title: Dual-channel continuous-flow system for determination of phenylalanine and galactose: application to newborn screening.
abstract: We describe a dual-channel AutoAnalyzer (Technicon) system for the simultaneous measurement of phenylalanine and galactose from blood specimens on filter-paper. Using a single 1/4-in.-diameter (6-mm) specimen, we measure both components fluorometrically at a rate of 70/h. Analytical recovery with the method and the linearity of measurements vs sample concentration are excellent through the ranges of interest, 0-200 mg/L for phenylalanine and 0-800 mg/L for galactose. Carryover at the critical values during screening, 40 mg/L for phenylalanine and 100 mg/L for galactose, is essentially zero. The dual-channel system provides the means to incorporate a low-incidence test, i.e., galactosemia (incidence 1/70 000), into an existing program for phenylalanine analysis, for which the higher rates (phenylketonuria, incidence 1/11 500) easily justify the cost of mass screening.
mesh_terms: D001322:Autoanalysis / Q000295:instrumentation*; D005693:Galactosemias / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D008403:Mass Screening / Q000191:economics; D010649:Phenylalanine / Q000097:blood*
chemical_list: D010649:Phenylalanine