A different application of the Aliquat® 336 loaded poly(vinylidene fluoride-co-hexafluoropropylene) based electrospun nanofibers disks for the preconcentration followed by flame atomic absorption spectrometry detection of low-level Bi(III)

It is the first report on the potential of electrospun nanofiber disks inserted in a filtration apparatus as a preconcentration strategy for the analysis of low-level metals. The nanofibers included 60 wt% of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and 40 wt% of ionic liquid Aliquat® 336. The electrospinning process was done by applying a voltage of 16 kV, an injection rate of 1 mL h⁻¹, and 10 cm distance of the needle tip location from the drum collector. A circular piece of the prepared nanofiber disks was placed in a filtration apparatus, and 200 mL solution containing 1 mg of Bi(III) adjusted to 0.5 mol/L of hydrochloric acid was transmitted from inside the nanofiber disk by controlling the flowrate (3.3 mL s⁻¹). The adsorbed Bi(III) was eluted by 10 mL of 0.2 mol/L solution of ethylendiaminetetraacetic acid and ammonium hydroxide mixture, and then was analyzed by flame atomic absorption spectrometry. The introduced technique (nanofiber disks-based solid phase extraction) can be used in the bismuth concentration range of 4–2000 µg/L, with a limit of detection 1.2 µg/L. The determined inter- and intra-day relative standard deviations (3 days and n = 7) for a solution of 100 µg/L of bismuth were 1.1 % and 2.4 %, respectively. The method offers a preconcentration factor of 200-fold. The fabricated nanofiber disks were used at least in 7 consecutive preconcentration experiments. The proposed method was selective towards Bi(III) and can be used satisfactory for its determination in real samples.