The sample is crushed in a mortar or in a mill and sieved in a 60mesh (250μm) sieve. After that it is placed for 12 hours in an oven at 60^o C. 0.5g of dried sample is treated with 70ml of hydrochloric acid 2N. The mixture remains in an oil bath at 70^o C for 24 hours. Then it is centrifuged and the HCl is removed. The sample is washed with distilled water until reaching neutral Ph and filtered through a pre-weighted ash-less filter paper. The filter paper with the sample is dried in an oven at 130^o C overnight and reweighted. Additionally, an elemental analysis can be followed in order to determine the oil sulfur content using a CHNSO Organic Elemental analyzer (Flash 2000Thermo Scientific)