Sentence:  The precipitate was washed twice with an 80 % <WSD>saturated</WSD> solution of * * f , dissolved in a small quantity of 0.1 M neutral phosphate buffer , dialyzed against cold distilled water till free from ammonium ions , and lyophilized using liquid nitrogen . 
Meaning of the word marked with <WSD> tags:  being the most concentrated solution possible at a given temperature; unable to dissolve still more of a substance