new test kit - checking combined chlorine?

[AnnaK]

The combined chlorine test builds on the free chlorine test and uses the same sample.

Add the DPD powder, enough to turn the sample pink.
Add R-0871 drop by drop, counting drops, until the sample is clear. The last drop that turned the sample clear is the last drop you count.
If you're using a 10 ml sample, the number of drops divided by 2 is your FC. So, 10 drops = 5 ppm FC.

To the same sample add 2 drops of R-0003. If your sample turns pink, you have CCs and need to continue. If it stays clear, you're fine. If you have CCs it'll turn pink immediately upon adding the R-0003.

To see how much CCs you have, add R-0871 one drop at a time, counting and dividing by 2. Three drops would equal 1.5 ppm CC, for instance.

The sample is "colorless" when the last drop turns it colorless. It may go back to pink when you let it sit but you don't care. In titration chemistry, the lat drop to produce a color change is the one we count. If another drop doesn't make a noticable change in color then the previous drop was the "last drop".

[samtex]

Thanks Anna!

[AnnaK]

To the same sample add 2 drops of R-0003. If your sample turns pink, you have CCs and need to continue. If it stays clear, you're fine. If you have CCs it'll turn pink immediately upon adding the R-0003.

That should read " . . . add 5 drops of R-0003." Five, not two.

My apologies for a very misleading typo.