Polyethylene glycol and production of the same

A process for preparing polyethylene glycol, comprising the steps of:

• distilling a triethylene glycol from a glycol mixture consisting essentially of mono-, di-, triethylene glycol and higher glycols, at a pressure of from 5 to 10 hPa and a temperature of from 140 to 160° C.,
• ethoxylating the triethylene glycol in the presence of a basic catalyst to form a polyethylene glycol.
• wherein the polyethylene glycol has a residual content of less than 30 ppm aldehyde, determined as formaldehyde as specified by European Pharmacopoeia, “macrogols” monograph 07/2003:1441.