FDSC 300 Lecture Notes - Lecture 5: Relative Permittivity, Nuclear Magnetic Resonance, Diethanolamine
Document Summary
Involve recovery of water by distillation process and then the measurement of the volume of water. Food sample mixed with distillation solvent, toluene or mineral oil, the vapour is cooled and collected. Distillation solvents are used as heat transfer media, should be chemically stable at temperature of distillation and free of water. 2 version of distillation solvents, both immiscible, one volatile (toluene) and one non volatile (mineral oil) Direct method of moisture analysis, water is quickly removed because of faster heat transfer. Mineral oil: immiscible, non volatile, boiling point 200-310, density 0,8g/ml. Toluene: immiscible, volatile, boiling point 110. 6 c, density 0,87g/ml, flammable. Other solvents like xylene boiling range 137-140c and tetrachlorethylene 121c. Better to use toluene than a non volatile liquid because distillation is more effective. Boiling point fairly close to the one of water. Water is heavier so will form the lower layer and its volume can be measured directly.
