English abstract
ABSTRACT
A selective and sensitive luminescence method for the assay of piroxicam (PX) is developed. The method is based on the luminescence sensitization of europium (Eu3+) by complexation with PX. The signal for PX-Eu3+ is monitored at hex = 358 nm and hem = 615 nm. Optimum conditions for the formation of the complex in methanol were 0.01 M TRIS buffer and 30 ppm of Eu+ which allows the determination of 0.1-2.0 ppm of
PX in batch mode and 0.1-1.0 ppm with limit of detection (LOD) = 23,0 ppb using sequential injection analysis (SIA). In the aqueous medium, the applied method was optimized in 0.15% micellar solution of Tween-80 (Tw-80) buffered at pH 7.5 in presence of 0.01 M TRIS buffer, 30 ppm of Eutand 2 uM of tri-n-octylphosphine oxide
(TOPO) as a synergic agent where 0-0.6 ppm of PX was determined in the batch method with LOD = 6.0 ppb. The chemometric optimization of the method in SIA technique required the use of 7.8 UM of TOPO and 130 ppm of Eu3+ which allowed the determination of PX in the concentration range 1.0-15.0 ppm with LOD = 0.7 ppm. The proposed method was successfully applied for the assay of PX in pharmaceutical formulations (Feldene capsules and tablets). Average recoveries of 101.0 + 0.3% and 98.8 2.7% were obtained for capsules in methanol using batch and SIA methods, respectively, while in aqueous medium, 102.9 +2.5% and 99.0 + 1.15% were determined for this type of formulations in batch and SIA modes, respectively. The % recoveries for the analysis of tablets were 99.3+1.5% in methanol using SIA and 100.8+3.2% and
102+0.7% in aqueous medium using batch and SIA techniques, respectively.
