Direct determination of triamterene in urine by matrix isopotential synchronous fluorescence spectrometry

A new method for the determination of triamterene for concentrations between 10 and 1000ng ml−1 by means of matrix isopotential synchronous fluorescence spectrometry and derivative techniques is proposed. This new method is useful for the determination of compounds in samples with unknown background fluorescence, such as triamterene in urine, without the need of tedious pre-separation. The determination was performed in an aqueous medium adjusted at a pH value of 6.2, provided by adding sodium citrate-citric acid buffer solution. Since triamterene is widely used as a doping substance in sport, the method was successfully applied to the determination of triamterene in urine. Better sensitivity and repeatability are achieved for these matrices with the proposed method than with the fluorimetric ones described in the literature. An extensive statistical analysis has been developed to all calibration graphs. This treatment includes robust regression such as least median of squares which also detects outliers and leverage points. The weighted least squares regression has been applied to find the more exact straight line which fits the experimental data. The error propagation has been used for the calculation of the detection limit, determination limit and the repeatability of the method.