Four simple, sensitive and accurate spectrophotometric methods have been developed for the determination of some calcium channel blockers: Amlodipine besylate (ADB), Diltiazem hydrochloride (DTZ) and Verapamil hydroch...Four simple, sensitive and accurate spectrophotometric methods have been developed for the determination of some calcium channel blockers: Amlodipine besylate (ADB), Diltiazem hydrochloride (DTZ) and Verapamil hydrochloride (VPM) in pharmaceutical formulations. These methods based on formation ion pair complexes with Sulfochlorophenol-S (SCPS), Bromopyrogallol red (BPR), Eriochromecyanine- R (ECC) and Pyrocatechol violet (PCV) in acidic medium. The colored products are extracted with chloroform and measured spectrophoto- metrically at 462, 600, 440 and 442 for ECC, SCPS, BPR and PCV, respectively. Beer’s low was obeyed in the concentration range, for ECC: 25 - 175 μg·ml-1, 50 - 150 μg·ml-1 or 100 - 250 μg·ml-1, for SCPS: 300 - 800 μg·ml-1, 200 - 700 μg·ml-1 or 100 - 550 μg·ml-1, for BPR: 50 - 400 μg·ml-1, 200 - 700 μg·ml-1 or 200 - 700 μg·ml-1 for VPM, DTZ or ADB, respectively and for PCV: 50 - 250 μg·ml-1 for VPM or 200 - 500 μg·ml-1 for DTZ with molar absorptivity, for ECC: 2.2 × 104, 2.1 × 104, 1.6 × 104 L·mol-1·cm-1, for SCPS: 3.8 × 103, 5.6 × 103, 8.1 × 103 L·mol-1·cm-1, for BPR: 11 × 103, 4.8 × 103, 6.9 × 103 L·mol-1·cm-1 for VPM, DTZ or ADB, respectively and for PCV: 19.5 × 103 L·mol-1·cm-1 for VPM and 6.6 × 103 L·mol-1·cm-1 for DTZ and relative standard deviation, for ECC: 0.76%, 0.86%, 0.46%, for SCPS: 0.94%, 0.96%, 0.86%, for BPR: 0.96%, 0.95%, 0.55% for VPM, DTZ or ADB, respectively and for PCV: 0.81% for VPM and 0.65% for DTZ. These methods have been successfully applied for the assay of drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.展开更多
The control of crystal growth is important but challenging for multi-disciplinary research.Violet phosphorus,the most stable phosphorus allotrope,has recently been produced as a unique semiconducting layered structure...The control of crystal growth is important but challenging for multi-disciplinary research.Violet phosphorus,the most stable phosphorus allotrope,has recently been produced as a unique semiconducting layered structure.The crystal orientation and morphology bring extra performance due to its unique structure and anisotropy.Herein,the layered violet phosphorus has been controlled to grow along the c-axis to give tunable length up to centimeters with the assistance of tin,while the reported flat bulk ones with thickness are limited to micrometers.The as-produced needle-shaped violet phosphorus has also been demonstrated to significantly enhance the photocatalytic degradation of methyl orange pollutants due to its special crystallographic orientation.About 98.6%of methyl orange pollutants with a concentration of 50 ppm were degraded within 80 min under visible light conditions by needle-shaped violet phosphorus,which is much more effective than that of amorphous red phosphorus with only 14.1%degradation.展开更多
文摘Four simple, sensitive and accurate spectrophotometric methods have been developed for the determination of some calcium channel blockers: Amlodipine besylate (ADB), Diltiazem hydrochloride (DTZ) and Verapamil hydrochloride (VPM) in pharmaceutical formulations. These methods based on formation ion pair complexes with Sulfochlorophenol-S (SCPS), Bromopyrogallol red (BPR), Eriochromecyanine- R (ECC) and Pyrocatechol violet (PCV) in acidic medium. The colored products are extracted with chloroform and measured spectrophoto- metrically at 462, 600, 440 and 442 for ECC, SCPS, BPR and PCV, respectively. Beer’s low was obeyed in the concentration range, for ECC: 25 - 175 μg·ml-1, 50 - 150 μg·ml-1 or 100 - 250 μg·ml-1, for SCPS: 300 - 800 μg·ml-1, 200 - 700 μg·ml-1 or 100 - 550 μg·ml-1, for BPR: 50 - 400 μg·ml-1, 200 - 700 μg·ml-1 or 200 - 700 μg·ml-1 for VPM, DTZ or ADB, respectively and for PCV: 50 - 250 μg·ml-1 for VPM or 200 - 500 μg·ml-1 for DTZ with molar absorptivity, for ECC: 2.2 × 104, 2.1 × 104, 1.6 × 104 L·mol-1·cm-1, for SCPS: 3.8 × 103, 5.6 × 103, 8.1 × 103 L·mol-1·cm-1, for BPR: 11 × 103, 4.8 × 103, 6.9 × 103 L·mol-1·cm-1 for VPM, DTZ or ADB, respectively and for PCV: 19.5 × 103 L·mol-1·cm-1 for VPM and 6.6 × 103 L·mol-1·cm-1 for DTZ and relative standard deviation, for ECC: 0.76%, 0.86%, 0.46%, for SCPS: 0.94%, 0.96%, 0.86%, for BPR: 0.96%, 0.95%, 0.55% for VPM, DTZ or ADB, respectively and for PCV: 0.81% for VPM and 0.65% for DTZ. These methods have been successfully applied for the assay of drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.
基金support for this research is from the National Natural Science Foundation of China(No.22175136)Fundamental Research Funds for the Central Universities.
文摘The control of crystal growth is important but challenging for multi-disciplinary research.Violet phosphorus,the most stable phosphorus allotrope,has recently been produced as a unique semiconducting layered structure.The crystal orientation and morphology bring extra performance due to its unique structure and anisotropy.Herein,the layered violet phosphorus has been controlled to grow along the c-axis to give tunable length up to centimeters with the assistance of tin,while the reported flat bulk ones with thickness are limited to micrometers.The as-produced needle-shaped violet phosphorus has also been demonstrated to significantly enhance the photocatalytic degradation of methyl orange pollutants due to its special crystallographic orientation.About 98.6%of methyl orange pollutants with a concentration of 50 ppm were degraded within 80 min under visible light conditions by needle-shaped violet phosphorus,which is much more effective than that of amorphous red phosphorus with only 14.1%degradation.
