Nitrogen content is an important parameter for petroleum refining processes. The combined use of mid-infrared attenuated total reflection spectroscopy and multivariate calibration allows accurate determination of nitr...Nitrogen content is an important parameter for petroleum refining processes. The combined use of mid-infrared attenuated total reflection spectroscopy and multivariate calibration allows accurate determination of nitrogen content in petroleum and its products. The calibration models of nitrogen content in crude oils have been established by partial least squares (PLS) method. The results predicted by this method were very close to those determined by standard methods. Compared with standard methods, this method is provided with advantages such as high-speed, simplicity and good-repeat- ability without any needs for pretreatment.展开更多
The dried leaves of Apocynum venetum L. （AVL） is a traditional Chinese medicine widely used as antihypertensive medicine in China. Accurate determination of its best harvest season is important for its effective and...The dried leaves of Apocynum venetum L. （AVL） is a traditional Chinese medicine widely used as antihypertensive medicine in China. Accurate determination of its best harvest season is important for its effective and safe use. In the present study, we developed a reliable method based on high-performance liquid chromatography-diode array detector-electro spray ionization-ion trap-time of flight （HPLC-DAD-ESI-IT-TOF） mass spectrometry and HPLC-DAD for the identification and quantification of major components in AVL leaves. Quantitative analysis of 24 samples collected weekly helped monitor the changes of compounds dynamically in AVL leaves to determine the best harvest season. A total of 30 compounds were identified, including quinic acid, five phenolic acids and 24 flavonoids. For the first time, 16 compounds were selected as marker compounds and simultaneously monitored weekly instead of monthly during the growth of the plant. The results showed that in May the leaves had the highest amount of phenolic acids, flavonoids and total compounds. Therefore, May should be the best harvest season for AVL leaves, which was distinct from previous studies. The established method was validated to be simple, accurate and precise, and thus it was of great importance for determination of the best harvest season.展开更多
文摘Nitrogen content is an important parameter for petroleum refining processes. The combined use of mid-infrared attenuated total reflection spectroscopy and multivariate calibration allows accurate determination of nitrogen content in petroleum and its products. The calibration models of nitrogen content in crude oils have been established by partial least squares (PLS) method. The results predicted by this method were very close to those determined by standard methods. Compared with standard methods, this method is provided with advantages such as high-speed, simplicity and good-repeat- ability without any needs for pretreatment.
基金Initiative Drug Discovery of National Science and Technology Major Project(Grant No.2014ZX09304307-001-011)
文摘The dried leaves of Apocynum venetum L. （AVL） is a traditional Chinese medicine widely used as antihypertensive medicine in China. Accurate determination of its best harvest season is important for its effective and safe use. In the present study, we developed a reliable method based on high-performance liquid chromatography-diode array detector-electro spray ionization-ion trap-time of flight （HPLC-DAD-ESI-IT-TOF） mass spectrometry and HPLC-DAD for the identification and quantification of major components in AVL leaves. Quantitative analysis of 24 samples collected weekly helped monitor the changes of compounds dynamically in AVL leaves to determine the best harvest season. A total of 30 compounds were identified, including quinic acid, five phenolic acids and 24 flavonoids. For the first time, 16 compounds were selected as marker compounds and simultaneously monitored weekly instead of monthly during the growth of the plant. The results showed that in May the leaves had the highest amount of phenolic acids, flavonoids and total compounds. Therefore, May should be the best harvest season for AVL leaves, which was distinct from previous studies. The established method was validated to be simple, accurate and precise, and thus it was of great importance for determination of the best harvest season.
