Novel method for tyrosine assessment in vitro using luminescence quenching of the nano optical sensor Eu-ciprofloxacin doped in a sol-gel matrix

A low cost and very sensitive method for the assessment of tyrosine in blood serum, urine and hair samples was developed. The method was based upon measuring the luminescence intensity of the nano optical sensor Eu-ciprofloxacin doped in a sol-gel matrix at 617 nm and in the presence of different concentrations of tyrosine in acetonitrile at pH = 9.1, lambda(ex) = 380 nm. The significant quenching of the luminescence intensity of the Eu-ciprofloxacin complex by different concentrations of tyrosine was successfully used as an optical sensor in acetonitrile at 617 nm. The effects of different analytical parameters, e.g. pH, solvent, tyrosine concentration and foreign ion concentrations, were fully analysed. A calibration plot was achieved over the tyrosine concentration range 1.2 x 10(-6) to 1.0 x 10(-9) mol L-1, with a correlation coefficient of 0.997 and a detection limit of 1.0 x 10(-10) mol L-1. The developed method is simple and proceeds without practical artifacts compared to other published methods.