Development of a new high temperature/high pressure flow system for the continuous digestion of biological samples

Abstract

The development of a new high temperature/high pressure flow system that incorporates resistively heated capillaries for the continuous digestion of various samples is presented. The system allows the continuous digestion of samples at temperatures of up to 260 °C and a pressure of up to 30 MPa (300 bar). Aqueous solutions of simple organic compounds such as glucose, as well as slurries of different biological materials, e.g., Bovine Liver, milk or juice, were digested. The determination of the residual carbon content was performed off-line by ICP-OES. Compared with other continuous flow digestion systems, unusually low residual carbon contents were obtained. For the majority of biological samples digested, the residual carbon content was 1-13%, corresponding to a digestion efficiency of 87-99%. The potential of the continuous digestion system was illustrated by the digestion of three certified reference materials (Dried Whole Animal Blood, Bovine Liver and Tomato Leaves) and subsequent determination of Mn, Cu, Zn and Fe with ICP-OES. Recoveries between 76 and 109% were found. The RSDs ranged from 2.5 (Mn in Tomato Leaves) to 15% (Fe in Dried Whole Animal Blood).