Evaluation of a high-pressure, high-temperature microwave digestion system

A high-pressure, high-temperature focused microwave digestion system was ev aluated and compared with a conventional, closed-vessel digestion system. A suite of 18 test elements was determined in six Standard Reference Materia ls (Peach Leaves, Orchard Leaves, Oyster Tissue, Bovine Liver, Bituminous C oal, and River Sediment) by inductively coupled plasma atomic emission spec trometry and electrothermal atomic absorption spectrometry. Observation of the graphite furnace background absorbance for the digestates, and their hi gh-performance liquid chromatograms, demonstrate that the high-pressure, hi gh-temperature system results in a more complete destruction of the sample matrix. The high-temperature system also shows higher accuracy for the test metals in the reference materials (average error 7.1%) than the convention al system (11.8%). Finally, the high-temperature system has a per-sample an alysis time (7.5 min) that is 10 min faster than the conventional system. O n the negative side, the high-temperature system is not capable of monitori ng temperature during a digestion program. As a result, vessel rupture is c ommon during method development. This results incomplete destruction of the vessel, and the emission of potentially dangerous exhaust fumes into the l aboratory environment.