Sample introduction in ICP

Montaser A, Tan H, lishi II, Nam SFI, CaiM (1991) Argon inductively coupled plasma mass spectrometry with thermospray, ultrasonic, and pneumatic nebulization. Anal Chem 63 2660-2665 Montaser A, Minnich MG, Liu FI, Gustavsson AGT, Browner RF (1998) Fundamental aspects of sample introduction in ICP spectrometry. In Inductively Coupled Plasma Mass Spectrometry. Montaser A (ed), Wiley-VCH, New York, p 335-420... 

Doherty M. P. and Hieftje G. M. (1984) Jet-impact nebulization for sample introduction in ICP spectrometry, Appl Spectrosc 38 405-411. 

Boomer D. W. and Powell M. (1988) Relative merits of two methods of sample introduction in ICP-MS electrothermal vaporisation and direct sample insertion, ] Anal At Spectrom 3 791-797. 

As the method has the same excellent possibilities for sample introduction as ICP-AES but in addition enables much lower detection limits to be achieved, covers more elements and allows the determination of isotope concentrations, ICP-MS rapidly developed into an established analytical method [496]. 

A comparison of flow injection sample introduction in the determination of Se (As, Sb) by hydride generation AAS and ICP optical emission spectroscopy has been carried out [102], while the isotopic determination of Se in biological materials using ICP-MS has been reported [103]. 

These measurements on solutions will fix the best precision that cannot at present be exceeded using a laser for sample introduction in the MC-ICP-MS. After preliminary remarks about the U-Pb system in a zircon mineral phase, the first section describes the method to achieve convenient preparation of the samples. In the second section, the laser conditions to achieve isotope measurements on zircon are listed, and some reference zircon samples, already dated by using other techniques, are dated to check the precision and accuracy of the LA-MC-ICP-MS protocol. Finally, an example of an investigation of very young zircons, which are the most difficult samples because they contain very little amounts of radiogenic Pb, is discussed. 

Analytical Precision. As sample introduction in the plasma is very stable, relative standard deviations in ICP-AES are ca. 1 % and the limiting noise is proportional, including flicker and nebulizer noise. Below 250 nm detector noise limitations may occur, especially with high-resolution spectrometers. At integration times beyond 1 s. the full precision is normally achieved. 

ICP-MS Besides the plasma torch and sample introduction supplies, ICP-MS requires consumables that are situated inside the mass spectrometer. The first area is the interface region between the plasma and the mass spectrometer, which contains the sampler and skimmer cones. These are traditionally made of nickel, which is recommended for most matrices, or platinum for highly corrosive samples and organic matrices. A set of nickel cones costs 700-1000, whereas a set of platinum cones costs about 3000-4000. Two sets of nickel cones and perhaps one set of platinum cones would be required per year. The other major consumable in ICP-MS is the detector, which has a lifetime of approximately 1 year, and costs about 1200-1800. Some systems also have a replaceable ion lens. It is suggested that five of these at 100 each are required for a routine laboratory. When all these are added together with the torch, the sample introduction components, and the vacuum pump consumables, investing in ICP-MS supplies represents an annual cost of 9,000-11,000. 

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