ATI ICP Question About Reference Values

[vtecintegra]

Two ATI ICPs days apart. My middle column is labeled reference value, another person's is labeled recommended value. All of my reference values are lower than the other ICP "recommended" values. For instance, my Mg reference is 1175, the other recommended value is 1285. My potassium reference is 364, the other 398. I know potassium should be around 400, so ATI's recommendation to dose to 364 would be under dosing. Any explanation?

My test:


Another person's test:

 

[Mike konesky]

What was the reported salinity of both samples? Looks like yours is low compared to the other sample. I believe ATI adjusts based on the salinity. For example while your Chloride is suggested at 17699, theirs is 19348.
I think their ALK calculation is based on IF your salinity was 35ppt. So when you run at 34ppt,and alk at 7.6ish, it reports around 9 on the ATI icp.

 

[vtecintegra]

Yeah, I think that has something to do with it. My salinity was reported as 32.1 and the other 34. I don't understand the logic though. Regardless what the salinity is, something like potassium should be targeted to 400. My test is saying to dose to 364, while the other test is saying to dose to 398.

 

[Randy Holmes-Farley Verified Community Expert]

Yeah, I think that has something to do with it. My salinity was reported as 32.1 and the other 34. I don't understand the logic though. Regardless what the salinity is, something like potassium should be targeted to 400. My test is saying to dose to 364, while the other test is saying to dose to 398.

But if you did add to the recommended amount and then just raised salinity to 35 ppt, then it would match.

They are trying (perhaps not clearly enough) to distinguish a low salinity problem from an ion being selectively low (or high).

 

[vtecintegra]

Thanks. I don't think I like it though. Now I have to figure out why they came up with 32 ppt, when my calibrated refractometer shows 35 ppt.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks. I don't think I like it though. Now I have to figure out why they came up with 32 ppt, when my calibrated refractometer shows 35 ppt.

It’s also easy enough to ignore the recommendations and just use the analytical values.

 

[vtecintegra]

Yeah, that's what I'm doing. Someone posted a nice spreadsheet for trace elements where you can input where you're at and tank volume, and it will calculate the dose for several different manufacturers products. Just need to get potassium up for the time being.