NON-HAZARDOUS ORGANIC-SOLVENTS IN THE PARAFFIN-EMBEDDING TECHNIQUE - A RATIONAL APPROACH - ALIPHATIC MONOESTERS FOR CLEARING AND DEWAXING -BUTYLDECANOATE

The aim of this study was to substitute hazardous compounds, used in t issue processing and dewaxing, with compounds having lowest possible t oxicity and inflammability without impairing the morphology, staining characteristics, or diagnostic value of the tissue sections. All aroma tic compounds and aliphatic hydrocarbons (e.g. alkanes, isoparaffins, petroleum distillates, etc.) were rejected, primarily due to their hig h vapour pressure. Based on a theoretical study of compounds used for clearing, a number of non-hazardous potential substitutes were chosen. The following experimental study narrowed the group to three unbranch ed, saturated, aliphatic monoesters containing 12-14 carbon atoms. On large-scale testing of these compounds, we found butyldecanoate to be the closest to an ideal substitute for aromatic and aliphatic hydrocar bons in the histology depart ment: the section quality is at least equ al to that obtained with xylene. For dewaxing, it is used at 30-35 deg rees C. Butyldecanoate is not suitable as a pre-mounting agent. In pra ctice, this is no problem as modern mounting agents permit mounting of coverslips directly from ethanol without impairing the appearance of the section in the microscope. Butyldecanoate has only a slight odour, insignificant vapour pressure (<0.01 kPa at 20 degrees C), and does n ot present a fire hazard (flash point 134 degrees C). The introduction of this compound in the laboratory poses no health hazard, and the su bstance is biodegradable.