A new design of staggered array semi-packed micro gas chromatographic column was presented based on the micro electromechanical system(MEMS)technology.It was a sensor for gas sample analysis.The internal velocity fiel...A new design of staggered array semi-packed micro gas chromatographic column was presented based on the micro electromechanical system(MEMS)technology.It was a sensor for gas sample analysis.The internal velocity fields of ten types of semi-packed micro gas chromatographic column were studied.The effects of array spacing and dislocation spacing on the flow field distribution were investigated.The results show that on the basis of ensuring the formation of virtual wall,with the increase of array spacing,the maximum velocity difference between the flow channels in the vertical direction decreases gradually,but the velocity difference in the flow channels a and b increases.When the inlet velocity was set to be 0.18 m/s,the maximum velocity difference in the channel of the staggered semi-packed micro gas chromatography column 3(CSAC3)was 0.05610 m/s.The maximum velocity difference in the channel a was 0.09160 m/s.The maximum velocity difference in the channel b was 0.02401 m/s.CSAC3 had a more uniform velocity field distribution,which can effectively suppress the laminar flow effect during chromatographic separation,and had a smaller pressure distribution,which puts forward lower requirements for carrier gas system.The staggered array semi-packed micro gas chromatography column proposed in this paper can effectively improve the velocity field distribution and pressure distribution in the channel,and provide a theoretical basis for the design of the new micro gas chromatography column structure.展开更多
为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一...为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一级和双井绿茶二级四个不同等级的双井绿茶的香气物质进行了检测分析。结果表明,从四个不同等级的双井绿茶中共鉴定出70种香气物质,主要包括醇类、烯烃类、烷烃类、酯类等化合物。不同等级的双井绿茶中香气物质组成及相对含量均有差异,通过主成分分析(Principal component analysis,PCA)和偏最小二乘法-判别分析(Partial least squares-discriminant analysis,PLS-DA),可以有效区分不同等级的双井绿茶。不同等级双井绿茶香气差异主要由反式-β-金合欢烯、香叶醇、水杨酸甲酯、茉莉酮、苯乙醇等14种关键化合物差异引起。在不同等级双井绿茶中关键香气物质表现出不同的分布规律,随着芽叶开展,α-椰油烯、石竹烯及己酸乙酯含量降低,而顺式-3-己烯醇、香叶醇及水杨酸甲酯含量呈增加趋势,芳樟醇、茉莉酮、反式-橙花叔醇含量从低到高,随后含量又迅速下降。本文研究了不同等级双井绿茶中香气物质的组成特征及关键香气物质的分布规律,为今后双井绿茶生产提供了理论依据。展开更多
Gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS) coupled with solid phase micro-extraction can provide a simple, extremely selective and sensitive technique for the analysis of volatile sulf...Gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS) coupled with solid phase micro-extraction can provide a simple, extremely selective and sensitive technique for the analysis of volatile sulfur and selenium compounds in the headspace of growing plants. In this work, the technique was used to evaluate the volatilization of selenium in wild-type and genetically-modified Brassica juncea seedlings. By converting toxic inorganic selenium in the soil to less toxic, volatile organic selenium, B. juncea might be useful in bioremediation of selenium contaminated soil.展开更多
以红枣发酵饮料为研究对象,利用顶空固相微萃取和气相色谱-嗅闻-质谱联用法分析其易挥发性成分并对其进行了分析,对影响固相微萃取操作条件的萃取头、萃取温度、萃取时间、样品用量、平衡时间和解吸时间进行系统的优化,旨在建立一种分...以红枣发酵饮料为研究对象,利用顶空固相微萃取和气相色谱-嗅闻-质谱联用法分析其易挥发性成分并对其进行了分析,对影响固相微萃取操作条件的萃取头、萃取温度、萃取时间、样品用量、平衡时间和解吸时间进行系统的优化,旨在建立一种分析红枣发酵饮料易挥发性成分的方法,并通过嗅闻检测结合气味活度值和香气强度值确定红枣发酵饮料的特征风味成分,采用草酸二乙酯做内标对特征风味成分进行了含量测定。结果表明:选用50/30μm DVB/CAR/PDMS固相微萃取头、Rtx-WAX色谱柱、样品用量8.0 m L/20.0 m L样品瓶、加盐量3.00 g、萃取时间70 min、萃取温度70℃、平衡时间20 min、解吸时间3 min,分析红枣发酵饮料易挥发性成分,共检出114种组分,确定结构96种,占总易挥发性成分总量的98.86%;气味活度值及香气强度值分析结果表明:乙酸乙酯、戊酸乙酯、己酸乙酯、2-辛酮、2-十一酮、乙酸-2-苯乙酯、苯丙酸乙酯、6-甲基-5-庚烯-2-酮、苯甲醛和3-羟基-2-丁酮为红枣发酵饮料的特征风味成分。展开更多
基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180098)National Laboratory of Solid State Microstructures,Nanjing University(Grant Nos.M32045 and M33042).
文摘A new design of staggered array semi-packed micro gas chromatographic column was presented based on the micro electromechanical system(MEMS)technology.It was a sensor for gas sample analysis.The internal velocity fields of ten types of semi-packed micro gas chromatographic column were studied.The effects of array spacing and dislocation spacing on the flow field distribution were investigated.The results show that on the basis of ensuring the formation of virtual wall,with the increase of array spacing,the maximum velocity difference between the flow channels in the vertical direction decreases gradually,but the velocity difference in the flow channels a and b increases.When the inlet velocity was set to be 0.18 m/s,the maximum velocity difference in the channel of the staggered semi-packed micro gas chromatography column 3(CSAC3)was 0.05610 m/s.The maximum velocity difference in the channel a was 0.09160 m/s.The maximum velocity difference in the channel b was 0.02401 m/s.CSAC3 had a more uniform velocity field distribution,which can effectively suppress the laminar flow effect during chromatographic separation,and had a smaller pressure distribution,which puts forward lower requirements for carrier gas system.The staggered array semi-packed micro gas chromatography column proposed in this paper can effectively improve the velocity field distribution and pressure distribution in the channel,and provide a theoretical basis for the design of the new micro gas chromatography column structure.
文摘为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一级和双井绿茶二级四个不同等级的双井绿茶的香气物质进行了检测分析。结果表明,从四个不同等级的双井绿茶中共鉴定出70种香气物质,主要包括醇类、烯烃类、烷烃类、酯类等化合物。不同等级的双井绿茶中香气物质组成及相对含量均有差异,通过主成分分析(Principal component analysis,PCA)和偏最小二乘法-判别分析(Partial least squares-discriminant analysis,PLS-DA),可以有效区分不同等级的双井绿茶。不同等级双井绿茶香气差异主要由反式-β-金合欢烯、香叶醇、水杨酸甲酯、茉莉酮、苯乙醇等14种关键化合物差异引起。在不同等级双井绿茶中关键香气物质表现出不同的分布规律,随着芽叶开展,α-椰油烯、石竹烯及己酸乙酯含量降低,而顺式-3-己烯醇、香叶醇及水杨酸甲酯含量呈增加趋势,芳樟醇、茉莉酮、反式-橙花叔醇含量从低到高,随后含量又迅速下降。本文研究了不同等级双井绿茶中香气物质的组成特征及关键香气物质的分布规律,为今后双井绿茶生产提供了理论依据。
文摘Gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS) coupled with solid phase micro-extraction can provide a simple, extremely selective and sensitive technique for the analysis of volatile sulfur and selenium compounds in the headspace of growing plants. In this work, the technique was used to evaluate the volatilization of selenium in wild-type and genetically-modified Brassica juncea seedlings. By converting toxic inorganic selenium in the soil to less toxic, volatile organic selenium, B. juncea might be useful in bioremediation of selenium contaminated soil.
文摘以红枣发酵饮料为研究对象,利用顶空固相微萃取和气相色谱-嗅闻-质谱联用法分析其易挥发性成分并对其进行了分析,对影响固相微萃取操作条件的萃取头、萃取温度、萃取时间、样品用量、平衡时间和解吸时间进行系统的优化,旨在建立一种分析红枣发酵饮料易挥发性成分的方法,并通过嗅闻检测结合气味活度值和香气强度值确定红枣发酵饮料的特征风味成分,采用草酸二乙酯做内标对特征风味成分进行了含量测定。结果表明:选用50/30μm DVB/CAR/PDMS固相微萃取头、Rtx-WAX色谱柱、样品用量8.0 m L/20.0 m L样品瓶、加盐量3.00 g、萃取时间70 min、萃取温度70℃、平衡时间20 min、解吸时间3 min,分析红枣发酵饮料易挥发性成分,共检出114种组分,确定结构96种,占总易挥发性成分总量的98.86%;气味活度值及香气强度值分析结果表明:乙酸乙酯、戊酸乙酯、己酸乙酯、2-辛酮、2-十一酮、乙酸-2-苯乙酯、苯丙酸乙酯、6-甲基-5-庚烯-2-酮、苯甲醛和3-羟基-2-丁酮为红枣发酵饮料的特征风味成分。
