We see in Avatar that Katara bloodbended (controlling another's blood inside their body, therefore you can control them) at least two people. But could you bend blood outside the body? For example if someone was bleeding on the floor, could you then bend that blood?
There are quite a few examples of waterbenders bending solutions (and mixtures) with the aid of others in some cases:
Solutions: It has been shown that waterbenders can manipulate any liquid that is partially water, or anything that contains water. For example, Katara bent the contents of the abbey's perfume vats.She used waterbending to stir and ladle stew into bowls, to spill ink out of a bowl, and to bend the water inside mud as well.
See special techniques on the wikia.
As it is, I'd like to point out that bloodbending is a misleading name. More likely it takes advantage of all the water stored in the body, e.g water solutions within cells as well as 'loose' in veins and other bodily ducts.
As blood (and the other liquids from the body) are mixtures and solutions they can be bent. Quite likely though is that with enough bending the liquid content would be removed from the blood separating cells (red/white cells and platelets) and liquid and anything suspended in it (sugars, salts, nutrients etc).
For more on Water Purification, see this page on the wikia.