Quartz tube atomizers

A Perkin-Elmer 5000 AAS was used, with an electrically heated quartz tube atomizer. The electrolyte is continuously conveyed by peristaltic pump. The sample solution is introduced into the loop and transported to the electrochemical cell. A constant current is applied to the electrolytic cell. The gaseous reaction products, hydrides and hydrogen, fonued at the cathode, are flowed out of the cell with the carrier stream of argon and separated from the solution in a gas-liquid separator. The hydrides are transported to an electrically heated quartz tube with argon and determined under operating conditions for hydride fonuing elements by AAS. 

Blais, J.-S. and Marshall, W.D. (1989) Determination of ionic alkyllead compounds in water, soil and sediment by high-performance liquid chromatography-quartz tube atomic absorption spectrometry./. Anal. At. Spectrom., 4, 271-277. 

Inorganic, methyl, and n-butyl tin compounds may be converted to volatile hydrides, and the latter separated on a chromatographic column prior to detection of tin by AAS.58 In this particular study, an electrically heated absorption cell was used, although a flame-heated quartz cell could have been employed equally well. Balls59 used on-line cryogenic trapping on a silanized glass-wool column to separate dibutyl tin and tributyl tin in sea water prior to transport to a quartz-tube atomizer for determination by AAS. 

S. Fragueiro, I. Lavilla, C. Bendicho, Direct coupling of solid phase microextraction and quartz tube-atomic absorption spectrometry for selective and sensitive determination of methylmercury in seafood an assessment of chloride and hydride generation, J. Anal. Atom. Spectrom., 19 (2004), 250-254. 

NaBHjCN (sodium cyanotrihydroborate), or electrochemical reduction to generate hydrides of As, Se, Bi, Sn, Sb, Ge, and Pb. These are then swept into either a flame directly or into a flame- or electrically heated tube for atomization. Atomization of the gaseous hydrides occurs in argon (or nitrogen)-hydrogen diffusion flame, electrically-heated quartz tube, flame-heated quartz tube (quartz tube atomizers QTA), flame-in-tube (FIT) atomizer or a graphite furnace. Other techniques of chemical vapor generation can be as chlorides, Ni carbonyl, tetramethyl lead or chelates. 

Quartz tube atomizer Some elements like antimony, arsenic, bismuth, lead, tin, can be vaporized as molecules (e.g., hydrides) by chemical reaction at room temperature. For this purpose a reductant solution (NaBH4, SnCli) is added to the sample solution and the obtained gaseous hydrides are transported to the quartz tube atomizer (hydride... 

Atomization of the hydrides is currently believed to proceed via interaction with free hydrogen radicals oxygen also plays an active role. In argon/hydrogen diffusion flames and quartz tube atomizers, a cloud of hydrogen radicals is formed by reactions between hydrogen and oxygen ... 

Guo M-M, Sturgeon RE, Mester Z, and Gardner G (2003) UV vapor generation for determination of selenium by heated quartz tube atomic absorption spectrometry. Analytical Chemistry 75 2092-2099. 

Matousek T, Dedina J, and Selecka A (2002) Multiple microflame quartz tube atomizer - further development towards the ideal hydride atomizer for atomic absorption spectrometry. Spectrochimica Acta 57B 451—462. 

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]. 

Lee [524] described a method for the determination of nanogram or sub-nan ogram amounts of nickel in seawater. Dissolved nickel is reduced by sodium borohydride to its elemental form, which combines with carbon monoxide to form nickel carbonyl. The nickel carbonyl is stripped from solution by a helium-carbon monoxide mixed gas stream, collected in a liquid nitrogen trap, and atomised in a quartz tube burner of an atomic absorption spectrophotometer. The sensitivity of the method is 0.05 ng of nickel. The precision for 3 ng nickel is about 4%. No interference by other elements is encountered in this technique. 

Willie et al. [17] used the hydride generation graphite furnace atomic absorption spectrometry technique to determine selenium in saline estuary waters and sea waters. A Pyrex cell was used to generate selenium hydride which was carried to a quartz tube and then a preheated furnace operated at 400 °C. Pyrolytic graphite tubes were used. Selenium could be determined down to 20 ng/1. No interference was found due to, iron copper, nickel, or arsenic. 

Discontinuous methods are performed in conventional separating funnels in one or more steps. In ultratrace analyses, tapered or specially profiled quartz tubes are recommended because of their easier cleaning (more compact size), the introduction of less contaminating material, and easier centrifugation in the case of difficulties with phase separation. Shaking must be continued until equilibrium is reached, which may last seconds, minutes, or (rarely) hours, depending on the physicochemical properties of the system more than 2-5 min requires a mechanical shaker. Microscale extraction carried out in autosampler tubes, followed by direct automatic introduction of the organic phase into the atomizer, is recommended. 

Chlorine atoms were produced by flowing a mixture of 5 % Cl2 in helium through a quartz tube, coated with a thin film of baked phosphoric acid to inhibit Cl atom recombination, and enclosed in a 2.45 GHz microwave cavity operating at 35 W. The purity of reactants was 99.5 to 97 %, and they were frequently subjected to several freeze-pump-thaw cycles. The reactants were flowed inside the reactor neat or diluted in helium (3% mixtures). 

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