Digestion microwave

Although experimental details are not included, the application of microwave digestion is discussed for the... 

Evaluate whether the microwave digestion method yields acceptable results in comparison with the standard digestion method. 

A web-site dedicated to sample preparation, which contains useft information about acid digestion and microwave digestion, is found at... 

Organic selenium compounds and siUceous materials (rock, ore, concentrates) are fused with mixtures of sodium carbonate and various oxidants, eg, sodium peroxide, potassium nitrate, or potassium persulfate. For volatile compounds, this fusion is performed in a bomb or a closed system microwave digestion vessel. An oxidizing fusion usually converts selenium into Se(VI) rather than Se(IV). 

Comparative studies were performed to evaluate microwave digestion with conventional sample destmction procedures. These included the analysis of shellfish, meats, rocks, and sods. Generally, comparable accuracy at much shorter digestion time was found for the MAE vs the classical digestion method (39). 

The apphed pretreatment techniques were digestion with a combination of acids in the pressurized or atmospheric mode, programmed dry ashing, microwave digestion and irradiation with thermal neutrons. The analytical methods of final determination, at least four different for each element, covered all modern plasma techniques, various AAS modes, voltammetry, instrumental and radiochemical neutron activation analysis and isotope dilution MS. Each participating laboratory was requested to make a minimum of five independent rephcate determinations of each element on at least two different bottles on different days. Moreover, a series of different steps was undertaken in order to ensure that no substantial systematic errors were left undetected. 

Johnson SG, Fearey BL (1993) Spectroscopic study of thorium using continuous-wave resonance ionization mass-spectrometry with rrltraviolet ionization. Spectrochim Acta Part B 48 1065-1077 Knoll GF (1989) Radiation Detection and Measurement. J. Wiley and Sons, New York Kuss HM (1992) Applications of microwave digestion technique for elemental analyses. Fresenins J Anal Chem 343 788-793... 

Lally AE (1992) Chemical procednres. In Uranium-Series Disequilibrittm Applicatiorrs to Earth, Marine, and Environmental Sciences, 2nd Ed. Ivanovich M, Harmon RS (eds) Oxford Univ. Press, Oxford Lamble KJ, Hill SJ (1998) Microwave digestion procedmes for enviromnental matrices. Analyst 123 R103-R133... 

Method development for high-pressure ashing and closed microwave digestion was reported for wet oxidation and extraction of Pb, Cd, Cr and Hg from various food packaging materials [57]. Use of HPA resulted in the highest median recoveries of the spiked elements (Pb and Cd, 92% Cr, 97% Hg, 83%). The use of In as an internal standard improved the accuracy... 

The use of microwave digestion-wet oxidation overcomes sample preparation problems for many polymer-based materials. However, this will result in a reduction in sensitivity compared with an ashing procedure, because of dilution. Use of an aqueous phase is not... 

Numerous microwave applications have been published on decomposition, fusion, dry and wet mineralisation, ashing and extraction. Knapp et al. [67] have reported decomposition efficiencies of over 96% for PE, PVC, PS and PB, using PMD. Boron in polyolefins was determined after high-pressure microwave digestion followed by ICP-MS [80]. 

Table 8.22 shows some rubber analyses by FAAS after dry ashing. The concentration of Rh in polymers was measured by FAAS [128], The accuracy of 10-20% was in agreement with a dissolution procedure the precision obtained for direct solid analysis was between 10 and 20 %. Due to the relatively high analyte content of lead in paint, the determination is mostly performed by FAAS. Typical digestion procedures include dry ashing, wet and microwave digestion. 

Applications A method for multi-element determination of major elements in commercial and in-house prepared polymer/additive formulations by MIP-AES after microwave digestion with nitric acid has been reported [212], The precision obtained varied between 2 and 4.5 %, depending on the element determined. 

Edible oils Microwave digestion with acid mixture (NH4)2P04 added as matrix modifier ICP/AES GFAAS 50 ng/g 30 ng/g 75-107 78-117 Allen et al. 1998... 

Mahan K.I., Foderaro T.A., Garza T.L., Martinez R.M., Maroney G.A., Trivisonne M.R., Willging E.M. Microwave digestion techniques in the sequential extraction of cadmium, iron, chromium, manganese, lead and zinc in sediments. Anal Chem 1987 59 938-945. 

A. Jurado Lopez, M.D. Luque de Castro, Optimisation of Focused Microwave Digestion of Proteinaceous Binders Prior to Gas Chromatography, Talanta, 65, 1059 1062 (2005). 

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