DCM amount reducing after each wash?

[methlab]

Hi guys. I have a last question: why do i allways have less DCM/Keton after my washes? I know that the precondition for a wash is that the solvents must be slightly soluble in each other. For example i had about 900ml of DCM/Keton before my washes. After 2x Bicarb, 3x Nacl and 3x NaOH there is just about 600-700ml left. Is this normal? I allways let it stand for about 30 minutes before separating, but it seems, that a small fraction of the DCM/Ketone is allways moving into the aquaeus layer.

[Rhodium]

The solubility of DCM in water is 1.6% at 20°C.

[Antibody2]

you can back extract your washs