Digestion bombs

Pressure dissolution and digestion bombs have been used to dissolve samples for which wet digestion is unsuitable. In this technique the sample is placed in a pressure dissolution vessel with a suitable mixture of acids and the combination of temperature and pressure effects dissolution of the sample. This technique is particularly useful for the analysis of volatile elements which may be lost in an open digestion [24]. 

Inorganic and organic materials can be dissolved rapidly in Parr acid digestion bombs with Teflon liners and using strong mineral acids, usually nitric and/or aqua regia and, occasionally, hydrofluoric acid. Perchloric acid must not be used in these bombs due to the high risk of explosion. 

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. 

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

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. 

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...

Digestion Techniques For nonvascularized or low-water-content tissues such as bone, cartilage, or hair, a mechanical technique may do little to disrupt cellular structure and extract analytes. Extreme measures such as digestion with strong acid (i.e., 12 N HC1) are routinely used for DNA or nucleic acids, which can tolerate the harsh conditions. Alternatively, certain enzymes can be used to digest tissue samples. Commercial devices are available which contain digestion bombs fabricated from material resistant to corrosive media. 

Hydrothermal synthesis does not require the water to be above its critical point. Huan, et al. published a synthesis of VOC6H5PO3XH2O prepared from phenylphosphonic acid, CeH5PO(OH)2 and vanadium(III) oxide, V2O3 (Huan et al., 1990). The two reagents were added to water, sealed in a Teflon acid digestion bomb, and heated to 200°C. Pure water has a vapor pressure of 225 PSI at 200°C, well within the bursting pressure of the bomb (1800 PSI). Unlike the quartz example, in this case, the solvent became incorporated into the final product. 

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

Okamoto, K., Fuwa, K. Low-contamination digestion bomb method using a Teflon double vessel for biological materials. Anal. Chem. 56, 1758-1760 (1984)... 

Uhrberg, R. Acid digestion bomb for biological samples. Anal. Chem. 54,1906-1908 (1982)... 

Matusiewicz, H. Modification of construction of Teflon digestion bomb. Chem. Anal. (Warsaw) 28, 439 52 (1983)... 

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)... 

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... 

PU + organometallic Ashing Microwave digestion Bomb method Added cone. 

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. 

Parr Bombs. Two types of Parr bombs were used. The acid digestion bombs were used for the ash dissolutions. About 0.2 g of shale or ash was dissolved in 3 mL aqua regia and 2 mL HF in the acid digestion bomb and heated at 110°C in an air-oven for two hours. After the dissolution, 1 g of boric acid was added to each sample solution, which was heated on a water-bath... 

Parr Bomb Dissolution of Shales. Originally the acid digestion bomb was developed by Bernas (14) for the dissolution of silicate matrices. An adaptation of this bomb is now marketed by Parr Instrument Company of Moline, Illinois. The dissolution procedure has been adapted to shales and was described in the Experimental Section. 

The results of using the acid digestion bomb for shales are included in Table IV. These three shales are distributed by the U.S. Geological Survey as "standard" shales Green... 

Table IV. Analysis of Oil Shales By Acid Digestion Bomb Dissolution and ICPES...

---