Speciation and determination of inorganic arsenic species in water and biological samples by ultrasound assisted-dispersive-micro-solid phase extraction on carboxylated nanoporous graphene coupled with flow injection-hydride generation atomic absorption spectrometry

Abstract

In this paper, the potential use of carboxylated nanoporous graphene (G–COOH) as a nanoadsorbent was evaluated in two types of ultrasound assisted-dispersive micro-solid phase extraction (US-D-μ-SPE) for rapid speciation of trace arsenic(V) and arsenic(III) ions in natural water and human biological samples prior to determination by flow injection-hydride generation atomic absorption spectrometry (FI-HG-AAS). High sample volume-ultrasound assisted-dispersive micro-solid phase extraction (H-US-D-μ-SPE), and low sample volume-ultrasound assisted-dispersive micro-solid phase extraction (L-US-D-μ-SPE) were developed to extract the analyte through two pathways. As(V) ions were quantitatively recovered on G–COOH at pH 3.5, while the recoveries of As(III) were below 5%. Total arsenic content was determined as As(V) after oxidation of As(III) to As(V) using potassium permanganate. Finally, the concentration of As(III) was calculated by subtracting the As(V) content from total arsenic. Carboxylated nanoporous graphene was characterized by XRD, Raman, FT-IR, BET, SEM, TEM, and EDAX analysis. The reusability and adsorption capacity of the nanosorbent were also investigated. Under the optimized conditions, limits of detection and preconcentration factor for As(V) were 0.0021 μg L⁻¹ and 50.3 in H-US-D-μ-SPE as well as 0.0248 μg L⁻¹ and 5.1 in L-US-D-μ-SPE. The developed methods were successfully applied for speciation and determination of inorganic arsenic in natural water and human serum/urine samples.