It looks and smells like para..but its definately not 100%. The blue dye can be partially washed out with alcohol or water..but it will still have a tint..and you will find when you go to use it..it wont fully dissolve. The best option here (if you have NO other alternatives) is to subliminate it in a filter flask. Direct the gas into cold distilled water. Even doing this you will probably only get a 25% yield. I think they use formaldehyde in ponds to control bacteria or something.