HPLC assay of phenylalanine and tyrosine in blood spots on filter paper.
Blood spots on filter paper are used to screen for phenylketonuria. We have developed a high pressure liquid chromatographic assay of phenylalanine and tyrosine after elution of these amino acids from filter paper. The analysis time is 20 min. The amino acids are separated using an ion-exchange resin with post-column ortho-phthalaldehyde derivatization and subsequent fluorescence detection. Other common amino acids do not interfere. The assay is linear from 20 pmol to at least 2,000 pmol with a coefficient of variation of 3%. The assay is as accurate as the determination of phenylalanine by ion-exchange ninhydrin-reactive methods currently in use, but is 100 times more sensitive. The method has the advantages of avoiding venipuncture, is cost effective, has a high sensitivity, and a rapid turnaround.
Roesel
R A
RA
Blankenship
P R
PR
Hommes
F A
FA
D000328:Adult; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D006801:Humans; D007231:Infant, Newborn; D008403:Mass Screening / Q000379:methods; D010209:Paper; D010649:Phenylalanine / Q000097:blood*; D010661:Phenylketonurias / Q000097:blood*; D014443:Tyrosine / Q000097:blood*
D014443:Tyrosine; D010649:Phenylalanine