Summary. The objective of this study was to develop and validate a novel, simple, and selective high-performance liquid chromatographic (HPLC) method with photodiode array detector for the estimation of tenofovir in rat plasma, which can be utilized in analyzing the pharmacokinetic samples from rats. Prior to analysis, an optimized protein precipitation technique was used to extract tenofovir from plasma. The mobile phase for this method comprised of 10 mM ammonium acetate buffer (pH 4) and methanol in the ratio of 97:3 v/v. Chromatographic separation of tenofovir was achieved using Spincotech C-18G enabled column (250 × 4.6 mm, 5 μm). Tenofovir was monitored at a wavelength of 260 nm, and the calibration curve was linear in the range of 250-4000 ng mL −1 (R 2 = 0.999). High recovery obtained after extraction (97%-101%) of plasma samples precluded the use of an internal standard. Validation studies were performed as per the standard guidelines, and the developed method was accurate, precise, and selective for the determination of tenofovir in the rat plasma. The stability studies performed during the sample pretreatment process and sample storage conditions did not show a quantifiable degradation of tenofovir. Further, this method was able to estimate tenofovir and determine its pharmacokinetic parameters, post IV bolus administration in male Wistar rats. The pharmacokinetic profile of tenofovir followed one compartmental open model.

D-Psicose/allulose, a rare sugar, is an essential raw material in the pharmaceutical and food industries. It is scantly found in nature and to meet its demand in industries, D-Psicose is generated enzymatically using D-fructose as a substrate.  In these conversations, it is important to monitor D-Psicose,  in order to control the process, impurities, optimize the reaction time and reduce the process cost The available analytical methods have their limitations in quantifying D-psicose and D-fructose mixtures. Hence there is a need for the development of a routine, sensitive, quick and precise analytical method for D-psicose production on-line monitoring of reaction mixer. In the present work, a simplified reverse phase HPLC technique is developed and validated for the quick reaction monitoring of D-psicose from D-fructose, during enzymatic conversation procedures. The analysis is conducted at different concentrations ranging from 0.05 % to 0.5 % of the standard solutions of the D-psicose and D-fructose, by using water and Acetonitrile (at a ratio of 20:80) as eluent with a flow rate of 1.0 mL/min on isocratic HPLC-RID system with an aminopropyl silane stationary phase [ZORBAX SIL 4.6 x 150 mm, 5 µm particle size column (USP-L8)]. The applicability of this method is illustrated in reaction monitoring, where D-fructose (substrate) is converted to D-psicose (product) in the presence of the enzyme:  D-Tagotose 3- epimerase. Separation of D-psicose and D-fructose is achieved within 8 minutes with a resolution ≥ 4 which is the key advantage for reaction monitoring and linearity is established with regression of ≥ 0.99.  Additionally, the current method uses a simple mobile phase, without any buffers. It can be used routinely for reaction monitoring.