Determination of homovanillic, isohomovanillic and vanillylmandelic acids in human urine by means of glass capillary gas-liquid chromatography with temperature-programmed electron-capture detection.

The determination of urinary homovanillic, isohomovanillic and vanillylmandelic acids as their trifluoroacetylhexafluoroisopropyl ester derivatives by glass capillary gas-liquid chromatography has been studied. It was shown that even with high column efficiencies a single peak-single compound relationship could not be assumed and for reliable quantitation it was necessary to check determinations with a second gas-liquid chromatography column.