Sulfonylcalix[4]arenetetrasulfonate as pre-column chelating reagent for selective determination of aluminum(III), iron(III), and titanium(IV) by ion-pair reversed-phase high-performance liquid chromatography with spectrophotometric detection

Sulfonylcalix[4]arenetetrasulfonate (SO(2)CAS) has been examined as a pre-column chelating reagent for ultratrace determination of metal ions by ion-pair reversed-phase high-performance liquid chromatography with spectrophotometric detection. Metal ions were converted into the SO(2)CAS chelates in an acetic buffer solution (pH 4.7). The chelates were injected onto a n-octadecylsilanized silica-type Chromolith(TM) Performance RP-18e column and were eluted using a methanol (50 wt.%)-water eluent (pH 5.6) containing tetra-n-butylammonium bromide (7.0 mmol kg(-1)), acetate buffer (5.0 mmol kg(-1)), and disodium ethylendiamine-N,N,N',N'-tetraacetate (0.10 mmol kg(-1)). Under the conditions used, Al(III), Fe(III), and Ti(IV) were selectively detected among 21 kinds of metal ions [AI(III), Ba(11), Be(II), Ca(II), Cd(II), Co(II), Cr(III), Cu(11), Fe(111), Ga(III), Hf(IV), In(III), Mg(II), Mn(II), Mo(VI), Ni(II), Pb(11), Ti(IV), V(V), Zn(II), and Zr(IV)]. The detection limits on a 3sigma blank basis were 8.8 nmol dm(-3) (0.24 ng cm(-3)) for Al(III), 7.6 nmol dm(-3) (0.42 ng cm(-3)) for Fe(III), and 17 nmol dm(-3) (0.80 ng cm(-3)) for Ti(IV). The practical applicability of the proposed method was checked using river and tap water samples. (C) 2003 Elsevier B.V. All rights reserved.