Arsenic quantification and speciation at trace levels in natural water samples by total reflection X-ray fluorescence after pre-concentration with N-methyl-d-glucamine functionalized quartz supports

Abstract

Total reflection X-ray fluorescence (TXRF) spectrometry is a very effective multi-elemental analytical technique for the determination of metals at ultra trace concentrations in aqueous samples. In this work a novel and simple TXRF based method has been developed for the quantification and speciation of arsenic (As) at ultra trace levels in water samples. The quartz supports used for TXRF measurements were functionalized by anchoring (3-glycidyloxypropyl)trimethoxysilane by the sol–gel method and subsequently reacting with N-methyl-D-glucamine (NMDG). The novelty of this work is the introduction of gold nano particles (Au-Nps) as an internal standard on the sample support itself. We have utilized in situ reduction of chloroauric acid to gold nanoparticles which are grafted on sites of the NMDG membrane attached to the quartz sample supports. Thus, the anchored NMDG on quartz support serves dual objectives as it binds with As(V) and reduces AuCl₄⁻ ions to form Au nanoparticles. The As loaded quartz supports were presented for direct TXRF measurements and As determination. The TXRF determination of As species after separation resulted in speciation and quantification of As in water samples. The developed method was used for quantification and speciation of arsenic in water samples by TXRF and thus has a great societal application for the quality assessment of water samples in As contaminated areas.