Simultaneous determination of ergotamine, caffeine and dipyrone in their ternary mixture by applying double divisor and first derivative ratio spectra methods

Two validated methods namely, double divisor ratio spectra derivative spectroscopy and derivative ratio spectroscopy with zero crossing point were applied to assay a ternary mixture of ergotamine tartrate (EGT), caffeine (CAF) and dipyrone sodium (DIP) without any additional separation steps. The linearity ranges using both methods were (1.0μg/mL-70.0μg/mL), (60.0μg/mL-100.0μg/mL) and (100.0μg/mL-300.0μg/mL) for EGT, CAF and DIP respectively. Double divisor ratio spectroscopy (method A) depends on dividing the different peak responses of EGT on (summation of peaks responses of CAF and DIP each of 10.0μg/mL concentration) at λ max=342nm, 310nm and 315nm for EGT, CAF and DIP respectively. Derivative ratio spectroscopy with zero crossing point (method B) depends on dividing the peak responses of two drugs (EGT and CAF) on (10.0μg/mL of DIP) and dividing the peak response of DIP on peak response of (10.0μg/mL of EGT). The detection limits of the studied drugs applying method A were (3.54, 12.96 and 8.748μg/mL), with quantitation limits of (10.73, 39.28 and 26.51μg/mL) for EGT, CAF and DIP respectively. Regarding method B, the limits of detection and quantitation for EGT were 0.604μg/mL and 1.829μg/mL respectively: with corresponding values of 19.44μg/mL and 58.92μg/mL for CAF and 20.44μg/mL and 61.9μg/mL for DIP. The obtained results were compared to those obtained by published methods and were found to be in accordance.