Analysis slurry nebulization

To date, slurry nebulization has not found widespread or routine application in environmental analysis by flame spectrometry. In the author s experience the time saving is small or even non-existent, because the use of standard additions procedures is time consuming, and samples often have to be processed one at a time when slurry atomization is to be used. 

Solid foods in powder form can be analyzed directly by means of LA- or ETV-ICP-MS to eliminate time-consuming sample dissolution procedures (see Table 8.2). However, this requires the preparation of homogeneous powdered samples and the subsequent analytical determination is not as straightforward as the one based on liquid sample introduction. Another way to perform direct analysis of solid foods is to grind and suspend them into slurries. The viability of slurry nebulization relies on the ability to prepare samples of fine particle size in a reproducible manner and on the adoption of suitable (e.g., high-solids) nebulizers. Otherwise, slurries can be analyzed by ETV-ICP-MS resorting to the ultrasonic slurry sampling technique [72-74]. 

Lobinski R., Van Borm W., Broekaert J. A. C., Tschopel P. and Tolg G. (1992) Optimization of slurry nebulization inductively-coupled plasma atomic emission spectrometry for the analysis of Zr02-powder, Fresenius J Anal Chem 342 563-568. 

Initial work on slurry nebulization shows this to be a very promising method of solid sample introduction for ICP-MS. It has been successfully applied for analysis of geological and soil samples, and industrial catalysts. 

Slurry nebulization Eliminates digestion and fusion steps Calibration with aqueous standards No available sample blanks Efficiency of calibration dependent on particle size and sample type Analysis of rocks, soils, hard-to-dissolve samples (such as coal)... 

TABLE 5.4 Typical Analysis of Selected Elements (p-g/g) in National Institute of Standards 1623b and 1635 Standard Reference Materials Using Slurry Nebulization Quantitation... 

A single multielement calibration standard is used to establish a relative sensitivity factor (R.) for each analyte (i) to be determined in the multielement analysis. For solution analysis, this multielement standard is usually prepared from high-purity metal salts dissolved in deionized water, with sufficient nitric acid added to stabilize their concentrations (pH 2 or less). Because this is only a semiquantitative analysis, matrix matching of the calibration standard to the matrix of the sample is not required. When using solid analysis techniques (i.e., slurry nebulization, laser ablation, etc.), an appropriate solid phase multielement calibration standard is most desirable however, novel approaches for the use of a solution standard have been used with some methods. 

Mochizuki,T., Sakashita, A., Iwata, H., Ishibashi,Y, and Gunji, N. (1991). Application of slurry nebulization to trace elemental analysis of some biological samples by inductively coupled plasma mass spectrometry. Fresenius J. Anal. Chem. 339(12), 889. 

Persaud,A.T.,Beauchemin,D.,Jamieson,H.E.,and McLean, R.J. (1999). Partial leaching as an aid to slurry nebulization for the analysis of soils by ICP-MS with flow injection and mixed-gas plasmas. Can.J. Chem. 77(4), 409. 

Because of the difficulty and inconvenience of sample dissolution for soil and geological samples prior to analysis by atomic spectrometry, a number of authors have investigated the possibility of direct nebulization of slurry samples into flames or plasmas.20,21 However Ebdon et al.22 reported problems... 

Over the past 15 years, ETV sampling for ICP-MS has mainly been used for the analysis of complex matrices including geological materials, biological fluids, seawater, o and coal slurries," which have proved difficult or impossible by conventional nebulization. By removal of the matrix components, the potential for severe spectral and matrix-induced interferences is dramatically reduced. Even though ETV-ICP-MS was initially applied to the analysis of very small sample volumes, the advent of low-flow nebulizers has limited its use for this type of work. 

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