Determination of carbamazepine in serum and pharmaceutical preparations using immobilization on a nylon support and fluorescence detection

A novel approach is presented for the spectrofluorimetric determination of the powerful anticonvulsant carbamazepine and its main metabolite in human serum. The strategy consists in the support of both compounds on a nylon membrane, and their subsequent determination through a solid-surface fluorescence methodology combined with a suitable chemometric analysis. The novelty of the present method lies in the fact that while carbamazepine does not fluoresce neither in solution nor supported on a variety of surfaces, significant emission signals are observed when it is supported on the nylon matrix, a property which has not been previously exploited by analysts. Multivariate calibration analysis was performed on three-way excitation-emission matrix data. The algorithms applied were: parallel factor analysis (PARAFAC), self-weighted alternating trilinear decomposition (SWATLD) and N-way partial least-squares regression (N-PLS). The results were compared with two-way calibration data analysed with partial least-squares regression (PLS-1). The methodology is highly specific, and it appears to be suitable for the routine monitoring of serum concentrations in patients receiving chronic therapy. In addition, the technique was satisfactorily applied to the determination of carbamazepine in pharmaceutical formulations.