Graphene and carbon nanotubes as solid phase extraction sorbents for the speciation of chromium: A review.

This is the eighth Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from December 2014. This ASU review deals with all aspects of the analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. The review does not cover fractionation, which is sometimes termed operationally defined speciation. As with all ASU reviews the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique. However, because speciation analysis is inherently focused on the relationship between the metal(loid) atom and the organic moiety it is bound to, or incorporated within, atomic spectrometry alone cannot be the sole analytical approach of interest. For this reason molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. As in previous years, As and Se speciation continues to dominate the current literature and there has also been an increase in the number of publications concerning solid state speciation. This is presumably due to the increase in the number of synchrotron facilities available and a greater awareness of their potential for speciation studies.

/pdf/atomic-spectrometry-update-review-of-advances-in-elemental-1a1e4m82lk.pdf

Atomic Spectrometry Update: review of advances in elemental speciation

The toxicity of elements largely depends on their chemical forms. Therefore, the elemental speciation analysis is of great importance and a hot topic in environmental science and engineering, food science, and biology. The use of nanomaterials in spectrometric detection provides a convenient, versatile, and sensitive technique for elemental speciation analysis. In this concise review, we aim to provide a brief overview of the versatility of nanomaterials in spectrometric elemental speciation analysis with focus on four elements: mercury, arsenic, chromium, and selenium. Various types of nanomaterials, together with their roles in the speciation analysis developed with prevailing spectrometric techniques, are discussed. We also offer an insight into the research trend of the application of nanomaterials for chemical speciation analysis.

Nanomaterials in speciation analysis of mercury, arsenic, selenium, and chromium by analytical atomic/molecular spectrometry

To investigate critical health effects, a supporting speciation analysis is often matter of concern in order to identify figure of the bioconcentration or biomagnification of elements like chromium. Chromium speciation study requires high capacity separation and high sensitivity detection because chromium naturally exists in small quantities. Scientific literature supports chromium speciation at trace levels by using different nanomaterials and methodologies. Nanoparticles adsorbent based speciation technique is a current state-of-art technique due to its exceptional surface area chemistry, maximum mechanical strength, optical, magnetism, unique electrical, catalytic and photonic properties. The present review is aimed to discuss significance of chromium speciation and specific properties of different nanoparticles as adsorbent and also explore the new possible nanomaterials for chromium speciation. All data used for chromium speciation with various kind of nano adsorbent has also been tabulated with their analytical figure of merit.

Nanomaterial's based chromium speciation in environmental samples: A review

Determination and speciation of ultratrace arsenic and chromium species using aluminium oxide supported on graphene oxide.

Using multi-walled carbon nanotubes (MWCNTs) as an adsorbent has been established for the on-line separation and preconcentration Cr(III) and chromium speciation. The surface functional groups and negative charges of MWCNTs are beneficial to the adsorption of Cr(III). At pH 3.0 - 6.0, a discrimination of Cr(III) and Cr(VI) is achieved on the MWCNTs surface. Cr(III) ions are adsorbed onto the oxidized MWCNTs surface, while Cr(VI) has no affinity for the MWCNTs. The adsorbed Cr(III) is quantitatively eluted by 10% (v/v) nitric acid with detection by flame atomic absorption spectrometry. By loading a 6.0-ml sample solution, an enrichment factor of 22, a detection limit (3σ) of 1.15 μg l(-1) and a precision of 1.7% RSD at the 30 μg l(-1) level (n = 7) are achieved for Cr(III) within a linear range of 5 - 200 μg l(-1) (r = 0.9994). After Cr(VI) has been reduced to Cr(III) with hydroxylamine hydrochloride, the total amount of chromium is obtained, and the content of Cr(VI) is given by subtraction. The procedure is validated by analyzing chromium in a certified reference material, and is further applied for the speciation of chromium in electroplating wastewater samples with satisfactory results.

http://www.jstage.jst.go.jp/article/analsci/28/12/28_1219/_pdf

Hongmei Yu

Papers

Study on multi-walled carbon nanotubes on-line separation/preconcentration of chromium(III) and chromium speciation.