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Old 09/12/2014, 12:57 AM   #51
Azmanjim
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Originally Posted by acorral View Post
It is ICP-OES
Same thing


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Old 09/12/2014, 01:11 AM   #52
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I saw a link on facebook talking about this method and decided to do some research on the subject...

As someone who has spent lots of time and money trying to determine trace element concentrations below 10ppb or even below that for some elements, I can tell you that unless they have found a new cutting edge method for removing chlorides from the samples it is impossible. Even with machines that cost hundreds of thousands of dollars. I don't see anywhere that they describing their detection limits for these elements in seawater and I'm guessing if result falls below the detection limit is converted to 0.0 ppb. (when it should read < X.XX ug/l) .Without them showing their quality control testing with replicates of a known sample they are just measuring backgound noise.

J
I believe the LODs in this circumstance are derived from a salt water matrix?? But I can ask if you would like. Out of interest, how much money have you spent?? It would suck if you could have just spent $50 right!!? Haha

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i assumed to be simplistic- that that's the level detected , and that the margine of error was 1.2 to 3.5 ppb

or am i mistaken
Yes, but such a presentation would never survive in a peer reviewed publication. I doubt most users would even read the LOD discussion.

It seems very misleading to say 0.00 in the measurement column and be comparing it to 0.01 ppb for "subtraction" when it really means up to 3.5 ppb in the actual measurement. It could actually be way above or way below that target subtraction value of 0.10 ppb.

It ought to read:

<3.5 ppb

compared to a seawater value of

<0.38 ppb (or 0.1 ppb, if you prefer that value)

So in that light, it isn't so revealing as it might first appear.

Perhaps it is too low, perhaps it matches NSW, or perhaps it is ten times higher than NSW.

Still a useful number if you understand the uncertainty, however.
Yet again, I think this is a problem with the website that needs to be worked over. Before the website was introduced, the figure would have been quoted below the specific LOD at that time. But I think it is at least credible that the LODs have been given as reference.

Many peer reviewed publications, might not even show LODs, accuracy, the machine actually used! Hence why I find it difficult to believe the numbers written in a lot of aquatic based blogs. Even if the references used were taken in the last 50 years!

Still I think 1-3 ppb is low enough to flag up some kind of copper contamination??


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Old 09/12/2014, 01:36 AM   #53
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Yes, but such a presentation would never survive in a peer reviewed publication. I doubt most users would even read the LOD discussion.

It seems very misleading to say 0.00 in the measurement column and be comparing it to 0.01 ppb for "subtraction" when it really means up to 3.5 ppb in the actual measurement. It could actually be way above or way below that target subtraction value of 0.10 ppb.

It ought to read:

<3.5 ppb

compared to a seawater value of

<0.38 ppb (or 0.1 ppb, if you prefer that value)

So in that light, it isn't so revealing as it might first appear.

Perhaps it is too low, perhaps it matches NSW, or perhaps it is ten times higher than NSW.

Still a useful number if you understand the uncertainty, however.
as i thought

however i do admit to not factoring this in when cross checking salt samples for exsample as to which is the purest for our use

human nature i guess!

though i do understand your points, ultimatly we are hobbiests, and though not perfect, its the best we have

i am not a triton user, i use my own 3 part which is the same thing only without a premium. I do not believe that runn8ng a tank based on the results of the icp, to tell you what potion of mainly chlorides to dose, or wether to water change is adviseable. it is also an expensive way af around the cost of 2/3rds of a bucket of salt.


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Old 09/12/2014, 01:51 AM   #54
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for me is a positive thing that some industry or lab make this kind of test at low prices (here cost less then 50$ shipped in germany)

not for the precision or for calibrate perfectly water like said someone..onlt to see if some unbalance are present or some toxic metals .. also No3 and PO4 are perfectly checked..


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Old 09/12/2014, 04:08 AM   #55
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Randy, based on your experience and chemistry knowledge on processes like this one, how much additive should I pour in the sample? I use your 2 part recipe 1 but I want to test it for impurities snd be able toncorrelate eith the results from my tank...
That is probably necessary so they can maintain roughly the same interferences, instead if trying to measure the other additives directly (which would give way lower detection limits but would be more work).

I'd boost calcium by 100 ppm and alkalinity by a few dKH.

The latter is very limiting in terms of understanding impurities, but if the alk is too high, calcium carbonate will precipitate, and potentially take impurities such as copper with it.


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Old 09/12/2014, 04:08 AM   #56
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for me is a positive thing that some industry or lab make this kind of test at low prices (here cost less then 50$ shipped in germany)

not for the precision or for calibrate perfectly water like said someone..onlt to see if some unbalance are present or some toxic metals .. also No3 and PO4 are perfectly checked..
I agree with that.


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Old 09/12/2014, 04:31 AM   #57
Azmanjim
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Originally Posted by justinzimm View Post
I saw a link on facebook talking about this method and decided to do some research on the subject...

As someone who has spent lots of time and money trying to determine trace element concentrations below 10ppb or even below that for some elements, I can tell you that unless they have found a new cutting edge method for removing chlorides from the samples it is impossible. Even with machines that cost hundreds of thousands of dollars. I don't see anywhere that they describing their detection limits for these elements in seawater and I'm guessing if result falls below the detection limit is converted to 0.0 ppb. (when it should read < X.XX ug/l) .Without them showing their quality control testing with replicates of a known sample they are just measuring backgound noise.

J
Ok so I have the answer and a better understanding. Chlorides will not affect the sample analysis at all. Neither will fluorides and most other halogens. The "energy" levels cannot be raised enough to emit a detectable source. Or words to that effect! Haha


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Old 09/12/2014, 11:53 AM   #58
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That is probably necessary so they can maintain roughly the same interferences, instead if trying to measure the other additives directly (which would give way lower detection limits but would be more work).



I'd boost calcium by 100 ppm and alkalinity by a few dKH.



The latter is very limiting in terms of understanding impurities, but if the alk is too high, calcium carbonate will precipitate, and potentially take impurities such as copper with it.

Thank you Randy

Regarding the impurities precipitation...

Wouldn't it be the same to have the copper binded to something than have it dissolved in water?

One guy at the audience at macna asked Ehsan Dashti if the composition of the sample wouldn't be altered due to bacterial consumption or some die-off on the one or two week shipping time frame, and he answered that it's just the same if there is something inside the vial dissolved or consumed by some bacteria, the same elements and amounts stay there...

How true is that?


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Old 09/12/2014, 12:07 PM   #59
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I don't know how they treat samples to know if precipitates are redissolved or not. Solids or bacteria stuck on the inside of the container will not get tested if not dissolved before an aliquot is withdrawn from it.

I agree that inside a bacteria or not, as long as it is suspended and not filtered off, is not a concern.


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Old 09/12/2014, 12:18 PM   #60
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I don't know how they treat samples to know if precipitates are redissolved or not. Solids or bacteria stuck on the inside of the container will not get tested if not dissolved before an aliquot is withdrawn from it.

I agree that inside a bacteria or not, as long as it is suspended and not filtered off, is not a concern.

Great Randy thanks..

I will be sending many samples:

1. Water from the tank
2. Water + Calcium additive
3. Water + Alk additive
4. Water + Mg additive
5. Fresh mix of Instant Ocean + 0tds water


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Old 09/12/2014, 12:31 PM   #61
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would it not be easier to contact the supplier of thd chemicals and ask for a typical coa?


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Old 09/12/2014, 12:45 PM   #62
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would it not be easier to contact the supplier of thd chemicals and ask for a typical coa?
Haha! Has that ever worked for you??


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Old 09/12/2014, 01:44 PM   #63
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Haha! Has that ever worked for you??
in the early days no

everything has specification, coa are a little harder to find


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Old 09/12/2014, 01:58 PM   #64
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in the early days no



everything has specification, coa are a little harder to find

Near impossible to find that information with mexican suppliers...


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Old 09/12/2014, 03:23 PM   #65
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Near impossible to find that information with mexican suppliers...
well bicarb and chloride are legal


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Old 09/18/2014, 10:05 PM   #66
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Just checked triton error correction guidelines but I cannot see nitrogen in there... Do anybody know if they actually test for nitrogen or nitrates?


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Old 09/19/2014, 03:08 AM   #67
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nitrate is tested on hplc not icp

along with fluoride and chloride


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Old 09/19/2014, 06:31 AM   #68
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Triton vs zeolit on 400l system !!

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nitrate is tested on hplc not icp

along with fluoride and chloride

Thanks Eyore, Do you know if those are part of triton testing service? Is it optional?

I see they do both test but not sure if they are part of the same "service" or not...


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Old 09/19/2014, 06:34 AM   #69
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Triton vs zeolit on 400l system !!

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Thanks Eyore, Do you know if those are part of triton testing service? Is it optional?

I see they do both test but not sure if they are part of the same "service" or not...

Just received confirmation on this from triton directly...

It is an additional test, costs the same and only tests for thise 3 things.


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Old 09/19/2014, 11:54 AM   #70
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a question for those who play with this kond of technology

why are these 3 elements not tested on icp like the rest? iodine is so why not other halogens
also wonder if nitrate is testable?

being honest i find the chloride reading of interest but from what i saw of hlpc results in the early days in the uk i could not trust the number nearly as much as sodium on icp.
fluoride is probably of a bit more consequence

in the early days i mentioned it was before icp was known to be available from triton, more was tested including calcium and magnesium and (probably if memory serves) potassium and strontium. I dont deny i was a little unimpressed by both the testing and the methods potential given this.


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Old 09/20/2014, 08:49 AM   #71
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You cannot distinguish nitrate by ICP from any other nitrogen-containing chemical, and you need a special method/instrument to remove N2 gas from the air and sample.


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Old 09/21/2014, 03:29 PM   #72
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I think I mentioned earlier the conversation I had with Ehsan about chloride and ICP. The same goes for fluorine. Apparently they cannot be raised in energy level enough to emit a clearly detectable "emission," for want of a better word. I imagine total nitrogen is testable because it is elemental. I'm pretty sure mitrate would be split in nitrogen and oxygen. It would be difficult to distinguish these accurately just from the air that is in the sample I imagine!


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Old 09/21/2014, 03:30 PM   #73
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Oh there you go Randy already answered that one


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Old 09/22/2014, 03:44 AM   #74
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I think I mentioned earlier the conversation I had with Ehsan about chloride and ICP. The same goes for fluorine. Apparently they cannot be raised in energy level enough to emit a clearly detectable "emission," for want of a better word. I imagine total nitrogen is testable because it is elemental. I'm pretty sure mitrate would be split in nitrogen and oxygen. It would be difficult to distinguish these accurately just from the air that is in the sample I imagine!
yes bit of a speaking before i thought it through on the nitrate tbh


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