salifert calcium test kit Q

[shyland83]

The salifert sponsor forum is gone, so hopefully someone here can answer my question. When doing the titration it turn a deep purple color a few drops before it turns "clear blue". do i read it when it turns from pink to purple, or not until it turns lighter blue"?

I have 2 API kits, one read 360 and the other reads 420. If i'm reading the salifert kit right (not until it turns light blue) then it's reading around 400. if so, i'm going to throw away the kit thats reading 360. i hate test kits!

Also i remember reading something about salifert having a bad batch of kits over the summer, i bought mine in june or july, i dont know if it affected the calcium kits. anyone know?

 

[greggnyce]

In the instructions it states that the reading should be done when it turns clear blue.

 

[chemisfun11]

What greggnyce said is true. the pink to purple is a clue that you are close to the endpoint of the titration. Depending on the indicator used, sometimes you get an intermediate color. The Mg is a similar titration, but no real intermediate color change (you'd hate that one

Another factor is how fast you add the reagent and how often you swirl/mix the test vial. I teach chem and students always have slightly high % error depending on how careful they are with their procedure (follow directions)

As long as you are consistent, the results shouldn't vary much. Good luck

 

[shyland83]

i have the mag kit and it's easier for me because the color change is easier to see. thanks for the help, i'm going to assume my calcium is around 400 and throw away the kit that keeps coming up 360 or less