As title states. I’m using Red Sea Calcium Pro for my calcium.
Is there a standard I can make?
Is there a standard I can make?
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I use a standard containing 50 mM of MgCl2 and 10 mM of CaCl2, with both the MgCl2 and CaCl2 stock solutions, as well as the mixed standard being standardized by a Morh titration of the Cl. The MgCl2 and CaCl2 stock solutions were also standardized in parallel by densitometry using an Anton-Paar DMA5000 densitometer.
Thinking more about this, I have, in the past, when working on certain projects, developed a controlled ASW mixture where I was able to take a base ASW mixture without any alkalinity, calcium, or magnesium (apart from whatever was present as contaminants in the source salts, most of which were pretty darned pure), and then add arbitrary known amounts of alkalinity, calcium, and magnesium, plus pure RODI water as needed to achieve specific concentrations of "the big three", while maintaining a target final salinity of 35 PPT. It was a lot of work, but I was able to successfully and repeatably produce such standards. So, it is doable, but, as @Randy Holmes-Farley said, it is quite difficult to do.Thus, a true standard may need a real seawater matrix, which makes it much harder to do.
spectrometer isn't really helpful for titrations (I use that spectrometer for all kinds of stuff - love it, btw). By which I mean the precision of endpoint color is not a significant source of error. eyeball comparison to a color card is plenty for establishing the endpoint of a titration.I do have a portable vernier spectrophotometer (GoDirect LED bluetooth model). I'd love to use that to expedite making a nice repeatable curve for my tests. I contacted them about their Ca specific
As I've been reading about the Ca titration, you're correct. I did use the spectrometer to get baselines for my phytoplankton cultures and copepod cultures. I believe I then killed the phytoplankton (ordering more stock). I was thinking more of using the spectrometer to read the test kits like phosphate and nitrate after making standards. I've always found the test solution cards difficult to read accurately.spectrometer isn't really helpful for titrations (I use that spectrometer for all kinds of stuff - love it, btw). By which I mean the precision of endpoint color is not a significant source of error. eyeball comparison to a color card is plenty for establishing the endpoint of a titration.