Determination of plasma homovanillic acid by liquid chromatography with electrochemical detection

We describe a simple method for extracting homovanillic acid (HVA) from plasma. An aliquot of 0.5 ml of the internal standard solution (3-hydroxy-4-methoxycinnamic acid in 0.2 mol/l phosphoric acid) and 0.5 ml of the sample are applied to a 1-ml Bond Elut C18 column prewashed with methanol and 0.2 mol/l phosphoric acid. The sample is drawn through the column at low speed. The column is washed with water and eluted with dichloromethane. The …