Green NP-HPTLC and green RP-HPTLC methods for the determination of thymoquinone: A contrast of validation parameters and greenness assessment

Guesstimate of thymoquinone diversity in Nigella sativa L. genotypes and elite varieties collected from Indian states using HPTLC technique

Thymoquinone is a valuable metabolite derived from the Nigella sativa L. seeds and has a variety of therapeutic properties. Thymoquinone was estimated using n-hexane:ethyl acetate (8:2, v/v) green solvent system and computed at a wavelength of 254 nm using the high-performance thin-layer chromatography densitometry method in distinct varieties and genotypes congregated from different geographical regions. Genotype Ajmer Nigella-13 has the paramount thymoquinone content (247.60 µg/100 mg seed) followed by Ajmer Nigella 19 (244.5 µg/100 mg seed), while the lowest amount of thymoquinone was recorded in the genotype Ajmer Nigella-6 (42.88 µg/100 mg seed). The hierarchical cluster analysis found that the collected genotypes and elite varieties were classified into four broad clusters, and the identified chemotypes with elevated thymoquinone proportion were positioned in cluster D. Significant genotypic variation in thymoquinone content is available, that can be used in exploiting pharmaceutical applications of N. sativa L. as well as a breeding programme for specific metabolite improvement perspective.

Box-Behnken Design (BBD) Application for Optimization of Chromatographic Conditions in RP-HPLC Method Development for the Estimation of Thymoquinone in Nigella sativa Seed Powder

Thymoquinone (THY) is a bioactive compound present in the seed powder of Nigella sativa (NS). This research aims to precisely and accurately estimate THY using high-performance liquid chromatography (HPLC) with a Quality by Design (QbD) application. Box-Behnken design (BBD) was employed to optimize the chromatographic conditions for HPLC method development, taking mobile phase flow rate, pH of the buffer, and λmax as independent variables and retention time and tailing factor as the measured responses. The mobile phase composition was methanol: acetonitrile: buffer (2.2 mM ammonium formate) at the ratio of 35:50:15 v/v/v on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column. In isocratic mode, it had a flow rate 0.9 mL min−1 and eluted analyte was detected at 249 nm. Validation parameters followed the International Council for Harmonization (ICH) guidelines for the new HPLC method. The method was linear over the range 6.25–100 µg mL−1 with a coefficient of determination (r2) of 0.9957. The limit of detection (LOD) and limit of quantification (LOQ) were 2.05 and 6.25 µg mL−1, respectively. The %RSD of system suitability for retention time was 1.42% and for the tailing factor it was 0.695%. In addition, the developed method was precise, accurate, and robust according to ICH criteria. The developed HPLC method is simple, accurate, quick, and robust, and it could be used for the routine analysis of THY in different kinds of formulations.

A Green High-Performance Thin-Layer Chromatography Method for the Determination of Caffeine in Commercial Energy Drinks and Formulations

The literature on green analytical approaches for caffeine estimation is limited. As a consequence, this study aimed to establish a reverse-phase high-performance thin-layer chromatography (HPTLC) technique for caffeine estimation in a variety of commercial energy drinks (ED) and pharmaceutical formulations that is rapid, sensitive, and green. The combination of ethanol-water (55:45 v v−1) was used as a mobile phase. The detection of caffeine was carried out at 275 nm. The green reverse-phase HPTLC method was linear in the concentration range of 50−800 ng band−1. Furthermore, the developed method for caffeine estimation was simple, quick, economical, accurate, precise, robust, sensitive, and green. The amount of caffeine in different marketed ED (ED1−ED10) was recorded in the range of 21.02−37.52 mg 100 mL−1 using the developed HPTLC method. However, the amount of caffeine in different commercial formulations (F1−F3) was estimated as 10.63−20.30 mg 100 mL−1 using the same method. The “analytical GREEnness (AGREE)” scale for the developed analytical method was predicted to be 0.80, utilizing 12 distinct components of green analytical chemistry, indicating the HPTLC approach’s excellent greener profile. Overall, the developed method for estimating caffeine in marketed ED and dosage forms was found to be reliable.

Rapid, Highly-Sensitive and Ecologically Greener Reversed-Phase/Normal-Phase HPTLC Technique with Univariate Calibration for the Determination of Trans-Resveratrol

The rapid, highly-sensitive and ecologically greener reversed-phase (RP)/normal-phase (NP) high-performance thin-layer chromatography (HPTLC) densitometric technique has been developed and validated for the determination of trans-resveratrol (TRV). The reversed-phase HPTLC-based analysis of TRV was performed using ethanol–water (65:35, v v−1) combination as the greener mobile phase, while, the normal-phase HPTLC-based estimation of TRV was performed using chloroform–methanol (85:15, v v−1) combination as the routine mobile phase. The TRV detection was carried out at 302 nm for RP/NP densitometric assay. The linearity was recorded as 10–1200 and 30–400 ng band−1 for RP and NP HPTLC techniques, respectively. The RP densitometric assay was observed as highly-sensitive, accurate, precise and robust for TRV detection in comparison with the NP densitometric assay. The contents of TRV in commercial formulation were recorded as 101.21% utilizing the RP densitometric assay, while, the contents of TRV in commercial formulation were found to be 91.64% utilizing the NP densitometric assay. The greener profile of RP/NP technique was obtained using the analytical GREEnness (AGREE) approach. The AGREE scales for RP and NP densitometric assays were estimated 0.75 and 0.48, respectively. The recorded AGREE scale for the RP densitometric assay indicated that this technique was highly green/the ecologically greener compared to the NP densitometric assay. After successful optimization of analytical conditions, validation parameters, AGREE scale and chromatography performance, the RP densitometric assay with univariate calibration was found to be better than the NP densitometric assay for the analysis of TRV.