Second-derivative spectrophotometric assay of pseudoephedrine, ibuprofen and loratadine in pharmaceuticals.

In this paper the second-derivative spectrophotometric method for the simultaneous determination of pseudoephedrine (CAS 90-82-4) in the combinations with ibuprofen (CAS 15687-27-1) and loratadine (CAS 79794-75-5) is described. Optimal conditions for the quantitative analysis of coated tablets (Test I) and tablets (Test II) were settled. The second-derivative order of the spectra in ethanol with the wavelength modulation was used. For the quantitative assay for all of the investigated substances in the laboratory mixture or in respective pharmaceutical dosage forms the "zero-crossing" technique was applied. The authors propose this second-derivative spectrophotometry for a rapid, simple, precise and accurate determination of the mentioned tests or a corresponding multicomponent mixture.