[denisa174]

Hello,

I have a question about purity of a standard. I need to buy a formic acid. I've found 99% (acidimetric) and 99% (alkalimetric) pure acids. What does "alkali-, acidimetric" here mean? Is that a method of determination of the purity or is it anything else?

Next question about the formic acid is: Do you have some tip for CE standard?

Thanks

[chenbeier]

Its the method by titration.

[Borek]

Its the method by titration.

Using titration to determine main component is a rather poor approach.

Assume you go 99.9% with titration error three orders of magnitude lower, so 99.9±0.1%. Does it tell you anything about amount of impurities?

Now assume you got the impurity as 0.1% with - again - an error three orders of magnitude lower, so 0.1±0.0001%. Do you see why this information is much better?

[chenbeier]

I think it didnt tell about impurities. It tell about the grade. Its 50, 80 or  99 % HCOOH. For impurities need other methods like HPLC,IR UV/Vis, AAS for metals, etc.

[Borek]

The 99% grade is given, no need to check it.

[chenbeier]

I think here is a misunderstanding. The question was 99% acidimetric, what does it mean? It means it was determined by a titration isnt it. Of course normaly it hasnt to be checked,