Hydrocarbon Analysis

Hi ter!

Can anyone solve tiz puzzle?

What is the purpose of doing the below steps in bioremediation of soil:- ??

This method is done according to work by Nocentini, Pineili and Fava ( 2000) . 5g of soil are inserted into centrifuge tube. Next, 5g of anhydrous sodium sulphate are added and mixture is ground to dry powder.Then, 10ml of 1:1 cyclohexane/acetone mixture are added.Tube will be shaken for 5 min, sonicated for 10 min and shaken again for another 5min. Then,the suspension are centrifuged and the organic fraction will be analysed. The samples collected will undergo TPH analysis as follows: 15g of soil are air dried for 8h. About 2.5g anhydrous sodium sulphate are added and mixture will be ground to dry powder. The sample then are extracted in Soxhlet apparatus with 250ml of 1:1 mixture of acetone and cyclohexane for 8h. The organic fraction are then analysed by concentrating to 5ml by a rotating evaporator. The TPH concentrations are expressed as mg of hydrocarbons per kg of dry soil.

And why after this method we need to examine the residual hydrocarbon in spectrophotometry using cold toluene method?What is and how to do cold toluene method extraction?