Effect of the Chemical Species of Arsenic on Sensitivity in Graphite Furnace Atomic Absorption Spectrometry

Abstract

The sensitivity of graphite furnace atomic absorption spectrometry (GFAAS) to arsenobetaine (AB) was 1.3-times higher than to inorganic As. In order to understand the mechanism underlying this observation, the atomization processes for both chemical species were investigated in terms of the enthalpy change (ΔH) during the atomization process in GFAAS. The enthalpy change of AB was slightly lower than that of inorganic As, which suggested that AB was atomized more efficiently than was inorganic As. Moreover, it was observed that some co-existing organic materials enhanced the analytical sensitivity of inorganic As. The sensitivity difference between inorganic As and AB depended upon the mechanisms of their atomization processes.

Determination of As, Cd, Cu, Hg and Pb in biological samples by modern electrothermal atomic absorption spectrometry

“…Recently, it has been noted that arsenobetaine exhibits a 30% higher sensitivity than inorganic As, possibly due to its slightly lower enthalpy, which permits better atomization [177]. Moreover, this study also reported that several other organic species yield enhanced sensitivity over inorganic As [177], highlighting the necessity of further studies to improve the atomization process in order to increase efficiency and obtain similar sensitivities for all chemical species of the same element.…”

“…Moreover, this study also reported that several other organic species yield enhanced sensitivity over inorganic As [177], highlighting the necessity of further studies to improve the atomization process in order to increase efficiency and obtain similar sensitivities for all chemical species of the same element.…”

“…As a consequence, lower detection limits have been successfully achieved. As recent examples, As has been successfully determined directly in acid digests, slurries or liquid-solid leachates [9,11,25,45,48,49,55,[59][60][61]64,70,73,76,97,102,154,163,176,177] and in biological fluids [45] with or without use of a modifier [75]. For direct liquid sampling, detection limits between 0.24 and 10 µg L − 1 were achieved.…”

“…The use of modifiers is especially pertinent to prevent volatilization of As during the pyrolysis stage. In most cases, modifiers such as Pd [59,177], Rh [76], (NH 4 ) 2 HPO 4 [70], Ir+Mg [104] and Pd/Mg(NO 3 ) 2 [9,25,48,52,61,69,70,73,97,132] have been applied. Pd + MgNO 3 is most commonly used and was proven to decrease interferences produced by phosphates [52] as well as allowing better thermal stability of As to yield the best results for digested marine tissues [25].…”

Atomic Spectrometry Update. Elemental speciation

“…Published work is often difficult to examine from this perspective, as the data for the response of the instrument to standards of the different species are often not reported, nor is it clear whether concentrations are based on the mass of the species or of the element of interest. Narukawa et al 175 found that the ETAAS sensitivity of As was 1.3-times higher for arsenobetaine than for iAs, which they attributed to differences in the mechanisms of their atomization processes, suggesting that the two species are not converted to a common form during the ashing stage and further suggesting that a chemical modifier is needed.…”