Measurement of polyethylene glycol 400 in urine by direct-injection high-performance liquid chromatography.

We describe a new "high-performance" liquid chromatographic (HPLC) method for estimating polyethylene glycol 400 (PEG 400) in urine. Direct injection of diluted urine samples onto the column eliminates the necessity for lengthy preparative steps, resulting in considerable saving of both time and chemicals. High analytical recoveries (94-102%) and a rapid rate of analysis are achieved. Results vary linearly with concentrations from 0.2 to 1.6 g/L and the six major components can be individually quantified precisely at all concentrations in this range. This method shows better sample recovery, sensitivity, and reproducibility than does a previously described method. The increased sensitivity should allow the use of lower oral doses of polyethylene glycol 400 in future studies of intestinal permeability.