Dear Sujatha,
could you explain better the procedure you follow to prepare BHF ?
What do you mean with "filtering the NH4F and DI water solution" ?
I don't filter the NH4F solution: we bought an already prepared solution
of NHF4 from sigma-aldrich.

Best regards,
Andrea

> Dear Friend,
> Are you filtering the NH4F and DI water solution or not?
> We are filtering the solution and then mixing the resultant soln. with HF
> acc.
> to our concen. requirement. We have not faced any problems.
> Try it.
> With good luck,
> Sujatha