A Comparative Study of Spectrophotometric Methods Versus Chemometric Methods; An Application on a Pharmaceutical Binary Mixture of Ofloxacin and Dexamethasone
Nagiba Y. Hassan
Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr-El Aini Street, 11562 Cairo, Egypt
Samia M. Elgizawy
Analytical Chemistry Department, Faculty of Pharmacy, Assuit University, 71515 Assuit, Egypt
Hayam M. Lotfy
Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr-El Aini Street, 11562 Cairo, Egypt
Sarah S. Saleh *
Analytical Chemistry Department, Faculty of Pharmacy, October University for Modern Sciences and Arts (MSA), 11787 6th October City, Egypt
*Author to whom correspondence should be addressed.
Abstract
Aim: To conduct a comparative study between the smart novel ratio difference spectrophotometric method (RDSM) versus four spectrophotometric methods: first derivative spectrophotometry (D1), first derivative of the ratio spectra (1DD), isoabsorpative point (Aiso), ratio subtraction (RS), and two chemometric techniques based on principal component regression (PCR) and partial least-squares (PLS-1) for the determination of a binary mixture of Ofloxacin (OFX) and Dexamethasone (DXM).
Study Design: The results obtained from the proposed methods were statistically compared to the reported HPLC method using student’s t-test, F-test and One way ANOVA.
Methodology: (OFX) was determined by the application of direct spectrophotometry, by measuring its zero-order (D0) absorption spectra at its λmax = 296.6 nm. (DXM) was determined by (D1) at 227.1 nm. By applying (1DD), (DXM) was determined at 237.3. The total concentration of both (OFX + DXM) was determined at their isoabsorpative point λiso= 238.3 nm, then the concentration of (DXM) in mixtures were calculated by subtraction. (DXM) was determined using the (RS) method at its λmax = 239 nm. (DXM) was determined using (RDSM) by measuring amplitude difference at two selected wavelengths (248.4 and 290 nm). A concentration of 10 µg.mL-1 of OFX was used as a divisor. The linearity range was found to be (1-10 µg.mL-1) and (2-14 µg.mL-1) for OFX and DXM respectively.
Results: The recovery percentage for OFX was found to be 100.07 ±0.65 and for DXM was found to be 100.41 ±0.84, 100.15 ±0.97, 100.14 ±0.91, 100.54 ±0.75 and 100.11 ±.66 for the five methods, respectively.
Conclusion: The novel method showed advantages over the other proposed methods regarding simplicity, minimal data manipulation and maximum reproducibility and robustness; which enabled the analysis of binary mixtures with overlapped spectra for routine quality control testing with quite satisfactory and in lower cost.
Keywords: Ofloxacin, dexamethasone, ratio difference, isoabsorpative point, ratio subtraction, chemometric