Second-derivative spectrophotometric determination of mixtures of phenylpropanolamine hydrochloride and dextromethorphan hydrobromide in some pharmaceutical preparations

Sensitive detection of dextromethorphan hydrobromide based on portable Raman spectrometer and CuO@AgNPs nano composite SERS substrate

A highly sensitive surface-enhanced Raman spectroscopy approach was established for the detection of dextromethorphan hydrobromide (DXM) utilizing nano CuO modified silver nanoparticles (CuO@AgNPs) as substrate. Ultraviolet visible spectra (UV-vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterized the synthesized CuO@AgNPs. UV-vis and fourier transform infrared (FT-IR) were adopted to investigate the interaction between DXM and CuO@AgNPs. The optimal experimental conditions (the dosages of CuO@AgNPs and NaCl as well as mixing time) were explored. The enhancement factor (EF) was 1.71 × 106. The linear relationship between SERS intensity and the concentration of DXM in the range of 67 - 1000 nmol L-1 was obtained as ISERS = 25.81 c + 40398.77, and the limit of detection (LOD) was 2.12 nmol L-1 (S/N = 3). The interference of K+, Mg2+, Zn2+, Ca2+, Cu2+, Fe3+, glucose, HSA, L-tryptophan, soluble starch and ibuprofen were investigated. The method was successfully applied to test DXM in serum samples. The recovery was 99.06% - 101.51% with the relative standard deviation (RSD) of 0.74% - 3.87%.

HPLC determination of phenylpropanolamine in pharmaceutical preparations using 4-dimethylaminobenzaldehyde as a derivatizing reagent

A method is described for the high performance liquid chromatographic (HPLC) determination of phenylpropanolamine (PPA) based on precolumn derivatization with 4-dimethylaminobenzaldehyde (DAB) and elution from phenomenex C-18 column with methanol-water and detection by spectrophotometry at 418 nm. Linear calibration was obtained with 9.4--46.9 microg ml(-1) with a detection limit of 4.7 ng ml(-1). Vitamin B(12) and rifampicin when present together with PPA separated completely and could be determined simultaneously. PPA was determined in pharmaceutical preparations with a relative standard deviation of 0.6--1.6%.

Simultaneous multivariate spectrophotometric analysis of paracetamol and minor components (diphenhydramine or phenylpropanolamine) in tablet preparations

The use of multivariate spectrophotometric calibration is reported for the analysis of two decongestant tablets, where paracetamol is the principal component and diphenhydramine or phenylpropanolamine are the minor components. The resolution of these mixtures has been accomplished without prior separation or derivatisation, by using partial least-squares (PLS-1) regression analysis of electronic absorption spectral data. Although the molar ratios of paracetamol to the minor components were 38:1 and 25:1 respectively, the latter have been determined with high accuracy and precision, and with no interference from tablet excipients. PLS is able to take into account small deviations of paracetamol from linearity in the studied concentration range. The application of classical least-squares (CLS) analysis yields unsatisfactory results, due to the low absorbances of the minor components within the range where all components obey Beer's law.