On-line coupling of isolation/in situ concentration integrated with derivative synchronous spectrofluorimetry for the simultaneous determination of epinephrine and norepinephrine in urine

An unsegmented flow system for the automated determination of epinephrine and norepinephrine in urine is proposed. The simultaneous determination involves the following on-line steps: 1. (i) matrix isolation/analyte preconcentration in an exchange minicolumn located in the loop of a injection valve; 2. (ii) elution-injection into the dynamic system and derivatization during the transport to the detector; 3. (iii) in situ concentration in the flow cell integrated with the synchronous spectrofluorimetric scan; 4. (iv) data acquisition and derivation by computer. The method thus developed enables a linear determination range between 2 and 60 ng ml−1 for both catecholamines with R.S.D.s of 1.0 and 2.0% for norepinephrine and epinephrine, respectively, and a sample throughput of 12 samples h−1. The utility of the method has been proved by applying it to urine samples with low and high concentrations of the target analytes.