Spark source mass preparation

Applications Real applications of spark-source MS started on an empirical basis before fundamental insights were available. SSMS is now considered obsolete in many areas, but various unique applications for a variety of biological substances and metals are reported. Usually, each application requires specific sample preparation, sparking procedure and ion detection. SSMS is now used only in a few laboratories worldwide. Spark-source mass spectrometry is still attractive for certain applications (e.g. in the microelectronics industry). This is especially so when a multi-element survey analysis is required, for which the accuracy of the technique is sufficient (generally 15-30% with calibration or within an order of magnitude without). SSMS is considered to be a... 

The flameless atomic absorption method has a reproducibility of about 2% or better for homogeneous specimens. Checks (3) between AA and NAA (with radiochemical separation after irradiation) and isotope dilution spark source mass spectroscopy on thoroughly homogenized tuna fish and Bureau of Mines round-robin coal specimens indicate good agreement between the methods. (0.425 0.9%, 0.45 3.5%, and 0.45 4.4% for tuna by AA, NAA, and SSMS, respectively, and 1.004 is the average ratio of NAA to AA results for five coal samples.) The similar results indicate that the technique used in sample preparation... 

Finally, the black-brown americium oxide is sieved through a 170 mesh 7.6 cm screen on a mechanical shaker. A complete analysis is done to determine whether the Am02 meets the required product specifications. The analysis of representative batches of americium oxide produced at LASL is shown in Table II. Radiochemistry, emission spectroscopy, calorimetry, and spark source mass spectrometry are used in the analysis of the Am02. Providing the Am02 meets all of the product specifications, it is prepared for shipment. Product not meeting these specifications is recycled through the process at the proper entry point. 

Techniques for analysis and sample preparation have been developed for using spark source mass spectrometry (SSMS) to study archaeological samples. Comparative studies of neutron activation and SSMS on identical samples have been made. The technique is used to determine the ores of origin of two series of early Peruvian artifacts. 

The laser ion source can be used for trace analysis of all elements down to the sub-ppm range. The main advantage of this method compared with spark source mass spectrometry is that little sample preparation is required so that minute sample amounts which are difficult to handle can be investigated. A mixture of the sample with the conducting material, such as graphite is not necesseny, because the conductivity of the sample has no influence on the ion production. 

In most analytical procedures, calibration is carried out by means of a calibration curve using com-pound(s) prepared with chemicals of an appropriate purity and verified stoichiometry. Matrix effects must often be taken into account and, consequently, the calibration solutions should be matrix-matched. CRMs of pure compounds may be used for calibration. However, matrix CRMs should in principle not be used for the purpose of calibration unless no other suitable calibrants are available, with the exception of those methods (e.g., spark source mass spectrometry, wavelength-dispersive XRF, etc.) that require calibration with CRMs of a similar, fully characterized matrix (e.g., metal alloys, cements). For such methods, accuracy can only be achieved when certified RMs are used for the calibration. 

In classical spectrographic analysis (i.e., direct current arc and controlled-waveform spark emission spectrography) the easiest method for sample introduction involved the direct analysis of solid samples.This approach was also used as the conventional sampHng technique for trace element analysis by spark-source mass spectrometry. Solid samples were easy to prepare, usu-... 

At suitably high laser irradiances at the solid surface, a plasma is formed as mentioned above. With properly chosen irradiation parameters, this plasma shows features, comparable to those of HF-spark sources, commonly used in mass spectrometry of inorganic solid samples. From results, reported in the literature (1, 2, 3), it can be deduced that the laser source may offer some advantages over classical spark sources with respect to sample preparation (nonconductors), reproducibility, collection efficiency and uniformity of elemental sensitivity factors. The laser in addition... 

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