Журнал хроматографии и методов разделения
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ICP-OES Determination of Titanium (IV) in Marine and Wastewater Samples after Preconcentration onto Unloaded and Reagent Immobilized Polyurethane Foams Packed Columns

El-Shahawi MS, Bashammakh AS, Alwael H, Al-Sibaai AA and Al-Ariqe HK

A novel method that utilizes untreated and polyurethane foam (PUF) physically immobilized with the reagent 4-(2-pyridylazo) resorcinol (PAR) or 2, 3, 5-triphenyl-2H-tetrazolium chloride (TZ+Cl-) as solid phase extractor packed column has been developed for preconcentration and subsequent determination of titanium(IV) ions in marine and wastewater samples. The method is based on retention of the titanium(IV) traces present in aqueous media at pH 3-4 onto the reagent treated PUF packed column, followed by recovery with HNO3 (2.0 mol dm-3) and subsequent ICP-OES determination. The uptake of titanium species onto the unloaded- and reagent impregnated PUF was fast and followed a first-order rate equation. Titanium sorption onto PUF followed Langmuir, Freundlich and Dubinin- Radushkevich (D-R) type isotherm models. Thus, a dual-mode sorption mechanism involving absorption related to “weak-base anion exchange” and an added component for “surface adsorption” seems a more likely retention model. PAR-immobilized PUF packed column has been applied successfully for complete collection of titanium(IV) species in fresh and wastewater samples at low level of titanium (<0.5 ng Ti mL-1) at pH 3-4. The retained titanium species were then recovered (97-101%) from the packed column with HNO3 and determined by ICP-OES. The proposed PUF packed column method was further applied for analysis of picomolar concentrations of dissolved Ti species in marine water.