How to trust ICP Testing

[Klemmetsmo]

I’m just venting, and wondering, about icp tests. Lately I’ve been discovering wildly different icp test results from different companies. I know they’re testing very small amounts of elements, but shouldn’t they at least be close? For example, my receipt icp from Triton reports 0 copper but a week prior a Moonshiners icp showed 3 for copper. There are other elements that make me doubt the results but it’s frustrating because the copper result made me panic and I bought absorber. I’m inclined to believe Triton and not do anything because the tank looks fine with the exception of my Goniapora that is closed up… Now who to trust? Should I trust any of them? Do you trust any of them?

How do you guys handle this? Do you just use one ICP company and run with it?

Frustrated

 

[ReefHunter006]

You have to remember any organics you capture when sampling the water (most copper is bound to organics), is likely why you see such different results. Just because you can’t see the particulates doesn’t mean it isn’t there.

i used copper as my example but it goes for any traces which can be expected to be found in the food.

Also LOD is small.

 

[Randy Holmes-Farley]

I’m just venting, and wondering, about icp tests. Lately I’ve been discovering wildly different icp test results from different companies. I know they’re testing very small amounts of elements, but shouldn’t they at least be close? For example, my receipt icp from Triton reports 0 copper but a week prior a Moonshiners icp showed 3 for copper. There are other elements that make me doubt the results but it’s frustrating because the copper result made me panic and I bought absorber. I’m inclined to believe Triton and not do anything because the tank looks fine with the exception of my Goniapora that is closed up… Now who to trust? Should I trust any of them? Do you trust any of them?

How do you guys handle this? Do you just use one ICP company and run with it?

Frustrated

Triton and Oceamo (presume that's what you mean by moonshiners) use different types of machines with different lower limits of detection. One can easily get a situation where the same actual value will show zero by ICP-OES (Triton) that will give a value by ICP-MS (Oceamo).

3 ppb copper does not, IMO, warrant any substantial action.

 

[Reefer Matt]

I have never done one. My understanding is that many variables like testing method, sample collection and handling, and human error all play a part in the inconsistencies. It seems more like another subscription plan that the industry tried to convince us to adopt.

 

[Js.Aqua.Project]

So short answer is...you don't. They can be widely inaccurate for a whole number of reasons.

I still do them, I just always take them with a grain of salt and use it more as a flood light to help find potential issues, not a spotlight to say "here's the problem".

There are certain trace elements, like Iron and Copper than come back very inaccurate from ICP tests. If you're really interested in tracking them I would suggest testing them yourself at home.

These articles by @Rick Mathew are really good for sorting out this issue:

How We Use ICP-OES Results Of Unknown Accuracy And Precision

A quantitative Method of Evaluating ICP-OES Results

www.reef2reef.com

SAMPLE STORAGE AND ITS IMPACT ON MEASUREMENT RESULTS PART 3

In my last post in July of last year I presented the case that samples sent for ICP analysis were not completely stable and that during the storage time before testing there was a change (reduction) in the measurable level of Phosphorous and thus...

www.reef2reef.com

HOBBY GRADE TEST KITS CAN OUTPERFORM ICP MEASUREMENTS…REALLY??

INTRODUCTION BACKGROUND In May of 2022 we (@Dan_P, @taricha and I) posted an article that looked at the quality of the data reported by ICP-OES measurements from several vendors. Our goal was to help bring some clarity to the community to help evaluate and interpret the results of an ICP test...

www.reef2reef.com

 

[Randy Holmes-Farley]

There are certain trace elements, like Iron and Copper than come back very inaccurate from ICP tests. If you're really interested in tracking them I would suggest testing them yourself at home.

For iron and copper? I don't think that is possible unless the values are very high. The spike tests in the last link are very high values, IMO.

 

[exnisstech]

How do you guys handle this? Do you just use one ICP company and run with it?

I handle by not testing. I did two tanks once out of curiosity once and the results were a joke. I haven't bothered since

 

[Klemmetsmo]

Triton and Oceamo (presume that's what you mean by moonshiners) use different types of machines with different lower limits of detection. One can easily get a situation where the same actual value will show zero by ICP-OES (Triton) that will give a value by ICP-MS (Oceamo).

3 ppb copper does not, IMO, warrant any substantial action.

Thank you Randy!

 

[Randy Holmes-Farley]

Thank you Randy!

You're welcome.

Happy reefing.