Hydride generation-flame atomic

R96013 Method 1632 Determination of Inorganic Arsenic in Water by Hydride Generation Flame Atomic Absorption... 

Analytical. Arsenic oxidation state determinations were per-formed by hydride generation-flame atomic absorption spectroscopy (AAS) at the University of Arizona Analytical Center. The analytical procedures are discussed in Brown, et al. (12). 

Kabengera, C., Bodart, P., Hubert, P., Thunus, L., Noirfalise, A. Optimization and validation of arsenic determination in foods by hydride generation flame atomic absorption spectrometry. J. AOAC Int. 85, 122-127 (2002)... 

Valkirs et al. [105] have conducted an interlaboratory comparison or determinations of di- and tributyltin species in marine and estuarine waters using two methods, namely hydride generation with atomic absorption detection and gas chromatography with flame photometric detection. Good agreement was obtained between the results of the two methods. Studies on the effect of storing frozen samples prior to analysis showed that samples could be stored in polycarbonate containers at - 20 °C for 2 - 3 months without significant loss of tributyltin. 

Valkirs, A.O., Seligman, PF., Olson, G.J., Brinckman, F.E., Matthias, C.L. and Bellama, J.M. (1987) Di- and tributyltin species in marine waters. Inter-laboratory comparison of two ultratrace analytical methods employing hydride generation and atomic absorption or flame photometric detection. Analyst, 112, 17-21. 

Metalloid compounds are usually determined by flowing-stream techniques hyphenated with hydride generation (HG)-atomic absorption or atomic fluorescence spectrometry. The continuous operation mode inherent to flow injection is specially suited for the latter detection technique as the tetrahyd-roborate reagent is a potential source of hydrogen for supporting the flame. Analyte preconcentration is frequently needed to detect the typical levels of metalloid species found in water matrices. In this context, cold trap collection of generated hydrides, sorbent extraction microcolumn methods, sorption... 

Common gas chromatographic detectors that are not element- or metal-specific, atomic absorption and atomic emission detectors that are element-specific, and mass spectrometric detectors have all been used with the hydride systems. Flame atomic absorption and emission spectrometers do not have sufficiently low detection limits to be useful for trace element work. Atomic fluorescence [37] and molecular flame emission [38-40] were used by a few investigators only. The most frequently employed detectors are based on microwave-induced plasma emission, helium glow discharges, and quartz tube atomizers with atomic absorption spectrometers. A review of such systems as applied to the determination of arsenic, associated with an extensive bibliography, is available in the literature [36]. In addition, a continuous hydride generation system was coupled to a direct-current plasma emission spectrometer for the determination of arsenite, arsenate, and total arsenic in water and tuna fish samples [41]. 

Numerous methods have been pubUshed for the determination of trace amounts of tellurium (33—42). Instmmental analytical methods (qv) used to determine trace amounts of tellurium include atomic absorption spectrometry, flame, graphite furnace, and hydride generation inductively coupled argon plasma optical emission spectrometry inductively coupled plasma mass spectrometry neutron activation analysis and spectrophotometry (see Mass spectrometry Spectroscopy, optical). Other instmmental methods include polarography, potentiometry, emission spectroscopy, x-ray diffraction, and x-ray fluorescence. 

This apparatus may also be adapted for what are termed hydride generation methods (which are strictly speaking flame-assisted methods). Elements such as arsenic, antimony, and selenium are difficult to analyse by flame A AS because it is difficult to reduce compounds of these elements (especially those in the higher oxidation states) to the gaseous atomic state. 

Although electrothermal atomisation methods can be applied to the determination of arsenic, antimony, and selenium, the alternative approach of hydride generation is often preferred. Compounds of the above three elements may be converted to their volatile hydrides by the use of sodium borohydride as reducing agent. The hydride can then be dissociated into an atomic vapour by the relatively moderate temperatures of an argon-hydrogen flame. 

Method abbreviations D-AT-FAAS (derivative flame AAS with atom trapping), ETAAS (electrothermal AAS), GC (gas chromatography), HGAAS (hydride generation AAS), HR-ICP-MS (high resolution inductively coupled plasma mass spectrometry), ICP-AES (inductively coupled plasma atomic emission spectrometry), ICP-MS (inductively coupled plasma mass spectrometry), TXRF (total reflection X-ray fluorescence spectrometry), Q-ICP-MS (quadrapole inductively coupled plasma mass spectrometry)... 

Total dissolved Fe and Mn were analyzed directly by flame atomic absorption spectrometry (AAS). As was measured by AAS with hydride generation (HG-FIAS). Total dissolved Se concentrations were determined by hydride-generation atomic fluorescence spectrometry (Chen etal., 2005). 

Compare atomic absorption (both flame and graphite furnace), ICP, flame photometry, cold vapor mercury, hydride generation, atomic fluorescence, and spark emission in terms of ... 

Hydride generation for analytical use was introduced at the end of the 1960s using arsine formation (Marshal Reaction) in flame atomic absorption spectrometry (FAAS). A simple experimental setup for a hydride generator is shown in Figure 5.18. Today, hydride generation,91,92 which is the most widely utilized gas phase sample introduction system in ICP-MS, has been developed into... 

H. Matusiewicz and M. Krawczyk, Determination of total antimony and inorganic antimony species by hydride generation in situ trapping flame atomic absorption spectrometry a new way to (ultra)trace speciation analysis, J. Anal. At. Spectrom., 23, 2008, 43-53. 

In an interlab oratory study involving 160 accredited hazardous materials laboratories reported by Kimbrough and Wakakuwa [28], each laboratory performed a mineral acid digestion on five soils spiked with arsenic, cadmium, molybdenum, selenium and thallium. Analysis of extracts was carried out by atomic emission spectrometry, inductively-coupled plasma mass spectrometry, flame atomic absorption spectrometry and hydride generation atomic absorption spectrometry. 

Basic techniques for speciation analysis are typically composed of a succession of analytical steps, e.g. extraction either with organic solvents (e.g. toluene, dichloromethane) or different acids (e.g. acetic or hydrochloric acid), derivatisa-tion procedures (e.g. hydride generation, Grignard reactions), separation (gas chromatography (GC) or high-performance liquid chromatography (HPLC)), and detection by a wide variety of methods, e.g. atomic absorption spectrometry (AAS), mass spectrometry (MS), flame photometric detection (FPD), electron capture detection (ECD), etc. Each of these steps includes specific sources of error which have to be evaluated. 

A number of techniques have been used for the speciation of arsenic compounds. The most important has been the formation of volatile hydrides of several species, separation by gas chromatography and detection by AAS. HPLC has been used to separate arsenic species. Several types of detectors have been studied for the determination of arsenic species in the column effluent. These have included AAS both off- and on-line, ICPAES and ICP-MS. An important comparative study of coupled chromatography-atomic spectrometry methods for the determination of arsenic was published (Ebdon et al., 1988). Both GC and HPLC were used as separative methods, and the detectors were FAAS, flame atomic fluorescence spectrometry (FAFS) and ICPAES. The conclusions were (1) that hydride generation and cryogenic trapping with GC-FAAS was the most... 

Spectrometric techniques based on atomic absorption or the emission of radiation flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and cold vapor (CV)/hydride generation (HG), mainly for trace and ultratrace metal determinations. 

We have already seen in Chapter 2 that choice of atomizer system to be used may have a dramatic effect upon sensitivity, and thus upon signal-to-noise ratio. It is necessary to choose not only between flames, electrothermal atomization (ETA), and cold vapour and hydride generation techniques (which are discussed in Chapter 6), but sometimes also between different flames. Those elements which tend to form thermally stable oxides, such as Al, Ti, Si, Zr, may only be determined in a hotter, reducing nitrous oxide-acetylene flame. They cannot be determined with useful sensitivity in the air-acetylene flame. Some elements, Ba and Cr for example, may be determined in air-acetylene, but are more efficiently atomized in nitrous oxide-acetylene. 

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