A (CH3)2CNHCH3PbBr3/CH3NH3PbBr3 core-shell heterostructure fabricated by an in situ a-site reaction for fast response 1D perovskite photodetectors.

Benefitting from their long carrier diffusion lengths, low trap densities and high carrier mobilities, metal halide perovskites are of great value in the field of energy and optical communications. Herein, we propose a reversible organic cation reaction for (CH3)2CNHCH3PbBr3/CH3NH3PbBr3 core-shell microwires (MWs), in which (CH3)2CNHCH3PbBr3 grow on bulk CH3NH3PbBr3 in acetone and then convert back to CH3NH3PbBr3 on the surface with the action of water. The core-shell MWs present excellent stability for more than 454 days with over 80% humidity.  Moreover, the employed core-shell heterostructure significantly increases the photoluminescence lifetime and improves the rise/recovery response. The (CH3)2CNHCH3PbBr3/CH3NH3PbBr3 core-shell heterostructure demonstrates excellent stability and fast response (2.8 ms/0.8 ms), which is anticipated to find comprehensive applications in future optical communication of one-dimensional devices.

Determination of isotoosendanin in rat plasma by liquid chromatography-tandem mass spectrometry: application to pharmacokinetics study.

A rapid, sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the quantification of isotoosendanin, an important bioactive component isolated from Meliae cortex. A Capcell PAK C18 column (100 × 4.6 mm) was used for the chromatographic elution using methanol-10 mM ammonium acetate-formic acid (80:20:0.1, v/v/v) as mobile phase at the flow rate of 0.6 mL/min. MS-MS analysis was performed on a triple quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization source in positive ion mode. Extraction of isotoosendanin and genistein (internal standard, IS) from rat plasma was determined by precipitating protein treatment. Quantification was performed by MS in the multiple reaction monitoring mode with positive ionization at m/z 557 → 437 for the analyte and m/z 271 → 215 for IS, respectively. Linear isotoosendanin calibration curves were obtained between 2.0-2,000 ng/mL with a correlation coefficient greater than 0.99. Acceptable precision and accuracy were acquired for concentrations over the standard curve range. Satisfactory results were achieved for sensitivity, specificity, recovery, freeze/thaw and stability. This analytical method was successfully applied to determine the pharmacokinetic parameters of isotoosendanin after an oral administration of 200 mg/kg to rats.

Development and validation of an LC-MS-MS method for determination of methyl kulonate in rat plasma.

A sensitive, rapid and specific LC-MS-MS method was established and validated for determination of methyl kulonate, a major bioactive constituent isolated from Meliae Cortex, in rat plasma. Plasma samples were treated by precipitating protein with methanol and were chromatographed using a Capcell Pak C18 column (100 x 4.6 mm, 5 µm) with the mobile phase comprising a mixture of methanol, 10 mM ammonium formate and formic acid (95:5:0.1, v/v/v). Detection and quantification were performed by mass spectrometry in the multiple reaction monitoring mode with positive atmospheric ionization at m/z 467 --> 311 for methyl kulonate, and m/z 469 --> 451 for dubione B (internal standard), respectively. A good linear response was observed over the concentration range 1.00-500 ng/mL with the lower limit of quantification 1.00 ng/mL in rat plasma. The method also afforded satisfactory results base on sensitivity, specificity, precision, accuracy, recovery, freeze-thaw and long-time stability. The validated method was successfully applied to determine the pharmacokinetic properties of methyl kulonate in rats after oral administration at dose of 100 mg/kg. This pharmacokinetic study of methyl kulonate is reported here for the first time.