What is the alternative of potassium antimonyl tartrate that can we add in the reaction for the detection of phosphate in the molybdenum blue method (Murphy and Riley, 1962) ?
Ascorbic acid and heat (boiling). It is/was to determine Phosphate in steel.
As I recall (its been 30 years), take your sample add a high concentration of ascorbic acid (~1g) and boil for 10 minutes. Sample will turn blue. Measure spectrophotometrically at 630 nm.
A Quantitative method to determine the amount of phosphate present in samples such as boiler feedwater is as follows. A measured amount of boiler water is poured into a mixing tube and ammonium heptamolybdate reagent is added. The tube is then stoppered and vigorously shaken. The next step is to add dilute stannous chloride reagent, which has been freshly prepared from concentrated stannous chloride reagent and distilled water, to the mixture in the tube. This will produce a blue color (due to the formation of molybdenum blue) and the depth of the blue color indicates the amount of phosphate in the boiler water. The absorbance of the blue solution can be measured with a colorimeter and the concentration of phosphate in the original solution can be calculated. Alternatively, a direct (but approximate) reading of phosphate concentration can be obtained by using a Lovibond comparator. This method for phosphate determination is known as Deniges' method.[1] [2] [3]
https://en.wikipedia.org/wiki/Phosphate_test
In Heinnonen 1981, he used Ammonium molybdate, Acetone, H2SO4 and Citric acid to determine Pi in sample.
The Ascorbic acid method, usually Ammonium molybdate, H2SO4 , Ascorbic acid and antimonyl tartrate .
Bruce Neagle, How can I replace antimonyl tartrate by Ascorbic acid ?
Try using or adapting this method.
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1541&context=usdaarsfacpub
In short the method you use depends on your sample matrix, but in all cases the P must be in the form of ortho-phosphate (not meta). Also, you are forming a phosphomolybdate complex and then reducing it to molybdenum blue complex.
Bruce , What do you think about this method , please ?
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.457.40&rep=rep1&type=pdf
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