Slotted tube atom trap

Water and white clover CRM Selenium Selenomethionine, selenocystine, selenite and selenate HPLC (anion exchange) FAAS with slotted tube atom trap 1 mg n1 Pedersen and Larsen (1997)... 

The development of new, highly efficient nebulizers, described in detail in the section on ICP-OES (Section 12.2.4.4.1), has meant that a more concentrated aerosol and a more sensitive FAAS determination is achievable. Similarly, the use of slotted tube atom traps (STATs) and water-cooled atom traps (WCAT)10 11—the latter have undergone modification in recent years12—enhances sensitivity with regard to volatile elements like Cd and Pb because of the long residence time of these atoms in the tube. 

For thallium, determinations at the 276.78 nm line with an acetylene/air flame are used throughout. Matrix problems are very low, but the sensitivity with regard to the low level of occurrence is poor. The sensitivity can be increased by mounting a slotted quartz tube on the burner head STAT = "slotted tube atom trap") (Milner, 1983), which leads to a detection limit of about 20 mg/kg in the solid sample, which is insufficient for the analysis of biological matrices. In MIBK extracts, determination of thallium is much more sensitive in flame AAS than in aqueous solutions (till about 7-fold). This can be used for solvent extraction of thallium from 0.1M HBr (Hubert and Chao, 1985), as xanthate at pH 8 (Aihara and Kiboku, 1980), or as iodide with tri-n-octylphosphinoxide into MIBK, and direct aspiration of the organic phase into the flame. 

Milner. B.A. (1983). The Pye Unicam Slotted Tube Atom Trap (STAT) for atomic absorption spectrometry, Pye Unicam Publication No 9498 924 90161. 

When slotted tube atom traps are used to enhance the sensitivity for some analytes, the lifetime of the quartz tubes may be prolonged 8-10 fold by FI sample introduction [16]. 

Slotted tube atom trap (STAT). A double slotted quartz tube supported above the air—acetylene flame of a conventional burner. One of the slots is set directly above the flame, and the tube is aligned with the optical path of the spectrometer. 

A number of methods have been described for improving the sensitivity of conventional FAAS in order to allow the analysis without resorting to more expensive techniques. Best known of these techniques are hydride generation, cold vapour, semi-flame (Delves cup, tantalum boat), and slotted tube atom trap (STAT) methods. 

Table 13 Sensitivities and detection limits (mgl ) by conventional and STAT (Slotted tube atom trap) FAAS methods for some volatile elements. (Source A. A. Brown and S. F. N. Morton, Laboratory Science and Technology, September, 1985)...

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