Simple and rapid determination of the active metabolite of nabumetone in biological fluids by heavy atom-induced room temperature phosphorescence

The maximum phosphorescence signal appeared instantly and the intensity was measured at λex = 328.4 nm and λem = 544.4 nm. The response obtained was linearly dependent on concentration in the range of 20-1000 ng mL−1. The detection limit, according to error propagation theory, was 11.6 ng mL−1 and the detection limit as proposed by Clayton, was 17.4 ng mL−1. The repeatability was studied by using 10 solutions of 100 and 800 ng mL−1 of metabolite; if the theory of error propagation is assumed the relative error is 4.3 and 0.66%. The S.D. of replicates was found to be 2.2 and 11.0 ng mL−1. This method was successfully applied to the analysis of 6-methoxynaphthylacetic acid in human serum and urine.