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 Chromolithtrade mark Performance RP-18e column and were eluted using a methanol (50wt.%)-water eluent (pH 5.6) containing tetra-n-butylammonium bromide (7.0mmolkg(-1)), acetate buffer (5.0mmolkg(-1)), and disodium ethylendiamine-N,N,N',N'-tetraacetate (0.10mmolkg(-1)). Under the conditions used, Al(III), Fe(III), and Ti(IV) were selectively detected among 21 kinds of metal ions [Al(III), Ba(II), Be(II), Ca(II), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Ga(III), Hf(IV), In(III), Mg(II), Mn(II), Mo(VI), Ni(II), Pb(II), Ti(IV), V(V), Zn(II), and Zr(IV)]. The detection limits on a 3sigma blank basis were 8.8nmoldm(-3) (0.24ngcm(-3)) for Al(III), 7.6nmoldm(-3) (0.42ngcm(-3)) for Fe(III), and 17nmoldm(-3) (0.80ngcm(-3)) for Ti(IV). The practical applicability of the proposed method was checked using river and tap water samples.