FIRST-DERIVATIVE NONLINEAR VARIABLE-ANGLE SYNCHRONOUS FLUORESCENCE SPECTROSCOPY FOR THE SIMULTANEOUS DETERMINATION OF SALICYLAMIDE, SALSALATE AND NAPROXEN IN SERUM AND URINE

Derivative variable-angle synchronous fluorescence spectrometry is dev eloped to improve the selectivity of fluorescence measurements without loss of sensitivity. The first derivative non-linear variable-angle s ynchronous scanning permits the rapid simultaneous determination of sa licylamide, salsalate and naproxen in a mixture from a single spectrum based on a single scan. The method is based on the intrinsic fluoresc ence of salicylamide, salsalate and naproxen in chloroform. The analys es are performed in the organic phase, using an alkaline medium provid ed by the addition of 0.40 M pyrrolidine chloroformic solution. The ra nge of application is 0.100-1.000 mu g/ml for all of them. A systemati c examination of the experimental data by applying an exhaustive stati stical analysis is reported. The method is applied in urine and serum samples spiked with all the drugs. Serum and urine samples are extract ed into chloroform-1% acetic acid solution, using in the aqueous mediu m a pH of 4.8 obtained by the addition of acetate buffer solution, and a basic medium is provided with pyrrolidine prior to instrumental mea surement. The simultaneous determination of salicylamide, salsalate an d naproxen in human serum and urine samples is performed with this tec hnique in the extracted chloroform phase, without necessity of any re- extraction step. The validity, applicability and simplicity of the met hod are demonstrated. (C) 1998 Elsevier Science B.V. All rights reserv ed.