Development and application of a micro-digestion device for elemental analysis of biological samples

A commercially available piece of equipment for high pressure ashing was adapted for the digestion of micro-samples of biological origin by a supplementary device. This attachment is shown to be suitable for solids with a sample amount of some micrograms and for liquids with a volume of a few microliters. In addition, the homogeneity of two reference materials NBS SRM 1571 “Orchard Leaves” and BCR CRM 414 “Plankton” is tested. For that purpose, the results of elemental analysis of small portions down to the level of 1 mg are compared with those for larger portions recommended by the supplier. Elements are found to be homogeneously distributed in test portions down to 100 mg but a few elements show an inhomogeneous distribution in portions ≤3 mg. For multi-element determinations, total reflection X-ray fluorescence spectrometry was used after addition of an internal standard to the digestion solutions.