Fluorimetric determination of salsalate in urine, serum and pharmaceuticalpreparations

A method for the determination of salsalate at concentrations between 0.10 and 1.00 mu g ml(-1) by means of fluorescence spectrometry technique is pro posed. Salsalate, lightly soluble in water, is totally extracted into chlor oform. In this organic phase, the drug shows low fluorescence but when an a lkaline medium is provided, salsalate undergoes a substantial increase of t he fluorescent intensity. Thus, the determination is performed in a chlorof ormic medium, where pyrrolidine chloroformic solution is added to give the basic character. The fluorescence measurements to quantify salsalate are ca rried out in its fluorescent band centered at lambda(ex) = 299 nm and lambd a(em) = 410 nm. The method was successfully applied to the determination of salsalate in authentic pharmaceutical preparations, urine and serum. Sampl es of these latter two matrices, urine and serum, are extracted into chloro form, using in the aqueous phase a pH 4.8, provided by adding acetic acid/s odium acetate buffer solution. Owing to matrix interference, the method of standard additions was used to determine salsalate in the serum. The sensit ivity and repeatability achieved with the proposed method are adequate for the determination of salsalate in these matrices. (C) 2000 Elsevier Science B.V. All rights reserved.