Regenerator bottoms from hydrogen fluoride (HF) alkylation areoften 2-phase systems. The lower phase is relatively rich in HF,containing about 30-40%; and the upper phase is essentiallyhydrocarbon containing small concentrations (about 0-5%) of HF. Thewater content of the HF-rich lower phase is usually less than 10%,and that of the upper phase is usually less than 5%. This method issatisfactory for the determination of water in both types ofsamples. The unsaturates present in the oil do not interfere in thetitration for water.