Comparative column chromatographic estimations of phenylalanine in plasma, whole blood, native and paper-dried capillary blood of healthy children and adults, and patients with hyperphenylalaninaemia.

The concentration of phenylalanine in plasma, whole venous and capillary blood, and paper-dried blood of 75 probands (25 healthy adults, 27 healthy children, and 23 patients with hyperphenylalaninaemia) were measured by use of a sensitive short column chromatography method. The comparison of the values in each group of probands by several statistic methods showed an excellent correlation of the phenylalanine concentration in paper-dried whole blood to those measured in venous plasma. Evaluation of the analytical method revealed a high sensitivity and accuracy by use of a sample volume of 50 microliter. We would therefore suggest that the estimation of phenylalanine for the diagnosis and therapy control in hyperphenylalanine is as accurate in paper-dried blood as in venous plasma and would simplify sampling for the patients as well as enhance the diagnosis and therapy control in hyperphenylalaninaemia.