I need PEG 400 with water content as low as 1%. Commercially available PEG 400 has higher water content. There is a protocol of drying PEG on protocol exchange

http://www.nature.com/protocolexchange/protocols/2417

however, its applicable on higher Molecular weight PEGs and lower order PEG is sensitive to temperature. So I have following questions.

1. Can i dry PEG 400 using a protocol that involves heating it to 170 C?

2. Would high vacuum drying at 60 or 80 C remove water content upto desired levels? Removal of peroxides for PEG 400 has been reported using vacuum drying.

3. Can i buy dehydrated or anhydrous PEG 400?

My Preference is 2 > 3 > 1