Investigation of the feasibility of TiO2 nanotubes for the enrichment of DDT and its metabolites at trace levels in environmental water samples

TiO2 nanotubes, novel nanomaterials synthesized from hydrothermal treatment, were investigated for being used as a new solid-phase extraction adsorbent with o,p′-DDT, [1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane, p,p′-DDT, [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane] and its principle metabolites p,p′-DDD, [1,1-dichloro-2,2-bis(4-chlorophenyl)ethane] and p,p′-DDE [1,1-(2,2-dichloro-ethanylidene)-bis(4-chlorobenzene)] as the target analytes. Several factors such as eluant and its volume, the sample pH, sample volume and the flow rate of samples, were optimized. The effect of humic acid, which is often present in natural water system, was also investigated. Under the optimal conditions, lower detection limits of 0.0031, 0.0037, 0.0053 and 0.0025 ng mL−1 for p,p′-DDD, p,p′-DDT, o,p′-DDT and p,p′-DDE, respectively, were obtained. The proposed method was successfully applied to the analysis of the target compounds in several environmental water samples. Good recoveries over the range of 81.2–115% were obtained. These results indicated that titanium nanotubes had enormous potential in environmental field as a novel SPE adsorbent material.