Nebulizers atomic spectroscopy

Outridge, P.M., Hughes, R. J., and Evans, R. D. (1996). Determination of trace metals in teeth and bones by solution nebulization ICP-MS. Atomic Spectroscopy 17 1-8. 

Longerich, H.P. (1989) The effect of nitric acid, acetic acid and ethanol on inductively coupled plasma-mass spectrometric ion signals as a function of nebulizer gas flow, with implications on matrix suppression and enhancements. J. Anal. Atomic Spectroscopy 4, 665-677. 

M.B. Denton, J.M. Freeiin and T.R. Smith, Ultrasonic, Babington and Thermospray Nebulization, in J. Sneddon (Ed.), Sample Introduction in Atomic Spectroscopy, Elsevier, Amsterdam, 1988. 

The nebulizer is normally interfaced directly to the LC column. It combines the eluent with a stream of gas to produce an aerosol. Much of the theoretical and practical basis of nebulization comes from atomic spectroscopy. The average droplet diameter and uniformity of the aerosol are the most important factors for ELSD sensitivity and reproducibility. As larger solute particles scatter light more intensely, an aerosol with large droplets and a narrow droplet size distribution leads to the most precise and sensitive detection. A good nebulizer should produce a uniform aerosol of large droplets with narrow droplet size distribution. The droplets cannot be too large, however otherwise, the solvent in a droplet will not be completely vaporized and errors in detection will occur. The nebulizer properties that can be adjusted to obtain the desired droplet properties are, primarily, the gas flow rate and the LC mobile phase flow rate. ... 

Berndt H. (1988) High-pressure nebulization a new way of sample introduction for atomic spectroscopy, Fresenius J Anal Chem 331 321-323. 

Fassel V. A. and Bear B. R. (1986) Ultrasonic nebulization of liquid samples for analytical ICP atomic spectroscopy, Spectrochim Acta, Part B 41 1089-1113. 

Duyck, C., Miekeley, N., Porto da Silveira, C. L., and Szatmari, P., Trace Element Determination in Crude Oil and Its Fractions by Inductively Coupled Plasma Mass Spectrometry Using Ultrasonic Nebulization of Toluene Solutions, Spectrochimica Acta Part B Atomic Spectroscopy, Vol. 57, 2002, pp. 1979-1990... 

Figure 20-8 (a) Ultrasonic nebulizer lowers the detection limit for atomic spectroscopy for most elements by an order of magnitude, (b) Mist created when sample is sprayed against vibrating crystal. (Courtesy Cetac Technologies, Omaha, NE.]... 

FIGURE 3.11 A cyclonic spray chamber (shown with a concentric nebulizer). (From S. A. Beres, P. H. Bruckner, and E. R. Denoyer, Atomic Spectroscopy, 1S[2], 96-99,1994.)... 

Speed of analysis is one of the attractive features of the atomic spectroscopy methods described here. An important discrimination can be made, however, between methods that determine elements sequentially and those, clearly much faster overall, that can determine a whole suite of elements simultaneously. In methods involving nebulization, the critical determinant is the time taken for the system to wash out , so that material from one test solution is completely... 

For inductively coupled plasma atomic emission spectroscopy (ICP-AES) the sample is normally in solution but may be a fine particulate solid or even a gas. If it is a solution, this is nebulized, resulting in a fine spray or aerosol, in flowing argon gas. The aerosol is introduced into a plasma torch, illustrated in Figure 3.21. 

Atomic emission spectroscopy can be employed, generally with an inductively coupled plasma for thermal excitation. The sample is introduced into the plasma as a mist of ultrafine droplets, and the monochromator and detector are set to measure the intensity of an atomic emission line characteristic of the element. This technique is powerful, general, sensitive, linear, and able to measure over 70 elements, and, as a result, is widely used. Response is typically linear over four orders of magnitude in concentration with relative standard deviations of 1 to 3%. In low-salt aqueous solutions, detection limits range from 10 to 1000 nanomolar without preconcentration. Significant problems with saline samples remain, but use of Babington nebulizers alleviates these problems somewhat. 

The AAS method has several limitations. For the trace elements, particularly the colorants cobalt and nickel, the dilution factor required for analyses of 12 elements by continuous nebulization places these elements close to the detection limits for flame AAS. More accurate data on these and other trace elements are necessary before conclusions can be drawn on the source minerals used to impart color. Phosphorus, a ubiquitous minor component of medieval stained glass, has not been determined by AAS in the course of this work, but has the potential to provide key information on sources of plant ash. A full understanding of the colorant role of the transition metal elements is not possible on the basis of analysis alone UV-visible spectroscopy, electron spin resonance spectrometry, and Mossbauer spectroscopy, for example, are necessary adjuncts to achieve this aim. The results of the application of these techniques and the extension of the AAS method to trace element determination by pulse nebulization and furnace atomization will be addressed in future reports. 

Direct nebulization of an aqueous or organic phase containing extracted analytes has been widely used in flame atomic absorption spectroscopy [69-72], inductively coupled plasma atomic emission spectrometry [73-76], microwave induced plasma atomic emission spectrometry [77-80] and atomic fluorescence spectrometry [81], as well as to interface a separation step to a spectrometric detection [82-85]. 

The burners used in flame spectroscopy are most often premixed, laminar flow burners. Figure 28-11 is a diagram of a typical commercial laminar-flow burner for atomic absorption spectroscopy that employs a concentric tube nebulizer. The aerosol flows into a spray chamber, where it encounters a series of baffles that remove all but the finest droplets. As a result, most of the sample collects in the bottom of the spray chamber, where it is drained to a waste container. Typical solution flow rates are 2 to 5 mL/min. The sample spray is also mixed with fuel and oxidant gas in the spray chamber. The aerosol, oxidant, and fuel are then burned in a slotted burner, which provides a flame that is usually 5 or 10 cm in length. 

McKinnon P. W., Giess K. C. and Knight T. V. (1981) A clog-free nebulizer for use in inductively coupled plasma-atomic emission spectroscopy, in Barnes R. M. (ed) Developments in atomic plasma spectrochemical analysis. Heyden, London, 287-301. 

D. T. Gjerde, D. Wiederin, F.G. Smith, and B.M. Mattson, Metal speciation by means of microbore columns with direct-injection nebulization by inductively coupled plasma atomic emission spectroscopy, / Chromatogr., 73, 1993. 

A high salt content can cause problems in the analysis step. For example, a high salt content can block the nebulizer used for sample introduction in both flame atomic absorption spectroscopy and inductively coupled plasma-based techniques (see Chapter 11). 

Finally, it is recommended that for inductively coupled plasma (ICP) analysis a final filtration (0.45 xm) is carried out in order to prevent nebulizer blockages. If graphite-furnace atomic absorption spectroscopy (GFAAS) is the method of analysis, it is recommended that the standard additions method of calibration is used (see Chapter 1). 

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