Polyethylene glycol 2000 (PEG2000, with average molecular weight 2000), polyethylene glycol 4000 (PEG4000, with average molecular weight 2000), sucrose, maltodextrin and other materials were of analytical grade.
Polyethylene glycol 2000 (PEG2000,with average molecular weight 2000), polyethylene glycol 4000(PEG4000, with average molecular weight 2000), sucrose, maltodextrinand other materials were of analytical grade.