Nebulisers characteristics

Clearly the most popular separation and preconcentration technique for atomic absorption analysis is solvent extraction. In this case it is easy to identify extraction systems which will remove a broad range of impurities from matrices such as acids, bases and alkali metal salt solutions. In addition to the advantages to be gained from separation, especially valuable in furnace work, and the concentration factors available, solvent extraction confers an additional advantage (typically a factor of 3—5) in flame analysis arising from the favourable nebulisation characteristics of several organic solvents. 

As the vast majority of LC separations are carried out by means of gradient-elution RPLC, solvent-elimination RPLC-FUR interfaces suitable for the elimination of aqueous eluent contents are of considerable use. RPLC-FTTR systems based on TSP, PB and ultrasonic nebulisa-tion can handle relatively high flows of aqueous eluents (0.3-1 ml.min 1) and allow the use of conventional-size LC. However, due to diffuse spray characteristics and poor efficiency of analyte transfer to the substrate, their applicability is limited, with moderate (100 ng) to unfavourable (l-10pg) identification limits (mass injected). Better results (0.5-5 ng injected) are obtained with pneumatic and electrospray nebulisers, especially in combination with ZnSe substrates. Pneumatic LC-FI1R interfaces combine rapid solvent elimination with a relatively narrow spray. This allows deposition of analytes in narrow spots, so that FUR transmission microscopy achieves mass sensitivities in the low- or even sub-ng range. The flow-rates that can be handled directly by these systems are 2-50 pLmin-1, which means that micro- or narrow-bore LC (i.d. 0.2-1 mm) has to be applied. 

GC-MIP systems have been investigated in considerable detail. Because of the low power of the plasma, it is easily quenched if the normal, atomic spectrometric sample introduction techniques, such as nebulisation, are used. Capillary columns overcome this problem as they require only low flow rates and small sample sizes more compatible with stable plasma operation. The capillary columns can be passed out of the oven, down a heated line, and the end of the column placed in the plasma torch just before the plasma, thus preventing any sample loss. A makeup gas is usually introduced via a side arm in the torch to sustain the plasma (Fig. 4.1, Greenway and Barnett, 1989). Other dopant gases can also be added in this way to prolong the lifetime of the torch and improve the plasma characteristics. 

Summary of Product Characteristics for Pulmozyme. Available at http //www.produktresume. dk/docushare/dsweb/Get/Document-14730/Pulmozyme%2CJ)inhalationsv%C3%83%C2% A6skeJ)tilJ)nebulisator%2CJ)opl%C3%83%C2%B8sningJ)lJ)mg-ml.doc. Accessed December 2007. 

O Doherty MJ, Thomas, S, Page C, Clark AR, Mitchell D, Heduan E, Nunan TO, Bateman NT. Does ss T human serum albumin alter the characteristics of nebulised pentamidine isethionate Nucl Med Commun 1989 10 523-529. 

Optimisation of operational characteristics (viewing height, RF plasma power and nebuliser argon flow) to carry out a multielemental analysis of slurry samples. Comparison of three optimisation procedures. 

A pneumatic cross-flow micronebuliser has been described for use in ICP-MS. The high efficiency cross-flow micronebuliser (HECFMN) has a narrow capillary placed inside the conventional sample capillary. The inner diameter of the nebuliser gas nozzle is reduced with respect to the conventional cross-flow design. Due to the characteristics of this device, the free liquid uptake rate (i.e. about 9 p-L/min) is lower than that found for either a conventional cross-flow nebuliser (i.e. 1900 pL/min) or concentric pneumatic micronebulisers (i.e. from about 30 to 100 pL/min). This fact makes the HECFMN attractive for CE ICP-MS interfaces. ... 

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