Accuracy of Phosphate ICP analysis

https://www.triton.de/en/
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BigJohnny

BigJohnny

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Thanks for the info, however The vials used are non reactive with seawater or constituent elements. (Confirmed long ago with Triton). The vendor you mentioned earlier had claimed that Trident was more accurate than an ICP as the Ca value varied between a Trident test and the ICP, so when you mentioned Trident, I assumed this to be the same source of “info”... :)

You can easily verify this (if ultra paranoid) by noting the manufacturer or plastics code on the vials and verifying reactivity.

Sometimes we over think things massively. An ICP is going to be more accurate than a hobbyists’ home test kit.

A valid cause of variation however, would be the presence of different compounds containing Phosphorus, which would skew the results when you perform the PO4 calculation, as it assumes all phosphorus is bound in PO4. Examples of this could be various forms of inorganic phosphorus, which are generally in particulate suspension. In the reef tank, a possible source would be flocculate from Lanathium Chloride dosing.

A 0.2um filter can used to remove such particulate matter prior to the sample being nebulised in the ICP-OES.

Merry Christmas to you, hope you enjoy some great time with the family.
Guess you didnt read the part where I said "not interested in debating this further". I didnt read your response, sorry
 

cjpitt80

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There is no doubt that certain plastics can absorb phosphate, that is a fact. Whether or not the triton icp vials are made of those plastics or not, I do not know.
This is also another variable as there are no "Triton ICP" vials. They use industry standard centrifuge tubes. I've had some from BD Falcon (Orange caps) and others from Eppendorf (Blue caps). They are both polypropylene and I assume the manufacturing can't be but so different, but again it's another variable. I guess the real question is to what degree (if any) polypropylene adsorbs phosphate in Sea water. I've done this test and noted no difference. I'll repeat again and record results
 

cjpitt80

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Following up on this, I got a Red Sea Phosphate Pro kit and it seems to be more in line with what my last Triton ICP test was reading (back in Oct). I also tested RODI with new filters and resin. Hanna read 0.04 whereas Red Sea was 0. So again in my system for some reason the Hanna definitely reads higher, but I'm more apt to believe Red Sea/Triton now
 

Lasse

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Following up on this, I got a Red Sea Phosphate Pro kit and it seems to be more in line with what my last Triton ICP test was reading (back in Oct). I also tested RODI with new filters and resin. Hanna read 0.04 whereas Red Sea was 0. So again in my system for some reason the Hanna definitely reads higher, but I'm more apt to believe Red Sea/Triton now
Interesting - A friend of mine that´s doing some research about different hobby tests and compare both with known standards, spiking samples and between ICP and hobby tests report the same about Red Sea Phosphate Pro and Hanna. I have order such a test too.

Sincerely Lasse
 

Rick Mathew

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Following up on this, I got a Red Sea Phosphate Pro kit and it seems to be more in line with what my last Triton ICP test was reading (back in Oct). I also tested RODI with new filters and resin. Hanna read 0.04 whereas Red Sea was 0. So again in my system for some reason the Hanna definitely reads higher, but I'm more apt to believe Red Sea/Triton now
Something to think about with regard to comparing ICP test results with results from any test method you do at home...See Link Below...We are still working on some of the questions posed at the end of this post...hope to have updates soon

 

cjpitt80

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Something to think about with regard to comparing ICP test results with results from any test method you do at home...See Link Below...We are still working on some of the questions posed at the end of this post...hope to have updates soon

That's awesome research, thanks! I'm still more apt to believe the Triton/Red Sea results since they appear to be closer and what I would have expected given the Phosphat-E dosing. Plus, the Non zero reading on RODI
 
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