Selection of method
For liquid samples,four methods are presented:the ;liquid-liquid partition-gravimetric method (B),the partition-infrared medthod(C),the Soxhlet method (D),and the solid-phase,partition-gravimetric method (G),method C is designed for samples that might contain volatile hydrocarbons that otherwise would be lost in the solvent-removal operations of the gravimetric procedure.method D is the method of choice when relatively polar,heavy petroleum fractions are present, or when the levels of nonvolatile greases may challenge the solubility limit of the solvent.for low levels of oil and grease