SEPARATION AND SIMULTANEOUS DETERMINATION OF ALUMINUM, IRON, AND MANGANESE IN NATURAL-WATER SAMPLES BY USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH SPECTROPHOTOMETRIC AND ELECTROCHEMICAL DETECTION

Reversed-phase liquid chromatography has been used to determine simultaneously trace levels of Al, fe, and Mn in natural water samples after direct injection of their 8-quinolinol complexes onto a Bondasphere ODS column. Chromatographic separation can be made with the mobile phase of 2:3 acetonitrile/20 mM acetate buffer solution containing 5 mM 8-quinolinol reagent. Excellent sensitivity is obtained by spectrophotometric detection at 390 nm. The spectrometric detection limits of these metals are at the part per billion levels of test solution. The tolerance limits of numerous other metal ions are reported. Only CR(III) and Ni(II) interfere with the determination of Al, and Mo(VI) interferes with the determination of Mn at concentrations less than a 100-fold excess. Analytical data obtained on river and sea water samples are in agreement with expected values. Amperometric detection of Mn and Fe with a thin-layer flow cell and a glassy-carbon working electrode is also described. This method is less sensitive but more specific than spectrophotometric detection.