It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and mi...It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.展开更多
The use of chiral organophosphoras derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The ...The use of chiral organophosphoras derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.展开更多
Objective:To analyze the effect of high-performance liquid chromatography(HPLC)for the determination of azithromycin and to provide references for related research work.Methods:The mobile phase was ammonixim dihydroge...Objective:To analyze the effect of high-performance liquid chromatography(HPLC)for the determination of azithromycin and to provide references for related research work.Methods:The mobile phase was ammonixim dihydrogen phosphate at 0.067 mol/L(mixed with triethylamine;pH value was adjusted to 6.5).The chromatographic column was Kromasil C18(250 mm × 4.6 mm;5.0μm)and the relative standard deviation(RSD)of the drug content level was 1.25%.The injection volume was set to 20μL,the detection wavelength was set to 210 nm,the external standard method was used to complete the quantitative work,and the theoretical plate number should be more than 1000 according to the drug peak calculation.The effect of HPLC on the determmation of azithromycin was analyzed.Results:The concentration of azithromycin was 1.40-3.40 mg/mL,and the linear relationship was good.RSD of the drug content level was 1.25%.The representative test product had strong stability within 8.0 hours and the method had good repeatability.According to the recovery experiment method,the recovery rates of three standard samples from low to high were 99.87%,100.15%,and 100.62%.The average recovery rate was 100.21%.RSD value was 0.39%.It means that the recovery rate of HPLC is good.Conclusion:In the determination of azithromycin,the use of HPLC to complete the work was of high sensitivity,simple,and fast.The method had good repeatability in the determination of drug components which is worthy of further promotion.展开更多
A more comprehensive calibration involving m/z and peak shape has been developed to attain the high spectral accuracy necessary to achieve unique elemental composition determination. This approach can be applied for f...A more comprehensive calibration involving m/z and peak shape has been developed to attain the high spectral accuracy necessary to achieve unique elemental composition determination. This approach can be applied for formula determination at much lower resolution such as single or triple quadrupole mass spectrometers.展开更多
基金This work is supported by the National Natural Science Foundation of China （Grant Nos. 60336010 ＆ 90401001）973 Program （Grant No. TG 2000036603）the Student Innovation Program of CAS （No. 1731000500010）.
文摘It is important to acquire the composition of Si1-xGex layer, especially that with high Ge content, epitaxied on Si substrate. Two nondestructive examination methods, double crystals X-ray diffraction （DCXRD） and micro-Raman measurement, were introduced comparatively to determine x value in Si1-xGex layer, which show that while the two methods are consistent with each other when x is low, the results obtained from double crystals X-ray diffraction are not credible due to the large strain relaxation occurring in Si1-xGex layers when Ge content is higher than about 20%. Micro-Raman measurement is more appropriate for determining high Ge content than DCXRD.
文摘The use of chiral organophosphoras derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.
文摘Objective:To analyze the effect of high-performance liquid chromatography(HPLC)for the determination of azithromycin and to provide references for related research work.Methods:The mobile phase was ammonixim dihydrogen phosphate at 0.067 mol/L(mixed with triethylamine;pH value was adjusted to 6.5).The chromatographic column was Kromasil C18(250 mm × 4.6 mm;5.0μm)and the relative standard deviation(RSD)of the drug content level was 1.25%.The injection volume was set to 20μL,the detection wavelength was set to 210 nm,the external standard method was used to complete the quantitative work,and the theoretical plate number should be more than 1000 according to the drug peak calculation.The effect of HPLC on the determmation of azithromycin was analyzed.Results:The concentration of azithromycin was 1.40-3.40 mg/mL,and the linear relationship was good.RSD of the drug content level was 1.25%.The representative test product had strong stability within 8.0 hours and the method had good repeatability.According to the recovery experiment method,the recovery rates of three standard samples from low to high were 99.87%,100.15%,and 100.62%.The average recovery rate was 100.21%.RSD value was 0.39%.It means that the recovery rate of HPLC is good.Conclusion:In the determination of azithromycin,the use of HPLC to complete the work was of high sensitivity,simple,and fast.The method had good repeatability in the determination of drug components which is worthy of further promotion.
文摘A more comprehensive calibration involving m/z and peak shape has been developed to attain the high spectral accuracy necessary to achieve unique elemental composition determination. This approach can be applied for formula determination at much lower resolution such as single or triple quadrupole mass spectrometers.
