Quantitative determination of new anti-inflammatory drug indomenthyl and its metabolite in rabbit plasma by HPLC-MS/MS.

Background: Indomenthyl is an innovative anti-inflammatory drug with a high analgesic activity. Indomenthyl releases indomethacin under the influence of neutrophil esterases in the inflammation focus. Methodology/results: This research is aimed at developing a highly sensitive method for the quantitative determination of indomenthyl and its active metabolite indomethacin in rabbit plasma by HPLC-MS/MS. Protein precipitation and extraction with acetonitrile were used for analyte isolation from plasma according to the QuEChERS principle. The target quantitative ion pairs m/z were respectively 496.4 → 358.0 for indomenthyl, 358.0 → 139.5 for indomethacin, and 340.1 → 202.1 for the IS. Conclusion: The calibration curve was linear over the range 0.1-1000 ng mL-1. The technique was applied to the pharmacokinetic study at a dose of 25 mg kg-1 to rabbits.

Development and validation of HPLC-UV method for quantitation of a new antithrombotic drug in rat plasma and its application to pharmacokinetic studies.

A selective and sensitive procedure for quantitation of a new antithrombotic drug (GRS) in rat plasma was developed and validated using an HPLC-UV. The method was validated according to recommendations of the FDA, EMA in terms of selectivity, linearity, accuracy, precision, recovery, matrix effect, stability, and carry-over. The preparation of the biological sample included liquid-liquid extraction with acetonitrile, separation of water-organic mixture with inorganic salts, organic phase clean-up with a sorbent (QuEChERS method), its evaporation to dryness and reconstitution of the residue with A:B eluents mixture (1:1). The chromatographic separations were performed on a micro-column 75 × 2 mm, 5 µm particle size sorbent ProntoSIL 120-5-C18 AQ. The flowrate was of 0.15 ml/min, detector wavelength was set at 360 nm for GRS and at 230 nm for papaverine (IS). It was found that GRS recovery from rat plasma is 94%, the response linearity is in the range of 10 to 1000 ng ml-1. The accuracy values for intra-day determination were of 93.2 to 101.8%, for inter-day determination were of 91.2 to 102.2%, coefficient of variation for intra- and inter-day precision did not exceed 4.1 to 9.3%. The application of the method was shown in pharmacokinetic studies of GRS in rats at a dose of 20 mg kg-1.

Simultaneous voltammetric determination of Brilliant Blue FCF and Tartrazine for food quality control.

Voltammetric determination of Tartrazine (Tz) and Brilliant Blue FCF (BB) in their mixture using novel type of carbon black-polyethylene composite electrode (CBPCE) with renewable surface modified by carbon ink (CI) was developed. Electrochemical properties of the tested dyes were investigated in 0.1 mol L-1 Britton-Robinson (BR) buffer by cyclic voltammetry (CV) and linear scan voltammetry (LSV). Simultaneous determination of the dyes is based on the application of supporting electrolytes with different pH: 2.0 for Tz and 10.0 for BB. Under the optimum experimental conditions, linear concentration dependences in the concentration ranges from 0.037 to 1.38 µmol L-1 for Tz and from 0.025 to 2.52 µmol L-1 for BB were obtained by LSV in the first-order derivative mode. Limits of detection (LODs) for Tz and BB were 0.019 and 0.011 µmol L-1, respectively. The modified electrode showed good stability and reproducibility and was successfully applied for the determination of the mixture Tz and BB in a candy and soft drink products.