Triple filtering is not necessary in my friend's opinion. He suggests you do an experiment to put your mind at ease.Splatt said:Chemists Own never fails. Just be patient and triple filter for safety.. Hell sometimes I even filter more so its basically totally clear and bitter as hell.
Buy some paracetamol capsules from a supermarket. (Ye Olde style capsules with the powdered paracetamol in the gelcap) and open one of em. Put the 500mg of powdered paracetamol in 100ml of water and try to dissolve it. It won't happen, no matter whether the water is hot or cold, it simply will not dissolve. Furthermore, the paracetamol that is left floating around in the water is very, very obvious.
Bottom line is, if it is impossible to dissolve even 500mg (a very safe dose) of paracetamol in 100ml of water, chances are that unless you have big white chunks floating around in solution after one filtration you shouldn't need to filter again.
I'm curious though; when you filter the second and third times, is there anything left behind on the filter paper? There certainly wasn't when my friend tried it.