Diatom extraction with HCl from animal tissues: a technical note.

Identification of diatoms from human or animal tissue may be affected by factors concerning techniques of extraction and analysis which cause fragmentation or loss of diatoms. In this brief technical note a novel efficient method of extraction of diatoms from animal tissues is presented. The authors have tested an H(2)O(2) plus HCl and HCl method to detect diatoms in several tissues from pig immersed in water rich in diatoms; they have also compared this method to other methods of extraction including enzymatic ones. The experiment showed that all siliceous frustules of fresh water diatoms are resistant to the treatment proposed and are still recognizable after the digestion. Among the different tests, treatment by 20% HCl (T1) proved to be more simple and time-saving, and seems to be a valuable diagnostic tool for routine forensic procedures in the extraction and detection of diatoms. The positive results obtained in all cases should lead to further studies in order to evaluate the reliability of the proposed methods also from a quantitative point of view.