PN-ICP

Shiraishi et al. [82] studied the distribution of uranium and thorium in freshwater samples collected in Ukraine, Russia, and Belarus. The analytes were detected directly by PN-ICP-MS and the isotope ratios were determined by increasing the signal integration periods to obtain good counting statistics. The isotopic compositions found for uranium were consistent with fallout from the Qiemobyl nuclear accident. Table 3.10 [33,83-93] shows some procedures for the determination of isotopes by ICP-MS. 

Of course, ETV-ICP-MS is applicable to the analysis of all aqueous sample solutions that are amenable to analysis via PN-ICP-MS. However, as a result of the transient nature of the signals, the precision attainable is typically limited to between 5 and 10% RSD, while the multi-element capabilities are reduced. Therefore, only for those sample types for which analysis with PN-ICP-MS is problematic or at least not self-evident does the use of ETV-ICP-MS become preferable. Bettinelli et used ETV-ICP-MS for trace element analysis of bee honey, used as an indicator... 

In ICP-AES and ICP-MS, sample mineralisation is the Achilles heel. Sample introduction systems for ICP-AES are numerous gas-phase introduction, pneumatic nebulisation (PN), direct-injection nebulisation (DIN), thermal spray, ultrasonic nebulisation (USN), electrothermal vaporisation (ETV) (furnace, cup, filament), hydride generation, electroerosion, laser ablation and direct sample insertion. Atomisation is an essential process in many fields where a dispersion of liquid particles in a gas is required. Pneumatic nebulisation is most commonly used in conjunction with a spray chamber that serves as a droplet separator, allowing droplets with average diameters of typically <10 xm to pass and enter the ICP. Spray chambers, which reduce solvent load and deal with coarse aerosols, should be as small as possible (micro-nebulisation [177]). Direct injection in the plasma torch is feasible [178]. Ultrasonic atomisers are designed to specifically operate from a vibrational energy source [179]. 

The concept of selectivity and specificity has been applied to characterize interferences appearing in two different ICP-MS techniques (Horn [2000]). Classical ICP-MS with pneumatic nebulization and ETV-ICP-MS are compared for the determination of traces of zinc in sea-water. Whereas spectral interferences decrease using the ETV device, nonspectral interferences increase significantly (Bjorn et al. [1998]). A quantitative comparison of the both analytical procedures, here called PN (pneumatic nebulization) and ETV (electrothermal vaporization, Sturgeon and Lam [1999]) is possible by means the specificity as a function of the Zn concentration (Horn [2000]). The spectral interferences on the four zinc isotopes are listed in Table 7.4. 

Proposition 3.2.17. Let IcP n be a smooth closed subvariety of dimension m. The locus where X has nth order contact with l-codimensional linear subvarieties of Pn has at most codimension... 

Kumar N, Anderson RF, Mortlock RA, Froelich PN, Kubik P, Dittrich-Hannen B, Suter M (1995) Increased biological productivity and export production in the glacial southern ocean. Nature 378 675-680 Malinovsky D, Stenberg A, Rodushkin I, Andren H, Ingri J, Ohlander B, Baxter DC (2003) Performance of high resolution MC-ICP-MS for Fe isotope ratio measurements in sedimentary geologic materials. J Anal... 

The review by Tblg (1987) (Extreme trace analysis of the elements - the state of the art today and tomorrow) is an insightful review by an experienced trace analyst concentrating on atomic spectrometric methods including AAS, OES, XRF, MS with many variants of excitation. A table is provided comparing the capability of determinative methods listing the method, the specific technique, limit of determination, matrix effects, multielement determination, and speciation analysis. Methods compared include AAS (flame, furnace, HG), ZAAS (furnace), OES-DCP(PN), OES-ICP(PN), OES-MIP(PN, ETV, HG), OES-HC (volatilization), FANES, AES (laser ICP/ICP, HC/... 

Data for ICPAES(PN) are from Boumans (1987b) (DLs, on a 2 s basis, are for conventional Ar ICPs and pneumatic nebulization and taken from eight reports specific instrumental conditions are reported i.e.,... 

For analysis of sample solutions, ETV-ICP-MS seemed promising as the analyte transport efficiency is considerably higher (> 10%) ° than that offered by PN, only pL- amounts of sample solution are required for analysis, and since the volatilisation of solvent(s), matrix components and analyte element(s) can be separated in time, both spectral and non-spectral interferences can be alleviated. On the other hand, when using ETV for sample introduction, transient signals, with a typical duration of a few seconds only, are obtained instead of stable continuous signals (see Figures 5.17 and 5.18 ). This limits the multi-element capabilities of ICP-MS vide infra)... 

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