To 200ml Milli-Q water add:

2.5g Ficoll (Sigma #F-9378)

2.5g Polyvinylpyrrolidone

2.5g BSA (Pentax Fraction V)

-Bring Volume to 250ml with Milli-Q

-Stir well

-Filter through 0.45 micron filter unit

-Dispense into 10ml Aliquots

-Store at -20'C