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Simultaneous estimation of rilpivirine (RLVN) and dolutegravir (DTGR) in bulk and tablet dosage forms via RP-HPLC-PDA with a Box–Behnken design (BBD) has been performed in this study to develop a fast, precise, timely and cost-saving method for estimating RLVN and DTGR in bulk and tablet dosage forms. The chromatographic conditions were optimized via the BBD, and the developed method was validated according to the ICH guidelines. Additionally, forced degradation studies were also conducted. RLVN and DTGR peaks were observed at retention times of 2.167 and 2.716 min, respectively, in a 6-min runtime. Kromasil 150 mm× 4.6 mm, 5 µm C 18 column was used. The flow rate of the mobile phase was 1.0 mL/min at a temperature of 30 °C. The mobile phase composition was a 0.1% OPA buffer and acetonitrile (ACN) in a 60:40 ratio. Elutes were measured at 260 nm (max) after being injected in a sample volume of 10 µL. The assay result of the marketed tablet was 99.19% and 99.09% for RLVN and DTGR, respectively. The results of forced degradation studies in different chemical environments conditions such as acid, base, dry heat, photo-stability, neutral, and oxidation conditions were observed for RLVN (5.96, 4.79, 3.27, 2.36, 0.99, and 4.35 in percentage degradation) and DTGR (5.67, 4.44, 4.09, 1.81, 0.43, and 4.28 in percentage degradation). The results of the validation parameters were within an acceptable range. The newly formed RP-HPLC-PDA method is novel, fast, precise, time-saving, and cost-effective.

A fixed-dose combination of paracetamol (PCM) and caffeine (CAF) tablets/capsules is the most frequently used over-the-counter medicine for fever and headache. In this paper, a simple, reliable, sensitive, rapid, and stability-indicating ultra-performance liquid chromatography (UPLC) analytical method was proposed for simultaneously assessing PCM and CAF in pharmaceutical formulations. The UPLC method was developed on an Acquity UPLC® CSHTM C18 column, and the column oven temperature was maintained at 35 ± 5 °C with isocratic elution by using a solution of methanol and water (30:70, v/v). The maximum absorbance of PCM and CAF was observed at 272.5 nm. The flow rate was 0.2 mL/min, and the injection volume was 1 µL, with the total run time of 2 min for the separation of PCM and CAF. The proposed UPLC method was validated according to the ICH guidelines, and it demonstrated excellent linearity, with correlation coefficients of 0.9995 and 0.9999 over the concentration ranges of 40–400 and 7–70 ng/mL for PCM and CAF, respectively. The mean retention times of 0.82 ± 0.0 and 1.16 ± 0.02 were observed for PCM and CAF, respectively. The limits of detection and quantification were 16.62 and 3.86 for PCM, respectively, and 50.37 and 11.70 for CAF, respectively. PCM and CAF were subjected to acidic, alkali, oxidative, phytochemical, dry-heat, and wet-heat degradation. The method was found to well separate the analytes’ peaks from degradation peaks, with no alterations in retention times. The proposed method is linear, precise, accurate, specific, and robust, and it can indicate stability and be used for the quantitative assessment of pharmaceutical formulations comprising PCM and CAF within a short period of time.

The gas chromatography–mass spectrometry (GC-MS) approach is established for the simultaneous determination of fenchone (FCO) and trans-anethole (TOH) in the essential oils and methanolic extracts of fennel (Foeniculum vulgare Mill.) fruits obtained from India (IND), Pakistan (PAK), and Saudi Arabia (SA). The simultaneous determination of FCO and TOH was performed via Agilent 190914S HP–5MS fused-silica capillary column (30 m × 250 µm ID, 0.25 µm film thickness). The proposed GC-MS approach was linear in the range of 0.10–50 µg/g for FCO and TOH. FCO’s detection (LOD) and quantification (LOQ) limits were calculated to be 0.04 and 0.12 µg/g, respectively. The LOD and LOQ values for TOH, on the other hand, were calculated to be 0.05 and 0.15 µg/g, respectively. In addition, the proposed GC-MS approach was accurate and precise for the simultaneous determination of FCO and TOH. The amount of FCO in essential oils of F. vulgare was computed as 0.021, 0.034, and 0.029 mg/g in the samples obtained from IND, PAK, and SA, respectively. The amount of TOH in the essential oils of F. vulgare was computed as 7.40, 14.8, and 10.2 mg/g in the samples obtained from IND, PAK, and SA, respectively. However, the amount of FCO in the methanolic extract of F. vulgare was estimated as 0.031, 0.021, and 0.057 mg/g in the samples obtained from IND, PAK, and SA, respectively. On the other hand, the amount of TOH in the methanolic extract of F. vulgare was estimated as 0.440, 0.498, and 1.74 mg/g in the samples obtained from IND, PAK, and SA, respectively. These findings suggested that the proposed GC-MS approach might be used to simultaneously determine the FCO and TOH in a variety of essential oils and plant extracts.