Inland Reef / Reefs.org Salt Analysis Project
- Thread starter MattM
- Start date
John -
We will rely on published studies for NSW composition. We will include an NSW sample in the test, but only as a test control on the lab - not for comparison to ASW.
I have asked Eric to look up a couple NSW analyses from literature that we will use for comparison. Where those came from depends on what studies are uncovered by Eric.
We will rely on published studies for NSW composition. We will include an NSW sample in the test, but only as a test control on the lab - not for comparison to ASW.
I have asked Eric to look up a couple NSW analyses from literature that we will use for comparison. Where those came from depends on what studies are uncovered by Eric.
randy holmes-farley
Advanced Reefer
- Location
- Arlington, MA
Some comments:
1.
Wouldn't it be funny if the differences that Ron saw had nothing to do with metals, but rather one of the many other possibilities, such as ammonia, nitrite, organics, etc. etc? Well, actually it wouldn't be funny. Unfortunately, this protocol won't get at the biological differences. I don't think simple testing of more salt mixes will either. Perhaps that is something that can be pursued in other ways in other studies.
2.
I would advise again to test NSW in addition to the RO/DI water. Without both, you will never know whether any elevated metals that you see came from the salt mixes themselves, or from some artifact of the methodology, such as the sampling implements, the mixing containers, the sample bottles, or some artifact in the ICP-MS testing itself. Scientists were mislead for many years by impurities arising from their handling of NSW samples. I think it is a mistake to think that a bunch of folks who have never done anything like this before won't suffer the same problems (whatever they may be). Even if the folks involved were to read in detail how these studies need to be done, whether or not their first tries at something difficult will succeed is an open question. I don't know what is involved, but when I read words like "Ultraclean room techniques" in "Chemical Oceanography" that does not sound like something that aquarists can whip up in a back room somewhere. This is why I did not respond to Bill's question about how to collect samples: I don't know.
Sending the RO/DI water will help a lot, but not necessarily solve this problem, especially since we are not sure exactly where the problems will come from.
Comments more specifically on the protocol:
3.
Mix each with RO/DI water to a s.g. of 1.025.
Why pick a vlaue below nsw salinity? I'd use a calibrated conductivity probe, and aim for 53 mS/cm (35 ppt salinity). Alternatively, a refractometer will do, but again pick NSW salinity.
Without knowing that otherwise is OK, I'd mix the solutions in teflon containers and send them in teflon bottles, since teflon bottles have specifically been mentioned as suitable. If someone finds that something else is suitable, then that will be fine, but I don't know at this point. Teflon is quite expensive, and will icnrease costs for the study.
I would not let the samples contact anything made of glass or metal.
4.
Make the initial mix a little high in s.g. so that we can adjust to 1.025 by adding water, not salt. This should improve consistancy somewhat.
I'm not sure why you'd want to do that. If you are tallking about mixing to 36 ppt and then diluting to 35 ppt, that would be OK, but if you are talking about 40 ppt or more, taht risks precipitation of things that might otherwise stay in solution.
5.
Stir until thouroughly dissolved and measure initial pH.
Continue to peroidically stir and let sit to allow any precipitates to settle.
Any aeration at this step? Some salt mixes initially mix to very high pH. Without aeration, the high pH may accelerate the precipitation of things, and result in artificial differences between brands just based ont eh initial pH.
6.
It is easy to get tables of NSW elements. We posted them in Ron's magazine author forum during one of the discussions about Ron's initial test results on aquaria:
http://reefcentral.com/forums/showthrea ... adid=61689
1.
Wouldn't it be funny if the differences that Ron saw had nothing to do with metals, but rather one of the many other possibilities, such as ammonia, nitrite, organics, etc. etc? Well, actually it wouldn't be funny. Unfortunately, this protocol won't get at the biological differences. I don't think simple testing of more salt mixes will either. Perhaps that is something that can be pursued in other ways in other studies.
2.
I would advise again to test NSW in addition to the RO/DI water. Without both, you will never know whether any elevated metals that you see came from the salt mixes themselves, or from some artifact of the methodology, such as the sampling implements, the mixing containers, the sample bottles, or some artifact in the ICP-MS testing itself. Scientists were mislead for many years by impurities arising from their handling of NSW samples. I think it is a mistake to think that a bunch of folks who have never done anything like this before won't suffer the same problems (whatever they may be). Even if the folks involved were to read in detail how these studies need to be done, whether or not their first tries at something difficult will succeed is an open question. I don't know what is involved, but when I read words like "Ultraclean room techniques" in "Chemical Oceanography" that does not sound like something that aquarists can whip up in a back room somewhere. This is why I did not respond to Bill's question about how to collect samples: I don't know.
Sending the RO/DI water will help a lot, but not necessarily solve this problem, especially since we are not sure exactly where the problems will come from.
Comments more specifically on the protocol:
3.
Mix each with RO/DI water to a s.g. of 1.025.
Why pick a vlaue below nsw salinity? I'd use a calibrated conductivity probe, and aim for 53 mS/cm (35 ppt salinity). Alternatively, a refractometer will do, but again pick NSW salinity.
Without knowing that otherwise is OK, I'd mix the solutions in teflon containers and send them in teflon bottles, since teflon bottles have specifically been mentioned as suitable. If someone finds that something else is suitable, then that will be fine, but I don't know at this point. Teflon is quite expensive, and will icnrease costs for the study.
I would not let the samples contact anything made of glass or metal.
4.
Make the initial mix a little high in s.g. so that we can adjust to 1.025 by adding water, not salt. This should improve consistancy somewhat.
I'm not sure why you'd want to do that. If you are tallking about mixing to 36 ppt and then diluting to 35 ppt, that would be OK, but if you are talking about 40 ppt or more, taht risks precipitation of things that might otherwise stay in solution.
5.
Stir until thouroughly dissolved and measure initial pH.
Continue to peroidically stir and let sit to allow any precipitates to settle.
Any aeration at this step? Some salt mixes initially mix to very high pH. Without aeration, the high pH may accelerate the precipitation of things, and result in artificial differences between brands just based ont eh initial pH.
6.
It is easy to get tables of NSW elements. We posted them in Ron's magazine author forum during one of the discussions about Ron's initial test results on aquaria:
http://reefcentral.com/forums/showthrea ... adid=61689
Hi guys:
Yes, those links and references have been listed and are available as Randy stated. I'll be happy and pull them and send them to you, if you want, or if Randy has them, he can send them, too. Alternately, we can just use the information as already presented. I may be mistaken, but I beleive Ron had them in one of his articles already, too...I can go back and check.
Yes, those links and references have been listed and are available as Randy stated. I'll be happy and pull them and send them to you, if you want, or if Randy has them, he can send them, too. Alternately, we can just use the information as already presented. I may be mistaken, but I beleive Ron had them in one of his articles already, too...I can go back and check.
Oh, and just in light of the NSW sampling idea, You would definitely want to run any water through a 0.5 micron Millepore or even smaller immediately after collection to remove any phytoplankton or bacteria (or particualtes) that would could and should take up dissolved organic and inorganic material from the water and seqester, metabolize, excrete it, in addition to any of the same that woudl could and should die and be decomposed and becasue these critters are quite "leaky" and may release materials not originally in the sewater and whcih are typically found a 10000 to 1000000 cells/ml in NSW, higher in coastal areas! Hence why I am in agreement that NSW is not something that should probably be taken on, esepcially since the data is available.
Randy Holmes-Farley":2h3mel1q said:
This is why I said earlier that we need to be careful about any conclusions from these analyses, or the earlier studies.
On the potential contamination of samples, be sure to use solvent and then acid washed polyethylene bottles for the samples. Polyethylene will not leach phthalates, byproducts of plastic production, into the solutions. Phthalates interfere with organics analyses, but not likely with metals analyses....but you never know. Do not use glass containers for mixing salt solutions or transporting the samples if metals are the target analytes. Metals will be adsorbed by the glass, thereby lowering the metal content.
Randy Holmes-Farley":ob7iln1l said:
That's exactly what we plan to do. We will use published data for comparison to the other salts, but we will include both NSW and RO/DI in each batch in order to identify problems like you mention.
Randy Holmes-Farley":ob7iln1l said:
Will do.
Randy Holmes-Farley":ob7iln1l said:
kazzoo":ob7iln1l said:
Which is it?
We had planned on using polyethylene throughout testing and shipping to lab. Are there reasons that polyethelene should be avoided in favor of teflon?Randy Holmes-Farley":ob7iln1l said:
You got it.
Randy Holmes-Farley":ob7iln1l said:
I was trying to avoid adding small amounts of salt to adjust salinity to the target value. But if we get a homogeneous sample and it is well mixed, perhaps this will not be a problem. We will attempt to get as close to the target salinity as possible in the initial mix.
Randy Holmes-Farley":ob7iln1l said:
Good point, but I was trying to avoid adding another variable - how do you ensure that each sample receives identical aeration? Or perhaps as long as they all get roughly the same it won't matter? Not sure.
Randy Holmes-Farley":ob7iln1l said:
Thanks, I will check.
randy holmes-farley
Advanced Reefer
- Location
- Arlington, MA
No, telfon is polytetrafluoroethylene, and I mentioned it just because it is the one described in Millero's book "Chemical Oceanography" that has successfully been used. I don't know if poleyethylene itself has enough metals in it to be a problem. Some polymerization catalysts are metals, but I don't know if that is the concern or not. Maybe it is just because of leachable organics from normal polyethylene.
No, you cannot weigh out the salt because they have moisture in them as well as salt. Using 35 g of salt mix to make 1 kg of fluid will result in salinity below 35 ppt. Different mixes will have different amounts of moisture, as Craig showed (IIRC) in his study.
No, you cannot weigh out the salt because they have moisture in them as well as salt. Using 35 g of salt mix to make 1 kg of fluid will result in salinity below 35 ppt. Different mixes will have different amounts of moisture, as Craig showed (IIRC) in his study.
I know that we never, well should have never, used any solvent rinse bottles that were anything other than polyethylene because of phthalate contamination. Phthalate esters really interfere with quantification of other organics because of co-elution. I'm not as familiar with metals analysis. However, I've been told to use clear plastics for sampling metals. The teflon and polyethylene will minimize organics contamination of the samples. The containers should be rinsed with solvent and then acid before use in any case to remove potential contaminants.
John -
No. But that really doesn't matter. If you read Randy's post about this:
The purpose of including an NSW sample is a check on the procedure, not for comparison to the ASW samples. I.e., we know from published studies that there should not be large amounts of copper in NSW. So if we show high copper levels in the NSW and RO/DI samples, it may indicate we have contaminated the sample set. Of course, we will try to ensure that the NSW sample is as pollution-free as possible -- we won't be getting it from Boston harbour!
Since we will use published data for our NSW comparison, it is really irrelevant if the NSW control sample comes from a reef or not.
No. But that really doesn't matter. If you read Randy's post about this:
The purpose of including an NSW sample is a check on the procedure, not for comparison to the ASW samples. I.e., we know from published studies that there should not be large amounts of copper in NSW. So if we show high copper levels in the NSW and RO/DI samples, it may indicate we have contaminated the sample set. Of course, we will try to ensure that the NSW sample is as pollution-free as possible -- we won't be getting it from Boston harbour!
Since we will use published data for our NSW comparison, it is really irrelevant if the NSW control sample comes from a reef or not.
- Location
- Holland/Germany
It is a lengthy thread and I might have missed some things. So sorry if it has been mentioned before.
Has the lab sufficient experience and know-how how to deal with seawater samples?
That is will they be measuring the right isotopes?
With ICP-MS there are many false positive interferences due to e.g. combinations of some elemenents with the carrier gas. I assume and hope that they will be highly alert and will indicate this for each sample and element.
It might be wise to have a blank run between each different brand salt sample. This to check for memory effects.
They should also remeasure the calibration solution and check how the response is. A calibration solution will usually contain several elements.
Also it might be wise to have the "check sample" run before everything else is measured. If the check samples deviate then it might be wise not to have the other samples measured, it could otherwise be a waste of money.
Has the lab sufficient experience and know-how how to deal with seawater samples?
That is will they be measuring the right isotopes?
With ICP-MS there are many false positive interferences due to e.g. combinations of some elemenents with the carrier gas. I assume and hope that they will be highly alert and will indicate this for each sample and element.
It might be wise to have a blank run between each different brand salt sample. This to check for memory effects.
They should also remeasure the calibration solution and check how the response is. A calibration solution will usually contain several elements.
Also it might be wise to have the "check sample" run before everything else is measured. If the check samples deviate then it might be wise not to have the other samples measured, it could otherwise be a waste of money.
I didn't see this mentioned earlier.
It is common when collecting environmental samples for analysis to include an "equipment blank". Basically a sample of D.I. water that has been placed through a similar set of processes as were used to collect/prepare the other samples. For this project an equipment blank could be D.I. water placed in the same type of mixing container as those used to mix the saltwater batches and stirred or agitated in a similar fashion then placed in a sample bottle. Equipment blanks are used to help indicate whether any contamination has occurred due to the sampling equipment.
I realize there has been a lot of discussion about QA/QC samples (trip blanks, equipment blanks, replicates, etc.). However, when dealing with things that are, by definition, in trace quantities one has to be very diligent.
Also, what type of gloves should be used when preparing the saltwater batches and samples? Mixing containers, eyedroppers, stirring rods, etc.? Contact with each of these items could potentially contaminate the samples.
Not to put a damper on the party but all of this work and expense will only be good until the day an ASW manufacturer puts a sticker on a bag of salt that says "NEW FORMULATION - FEWER TRACE MINERALS!".
-Lee
It is common when collecting environmental samples for analysis to include an "equipment blank". Basically a sample of D.I. water that has been placed through a similar set of processes as were used to collect/prepare the other samples. For this project an equipment blank could be D.I. water placed in the same type of mixing container as those used to mix the saltwater batches and stirred or agitated in a similar fashion then placed in a sample bottle. Equipment blanks are used to help indicate whether any contamination has occurred due to the sampling equipment.
I realize there has been a lot of discussion about QA/QC samples (trip blanks, equipment blanks, replicates, etc.). However, when dealing with things that are, by definition, in trace quantities one has to be very diligent.
Also, what type of gloves should be used when preparing the saltwater batches and samples? Mixing containers, eyedroppers, stirring rods, etc.? Contact with each of these items could potentially contaminate the samples.
Not to put a damper on the party but all of this work and expense will only be good until the day an ASW manufacturer puts a sticker on a bag of salt that says "NEW FORMULATION - FEWER TRACE MINERALS!".
-Lee
Here's the current tally of the donations:
Direct donations received: $645.00
Received from Reef Central: $1300.00 (Check is in the mail from John)
Spent so far on testing: $0.00
Remaining funds available: $1945.00
Next update: Friday, 28 March (No Sooner, No Later :wink
Direct donations received: $645.00
Received from Reef Central: $1300.00 (Check is in the mail from John)
Spent so far on testing: $0.00
Remaining funds available: $1945.00
Next update: Friday, 28 March (No Sooner, No Later :wink
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