ABSTRACT
Oil and grease in aqueous samples can be determined by the following methods: partition-gravimetric method, partition-infrared method, soxhlet extraction method and solid phase partition-gravimetric method. This chapter briefly outlines these methods. The selection of the method depends on several factors including the nature of the sample, volatile substances present in the sample, the availability of materials and equipment for analysis, and the time and cost of analysis. Gravimetric procedures are always time consuming. It may be noted that gravimetric measurements are susceptible to errors; weighing especially has to be very accurate in gravimetry and the cycle of heating and cooling of the crucible and the residues must be continued until constant weights are attained. The first two methods, the partition-gravimetry and the partition-infrared methods are based on liquid–liquid extraction. In these extractions, oil and grease materials which include biological lipids and mineral hydrocarbons are extracted from water into a suitable solvent that provides much greater solubility over water.
