Solvent extraction removing water from frozen

Removing Water from Frozen Books by Solvent Extraction. Solvent Extraction/Air Dry. Frozen books are submerged in a precooled anhydrous solvent in a sealed container and stored in a freezer. As the ice dissolves the water/solvent mixture is replaced periodically until all water is removed. Books saturated with solvent are then interleaved with absorbent paper and air dried (5). 

Freeze-thaw vacuum, inter leave-air, and solvent extraction processes offer the greatest potential in drying these types of coated- and uncoated-paper books after they have been wetted and frozen. The drained-air, vacuum-air cycle, vacuum, microwave, and dielectric drying processes work well on uncoated paper, but they fail to dry books containing this type of coated paper. Small and large units for freeze-thaw, vacuum drying have been used successfully to remove water from these frozen coated and uncoated books. 

In the case of selective extraction of compounds from steam distillate after pH adjustment, about 1.5 L distillate were collected by co-distilling 200 g of powdered nuts with 2.5 L of water. The basic, neutral and acidic compounds were extracted using either methylene chloride or ether and the solvent was removed by distillation. In the case of the acidic fraction, the ether extract was methylated by refluxing with methanol-sulphuric acid (50 1) reagent for 2 hours. The methylated samples were washed free of acid and extracted with redistilled hexane, dried and stored frozen. 

The candidate compound is added to the perfusate before the isolated liver is transferred to the perfusion setup. After 5 minutes recirculation in the system without the organ a sample of the perfusate is collected for determination of the starting concentration of the candidate compound (value at time 0). Then the isolated liver is connected to the perfusion chamber and subsequently samples of the perfusate are taken in 10 to 15 minute intervals as well as bile samples are taken in 15 minutes intervals for the determination of compound levels. The volume of excreted bile per 30 minutes is determined gravimetrically (difference between tube weight without and with bile per collection period) with the assumption that 1 g is equivalent to 1 ml of bile. If radioactive-labelled candidate compounds are used the intervals for bile collection can be much shorter (1 to 2 minutes). The liver is perfused for 2 hours and at the end of the perfusion experiment the liver is removed and immediately frozen for determination of tissue level of the compound in liquid nitrogen and later on stored at -20 °C until analysis. For analysis of tissue levels of the candidate compound the frozen livers are homogenized in water (1 g tissue in 1 ml water (or solvent to extract the candidate compound from the tissue)) using an ultra-turrax. 

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