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Phosphate Determinations in Waters Using an Anion Exchange Resin
Author(s) -
Blanchar R. W.,
Riego Domingo
Publication year - 1975
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1975.00472425000400010010x
Subject(s) - chemistry , phosphate , hydrolysis , ammonium molybdate , molybdate , pyrophosphate , elution , reagent , column chromatography , ion exchange resin , phosphoric acid , ion chromatography , chromatography , nuclear chemistry , inorganic chemistry , zinc , organic chemistry , enzyme
Amounts of water samples from 1 to 1000 ml were passed through 10‐cc columns of 100‐ to 200‐mesh Dowex 1‐X8 anion‐exchange resin. Orthophosphate was quantitatively removed from the water sample by the resin and could be eluted from the column with 25 ml of 1 M KCl. Phosphate in the 1 M KCl eluent was reacted with ammonium molybdate, extracted into isobutanol, reduced with SnCl 2 , and the optical density of the blue complex measured. The working range of the method was between 1 and 8 µ g of P. Arsenic does not interfere in the phosphorus determination if the phosphomolybdate complex is extracted into isobutanol before reduction with SnCl 2 . Pyrophosphate if present will be approximately 20% hydrolyzed and the hydrolyzed portion indicated as orthophosphate in the method described. An alternate elution procedure to separate and determine ortho‐, pyro‐, and tripoly‐phosphate eliminated condensed phosphate interference in the orthophosphate determination. Glucose‐1‐phosphate, glucose‐6‐phosphate, and glycero‐phosphate are removed from the column with the ortho‐phosphate fraction but are not hydrolyzed and indicated as ortho‐phosphate. Phytic acid phosphate and para nitrophenyl phosphate are not leached from the column with KCl and do not interfere. Analysis of water samples indicated that in the 1 to 20 ppb P range an appreciable amount of the phosphate exists as pyro‐ and tripoly‐phosphate. The resin method is not specific for dissolved orthophosphate in water, but may give a more valid estimate than direct reaction with the acid molybdate reagent.