Determination of polyethylene glycols 4000 and 6000 in plasma protein preparations

Polyethylene glycols 4,000 and 6,000 were determined in different plasma protein preparations by the formation of complexes with barium and iodide ions after precipitation of the proteins with perchloric acid. The method, which is fast and reliable, can be used for the determinations of PEG down to 0.005% (w/w) of the total protein content.