Bwiti, they are right about the amount of impurities being removed. It's very small, but it's ok. however, the idea that the NaOH might cause some polymerization (with a little heat or if it sits overnight) makes me think that it's not the best idea. Don't wash anything- distill first, then wash to help clean the final product. Be sure to dry your product and then do a final distillation.
if done correctly (and if you starting material was worth the money) you should get 98%+ purity.