Microwave oven digestion

Principles and Characteristics Instead of thermal initiation, microwave decomposition may be of use for sample preparation involving combustion or acid digestion. The advantages over thermal initiation lie in the shorter time needed (minutes instead of hours). Microwave oven digestion (MOD) systems are not analytical instruments. Functionally, they are chemical... 

M. A. de la Fuente, M. Juarez, Rapid determination of calcium, magnesium, sodium and potassium in milk by flame atomic spectrometry after microwave oven digestion, Analyst, 120 (1995), 107-111. 

R. Saraswati, T. W. Vetter, R. L. Watters, Jr, Comparison of reflux and microwave oven digestion for the determination of arsenic and selenium in sludge reference materials using flow-injection and atomic absorption spectrometry, Analyst, 120 (1995), 95-99. 

Carbonell, V., de la Guardia, M., Salvador, A., Burguera, J.L., Burguera, M. On-line microwave oven digestion flame atomic absorption analysis of solid samples. Anal. Chim. Acta 238, 417 21 (1990)... 

S. Hinkamp, G. Schwedt, Determination of total phosphorus in waters with amper-ometric detection by coupling of flow-injection analysis with continuous microwave oven digestion, Anal. Chim. Acta 236 (1990) 345. 

Chakraborti D, Burguera M and Burguera JL (1993) Analysis of standard reference materials after microwave-oven digestion in open vessels using graphite furnace atomic absorption spectrophotometry and Zeeman-effect background correction. Fresenius J Anal Chem 347 233-237. 

Sant Ana, F.W., Santelli, R.E., Cassella, A.R., Cassella, R.J., (2007), Optimization of an open focused microwave oven digestion procedure for determination of metal in diesel oil by inductively coupled plasma optical emission spectrometry, /. Hazardous Materials, 149,67-74. 

Bettinelli, M., Spezia, S., Baroni, U., and Bizzarri, G. (1998). Microwave oven digestion of power plant emissions and ICP-MS determination of trace elements. At. Spectrosc. 19(3), 73. 

A procedure for using a microwave oven to digest samples of Ni ore and to dry precipitates of nickel-dimethylgloxime is described in this experiment. 

The most universal method for sample destmction before SPh metal determination (Ee, Mo, A1 and etc.) is the sulfur acid digestion at high temperature by Kjeldall. It can be enforced by microwave decomposition in the microwave oven. 

Raw foods were freeze-dried and analyzed for carbon isotopes using mass spectrometry. Cooked foods were prepared following historic recipes, then were freeze-dried prior to analysis. For the trace element analysis, foods (both raw and cooked) were wet ashed using nitric acid in Teflon lined pressure vessels and digested in a CEM Microwave oven. Analysis of Sr, Zn, Fe, Ca and Mg was performed using Atomic Absorption Spectrometry in the Department of Geology, University of Calgary. 

Reactions were performed in sealed thick-walled glass tubes or in Teflon acid-digestion vessels, in domestic microwave ovens [13]. Teflon vessels can be used at pressures up to 14 atm, at temperatures below 250 °C, and are resistant to most commonly used chemicals, although they deform at temperatures >250 °C. 

Most average homes contain a microwave oven. Researchers have taken that same technology and applied it to sample extraction. Using microwave technology with acidic solutions has become a commonplace replacement for traditional acid digests. The sample is placed in a closed, chemical-resistant vessel and heated in a microwave. This process is much faster than hot-plate techniques and has become widely accepted by such agencies as the US EPA. 

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],... 

Several manufacturers supply microwave ovens and digestion bombs (Tables 14.6 and 14.7). CFM Corporation state that their solid PTFE bombs are suitable for the digestion of soils and sediments. 

Man, Y-g. and Tavassoli, F. A. (1996) A simple epitope retrieval method without the use of microwave oven or enzyme digestion. Appl. Immunohistochem. 4, 139-141. 

Recently, work has been undertaken to develop an on-hne microwave analyser. Acidified sample is injected into a carrier stream which passes into a microwave oven. During the digestion period of 1 min, phosphorus-containing compounds are converted into the orthophosphate form. After coohng, reagents are added to form phosphomolybdenum blue, which is measured spectrophotometrically at 690 nm. 

---