Extensive purification is needed as Lionel mentioned:</br>
Acetic acid chemically pure, Acetic acid food grade E 260 and
Acetic acid
pharmaceutical grade are obtained from Acetic acid
technical grade by special chemical and physical treatments.</br>
Acetic acid
pharmaceutical grade meets in particular special purity
requirements for intermediates and end products in the pharmaceutical
sector for the various medical forms of application</br>
For a comparison of the specs for different grades of Acetic Acid:</br>
http://www.chemvip.com/euproddesc-aceticacid-en.pdf