Argon plasma emission

Schematic diagram of an argon plasma emission spectrometer.

Francesconi, K.A., P. Micks, R.A. Stockton, and K.J. Irgolic. 1985. Quantitative determination of arsenobe-taine, the major water-soluble arsenical in three species of crab, using high pressure liquid chromatography and an inductively coupled argon plasma emission spectrometer as the arsenic-specific detector. Chemosphere 14 1443-1453. 

An alternative approach is to analyze the samples using procedures or instrumentation that will give the maximum amount of data for each sample. For example, recent advances in atomic spectroscopy, i.e., inductively coupled argon plasma emission spectroscopy (ICP-AES), allow 20 to 30 elements to be detected simultaneously. 

This effect has been successfully employed to improve the LC detection of metal ions as their metal complexes (496.497.499). Recently, it has also been demonstrated that metal ions can be detected by direct-current argon plasma emission spectroscopy after LC separation with micellar mobile phases (490). 

Phosphate rock and phosphoric acid Wet digestion separation by extraction with trioctylphosphine oxide destruction of complex prior to analysis Argon plasma emission spectrometry No data 98-100 Woodis et al. 1980 ... 

Greene B, Uranga A, Sneddon J. 1985. Observations on the determination of uranium in waters by direct current argon plasma emission spectrometry. Spectroscopy Letters 18(6) 425-436. 

Norman JD, Stumpe LA, Trimm J, et al. 1983. Argon-plasma emission spectrometry of uranium in phosphatic materials (e.g., fertilizers). J Assoc Off Anal Chem 66 949-951. 

Woodis TC Jr., Trimm JR, Holmes JH, et al. 1980. Determination of uranium in phosphate rock and wet-process phosphoric acid by argon-plasma emission spectrometry. J Assoc Off Anal Chem 63 208-210. 

The inductively coupled argon plasma emission spectrometer used for quantitative analysis of trace elements. 

Uden, P. C., Bigley, I. E. High-pressure liquid-chromatography of metal diethyldithiocar-bamates with U. V. and D. C. argon-plasma emission spectroscopic detection. Anal. Chim. Acta 94, 29 (1977)... 

Natajaran S. 1988. Determination of parts-per-trillion levels of mercury with low-power microwave-induced argon-plasma emission spectrometry. Atom Spectrosc 9(2) 59-62. 

Inductively coupled argon plasma emission spectrophotometry (ASTM D-5708) has an advantage over atomic absorption spectrophotometry (ASTM D-4628, ASTM D-5863) because it can provide more complete elemental composition data than the atomic absorption method. Flame emission spectroscopy is often used successfully in conjunction with atomic absorption spectrophotometry (ASTM D-3605). X-ray fluorescence spectrophotometry (ASTM D-4927, ASTM D-6443) is also sometimes used, but matrix effects can be a problem. 

It is necessary, however, to use other methods, such as atomic absorption, inductively coupled argon plasma emission spectrophotometry, and ion chromatography to determine the composition of the salts present. A method involving application of extraction and volumetric titration is also used (IP 77). 

In the inductively coupled argon plasma emission spectrometer method, nickel, iron, and vanadium content of gas oil samples in the range from 0.1 to 100 mg/kg. Thus a 10-g sample of gas oil is charred with sulfuric acid and subsequently combusted to leave the ash residue. The resulting sulfates are then converted to their corresponding chloride salts to ensure complete solubility. A barium internal standard is added to the sample before analysis. In addition, the use of the ICAP method for the analysis of nickel, vanadium, and iron present counteracts the two basic issues arising from metals analysis. The most serious issue is the fact that these metals are partly or totally in the form of volatile, chemically stable porphyrin complexes and extreme conditions are needed to destroy the complexes without losing the metal through volatilization of the complex. The... 

The sampled species emission increases, peaks and fall off with time while the argon plasma emission is constant throughout as shown in Figures 9 and 10. 

WoLNiCK HA, Feicke FL, Hahn MH and Caeuso JA (1981) Sample introduction system for simultaneous determination of volatile clement hydrides and other elements in foods by inductively coupled argon plasma emission spectrometry. Anal Chem 53 1030-1035. 

Mitchell, P.G., Greene, B. and Sneddon, J. (1986) Direct determination of mercury in solid algal cells by direct-current argon-plasma emission spectrometry with sample introduction by electrothermal vaporization. Microchim. Acta, 1986 I, 249-258. 

In the last 6 to 7 years, argon plasma emission (PES) instrumentation has been commercialized with detection limits usually intermediate between flame and furnace AA. The two most common types of plasma instruments are the inductively coupled plasma (ICP) and direct current plasma (DCP). 

Finally, argon plasma emission spectroscopy can determine the presence of two other elements, which can be present as anions, B and P. The technique is far more sensitive for the former element which can be detected at the ppb level in solution, while P can be detected at the ppm level. Both elements can also be analyzed by atomic absorption spectroscopy, but with less sensitivity. 

ICP-AES Nebulization pneumatic or ultrasonic High- temperature argon plasma Emission measured by spectrophotometer ppm-ppb Multielemental High throughput Low interferences Refractory clem. High dissolved solids tolerance Relatively expensive Limited sensitivity Spectral interferences... 

Fig. 221. DC argon plasma emission chromatogram of cyclopenta-dienylmanganesetricarbonyl (c3nnantrene) (100 ng) and methylcyclopentadienylmanganesetricarbonyl (MMT) (50 ng) in 5 yl iso-octane solution. Column 2 meter, stainless steel, g in. o.d. 2% Dexsil 300 GC on 100-120 mesh Chromosorb 750, 130°C.

Fig. 2.4. Chromatogram of a solution containing arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, phenylarsonic acid, selenite, and phosphate recorded with an ARL 34000 simultaneous inductively coupled argon plasma emission spectrometer as the multi-element-specific detector [Hamilton PRP-1 resin-based reverse-phase column, Waters Associates Inc. Model 6000A high pressure liquid chromatograph, 0.1 ml injected flow rate 1.5 ml min", mobile phases 0.002 M aqueous HTAB at pH 9.6 to 250 sec, 99/1 (v/v) H2O/CH3COOH 250-1100 sec, 90/10 (v/v) H20/dimethylformamide 1100-1700 sec. ICP As 189.0 nm, P 241.9 nm, Se 203.9 nm, integration time 5 sec]. Redrawn from Spectrochimica Acta [11] by permission of Pergamon Press and the authors.

Inductively-coupled argon plasma emission detectors... 

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