TF-100 kit TA test

[napkin41]

Hey all,

Just a quick question about testing TA with the TF-100 kit. I notice at drop 7 of R-0009, the solution is "not green" and is this sort of very light red-but-mostly-clear hue, and then the next drop turns it into a fiery red.

The instructions say when it "turns red" you're done, but I was curious to see how you guys would weigh in on this test. Do you call it at "not green" or "bingo red"?

Thanks!

 

[JoyfulNoise]

It’s when it stops turning a deeper red. It’s an end-point test, not a transition test. CH and TA are the same - you call the end of test when the color stops changing. Some people go one drop extra to be sure and then subtract one drop from the result.

Your TA wa likely 90ppm based on your reported color.

 

[napkin41]

That makes sense. When it stops changing color, that's the key. Got it!