Thermal instability of electrophoresis gels

Under certain, defined conditions the temperature‐conductivity relationship of electrolytes leads to instabilities in the temperature distribution of electrophoresis gels if these are not efficiently thermostatted. These instabilities manifest themselves in practice in two ways: (i) as unequal temperatures of two identical gels connected in parallel and (ii) as an uneven temperature distribution across the face of individual gels. The latter is a principal cause of the undesirable “smile” effect that occasionally bedevils RNA and DNA sequencing gels. A quantitative description of these instabilities is put forward and suggestions for their avoidance are made.