Hi,
Phosphoric acid and orthophosphoric acid are often considered as the same thing (http://www.sigmaaldrich.com/catalog/product/aldrich/345245?lang=en®ion=US).
The one mentioned in the protocol was 85% (w/v) from vendor. I did not dilute it. Whatever the concentration of your H3PO4 stock is, its final concentration in the reagent should be 8.5% (w/v).
Hope this helps.
Fanglian