Microwave digestion/dissolution

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. 

More recently, microwave ovens have been used for sample dissolution. The sample is sealed in a Teflon bottle or a specially designed microwave digestion vessel with a mixture of suitable acids. The high-frequency microwave, temperature (ca. 100-250°C) and increased pressure have a role to play in the success of this technique. An added advantage is the significant reduction in sample dissolution time [25, 26],... 

Earlier methods for the determination of uranium in soils employed spectrophotometry of the chromophore produced with arsenic(III) at 655 nm [237 ] and neutron activation analysis [238]. More recently, laser fluorescence [239] and in situ laser ablation-inductively coupled plasma atomic emission spectrometry [240] have been employed to determine uranium in soil. D Silva et al. [241] compared the use of hydrogen chloride gas for the remote dissolution of uranium in soil with microwave digestion. 

R. Garcia and B. Kahn, Total Dissolution of Environmental and Biological Samples by Closed-Vessel Microwave Digestion for Radiometric Analysis, J. Radioanalytical and Nuclear Chemistry 250, 85-91 (2001). 

The results confirmed that the ancillary materials used in an analytical procedures might contribute to blank values more than reagents themselves do, especially glassware and microwave digestion systems. Although the latter have been extensively employed to shorten the time required for sample dissolution, some problems have been ascribed to this procedure, as reported by Lima et al. [8],... 

Reliable analytical information can be obtained by using microwave digestion sampling for trace element determination in brain and liver. Krachler et al.52 reported two microwave digestion systems (open-focused and closed-pressurized). They created a mineralization of human brain and bovine liver as dissolution steps prior to the determination of 16 trace elements (bismuth, cadmium, cobalt, cesium, copper, iron, mercury, manganese, molybdenum, lead, rubidium, antimony, tin, strontium, thallium, and zinc) by ICP-MS. 

A90. Rhoades, C.B. and R.T. White Mainstream smoke col- 20A108. lection by electrostatic precipitation for acid dissolution in a microwave digestion system prior to trace metal determination J. AOAC Int. 80 (1997) 1320-1331. 20A109. 

Garcia, R. and Kahn, B. 2001. Total dissolution of environmental and biological samples for radiometric analysis by closed-vessel microwave digestion. J Radiological Nucl Chem 250, 85-91. 

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