Hanna Accuracy v. ICP

[Ian Baxter]

I recently got my ICP test results back from ATI and noticed that some of my Hanna checkers are close in results and other's far off. I know there could be procedure error or dirty cuvettes on my part, but my checker numbers have remained consistant and I test weekly. For future testing, should I just subtract or add the approximate difference between them below (Ca, NO3, P)? I also had the same issue with salinity. They said 32.33 which converts to 1.0243, but my refractometer is at 1.026.

ATI Hanna Aprox. Difference
KH - 8.85 8.4
Ca - 421.3 527 -100
Mg - 1363 1365
NO3 - 60.79 40 +20
P/PO4 - 32.24/.1 51/.16 -20/-.05

 

[Randy Holmes-Farley Verified Community Expert]

The Hanna calcium seems to be the most problematic of the Hanna kits. Most folks give up on it.

Phosphate, if just by ICP of P can detect a wider range of chemicals than kits and may be higher for that reason.

How did you calibrate the refractometer?

 

[Ian Baxter]

The Hanna calcium seems to be the most problematic of the Hanna kits. Most folks give up on it.

Phosphate, if just by ICP of P can detect a wider range of chemicals than kits and may be higher for that reason.

How did you calibrate the refractometer?

I might go back to Salifert for Ca

The ICP also gave PO4 at .1

I used RODI for the calibration but was reading your article yesterday on how to make the calibration solution. That's going to be my plan.

 

[Randy Holmes-Farley Verified Community Expert]

Sounds good.

Happy reefing

 

[John Neuzil]

I have used ATI icp three or four times over the past few months and they listed my salinity at 33 each time. My Tropic marin hydrometer and my refractomer were at 35 or 1.026.
I just started up with the Triton subscription and their
icp reported my sality at 35 matching my results.

 

[Lasse]

As phosphate - many ICP vendors do not measure PO4 - just transfer the P readings from the ICP to PO4. I do not know how ATI does. I use OCEAMO and they analys PO4 with photometric methods. Both the OES kit and MS kit include a 0.2 µm filter for the phosphate sample and the MS also include a stabilisator for the PO4 sample. I use my ICP-MS kits reported PO4 concentrations as the real measurement. My Hanna Marin Master is normally not even close sometimes.

Sincerely Lasse

 

[Ian Baxter]

I have used ATI icp three or four times over the past few months and they listed my salinity at 33 each time. My Tropic marin hydrometer and my refractomer were at 36 or 1.026.
I just started up with the Triton subscription and their
icp reported my sality at 36 matching my results.

That’s very interesting and good to know. My Apex probe was also reading at 36–37. What test kit do you use for the rest of your parameters? I’m curious to see if the triton test is much different than the ATI.

 

[Ian Baxter]

As phosphate - many ICP vendors do not measure PO4 - just transfer the P readings from the ICP to PO4. I do not know how ATI does. I use OCEAMO and they analys PO4 with photometric methods. Both the OES kit and MS kit include a 0.2 µm filter for the phosphate sample and the MS also include a stabilisator for the PO4 sample. I use my ICP-MS kits reported PO4 concentrations as the real measurement. My Hanna Marin Master is normally not even close sometimes.

Sincerely Lasse

I use the Hanna phosphorus checker and was surprised at how much difference there was. I’ve been battling prospects for quite a while now and using Rowaphos to bring it down and I would hate to bottom it out, so I don’t know which one would be more accurate. I would assume it would be the ICP test.

 

[John Neuzil]

That’s very interesting and good to know. My Apex probe was also reading at 36–37. What test kit do you use for the rest of your parameters? I’m curious to see if the triton test is much different than the ATI.

Hanna for everything except magnesium. Magnesium is Salifert. I just purchased a Milwaukee salinity meter which i really like. Matches my hydrometer and refractomer.

 

[ReneReef]

Hanna for everything except magnesium. Magnesium is Salifert. I just purchased a Milwaukee salinity meter which i really like. Matches my hydrometer and refractomer.

According to your earlier post, your hydrometer and refractometer did not match. So this can’t be correct.

A salinity of 36 ppt matches with an S.G. of 1.0271 not 1.026.

The device to trust is the one calibrated with a reliable reference.

 

[Lasse]

I would assume it would be the ICP test

I do not know how ATI calculate the phosphate - if they use photometric methods, if you have to filter the sample and if they send with a stabilizer - but I know that OCEAMO´s way of have you to prepare the sample (with the ICP-MS package) and the way they analyze it is by the book. hence I rely on their result.

Sincerely Lasse

 

[John Neuzil]

According to your earlier post, your hydrometer and refractometer did not match. So this can’t be correct.

A salinity of 36 ppt matches with an S.G. of 1.0271 not 1.026.

The device to trust is the one calibrated with a reliable reference.

Your absolutely correct. Old fingers miss typed. 35ppm is correct. I fixed it. Thanks for pointing that out