Selective extraction and preconcentration of ultra-trace amounts of arsenic(V) ions using carbon nanotubes as a novel sorbent

Abstract

In the present study, multiwalled carbon nanotubes (MWCNTs) as solid phase extraction sorbent were developed for preconcentration of arsenic(V) species prior to graphite furnace atomic absorption spectrometry (GFAAS) determination. Arsenic(V) was selectively sorbed on the packed column with MWCNTs within a pH 9.5 in the presence of 2-(5-bromo-2-pyridylazo)-5-diethyl amino phenol (5-Br-PADAP). The adsorbed species was then desorbed with 1 mL of 2.0 M HNO₃. Experimental parameters including pH, sample volume and flow rate, type, volume and concentration of eluent that influence the recovery of the arsenic(V) species were optimised. Under the optimised conditions, the calibration curve was linear in the range of 0.2–10.0 µg L⁻¹ with detection limit of 0.016 µg L⁻¹. The relative standard deviations (RSD) for seven replicate determinations at 1.0 µg L⁻¹ level of arsenic was 6.69%. The proposed method was successfully applied to the determination of arsenic in water samples and certified reference material (NIST RSM 1643e).

Keywords:

• selective extraction
• preconcentration
• arsenic determination
• carbon nanotubes