Another ICP-Analysis discussion

[Empire]

Hello! I’ve been using icp-analysis.com these last few months (since February, at least once a month). Looks like they just changed measurements to ppb from ppm. Some of my most recent readings (7/15 ppb) vary significantly from my last reading (6/06 ppm). Let’s just focus on phosphorus for now. On 6/6, Icp tested phosphorus at .08ppm vs my Hanna phosphate 774 of .10ppm. 7/15 icp Phosphorus 262ppb vs my Hanna 774 .15ppm. I understand they are different instruments but I cannot believe this to be true. My Hanna 736 measured in line with my 774 during my 7/15 year. Wouldn’t my tests vary by the same ratio? I tried bringing this up to icp analysis and they pretty much told me to GFY. Never using them again. Would love some advice before I dose my tank with some lacl

 

[Randy Holmes-Farley]

Hello! I’ve been using icp-analysis.com these last few months (since February, at least once a month). Looks like they just changed measurements to ppb from ppm. Some of my most recent readings (7/15 ppb) vary significantly from my last reading (6/06 ppm). Let’s just focus on phosphorus for now. On 6/6, I tested .08ppm vs my Hanna phosphate 774 of .10ppm. 7/15 I tested 262ppb vs my Hanna 774 .15ppm. I understand they are different instruments but I cannot believe this to be true. My Hanna 736 measured in line with my 774 during my 7/15 year. Wouldn’t my tests vary by the same ratio? I tried bringing this up to icp analysis and they pretty much told me to GFY. Never using them again. Would love some advice before I dose my tank with some lacl

The units reported certainly do not impact the values, unless they are unable to move a decimal point properly. 1 ppm = 1,000 ppb.

The difference between 0.15 ppm (150 ppb) and 262 ppb is not staggeringly high.

"On 6/6, I tested .08ppm vs my Hanna phosphate 774 of .10ppm"
0.08 ppm = 80 ppb is very similar to 0.1 ppm (100 ppb).

 

[Empire]

It’s phosphorous to phosphate - sorry I don’t think I was clear enough

 

[Randy Holmes-Farley]

It’s phosphorous to phosphate - sorry I don’t think I was clear enough

I guess I'm not understanding the issue.

You think they did a conversion wrong, or their values do not match values you got? (the latter is normal, to some extent, for a variety of reasons)

 

[Empire]

I guess I'm not understanding the issue.

You think they did a conversion wrong, or their values do not match values you got? (the latter is normal, to some extent, for a variety of reasons)

the latter for sure. I didn’t expect my Hanna checkers to be identical to an icp test but to have it so far off scares me, especially since my older tests with ICP-analysis compared to Hanna were much closer.

icp: 262ppb of phosphorus = .7-.8ppm of phosphate.

hanna HI 736 : tests UlR for phosphorus in ppb. I ran the test and returned 41 and 46 ppb which is .12-.14ppm.

Hanna hi774 : tears ulr for phosphates in ppm. I ran the test twice and returned .15 and .17 ppm.

If my phosphate levels are what ICP analysis is suggesting, then I need to hit my tank with LACL pronto. If Hanna is right, then I can treat it with some gfo and move on with life.

 

[Randy Holmes-Farley]

I don't know which, if either, is more likely to be correct.

Can you post the actual ICP results?

 

[Saltydog69]

following

 

[Empire]

I don't know which, if either, is more likely to be correct.

Can you post

Attached! To further complicate things, last night i thoroughly cleaned all of my cuvettes with Hanna's cuvette cleaner (in and out); rinsed out with RODI, probably at least a gallon per cuvette. I redid my tests 4x each with the HI 736 which tests Phosphorus ULR PPB and the HI 774 which tests Phosphates ULR PPM.

HI 736 Phosphorus ULR PPB Tests : 44, 41, 24, 22. This translates to phosphates ppm : .14, .13ish, .07, .06

HI 774 Phosphate ULR PPM Tests : .17, .14, .13, .13

 

[Cjeippert]

Attached! To further complicate things, last night i thoroughly cleaned all of my cuvettes with Hanna's cuvette cleaner (in and out); rinsed out with RODI, probably at least a gallon per cuvette. I redid my tests 4x each with the HI 736 which tests Phosphorus ULR PPB and the HI 774 which tests Phosphates ULR PPM.

HI 736 Phosphorus ULR PPB Tests : 44, 41, 24, 22. This translates to phosphates ppm : .14, .13ish, .07, .06

HI 774 Phosphate ULR PPM Tests : .17, .14, .13, .13

Same thing just happened to me. My test was 7/15. Hanna phosphorus checker is consistently at 5 to 10ppb which is around .02 to .03 ppm phosphate. Salifert and api test kits show zero phosphates. So how in the heck is the ICP showing 10.6 ppm Phosphorus!!! Not phosphate. I would expect 10.6 ppb not ppm. Maybe they just messed up the ppb with ppm. This is ridiculous, I am going to spend $15 more for the Triton to see what is up.

 

[Cjeippert]

Same thing just happened to me. My test was 7/15. Hanna phosphorus checker is consistently at 5 to 10ppb which is around .02 to .03 ppm phosphate. Salifert and api test kits show zero phosphates. So how in the heck is the ICP showing 10.6 ppm Phosphorus!!! Not phosphate. I would expect 10.6 ppb not ppm. Maybe they just messed up the ppb with ppm. This is ridiculous, I am going to spend $15 more for the Triton to see what is up.

Another thing… a reef tank would be expected to have .08 phosphate… not the .08 ppm phosphorus level they state in the picture. They definitely got something backwards

 

[Randy Holmes-Farley]

Another thing… a reef tank would be expected to have .08 phosphate… not the .08 ppm phosphorus level they state in the picture. They definitely got something backwards

0.08 ppm phosphorus (~0.24 ppm phosphate) is a perfectly "normal" reading for a reef tank. It's on the higher side and I'm not sure what they mean by it, but its not indicative of a big error.

 

[Randy Holmes-Farley]

Salifert and api test kits show zero phosphates. So how in the heck is the ICP showing 10.6 ppm Phosphorus!!! Not phosphate. I would expect 10.6 ppb not ppm. Maybe they just messed up the ppb with ppm. Th

That's likely the case. Do they list the P level in any other location on the report?

 

[RGoltz]

Not speaking specifically to phosphorus or ICP Analysis but I/we have seen variance in results from other ICP vendors. For example, I have seen flourine off the mark. So at some point you consider: history, trend, and your own observation.

Specifically with phosphorus you would also want to have the same measurement time for both samples, etc.