Automated determination of 5-hydroxyindolylacetic acid in urine by high-performance liquid chromatography

5-hydroxyindolylacetic acid (5-HIAA), a major serotonin cata-bolite, is eliminated in urine. In carcinoid tumours, 95 ofwhich occur in the small intestine, large quantities of serotonin are secreted by the entero-chromaffin cells of Kultchizky-Masson. Early detection of these tumours is essential, since unless they are surgically treated in the initial stages then their prognosis is serious. Early detection can be ensured by measuring blood serotonin and urinary 5-HIAA [1]. Systematic determination of urinary 5-HIAA needs a quick, reliable and automated technique. Neither the e-nitrosonaphtol colorimetric method [2] nor spectrofluorometry after ethyl acetate extraction [3] are suitable: the first lacks specificity and the second is a lengthy and tricky process. Both these methods are manual. Low-pressure chromatography techniques are time-consuming (5-HIAA retention time is over 30min.) and they are either insufficiently sensitive or unreliable [4,5, 6]. Reverse-phase separation chromatography also lacks sensitivity and specificity [7-1, unless it is preceded by manual extraction which, again, is often time-consuming and reduces the technique's precision. High-performance liquid chromatography (HPLC), however, allows fast separation [8].