pfluffernuugen

The water should be fine. It's from a milliQ system with a measured resistance of around 18MOhm

I need to make a series of 6M and 8M guanidinium HCl buffers for a protein purification, but I can't seem to get the GdnHCl into solution. I'm able to make a clear 8M solution, but when I make the 6M solution, theres some sort of cloudy precipitate that eventually settles. I've tried using the 8M solution as a stock and diluting it down to 6M, but I've noticed that it starts to crash out at around 7.3M. Heating it to 35C doesn't make a difference, nor does stirring it for several days. Is there some trick to it or has my GdnHCL probably gone bad?