Determination of p-hydroxyphenylglycine by reaction with o-phthalaldehyde using a flow-injection fluorimetric procedure.

In the present study, new flow injection procedures for the determination of p-hydroxyphenylglycine using either photometric or fluorimetric detection are proposed. The methods are based on the reaction of the amino acid with o-phthalaldehyde and 2-mercaptoethanol. The calibration graphs based on peak area were linear in the ranges 20-300 ng ml-1 with fluorimetric detection and 5-60 micrograms ml-1 using the photometric mode. The detection limit calculated for the fluorimetric procedure was 10 ng ml-1. The method was applied to the determination of the free p-hydroxyphenylglycine present in industrial pharmaceutical samples of a Dane salt.