Syringe Membrane Micro-Solid-Phase Extraction (SPE) with Flexible Titanium(IV) Oxide@Silica Nanofiber Membrane for the Speciation of Te(IV) and Te(VI) with Graphite Furnace Atomic Absorption Spectrometry (GFAAS)

In this work, syringe membrane micro-solid phase extraction (SMMSPE) was described for the enrichment and separation of Te(IV) and Te(VI) prior to graphite furnace atomic absorption spectrometry detection. SMMSPE device is composed of a syringe and a disk filter, which was filled with flexible titanium(IV) oxide@silica nanofiber membrane as the sorbent. The adsorption behavior of Te(IV) and Te(VI) on the sorbent was studied in detail. The results showed that Te(IV) was quantitatively adsorbed on the sorbent in the pH range of 3.0-5.0, while Te(VI) remained in the aqueous phase. Te(VI) content was obtained by subtracting Te(IV) from total Te concentration. Total Te was detected after reducing Te(VI) into Te(IV). The key factors affecting the extraction efficiency and determination of target species were investigated. Under the selected conditions, the limit of detection was 1.8 ng L-1 for Te(IV). The precision expressed as relative standard deviation was 5.7% (n = 9). This method was utilized for the determination of Te(IV) and Te(VI) in environmental water samples with satisfactory results. To verify this method, a certified reference material of water sample was analyzed, and the obtained result was in good agreement with the certified value. Besides, the developed sorbent exhibited good efficiency, flexibility and recyclability.