The ionization constant of fluorescent reagent gibberellic acid (GA) was established spectrophotometrically. The fluorescent reaction of this reagent with lead was studied. Based on this chelation reaction, a sensitive, direct spectrofluorimetric method for the determination of trace lead with use of GA has been developed. The reaction conditions for the fluorescence system of lead with GA were studied. The lead ion can form a stable binary chelate with GA, having a ratio of 1:2 in the pH range 7.0‐8.0. The maximum excitation and emission wavelengths are 205.0 nm and 308.8 nm for the lead chelate, respectively. The reaction is instantaneous and the fluorescence intensity of the lead chelate remains stable from 20 to 150 min. Under the optimal experimental conditions the fluorescence intensity is a linear function of concentration in the range 1.0‐10.0 ng/mL of lead and the detection limit is 0.52 ng/mL of lead. Interferences of other ions were studied. The method has been successfully applied to the determination of lead in common paint. 相似文献
A 3-component cascade synthesis of bis(2-arylallyl) tertiary amines from aryl iodide, allene and primary aliphatic amines is described; chiral amines give analogous products with no detectable racemisation; mixtures of two different aryl iodides can be utilised to give the mixed tertiary amines as the sole, or major, product; the reaction is sensitive to stereoelectronic effects which lead to mono(2-arylallyl) secondary amines. 相似文献
Several mono-and bis(benzo-18-crown-6) ethers comprising o-nitrophenyl urethanemoieties were synthesized and studied as ionophores in PVC membrane electrodes. Thebis(crown ether)s were found to exhibit good potentiometric Cs+ selectivity overmono and divalent cations as compared to the respective mono(crown ether)s. 相似文献
The surgical masks have been essential consumables for public in the COVID-19 pandemic. However, long-time wearing masks will make wearers feel uncomfortable and massive discarded non-biodegradable masks lead to a heavy burden on our environment. In this paper, we adopt degradable chitosan@silver (CS@Ag) core–shell fibers and plant fibers to prepare an eco-friendly mask with excellent thermal comfort, self-sterilization, and antiviral effects. The thermal network of CS@Ag core–shell fibers highly improves the in-plane thermal conductivity of masks, which is 4.45 times higher than that of commercial masks. Because of the electrical conductivity of Ag, the fabricated mask can be electrically heated to warm the wearer in a cold environment and disinfect COVID-19 facilely at room temperature. Meanwhile, the in-situ reduced silver nanoparticles (AgNPs) endow the mask with superior antibacterial properties. Therefore, this mask shows a great potential to address the urgent need for a thermally comfortable, antibacterial, antiviral, and eco-friendly mask.