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 tissue processing and dewaxing, with compounds having lowest possible toxicity and inflammability without impairing the morphology, staining characteristics, or diagnostic value of the tissue sections. All aromatic compounds and aliphatic hydrocarbons (e.g. alkanes, isoparaffins, petroleum distillates, etc.) were rejected, primarily due to their high 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 unbranched, 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 hydrocarbons in the histology department: the section quality is at least equal to that obtained with xylene. For dewaxing, it is used at 30-35 degrees C. Butyldecanoate is not suitable as a pre-mounting agent. In practice, 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 not present a fire hazard (flash point 134 degrees C). The introduction of this compound in the laboratory poses no health hazard, and the substance is biodegradable.