Novel spectrophotometric method for selective determination of compounds in ternary mixtures (dual wavelength in ratio spectra)

• Simple spectrophotometric method for selective determination of ternary mixtures.
• No reported spectrophotometric method for the determination of the studied mixture.
• Merging ratio difference & dual wavelength for determination of ternary mixtures.
• Application of dual wavelength in the ratio spectrum.
• New hybrid method by merging two analytical methods used for binary mixtures.

A simple selective spectrophotometric method for determination of compounds in ternary mixture was developed by combining the resolution power of two well-known methods that are commonly used for binary mixtures; namely ratio difference method and dual wavelength. The new method (dual wavelength in ratio spectra) was successfully applied for the determination of a ternary mixture of betamethasone dipropionate (BM), clotrimazole (CT) and benzyl alcohol (BA) in pure powder form and in their pharmaceutical preparation. The difference in amplitudes (ΔP) in the ratio spectra at 252.0 and 258.0 nm (ΔP252.0–258.0nm) corresponds to BM, while ΔP266.8–255.4nm and ΔP254.2–243.5nm corresponds to CT and BA, respectively. The method was validated as per the USP 2005 guidelines. The developed method can be used in quality control laboratories for routine analysis of compounds in ternary mixtures.

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