Ralph ATL
02/08/2008, 06:30 PM
Dear AWT:
I tested the same sample that I sent to you (yes, I did it correctly) against Elos, API, & Salifert trying to determine which of those kits is correct. Considering I get calcium precipitate if I raise my calcium much higher, and considering my alk is 3.66, (you have my alk at 3.66, so if you have my calcium at 284, logically it would not precip by raising it slowly) how are you so low?
Same sample tested with:
Elos:425
API:520
Salifert:480
AWT: 284
There response:
Hello Ralph,
I've gotten this question quite a bit lately. We are looking into the situation at this time, but we believe that our probe is reading accurately.
The difference likely comes from the fact that our electrode only reads calcium ions, whereas your titration kit reads all forms of calcium.
According to Randy Holmes-Farley, as much as 20% of your total calcium can be complexed with other compounds, such as carbonate, bicarbonate, chlorides, ect. We will spend time working on the calibration curve of the probe this weekend, but I can tell you that at this moment, the probe is in a specially-made, calcium chloride standard that has 400.7ppm calcium in it, and the probe is reading 401ppm, so if it is off, it's not off by much. I'll let you know of any adjustments we make at the first of next week.
I tested the same sample that I sent to you (yes, I did it correctly) against Elos, API, & Salifert trying to determine which of those kits is correct. Considering I get calcium precipitate if I raise my calcium much higher, and considering my alk is 3.66, (you have my alk at 3.66, so if you have my calcium at 284, logically it would not precip by raising it slowly) how are you so low?
Same sample tested with:
Elos:425
API:520
Salifert:480
AWT: 284
There response:
Hello Ralph,
I've gotten this question quite a bit lately. We are looking into the situation at this time, but we believe that our probe is reading accurately.
The difference likely comes from the fact that our electrode only reads calcium ions, whereas your titration kit reads all forms of calcium.
According to Randy Holmes-Farley, as much as 20% of your total calcium can be complexed with other compounds, such as carbonate, bicarbonate, chlorides, ect. We will spend time working on the calibration curve of the probe this weekend, but I can tell you that at this moment, the probe is in a specially-made, calcium chloride standard that has 400.7ppm calcium in it, and the probe is reading 401ppm, so if it is off, it's not off by much. I'll let you know of any adjustments we make at the first of next week.