Influence of different kind external fields on DNA yield at isolation on silica from model solutions. 1. Effect of temperature

The temperature dependence of the M. tuberculosis DNA yield on commercial silica microcolumns from the model solutions in the range of 20 to 90 °C was studied. Linear yield-temperature relationship from 20 oC up to 70 °C was revealed ( r = 0.990), with maximum yield peaked at 70 °C. DNA yield show a slight decrease when heated at higher temperatures. The value of maximum yield is 73 %, i.e. DNA isolation is 50 % more efficient at 70 °C as against room temperature. The best DNA yield temperature is slightly below DNA melting temperature (76 °C). Assuming that the viscosity changes with temperature increase are mainly responsible for the observed data the applicability of diffusion equations was evaluated to account for the linear yield-temperature relationship. The calculated values are slightly overestimated but qualitatively agree well with experimental temperature dependence of DNA yield in case of DNA-H 2O system. The calculated data fit the experimental yield-temperature dependence well up to 70 °C with some electrolyte solutions in place of pure water in DNA solutions. The conceivable effects of some physico-chemical and hydrodynamic processes in the course of the liquid passage through porous silica are briefly touched along with something of side actions of the experimental conditions.