0.83 mol/L perchloric acid and centrifuged; the supernates are mixed with lumogallion reagent. Urine samples are pretreated with sodium hydroxide (2 mol/L) and methanol, kept for 1 h at - 20°C, and then centrifuged; the precipitate is resuspended in perchloric acid and mixed with lumogallion reagent, as for serum. The maximal fluorescence complex is formed after 1 h at pH 5 ± 0.5. The HPLC mobile phase consists of (per liter) 100 mL of 0.2 mol/L potassium hydrogen phthalate, 220 mL of acetonitrile, and distilled deionized water. The flow rate is 1 mL/min, and the injection volume is 5 μL. The major aluminum species is eluted at 3.5 min, the lowest detection limit being 0.45 pg. We validated the method with samples collected from normal subjects and from workers occupationally exposed to aluminum. Comparing the results with those by traditional atomic absorption spectrometry of urinary aluminum suggests that the proposed method is reliable.