Chemical Vapor Generation:  Atomic Absorption by Ag, Au, Cu, and Zn Following Reduction of Aquo Ions with Sodium Tetrahydroborate(III)

Abstract

Volatile species of Ag, Au, Cu, Zn, Cd, and As were generated at room temperature by the addition of sodium tetrahydroborate(III) to an acidified solution of the analytes. The vapor-phase species were rapidly transported to a heated quartz tube atomizer (QTA) for detection by atomic absorption spectrometry. A univariate approach was used to achieve optimized conditions and derive analytical figures of merit. The analytes are released from solution as molecular species (likely as metal hydrides) and are (partially) atomized in the QTA under nonoptimized conditions. Detection limits range from 1.8 (Zn) to 420 ng (Au). The efficiency of the generation process is estimated to be 92 +/- 4% for Au. Loss of analyte during transport to the QTA was minimized through use of the minimum length of narrow-bore Teflon transfer line possible.

A geração química de vapor em espectrometria atômica

“…Ainda que, nesta revisão, tenha sido dada ênfase aos elementos formadores de hidretos covalentes, é importante registrar o aparecimento recente, na literatura de alguns artigos estendendo a técnica de geração química de vapor pelo tetraidroborato de sódio a metais, como Ag, Au, Cd, Cu, Ni, Pd, Rh e Zn 22,223 .…”

“…O uso do tetrahidroborato de sódio ampliou o número de elementos determináveis por geração química de vapor (no caso, ainda, somente hidretos voláteis), que passou a incluir, também o Bi, Ge, Pb, Sb, Se, Sn e Te 14 . Atualmente, a determinação tem sido estendida para incluir o P 16 , Tl 17 , In 18 e Cd [19][20][21] , sendo que Luna et al 22,23 mostraram que os elementos Cu, Au, Ag e Zn também podem ser determinados por HGAAS. Limites de quantificação ao nível de µg L -1 podem ser alcançados, normalmente suficientes para análise de amostras de interesse ambiental, clínico ou tecnológico.…”

The Binomial Distribution of Hydrogen and Deuterium in Arsanes, Diarsanes, and Triarsanes Generated from As(Iii)/[BHnD4-n]− and the Effect of Trace Amounts of Rh(Iii) Ions

“…The main advantage of this technique lies with the possibility of separating the analyte from its matrix in the form of a vapor, thus allowing for better sensitivity, detection power, and less interference [2]. Chemical vapor generation using NaBH 4 is a common practice in analytical chemistry and it finds routine application for the determination of many elements [3]. Furthermore, other boranes, such as NaBEt 4, and more recently, triethyloxonium tetrafluoroborate, have been successfully applied for speciation of organometallic compounds [4] and vapor generation of anionic substrates such as Br − , NO 3 − , and NO 2 − [5,6].…”

“…Reaction of inorganic As(III) with NaBH 4 occurs via a concerted multistep process wherein all hydrogen atoms in AsH 3 arise from different [BH 4 ] − molecules [11]. This mechanism, however, is strongly altered in the presence of noble metals such as Au(III), Pd(II), and Pt(II)-their action on hydride generation cannot be completely explained as causing a decrease in the amount of hydride generated (yield interference) [12]; they play an active role in the transfer of hydrogen from [BH 4 ] − to the arsenic (mechanistic interference) [13].…”

Versatile Thin-Film Reactor for Photochemical Vapor Generation

“…Following the report of detection of a volatile species of copper generated by merging its acidified sample solution with sodium tetrahydroborate, 2 a significant effort has arisen to use the acid-tetrahydroborate system to form (volatile) species of transition and noble elements (Ag, Au, Fe, Cr, Co, Cu, Ni, Os, Pd, Rd, Rh, Tl and Zn) which can be phase separated and transported to detectors by a carrier gas. [3][4][5][6][7][8][9][10][11][12][13][14][15][16] Because there is little information on either the identity of the species generated, or the reaction mechanism, such studies remain largely in a state of debate due to the complex nature of the reaction and the rather low generation efficiency. Several studies suggest that the metal ions are reduced to unstable reaction intermediates by tetrahydroborate, ultimately p roducing free atoms, hydrido-metal complexes and nanoparticles.…”