Objective: Present study aimed to develop and validate a novel, unique, simple, quick, cost-effective, sensitive, specific, accurate, precise, rugged, and robust bioanalytical method for the quantification of gallic acid in rat plasma by reverse phase high-performance liquid chromatography (RP-HPLC) using gradient elution technique. Methods: The stationary phase was a Zorbax SB C18 5 µ (4.6*150) mm column, with the mobile phase being water with 0.1 percent formic acid (A): acetonitrile (ACN) with 0.08 percent formic acid (B). Gradient chromatographic method was used throughout this experiment from the point of view of the estimation of gallic acid from herbal formulations when present along with other phytoconstituents. So at the gradient method, all the present phytoconstituents has cleared off from the column and no any strongly adsorption of phytoconstituents occurred. The experiment was carried out at a flow rate of 1.0 ml/min at 30 °C utilising PDA detectors at 271 nm. The proposed method was validated for different parameters. Results: The approach was found to be linear in the concentration range of 0.5-100 µg/ml, with a r2 of 0.9998. There was not observed any interference of co-eluting peaks of endogenous compounds from the biological matrix at the same retention time (Rt) of gallic acid. The RSD (%) of intra and interday precision was found to be within acceptable limit. The overall % mean recovery was found to be 99.97%. LOD and LOQ were found to be 0.1 and 0.5 μg/ml, respectively. In terms of fluctuation in essential parameters and operating settings, the devised bioanalytical approach was shown to be rugged and resilient. Short-term, long-term, autosampler, bench-top, and freeze-thaw stability experiments revealed that gallic acid is stable. Conclusion: The developed method described in this report was found to be well within an acceptable range. Hence, in the future, this method can be used successfully for the estimation of gallic acid alone or in combination with another analyte or marker present in bulk or an extract containing various phytoconstituents in pharmacokinetic, bioequivalence, and therapeutic drug monitoring studies in clinical laboratories.

The goal of this study was to provide a new, easy, accurate, cost-effective, exact, sensitive, specific, robust, and rugged method for quantifying Epigallocatechin 3 gallate in wistar rat plasma using reverse phase high-performance chromatography (RP-HPLC). The stationary phase was a Zorbax SB C18 5µ (4.6*150) mm column, while the mobile phase was water with 0.1 percent formic acid (A) and acetonitrile (ACN) with 0.08 percent formic acid (B). The experiment was conducted at 30°C with a flow rate of 1.0 ml/min with PDA detectors at 274 nm. With an r 2 of 0.9999, the method was shown to be linear in the concentration range of 0.2-25 µg/ml. At the same retention time (Rt) of epigallocatechin 3 gallate, no interference of co-eluting peaks of endogenous chemicals from the biological matrix was found. The intraday and interday precision RSD (%) was found to be within acceptable limits (less than 2%). The overall mean recovery percentage was determined to be 96.92 %. The LOD and LOQ were determined to be 0.0682 ± 0.0011 µg/ml and 0.205 ± 0.004 µg/ml, respectively. In short-term and long-term stability tests, auto sampler, bench-top, and freeze-thaw stability tests were found to be stable. The developed approach reported was determined to be well within acceptable limits. As a result, in the future, this method can be successfully employed in clinical laboratories to estimate epigallocatechin 3 gallate alone or in conjunction with other analytes or markers in pharmacokinetic, bioequivalence, and therapeutic drug monitoring.