[Thin layer chromatography screening test for semiquantitative detection of 4-hydroxy-3-methoxy mandelic acid (HMMA)...

A thin layer chromatography (TLC) screening test is described, which allows the semiquantitative determination of HMMA in urine samples. From the collected 24 hour urine a measured sample is applied without extraction to a special TLC plate, which is developed in one dimension. In comparison to a series of graded standard solutions the daily HMMA output can be estimated semiquantitatively. In 102 patients over 18 years of age, suffering from high blood pressure, the daily HMMA output was estimated by both the Pisano method (Pisano, J.J., Crout, J.R. & Abraham, D. (1962), Clin. Chim. Acta 7,285--291) and the TLC method. Coincident results with both methods were obtained in 99 of these cases. The residual 3 cases show pathological results with the Pisano method and results in the normal range or the warning range, respectively, with the TLC method. These cases can probably be classified as false positive results of the Pisano method. The TLC method is recommended as a screening test for estimating the daily HMMA excretion.