Green Approach for Ultratrace Determination of Divalent Metal Ions and Arsenic Species Using Total-Reflection X-ray Fluorescence Spectrometry and Mercapto-Modified Graphene Oxide Nanosheets as a Novel Adsorbent

Abstract

A new method based on dispersive microsolid phase extraction (DMSPE) and total-reflection X-ray fluorescence spectrometry (TXRF) is proposed for multielemental ultratrace determination of heavy metal ions and arsenic species. In the developed methodology, the crucial issue is a novel adsorbent synthesized by grafting 3-mercaptopropyl trimethoxysilane on a graphene oxide (GO) surface. Mercapto-modified graphene oxide (GO-SH) can be applied in quantitative adsorption of cobalt, nickel, copper, cadmium, and lead ions. Moreover, GO-SH demonstrates selectivity toward arsenite in the presence of arsenate. Due to such features of GO-SH nanosheets as wrinkled structure and excellent dispersibility in water, GO-SH seems to be ideal for fast and simple preconcentration and determination of heavy metal ions using methodology based on DMSPE and TXRF measurement. The suspension of GO-SH was injected into an analyzed water sample; after filtration, the GO-SH nanosheets with adsorbed metal ions were redispersed in a small volume of internal standard solution and deposited onto a quartz reflector. The high enrichment factor of 150 allows obtaining detection limits of 0.11, 0.078, 0.079, 0.064, 0.054, and 0.083 ng mL(-1) for Co(II), Ni(II), Cu(II), As(III), Cd(II), and Pb(II), respectively. Such low detection limits can be obtained using a benchtop TXRF system without cooling media and gas consumption. The method is suitable for the analysis of water, including high salinity samples difficult to analyze using other spectroscopy techniques. Moreover, GO-SH can be applied to the arsenic speciation due to its selectivity toward arsenite.

Total reflection X-ray fluorescence

“…Extraction, adsorption, or preconcentration of the analyte of interest is another way to improve detectability. Several methods have been developed including the use of graphene oxide nanosheets for analysis of divalent metal ions and arsenic species, liquid-liquid microextraction for chromium speciation and selenium detection as well as preconcentration by means of co-deposition and microextraction to form complexes of rare earth elements [27][28][29][30][31][32][33]. Quantitative analysis of volatile elements like mercury has been achieved by complexation and oxidation [34].…”

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

“…227,228 A novel technique using total reflection X-ray fluorescence spectrometry (TXRF) has been proposed for the measurement of arsenic species, which combines a pre-concentration system based on dispersive micro solid phase extraction (DMSPE), and uses a newly synthesized novel adsorbent. 229 The literature warns that the application of these techniques to complex matrices, such as environmental or food samples, is still a challenge.…”

Speciation of trace metals and metalloids by solid phase extraction with spectrometric detection: a critical review

“…It was shown that GO-SH adsorbs As(III) selectively in the presence of As(V). 42 The adsorption of As(III) as nonionic As (H 3 AsO 3 ) was performed at pH 3-8.…”