Flow method based on cloud point extraction for fluorometric determination of epinephrine in human urine

Abstract

A novel stepwise injection fluorometric method for the determination of epinephrine in human urine has been developed. In the current study, the stepwise injection analysis (SWIA) was successfully combined with on-line in-syringe cloud point extraction (CPE) and fluorometric detection. The procedure was based on the epinephrine derivatization in the presence of o-phenylenediamine followed by the preconcentration stage based on the CPE with the nonionic surfactant Triton X-114. After the phase separation into a syringe of the flow system, the micellar phase containing the epinephrine derivative was transported to a fluorometric detector. The excitation and emission wavelengths were set at 447 nm and 550 nm, respectively. The conditions of epinephrine derivatization and CPE have been studied. The calibration plot constructed using the developed procedure was linear in the range of 1·10−11–5·10−7 mol L−1. The limit of detection, calculated as 3 σ of a blank test (n = 10), was found to be 3·10−12 mol L−1. The proposed method was successfully applied for the determination of epinephrine in human urine samples.