Knapp digestion

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]. 

A microwave-assisted, high-temperature, and high-pressure UV digestion reactor has been developed by Florian and Knapp [44] for analytical purposes. The apparatus consists of the immersed electrodeless discharge lamp operating as a result of the MW field in the oven cavity (Fig. 14.8). An antenna fixed to the top of EDL enhanced the EDL excitation efficiency. Another interesting MW-UV reactor has... 

Figure 28-11 High-pressure autoclave allows digestion up to 270°C without HjSO, in open vessels inside autoclave. [Adaped from B. Maichin. M. /ischka. and G. Knapp. "Pressurized Wei Digestion in Open Vessels" Anal. Bioanal. Chem. 2003, 376, 715.]...

Florian, D. and G. Knapp. 2001. High-temperature, microwave-assisted UV digestion A promising sample preparation technique for trace element analysis. Anal. Chem. 73 1515-1520. 

Pichler, U., Haase, A., Knapp, G., Michaelis, M. Microwave-enhanced flow system for high-temperature digestion of resistant organic materials. Anal. Chem. 71, 4050-4055 (1999)... 

Knapp, G., Maichin, B., Baumgartner, U. Interferences in ICP-OES by organic residue after microwave-assisted sample digestion. At. Spectrosc. 19, 220-222 (1998)... 

Wasilewska, M., Goessler, W., Zischka, M., Maichin, B., Knapp, G. Efficiency of oxidation in wet digestion procedures and influence from the residual organic carbon content on selected technique for determination of trace elements. J. Anal. At. Spectrom. 17, 1121-1125 (2002)... 

G. Knapp, Mechanical Techniques for Sample Decomposition and Element Preconcentration, Mikrochim. Acta, II (1991) 445. Lists acid mixtures and uses for digestions and other decomposition methods. 

Knapp. G, Panholzee F, Schalk A and Kettisch P (1997) Pressure-controlled microwave-assisted wet digestion. In Kingston HM and Haswell SJ, eds. (1997) Microwave-Enhanced Chemistry, Eunda-mentals, Sample Preparation, and Applications, pp. 423-451. American Chemical Society, Washington, DC. 

Wet digestion of blood and serum can be carried out at normal as well as higher pressures (Knapp, 1988) using common mineral acids without or in combination with... 

The digestion can be accelerated using a pressure digestion system (Knapp, 1988). 0.1 g of the sample is treated with 1 mL suprapure nitric acid (65% v/v) and 0.2 mL perchloric acid (63% v/v) and heated at 100 bar to 320°C for 4 h. The contents are cooled and diluted with ultrapure water to volume. 

F.P.Landauer, J.R.Janesick, S.L.Knapp, M.M.Blouke, J.R.Hall 1978 Government Microcircuit Application Conf Digest of Papers, Vol. 7, 394 (1978) Joy Morrealle... 

High-Pressure Digestion, The introduction of a high-pressure ashing (HPA) technique by Knapp [45] has not only reduced the effective ashing time to ca. two hours but also opened the way to digestion of extremely resistant materials [46J. High-... 

Heat and pressure have little influence on the effectiveness of the digestion procedure. Good results have been attained using Teflon bombs in a microwave oven (Knapp etal., 1997). The Teflon bombs can be cleaned to a high level of purity and are pressure-resistant up to some 10 bars (10 Pa). The decomposition of the filter material (polycarbonate) and, to a varying extent, of the organic sample material, leads to the release of CO2. To attain a slow, controllable pressure increase, the temperature programmeme has to raise the micro-wave power stepwise. 

Numerous procedures are described in the literature for digestion of SPM collected on filters (for an overview see Knapp, 1985). In the following a few of these digestion techniques are outlined which have been applied successfully by the authors of this chapter over several years. 

Zischka M., Kettisch P., Schalk A. and Knapp G. (1998) Closed microwave-assisted wet digestion with simultaneous control of pressure and temperature in all vessels, Fresenius J. Anal. Chem. 361 90-95. 

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