Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: irisz on July 25, 2006, 10:03:05 AM
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hi everyone
i am trying to find the right way for measuring organic phosphorus (effluents and soil leachates originated) in ICP-AES. so far i learned that i can't get a reliable full result by just a straight forward measurement.
does any body know of the right pre-treatment ?
i suspect autoclaving should be the direction but still need the right "prescription" that won't harm the ICP itself (too much persulfate might).
thaks a lot for any help
iris
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The articles that I have read indicate that organophosphorus compounds should be nearly quantitatively oxidized into water soluble species with typical oxidizing acids (nitric / sulfuric). The problems typically described revolve around partial volatilization of the phosphorous (ie systematically low values reported because part of the phosphorus goes airborne during digestion). This is usually circumvented by doing a Parr bomb oxidation or closed cap Teflon microwave oxidation to minimize volatilization losses.
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thank you for your answer. did you refer in your answer to an oxidizing step ahead of use of icp-aes or just pre treatment for measuring (colourimetrically, for instance) P-total ?
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Phosphorus in organic matrix can be measured directly with ICP-OES with out digestion. You can just dilute the sample with kerosene/xylene and you must have your standards in oil (available easily). Search in google for application notes from manufactures of ICP-OES. Give the key word "analysis of biodiesel using ICP-OES". Don't get confused with biodiesel. After all you will set up the method in a similar manner.