Here is a slightly fuller answer. The liver's part in purifying the blood is to produce enzymes that break down toxins into less poisonous compounds. The actual removal takes place in the kidneys where the impurities are excreted in the urine. That is why athletes provide a urine sample to test for the illegal use of performance enhancing substances.
That all depends on what you define as an impurity. Yes the immune system is very active in the lymph. The lymph ultimately drains back into the blood where the mechanisms above apply for removal. Does sbar include waste products as impurities? If so, then a number of other mechanisms will aply.