A nonsteroidal drug called flurbiprofen (FBN) has analgesic, anti‐inflammatory and antipyretic activity. Currently the determination of FBN in cataplasm does not have any pharmacopeial method. However, the drug substance, tablet and ophthalmic solution formulations do have pharmacopeial methods. The development and validation of an accurate, precise and stability‐indicating analytical method for the determination of FBN in cataplasm formulations is reported. The gradient method was employed for the quantification of FBN in the presence of internal standards such as biphenyl. A nonpolar separation phase (C18, 250 × 4.6 mm, 5 μm Inertsil column; GL Sciences) was used. The optimal flow rate, column oven temperature, injection volume and detector wavelengths were 1.0 ml/min, 40°C, 20 μl and 245 nm, respectively. Mobile phase A was a mixture of water and glacial acetic acid (30:1 v/v) pH adjusted to 2.20 with glacial acetic acid or 1 m NaOH; mobile phase B was methanol (100%). The gradient elution program was [time (min)/% B]: 5/60, 20/70, 25/70, 30/60 and 40/60. The obtained RSDs for the precision and intermediate precision were 0.7 and 0.5%. The percentage recovery ranged from 99.2 to 100.4%. The linear regression coefficient >0.9996 indicates that all peak responses were linear with the concentration. The sample and standard solutions were stable for up to 24 h on the benchtop and in the refrigerator. The critical peaks were well separated from the generated peaks owing to forced degradation, including diluent and placebo peaks. The method validation data and quality by design‐based robustness study results indicate that the developed method is robust and fit for routine use in the quality control laboratory. The proposed method is specific, accurate and precise, and the quality by design utilized the first method for the determination of FBN in cataplasm formulations. Transdermal patches and gels have low extraction capacity and this method is applicable for quantification.

The developed method was validated according to ICH guidelines with respect to specificity, linearity, limits of detection, quantification, accuracy, precision, and robustness. The stability-indicating reverse-phase high-performance liquid chromatography (RP-HPLC) method is precise; it has been developed for the simultaneous estimation of assay of guaifenesin (GN) and dextromethorphan hydrobromic (HBr) (DN) in drug substance and drug product. The chromatographic separation was done in an isocratic mode using the Syncronus C8 (250 × 4.6 mm, 5 μ particle size) column with mobile phase containing a 10 mM ammonium acetate in water (modulated pH 4.30 with orthophosphoric acid) and acetonitrile in the ratio of 60:40 (% v/v) used for efficient chromatographic separation. The flow rate of the mobile phase was 1 mL/min with ambient column temperature and detection of wavelength at 279 nm; injection volume 10 μL was fixed for achieving good elution of eluents. The retention time for GN was found to 3.46 minutes and DN was found to 7.58 minutes. GN and DN were linear in the concentration range from 357 to 1,428 and 19 to 75 μg/mL, respectively. Regression analysis showed that the r value (correlation coefficient) greater than 0.999 for GN r value was found to be 0.999, GN r value was found to be 0.999, DN r value was found to be 0.999. Limit of detection (LoD) and limit of quantification (LoQ) of GN was found to be 0.151 and 0.904 μg/mL, DN was found to be 0.241 and 0.726 μg/mL. The developed method was validated and found to be accurate, specific, and robust. Both the drugs were subjected to the stress conditions like acidic, basic, oxidative, photolytic, and thermal conditions. The degradation results were found to be satisfactory. In peroxide stress condition, GN was found stable over DN, and DN was found to degrade significantly. The degradation products were well resolved from GN, DN, and their impurities. The peak purity test results confirmed that the GN and DN peak were homogenous and pure in all stress conditions, thus, proving the stability-indicating nature of the method. This method could be applied for the simultaneous estimation of GN and DN in drug substance and drug product.

A simple, precise and robust UPLC-Q-TOF-MS method was developed for the quantification of four marker compounds, namely citric acid derivative, iso garcinol, garcinol and garcimultiflorone-A in Garcinia morella, in order to study the fragmentation pathways of four marker compounds. The developed method was validated according to ICH guidelines in terms of linearity, LOD and LOQ, precision and accuracy. Optimized chromatographic conditions were Waters Acquity BEH C18 (100 X 2.1mm, 1.9 m) column, flow rate of 0.6 mL min-1, 8.0 minutes run time and mobile phase being 0.1 % formic acid in water / acetonitrile. The gradient elution programme 0 (95/5), 0.5 (95/5), 2.50 (5/95), 5.0 (5/95), 6.5 (95/5) and 8.0 (95/5) was carried out on Waters instrument UPLC-Q-TOF-MS. The obtained retention times of citric acid derivative, iso garcinol, garcinol and garcimultiflorone-A were 2.14, 3.86, 4.31 and 5.05 minutes, respectively. LOD and LOQ data was found to be in 0.32-0.56 and 0.99-1.69 mg mL-1, respectively.

Parental products buffer agents viz. calcium phosphate (CP), potassium phosphate (PP) and sodium phosphate (SP) were successfully qualitatively and quantitatively determined on RP-HPLC in the UV detection. The three components were retained in reverse phase by utilizing polymethacrylate resin stationary phase. The quantification was done by using the waters IC-Pak (50 × 4.6) mm, 10 μm column with 1.0 mL/min flow rate. 0.1 M nitric acid solution was used as a mobile phase. The detection was done at 288 nm, column temperature was 30 ºC, injection volume was 50 μL and the total run time was 5 min. The method was validated as per the regulatory and ICH guidelines. The accuracy was found from 98.5% to 101.5% and the precision data was found from 0.5% to 0.9%. The linearity resulted in r value more than 0.999. Quality by design software was used to establish the method robustness. Green chemistry principles and tools were used to assess the method eco-ness. The developed method can be utilized as an application to quantify the buffer agent content in selected parental products.