Excessive water in herbal medicines (HMs) can cause pests infestation, mildew, and decomposition of active ingredients during storage. The classical detection methods for water content are still unsatisfactory due to the requirement of sophisticated manipulation, long time consumption and usage of large amounts of toxic toluene. Herein, hot injection method was adopted to synthesize humidity-sensitive CsPbBr 3 perovskite, which was used to develop a novel photoluminescent (PL) sensor on a paper substrate for rapid detection of water content in HMs with a turn-off mode. Due to the strong ionic nature of CsPbBr 3 and the high aqueous solubility of CsBr, CsPbBr 3 perovskite is very unstable upon the exposure of water. The signal off can be attributed to the phase change from luminescent CsPbBr 3 to non-luminescent CsPb 2 Br 5 according to the results of XRD pattern analysis of CsPbBr 3 perovskite before and after water exposure. The PL intensity of CsPbBr 3 is linearly related to the water content within the range of 1–17 %. For Seutellaria baicalensis and Astragalus flavone , the detection limits are 0.75 % and 0.67 %, respectively. The results of recovery tests for the two HMs are within the range of 96.7–102.5 %. This work realizes the application of CsPbBr 3 perovskite in the field of pharmaceutical analysis, and shows the application potential for the control of water content in other types of samples sensitive to humidity.
Perovskite-type lithium-ion conductor Li 0.33 La 0.56 TiO 3 was prepared via microwave sintering. The influence of lithium sources on the properties of the samples prepared and the compensation of lithium loss were investigated. XRD patterns, exhibiting a mixture of tetragonal and cubic phase, were all similar for the samples made with different lithium sources. The total conductivity of the sample made with Li 2 CO 3 achieved 0.51 × 10 −4 S/cm, which was the highest among all the samples made with different sources. The highest total conductivity of the sample made with Li 2 CO 3 was attributed to the largest grains, which would result in a smaller concentration of less-conductive grain boundaries. The total conductivity of the sample compensated with 5% Li 2 O was 38% higher than the sample made stoichiometrically. Given that grain sizes were similar for the samples compensated with a varied amount of Li 2 O and the relative density of the sample compensated with 5% Li 2 O was even the lowest among these samples, the highest total conductivity was rooted in the highest ratio of cubic phase. These results indicated that lithium sources could influence the properties of the LLTO samples greatly by resulting in a variation on crystalline phase, grain size, and relative density, which collectively determine the migration of lithium ions in polycrystalline Li 0.33 La 0.56 TiO 3 .
危险品化学品经营许可证（带存储）