Chemical vapor generation-atomic spectrometry

D Ulivo A, Loreti V, Onor M, Pitzalis E, and Zamboni R (2003) Chemical vapor generation atomic spectrometry using amineboranes and cyanotrihydroborate(III) reagents. Analytical Chemistry 75 2591-2600. 

Chen, M. L, A. M. Zou, Y. E. Yu, and R. H. He. 2007. Hyphenation of flow injection/ sequential injection with chemical hydride/vapor generation atomic fluorescence spectrometry. Talanta 73 599-605. 

Whatever the analytical method and the determinand may be, the greatest care should be devoted to the proper selection and use of internal standards, careful preparation of blanks and adequate calibration to avoid serious mistakes. Today the Antarctic investigator has access to a multitude of analytical techniques, the scope, detection power and robustness of which were simply unthinkable only two decades ago. For chemical elements they encompass Atomic Absorption Spectrometry (AAS) [with Flame (F) and Electrothermal Atomization (ETA) and Hydride or Cold Vapor (HG or CV) generation]. Atomic Emission Spectrometry (AES) [with Inductively Coupled Plasma (ICP), Spark (S), Flame (F) and Glow Discharge/Hollow Cathode (HC/GD) emission sources], Atomic Fluorescence Spectrometry (AFS) [with HC/GD, Electrodeless Discharge (ED) and Laser Excitation (LE) sources and with the possibility of resorting to the important Isotope... 

Hydride generation techniques are superior to direct solution analysis in several ways. However, the attraction offered by enhanced detection limits is offset by the relatively few elements to which the technique can be applied, potential interferences, as well as limitations imposed on the sample preparation procedures in that strict adherence to valence states and chemical form must be maintained. Cold-vapor generation of mercury currently provides the most desirable means of quantitation of this element, although detection limits lower than AAS can be achieved when it is coupled to other means of detection (e.g., nondispersive atomic fluorescence or micro-wave induced plasma atomic emission spectrometry). 

ISE, ion-selective electrode FAAS, flame atomic absorption spectrometry ETAAS, electrothermal atomic absorption spectrometry FES, flame emission spectrometry FIG, hydride generation CV, cold vapor AFS, atomic fluorescence spectrometry Bl, biamperometry FIPLC, high-performance liquid chromatography LC, liquid chromatography GC-MS, gas chromatography-mass spectrometry Br-PADAP, 2- 5-bromo-2-pyridylazo)-5-(diethylamino)phenol Cig, octadecyl-chemically modified silicagel PAN, 1-(2-thiazolylazo)-2-naphthol. 

Several interfaces have been used for CCC-MS (mass spectrometry). The first employed is thermospray (TSP). When a column is directly coupled with TSP MS, the CCC column often breaks due to the high back-pressure generated by the thermospray vaporizer. By contrast, other interfaces, such as fast atom bombardment (FAB), electron ionization (El), and chemical ionization (Cl), have been directly connected to a CCC column without generating high back-pressure. Such interfaces can be applied to analytes with a broad range of polarities. As it is suitable to introduce effluent from the column CCC into MS at a flow rate of only between 1 and 5 L/min, the effluent is usually introduced into the MS through a splitting tee, which is adjusted to an appropriate ratio. 

Fiydride generation (and cold-vapor) techniques significantly improve atomic absorption spectrometry (AAS) concentration detection limits while offering several advantages (1) separation of the analyte from the matrix is achieved which invariably leads to improved accuracy of determination (2) preconcentration is easily implemented (3) simple chemical speciation may be discerned in many cases and (4) the procedures are amenable to automation. Disadvantages with the approach that are frequently cited include interferences from concomitant elements (notably transition metals), pH effects, oxidation state influences (which may be advantageously used for speciation) and gas-phase atomization interferences (mutual effect from other hydrides). 

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