Automated kinetic-spectrofluorimetric method for the determination of morphine in urine

The continuous addition of reagent technique was used with spectrofluorimetric detection for the kinetic determination of morphine in urine samples. The method thus developed is based on the oxidative dimerization of morphine to fluorescent pseudomorphine by potassium hexacyanoferrate(III) in a basic medium. The optimum pH, oxidant concentration and instrumental variables were determined. The method permits the sensitive determination of morphine over a wide concentration range (15-925 ng ml-1) with high precision (relative standard deviation approximately 2%), selectivity and sample throughput (48 samples h-1). A novel sorption--desorption procedure was used to isolate morphine from whole urine, which provided recoveries of between 85 and 100%. The results showed the usefulness of the proposed method for controlling a wide variety of medicinal problems (e.g., therapeutic, overdose and doping analysis).