In the industrial processing of birch wood as a by-product accumulates birch outer bark (BOB) which often is burned as a fuel. However, birch bark can also be a promising raw material for compounds with a very broad range of applications - in the field of pharmaceutical, cosmetic, food and material science. In recent decades, attention of scientists has deserved lupane type pentacyclic triterpenes. Betulin is main representative of triterpenes in BOB. Birch bark comprises about 12.50 wt.% of the tree mass from which up to 3.40% is outer bark which contains 25% of betulin. Such a high content of individual compound in natural resources is very uncommon; therefore it makes the isolation of betulin from birch outer bark economically favourable on an industrial scale. Non-polar hydrocarbons is referred as most selective solvents for isolation of betulin in the extraction process [1]. Therefore, it is necessary to choose the best solvent taking into account important factors such as price, toxicity, etc. Experimental studies showed that the most suitable solvent for the extraction of BOB is petroleum ether with a boiling range of 100-140°C (PE140). It consists of a mixture of hydrocarbons, mainly of heptane, octane, nonane, decane, with an average density of 0.74 kg/m3.