Dear Astelia

if you have the right PEG powder (same PEG size) you can certanilly prepare the buffers by yourself. I did it many time during my PHD. The main problem is the regulation of the pH, because the solutono is quite viscous and not all the pH-meter works well with this kind of solution and of course it is possible that your reproducibility on buffer preparation is not the same of commerciall buffer, but you can certanilly try to do it.

Manuele

Dear Astelia

I also agree with previous answer. Certainly you can use PEG powder for making crystallization buffer, provided it should be from some good company and of high grade. We routinely use PEG powders of desired molecular weight from SIGMA and it works extremely well. Only problem is it becomes very viscous and filtering it is little difficult.

All the best !!

Just remember that PEG is very hygroscopic, making weighing imprecise. You'll need to determine the exact concentration of your solution, for example by measuring osmotic pressure.

Hi Astelia,

PEG is very hygroscopic, and it often becomes viscous during the configuration process and cannot be completely dissolved. You can try to slowly add ddH2O to dissolve the powder and increase the temperature as you dissolve it. In addition, you’d better buy high-quality powder.

Hope it helps!

Certainly you can use PEG powder to prepare crystallization solutions. I did that back in graduate school and could reproduce crystals initially grown from commercial PEG solutions. The thing is home-made PEG solutions are often not as reproducible as commercial ones due to their high viscosity, so it might be difficult to optimize/reproduce crystals that are picky.

Highly pure PEG prepared from powder can be used for crystallization.

Manuele Martinelli Ashish Kumar Engelbert Buxbaum Roger Davis Qian Yin Smita Yadav

Thank you very much for your helpful answers!