Microwave digestion bombs

Table 14.7 Microwave digestion bombs supplied by Parr Instruments...

Figure 28-8 Microwave digestion bomb lined with Teflon. The outer container retains strength to 150°C but rarely reaches 50°C. [Courtesy Parr Instrument Co.. Moline. ILJ...

Today, there are a number of microwave-digestion bombs and systems available [42]. 

PU + organometallic Ashing Microwave digestion Bomb method Added cone. 

Figure 2-18 Microwave digestion bomb lined with Teflon. [Parr Instrument Co., Moline, IL] A typical 23-mL vessel can be used to digest as much as 1 g of inorganic material (or 0.1 g of organic material, which releases a great deal of gaseous CO2) in as much as 15 ml of concentrated acid. The outer container maintains its strength up to 150°C, but rarely rises above 50°C. If the internal pressure exceeds 80 bar, the cap deforms and releases the excess pressure.

Microwave Energy Method For Solubilization. A microwave oven was preheated (3). A 0.1% starch sample was prepared by suspending 5.5 mg. of starch (dry basis) in 5.0 ml. of deionized water. The sample was prepared In a teflon microwave digestion bomb (model no. 4782,... 

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). 

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. 

Decomposition in closed Teflon vessels at high pressure (up to 85 bar) with microwave heating. (Microwave Acid Digestion Bomb, Parr Instrument Company, USA.)... 

S.R. Grobler, A.J. Louw, A new microwave acid digestion bomb method for the determination of total fluorine. Caries Res. 32 (1998) 378-384. 

Nicholson, J.R.P., Savory, M.G., Savory, J., Wills, M.R. Micro-quantity tissue digestion for metal measurements by use of a microwave acid-digestion bomb. Clin. Chem. 35, 488 90 (1989)... 

Matusiewicz, H., Sturgeon, R.E., Berman, S.S. Vapour-phase acid digestion of inorganic and organic matrices for trace element analysis using a microwave heated bomb. J. Anal. At. Spectrom. 6, 283-287 (1989)... 

Fish (total) Digestion of samples with nitric acid in a microwave acid digestion bomb, reduction to elemental mercury CVAAS 0.195 ng/mL >95 Navarro et al. 1992... 

Sample preparation using the bombing combustion method has an advantage over the microwave digestion method in that it does not require very strong multi-acidic solutions... 

The selectivity and sensitivity offered by atomic spectroscopy techniques can be used for direct and indirect determination of metals in a range of pharmaceutical preparations and compounds. Metals can be present in pharmaceutical preparations as a main ingredient, impurities, or as preservatives which can be prepared for analysis using non-destructive (direct or solvent dilution) or destructive methods (microwave acid digestion, bomb combustion, extraction, etc.) and the metal of interest measured against standards of the metal prepared in the same solvents as the sample. Methods associated with some pharmaceutical products are already described in the international pharmacopoeias and must be used in order to comply with regulations associated with these products, e.g titration techniques are carried out according to methods that are the same for all pharmaceutical products. 

Phosphorus (total) Foodstuffs Microwave-assisted digestion with concentrated nitric acid UV-Vis 20.0-400.0 mg L 1 Sequential injection system digestion bomb inside the microwave oven as a peripheral component of the system [135]... 

For sulfated ash digestions, either 250-ral Vycor beakers or dishes may be used (Fisher Scientific). The microwave digestion vessels used were high pressure. Teflon lined, 45-mL Model 4782 bombs that are available from Pair Instrument Company, Moline, Illinois, USA. The polypropylene volumetric flasks used to dilute digested samples to volume are available from Fisher Scientific. 

From a safety perspective, it is critical that no more than 0.1 g of sample be used for this technique. The sample is weighed into the Teflon digestion vessel. Approximately 4 mL of nitric acid are added. The vessel is capped and placed into the microwave oven. Four vessels are simultaneously processed. The microwave is set at 125 W for 15 min. The oven then ramps up to 190 W for another 15 min. Care must be taken not to keep internal temperature and pressure within the capability of the vessels. Excessive heat and pressure will cause the digestion bombs to deform and potentially leak. After the cycle is finished, the vessels are placed into an ice bath for at least one hour to cool. The dissolved sample is washed into a 25-ml volumetric flask and brought to volume with water. 

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