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Because saltwater or high tds aqueous solutions will block up the flow into the ICP so a dilution is required, unless you are specifically set up to run those matrixes. But even then you will dirty up and require more pm on the parts (nebulizer, torch, etc.) leading in to injection.
You also typically want to match the solvent matrix between samples and standards. Typically you can choose the matrix or have custom made but 2% nitric is the most common, which I hope your tank (sample) is not close to.
There was a long discussion here between Triton and some others (e.g., Richard Ross and Craig Bingman) about the method details, and Triton does not use a standard method,and does not acidify the samples.
There was a long discussion here between Triton and some others (e.g., Richard Ross and Craig Bingman) about the method details, and Triton does not use a standard method,and does not acidify the samples.
Interesting. It is unfortunate that it seems to be a secret. I would like to see the paperwork on the development and qualification / verification.
Ehsan said they spent a great deal of time optimizing the method for seawater before they commercialized it, so they don't want to just give it away to copycats that are already entering the market.
That said, they do show standard curves and the LOD for most elements:
https://www.triton-lab.de/fileadmin/user_upload/triton-lab/TRITON_LOD.pdf
Sorry to unearth such an old post, but I'm curious about this.
In the lab I work, whenever we have to store samples for stuff like No2, No3 and others we always preserve them. Either by filtering through a 0.2 micron filter, by acidification or at least freezing them. The main point is to stop bacterial growth that would ruin the sample.
However icp test kits are just sent raw. How can this be precise? Anyone ever got a answer from any of the icp providers regarding this?
@Randy Holmes-Farley @Cory @Lance M.
Hi Randy.Well, it depends a bit on how the samples are treated, but remember the chemical form doesn't matter for ICP, so bacterial conversion from one form to another makes no difference. Nitrogen is not sampled anyway since N2 from the air would interfere, but phosphate or certain trace elements might be taken up by bacteria and later centrifuged out as whole bacteria if that is how it is processed before testing. We aren't really privy to the processing techniques despite asking. I'm not sure how significant this is, but it is a possible issue.
Hi Randy.
Thanks for the answer.
While it makes very much sense, in a trial i'm currently running I have seen bacteria numbers and activiti doubling in about 3 hours in samples kept in the fridge after being collected from aquaculture system (much higher organic content). In the icp case there are at least two or three days for bacteria to grow, much more in some cases.
While I image a lot of chemical compounds will not change, I could imagine large changes to organic components, and in an extreme even dinitrification happening (depending on loading, oxygen conditions and transportation time).
Maybe I'm overthinking this, but I find it weird that samples can be kept unpreserved for so long and still deliver accurate results across so many parameters.
I guess thats a fair point Miller professional stress I guessI am no chemist, but I think most of us sending ICP in are looking for contaminants like heavy metals, and salt values (cal, mag, and so forth). I wouldn't think bacteria would impact that much if at all. I would wonder more if their N-doc was affected by bacteria then their standard ICP test.
I guess thats a fair point Miller professional stress I guess