Je. Gliksman et al., COMPARISON OF DIRECT EXTRACTION AND AOAC OFFICIAL METHODS FOR AVAILABLE P2O5 IN FERTILIZERS - COLLABORATIVE STUDY, Journal of AOAC International, 77(4), 1994, pp. 795-802
Fifteen fertilizer samples were sent to 13 laboratories for determinat
ion of available P2O5. Eleven laboratories, including author's laborat
ory, completed the analyses. Each sample was analyzed twice for availa
ble P2O5 by the new direct extraction method, and by either of the AOA
C Official Methods using direct or indirect extraction. Results were f
avorable for the new direct extraction method even though the range an
d types of samples were highly variable. The direct extraction method
was adopted first action by AOAC INTERNATIONAL.