ICP-MS measurement of Seawater Certified Reference Material

Randy Holmes-Farley

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Is it possible to balance Phosphorus with Phosphate? I’ve noticed a lot of ICP analysis reveal a ratio that appears to be unbalanced on most tanks according to the normal levels provided by the analysis.

What do you mean balanced? There's no preferred ratio and I don't think your values are even independent measurements. I suspect they are just P x 3.06 = phosphate because phosphate weighs 3.06 times as much as phosphors.
 
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What do you mean balanced? There's no preferred ratio and I don't think your values are even independent measurements. I suspect they are just P x 3.06 = phosphate because phosphate weighs 3.06 times as much as phosphors.
Yes we know there are only taking the Atomized Phosphorus and calculating the Phosphate, but according to these ICP analysis there’s apparently “ideal” or “normal seawater values” so wouldn’t it be possible for these to be unbalanced or “out of range”? If you had a phosphorus level of 200 and a PO4 level of 0 to me that would indicate too much phosphorus and depleted PO4 or vice versa. I’ve noticed a lot of tanks doing much better when their results were closer to the analysis set points on both Triton and ATI.
 

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We do measure total phosphorus (via ICP-OES or ICP-MS, depending on which method the customer chooses) and also orthophosphate (PO4) using a photometric method based on the molybdenum blue/ascorbic acid method. We are using a Shimadzu Lab photometer with 4 cm optical path to have low detection limits. We do not calculate a phosphate value from the ICP data.

Phosphate is not very sensitive on ion chromatography (since it has a low specific conductivity), thus IC is not very useful for detection of phosphate in reef tanks. Photometry is the superior method in this case.

In case of higher phosphate levels total phosphorus and orthophosphate often agree very well - so most of the phosphorus in the sample is actually phosphate. This is not always the case, especially at lower nutrient levels, where a significant proportion of total phosphorus can be something else (might be oligophosphates or DNA or other phosphorus containing molecules).
So now that we have OCEAMO for independent measurements would it make sense to look more closely at these measured values and would there be a way to bring them closer to the set points?

I know for sure I can target a PO4 level exactly where I want it within a few ppm.

Phosphorus is a different story since I can only measure inorganic phosphate with my limited hobby grade equipment and even if I had a ICP in house for Atomized phosphorus measurement…what would I do if the phosphorus was depleted since apparently there is no form of phosphorus that is reef safe or able to be dosed! So what is the point of looking at the value with a set point! Is it so we can know what we cannot do and wish we could? :yawning-face: :) My gosh! You guys are leaving me with no options! :grinning-face-with-sweat:
 

Randy Holmes-Farley

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Yes we know there are only taking the Atomized Phosphorus and calculating the Phosphate, but according to these ICP analysis there’s apparently “ideal” or “normal seawater values” so wouldn’t it be possible for these to be unbalanced or “out of range”? If you had a phosphorus level of 200 and a PO4 level of 0 to me that would indicate too much phosphorus and depleted PO4 or vice versa. I’ve noticed a lot of tanks doing much better when their results were closer to the analysis set points on both Triton and ATI.

I think there is still confusion. Analysis set points are ONLY what the icp company thinks is good for phosphate, whether they show it as P or PO4, or both. No one is making recommendations for types of phosphate other than inorganic phosphate.

I agree that if there were any tanks with significant organic phosphate, that could be a good learning experience, but like Triton’s organic determinations, it’s only useful if it is known to correlate with something a reefer cares about. Right now that info is not known as far as I know.
 

Hans-Werner

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If you had a phosphorus level of 200 and a PO4 level of 0 to me that would indicate too much phosphorus and depleted PO4 or vice versa.
This is not possible. In the biosphere and on earth generally nearly all phosphorus is phosphate. So the calculatory conversion with the factor 3.06 Randy suggested is generally applicable.

In analysis there are other differences that shine up as possible differences between wet-chemical and ICP-results. Test kits and photometers both only show reactive phosphate or ortho-phosphate while ICP will also show phosphate esters, polyphosphates and other phosphates with pyrophosphate bonds, that test kits and photometers don't show. However this has nothing to do with phosphorus vs. phosphate. It is just phosphates with different bonds.

ICP results show all phosphates (total phosphate) which in general are also bioavailable. This is an advantage but we do have little experience with the concentrations of total phosphate.

Test kits and photometers only show orthophosphate which may be as little as 10 % or as much as 90 % of total phosphate according to my own few experiences and reported results after a digestion process. However, these are concentrations with which we have experiences and which we have learned to judge.

Nevertheless I think the ICP results are more valuable and I would rate them higher if they are similar exact as photometer results.
 
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This is not possible. In the biosphere and on earth generally nearly all phosphorus is phosphate. So the calculatory conversion with the factor 3.06 Randy suggested is generally applicable.

In analysis there are other differences that shine up as possible differences between wet-chemical and ICP-results. Test kits and photometers both only show reactive phosphate or ortho-phosphate while ICP will also show phosphate esters, polyphosphates and other phosphates with pyrophosphate bonds, that test kits and photometers don't show. However this has nothing to do with phosphorus vs. phosphate. It is just phosphates with different bonds.

ICP results show all phosphates (total phosphate) which in general are also bioavailable. This is an advantage but we do have little experience with the concentrations of total phosphate.

Test kits and photometers only show orthophosphate which may be as little as 10 % or as much as 90 % of total phosphate according to my own few experiences and reported results after a digestion process. However, these are concentrations with which we have experiences and which we have learned to judge.

Nevertheless I think the ICP results are more valuable and I would rate them higher if they are similar exact as photometer results.
Thanks for clarifying that Dr. Balling. :)
 

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Recently I’ve encountered a very strange event with my new tank. I have not seen anything like this in the last decade. After curing some Marco dry rock in a brute for over 1 year I finally added it to my new system. When the rock was initially put in the brute can I fed it well, introduced different bacteria species such as Dr. Tim’s One and Only, Waste Away, & Eco-Balance. I also introduced live sand from the beach and added some coralline algae. After the 1st 6 months the water was crystal clear. I dosed some N&P and coral food to keep the bacteria population up. The second 6 months I slacked on water changes, feeding, etc. I’m pretty sure the nutrients became depleted.

After adding the new rock to the tank, I noticed that from the beginning I had very little algae growth. There was never algae on the glass, overflow box etc. The highest PO4 I’ve seen in this tank was .06 ppm which is way below the normal for any dry rock tank that I’ve started in the first three months.

The nutrients bottomed out and I started dosing Trisodium Phosphate. I was up to .13 ppm daily and was not getting readings on my Hanna Phosphorus ULR. However, the rocks were getting darker and darker (very dark brown and almost black) and the skimmate was a deep rich coffee color. I was still not getting readings on the Hanna ULR’s, but I know the phosphate was in the system. My eagents were not expired and I used two different boxes. I was also using two different Hanna ULR meters.

F93B4D75-8DAC-4585-8B08-963633792DB4.jpeg
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I was observing what appeared to be the start of Dino’s on the rocks. I also noticed the water becoming more cloudy during the peak photo period, but it was cloudy anyway. This is all consistent with low or depleted nutrients and is exactly what I’ve seen with every system prior that had PO4 either at or below .01-.02 ppm and NO3 at zero. Or NO3 at 0-1 and PO4 at 0.

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As I continued to dose TSP…I was not seeing the results I was hoping for. It appears that TSP was not able to saturate the tank and was unable to be taken up by the corals for some reason. Essentially I was purposely overdosing the tank to try and get a reading (looking for the saturation point). I haven’t ever encountered this and I’ve been reefing for quite a long time now. However, I did start using a product that was much better (will discuss this later). Almost immediately when I started dosing the product I saw positive results. The rocks started to get a green tint and very light surface algae (already present) was starting to get a hint of light green. The water also started to clear up a bit. The Hanna FINALLY gave me a 12 ppb reading.

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Bear in mind this reading appeared within 24 hrs. The next morning the water was crystal clear when I got home from work. I started to notice the corals gaining more color in some of the more pale areas. Especially the Garf Bonsai. I also noticed increasing polyp extension. Today there’s more polyp extension than there’s been since I started the tank 3 months ago.

Coincidence? I don’t know, but at this point I’m a believer. Still testing though and my data will speak for itself which I will show you guys very soon. Which leads me to this question.

What is the best bioavailable phosphate supplement other than Trisodium Phosphate?

I will never dose that again after this last observation. It may be good for minor tweaks and I do have documented evidence to prove that (with pictures that are time stamped)., but I feel there are much better options for phosphate supplementation. especially if a tank is drinking PO4. It’s just not a good choice IMO. This is only my opinion and I’m not trying to convince anybody one way or the other.

Also…is it POSSIBLE to make/mix up a phosphorus element that is not dangerous which could be dosed to a reef tank?
 
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Lasse

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I’m gonna be really ticked if I’ve been dosing Trisodium Phosphate and using the Hanna ULR phosphorus to try and detect it if it really cannot detect it. It’s somehow being working for years if that is the case. :)

I’m getting Zero’s on both Hanna Phosphate ULR and Phosphorus ULR…

Sooooo….:face-with-spiral-eyes:

ICP below:


It has been answered before but I will just stress that both Hanna Phosphate ULR and Phosphorus are basically the same meter and the only difference is the software there Hanna ULR Phosphorous multiplicate the result with 1000 and also divides it by 3.0645 - just in order to show it in ppb P

Edit - wrote ULR phosphate first - was wrong - changed to Phosphorous

I have never had to dose so much PO4 back to any system. There must be A LOT of consumption, metabolism, absorption, etc…by everything in the tank right now.
IME - this is very common and I use to named it the ketchup effect of dosing PO4. If you place rock with no bond phosphorous (like all the types of ancient coral reefs mined on dry land) there will be a fast uptake until the bonding capacity of the rocks is reached and/or bond PO4 and dissolved PO4 are in equilibrium. After this - its only the biological uptake that is active and when you measure the not used PO4 (because chemical bonding capacity is reached) it will sky rocket. Imo when you se a steady measurement over 0 for a day or two - take down your dose till you reach 0 again. When you read zero again - rise your dosing very carefully till you see a little "waste" PO4 (in my world between 0.05 - 0.1). If you not reach zero again - your feeding is enough for you biological PO4 demands.

IME - the same happens when you have read 0 for a prolonged period in a mature aquarium using PO4 depleting methods - you have deplete your aquarium from the stored PO4 in your decoration (stones, sand and so on)

I know that it is common to "cure" stones - even ancient coral reefs mined on dry land - but IMO this will be counterproductive because it will deplete the stored PO4 that is well needed in a start up for both LR and dry rocks. IMO - Do not cure LR and f you want to "cure" your dry rocks - place them in water with measurable PO4 and they will act as an buffer later on.

Its also important - IMO - to stress that if you read 0 mg/L PO4 (or 0 ppb P) in an aquarium that have had detectable concentrations before - do not panic - your rocks and sand will help you in the flux of PO4 to your corals and algae. But do not let this be for a prolonged time and dose gently up the till you can detect again. If you dose - even when you can´t detect any leftover - you know that it will go back and forward between your stones/sand and water column and your corals and algae will take benefit of it. But - IMO - its good to detect some leftover - when you have a lot of reaction time.

I just realized Seachem Flourish “Phosphorus” is “potassium phosphate.”
If you use that - keep an eye on your potassium concentrations if you have fish in your system

However - This is Christoph´s tread about ICP-MS. He has mentioned that they analyze PO4 with photometric methods and if some substances are sensitive for transport - it is PO4. It will - in a bioactive water as aquarium water - be fast depleted by bacterial growth. Normal way to hinder this is to acidify the sample but you can also filtrate the sample through a 0.2 µ filter - which is the method used by OCEAMO. When I have tested filtrated samples both with Hanna checker and OCEAMO test - it has been rather similar. But another thing not mentioned here is that they also analyze nitrate in a good way. I have a long serie of ICP tests by another supplier (Triton) - that's my base for my decisions but I use OCEAMO tests for the calibration of my own nutrient analyzes and a second opinion and i will probably change over to ICP-MS for this second opinion.

Sincerely Lasse
 
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IME - this is very common and I use to named it the ketchup effect of dosing PO4. If you place rock with no bond phosphorous (like all the types of ancient coral reefs mined on dry land) there will be a fast uptake until the bonding capacity of the rocks is reached and/or bond PO4 and dissolved PO4 are in equilibrium

That is exactly what happened Lasse. I think this was a direct result of how I cured the rock. When I cured the rock, I took care of it well in the 1st 6 months. However, the 2nd 6 months I got completely obliterated by Covid (really really busy at work) and I let the rock become depleted of nutrients. Had I kept dosing nutrients it would have never binded the PO4 so aggressively or for that amount of time. Lesson learned.
 
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Lasse

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I think you mean Multiply by 3.066 and divide by 1000. :)
No the fault was not in the math - it was that I write Hanna Phosphate ULR - it should be Hanna ULR Phosphorous. Have fixed that now - thank you

Sincerely Lasse
 

FRAReef

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Thank you for the data.

Being in quality this is nice to know you run reference standards with your analysis. It would be nice to see other companies provide the same in the future!

Are you guys certified in any capacity? ISO, etc.?
Hello, no they are not. Of course, proof of competence is associated with costs, especially for the personell - after almost 3 decades, both in certified and non-certified laboratories, I have to say: the difference in working methods is like night and day. In the field of ultra-trace analysis, Christoph's offer is an absolute bargain. For example, we (certified) have to work in a metal-free clean room for this analysis (contamination) - all devices and in particular the accessories (tubes) must also have been manufactured and certified for the analysis in a metal-free clean room, sampling must be carried out and recorded by competent personnel etc. etc. ... This is only a small part of the cost-incurring positions in a proven competent laboratory - on top of that, of course, there are the personnel costs... The hobby laboratories would of course also have to pass these costs on to you. Very few would be willing to pay them - just as Christoph's statement on the certification is only an opinion and not a fact - in my opinion Oceamo is one of the hobby laboratories that at least know what is important.
 
OP
Christoph

Christoph

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Hello FRAreef, and greetings to Frankfurt :)

Thanks for your comments. I agree with you that the cost of certification is (too) high for operating in the hobby sector.

But we are aware of potential pitfalls in trace analysis,m and we are giving our best to avoid them.

For example we are operating the lab under positive pressure of filtered air. Also ICP-MS samples are mainly handled under a laminar flow unit (HEPA filtered air). - Still this is far from a certified clean room, but very significant improvements over "normal room environment" when considering airborne particles/dust.

The tubes we are using in the testkits for trace metal analysis are obtained as "certified metal free", and we cannot detect any inorganic contaminants coming from the tubes or filters, even with ICP-MS.

All the best from Austria,
Christoph
 

FRAReef

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Hello FRAreef, and greetings to Frankfurt :)

Thanks for your comments. I agree with you that the cost of certification is (too) high for operating in the hobby sector.

But we are aware of potential pitfalls in trace analysis,m and we are giving our best to avoid them.

For example we are operating the lab under positive pressure of filtered air. Also ICP-MS samples are mainly handled under a laminar flow unit (HEPA filtered air). - Still this is far from a certified clean room, but very significant improvements over "normal room environment" when considering airborne particles/dust.

The tubes we are using in the testkits for trace metal analysis are obtained as "certified metal free", and we cannot detect any inorganic contaminants coming from the tubes or filters, even with ICP-MS.

All the best from Austria,
Christoph
Hello Christoph, greetings to Austria. That's why I always say: Oceamo knows what matters. This is not least due to your professional background. In the meantime, we have a big number of hobby laboratories in Europe, unfortunately a not small number of them are operated by people who, for example, participate in a single ICP-OES/MS training course and then: here we go (without considering the large number of pitfalls in the analysis procedure). I recently pointed out to someone that difficulties can arise with these facilities as early as the selection of the correct standard - example: ordering a multi-element standard that they still have to dilute internally and contaminate in the process of dilution. I like the lab work of oceamo
Sincerely FRAreef
 
AquaSD

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