Parameters changes in mail - ICP
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Righteous
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My understanding is that nothing will change. ICP uses plasma to ionize the sample (ie tear apart the molecules) and then measures individual elements. So even if there are chemical reactions occurring in the sample during the 2 weeks, the element ratios will remain fixed.
As @Righteous stated - ICP analyse chemical elements not chemical compounds - therefor transport in a closed vial will not change the measurement (if it not contain radioactive elements) even for 1000 years or more.
Sincerely Lasse
Sincerely Lasse
Righteous
Well-Known Member
I was reading a little more actually, and the one thing I started to wonder about was that I believe @Randy Holmes-Farley said they do centrifuge the sample to remove particulates. Is it possible that biotic activity might occur like uptake of phosphorus, etc during transport, and then those bacteria get removed from the sample?
flagg37
Custom stair builder - TreeofLifeStairs.com
This came up in another thread. Someone was seeing very different po4 results from their test kit at home vs the ICP results. The question was if the vial could absorb some of the po4. I don’t think it was definitively answered.
IMO - Its limited oxygen in the vial - this means that the fast biological reactions are very limited. The bacteria activity will happens mostly on the organic particles - this means that if something will be altered at all - it will be a release of P or N into the water instead. But aquarium water is normally very low in particles but if they analyse without centrifuge the samples the fault reading will be larger
2 remarks. You do not know which test is right - the hobby test or the more professional test. IMO - I relay more on a ICP test compared with a Hanna test.
ICP analyse elementary P and N. If Triton report a PO4 figure - they have assumed that all detected elementary P is in the form of PO4
Sincerely Lasse
flagg37
Custom stair builder - TreeofLifeStairs.com
That’s pretty much what was discussed in the other thread. Everyone was leaning towards the icp being correct but there was no way to know if the po4 was absorbed by the container. The icp would have tested correctly for what was in the vial but if the vial absorbed an unknown amount in the two weeks it was sitting in it then it still makes the results inconclusive.
The vials that I’ve seen are high density polyethylene which does a pretty good job of not reacting with what it touches but I’m not an expert on it. If it is absorbing po4 it begs the question of if there are other things that it’s possible for it to absorb too.
An dense inert material (plastic with no electrical potential) with water containing different ions (with different electrical potential) that will be high speed centrifuged before a sample will be taken - how in the whole word could a positive charged ion stick to its walls? At least I want to have at least a theoretical explanation how this can happen before I start to speculate.
If it was waste water - I could believe that biological activities could change some parameters (rise some and decrease some) but in a water with low BOD (as water from a salt water tank) - no chance IMO
Sincerely Lasse
If it was waste water - I could believe that biological activities could change some parameters (rise some and decrease some) but in a water with low BOD (as water from a salt water tank) - no chance IMO
Sincerely Lasse
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My concern is in an oxygen deprived environment when anerobic bacteria consume any remaining po4 and no3. They turn that into biomass. Then if centrifuged the bacteria wouldnt be in the icp analysis along with any po4 they took with them. So you might get a lower po4 reading for that.
IMO If something happens at all it will be that anaerobic bacteria break down organic particles and release inorganic P and N instead. To grow on the sides of the vial during some weeks they need plenty of DOC in the water because their growth is normally carbon limited. Our tank water is normally very low in DOC.
Sincerely Lasse
Sincerely Lasse
YankeeTankee
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Several youtubers as well as reefers I know have sent in ICP tests to the various companies and received substantially different results, the water was collected at the same time, same place. What could be the cause of this? With these findings you simply cannot trust the results.
There's are other threads on this including: https://www.reef2reef.com/threads/icp-analysis-comparison.326951/
There's are other threads on this including: https://www.reef2reef.com/threads/icp-analysis-comparison.326951/
Paul Howard
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Yes, what the heck?
Randy Holmes-Farley
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I think they do not drop enough to be important in most cases. I asked triton to do some freezing studies and they survived that Ok.
Randy Holmes-Farley
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That is not necessarily from the shipping. Do not blindly assume all such tests are adequate.
Righteous
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Resurrecting an old thread since my ICP P04 numbers are always 3x lower than my Hanna and got me thinking.
Anyone tried sterilizing the sample before shipping to rule out biotic processes?
Was thinking of using something like this as a test?
Anyone tried sterilizing the sample before shipping to rule out biotic processes?
Was thinking of using something like this as a test?
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PO4 is the most likely element to change (decrease) during storage and shipping. The formation of a biofilm on the sample tube inner surface is a possible explanation. Iron and silica are another two elements that might also be affected by storage. Contact @Rick Mathew for the latest on this subject.
Rick Mathew
Valuable Member
Interesting Idea...I just put 7 ppm Chlorine in my samples and that did the trick ...There is the concern that the chlorine could interfere with other measurements...here is the work that I did to answer the exact same question you have..... https://www.reef2reef.com/ams/sample-storage-and-its-impact-on-measurement-results-part-3.800/ This is part 3...... links to the first two are in this article
Righteous
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Look like a great read… going to dig into that tonight!
If I try a sterilization test I’ll make sure to post. I’m thinking of sending in two samples to Triton, both taken at the same time (one on a “test” aquarium) to compare readings and see any possible effect. Might also consider doing the same with one of the NDOCs just for fun.
Rick Mathew
Valuable Member
Just a word of warning...The results have the potential of turning you into a skeptic
...but you will be in good company...
