Gas chromatographic measurement of urinary catecholamines by an electron capture detection procedure

A gas-liquid Chromatographic procedure with electron capture detection has been developed to measure the catecholamines, noradrenaline, adrenaline and dopamine in normal human urine as their pentafluoropropionyl derivatives. The amines are absorbed from urine at pH 8.5 on micro-columns of alumina, eluted with acetic acid and derivatized with pentafluoropropionic anhydride. Some improvements in the conventional procedure of chromatography on alumina have been introduced. Quantification is obtained by comparing peak heights with those of internal standards added to urine and taken through the entire determination. Normal urinary excretion values of free catecholamines (mean ± S.D.), expressed as μg per 24 h, were: noradrenaline, 52.1 ± 15.0, adrenaline, 24.2 ± 4.0 and dopamine 402.4 ± 86.3. Conjugated dopamine can be determined after acid hydrolysis (pH 1, 100°, 20 min). About 50 to 75% of total dopamine output is excreted in conjugated form.