A GC-MS method for the confirmation of benzthiazide is reported for the first time. This method is based on, the main decomposed product of the methylated derivative and provides a reliable detection of this drug. The...A GC-MS method for the confirmation of benzthiazide is reported for the first time. This method is based on, the main decomposed product of the methylated derivative and provides a reliable detection of this drug. The detection limit of the method is 1.0 ng with selected ion monitoring.展开更多
Gas chromatography equipped with an electron capture detector （GC-ECD） has been widely used for measuring atmospheric N2O,but nonlinear response and the influence of atmospheric CO2 have been recognized as defects f...Gas chromatography equipped with an electron capture detector （GC-ECD） has been widely used for measuring atmospheric N2O,but nonlinear response and the influence of atmospheric CO2 have been recognized as defects for quantification.An original GCECD method using N 2 as carrier gas was improved by introducing a small flow rate of CO2 makeup gas into the ECD,which could well remedy the above defects.The N2O signal of the improved method was 4-fold higher than that of the original method and the relative standard deviation was reduced from 〉 1% to 0.31%.N2O concentrations with different CO2 concentrations （172.2×10-6-1722×10-6mol/mol） measured by the improved GC-ECD method were in line with the actual N2O concentrations.However,the N2O concentrations detected by the original method were largely biased with a variation range of-4.5%～7%.The N2O fluxes between an agricultural field and the atmosphere measured by the original method were greatly overestimated in comparison with those measured by the improved method.Good linear correlation （R2=0.9996） between the response of the improved ECD and N2O concentrations （93×10-9-1966×10-9mol/mol） indicated that atmospheric N2O could be accurately quantified via a single standard gas.Atmospheric N2O concentrations comparatively measured by the improved method and a high precision GC-ECD method were in good agreement.展开更多
The methods of determination of 6-methyl coumarin in cosmetics by HPLC-DAD and GC-FID were compared. The positive samples were confirmed by GC-MS. Methanol was used to extract 6-methyl coumarin from cosmetics. The chr...The methods of determination of 6-methyl coumarin in cosmetics by HPLC-DAD and GC-FID were compared. The positive samples were confirmed by GC-MS. Methanol was used to extract 6-methyl coumarin from cosmetics. The chromatographic conditions of the two methods were optimized and the samples were determined. The recovery, precision, correlation coefficient, detection limit and quantitative limit of the two methods were compared. The results showed that the linear relationship between the two methods was good. The percentage recovery of standard addition by HPLC-DAD was 92.20%~102.80%, by RSD was 0.77%~2.00%;the detection limit was 0.05 mg/kg, the quantitative limit was 0.17 mg/kg. The percentage recovery of standard addition by GC-FID was 97.30%~103.28%, by RSD was 0.47%~4.87%;the detection limit was 1.3 mg/kg, the quantitative limit was 5.0 mg/kg. The detection limit by HPLC-DAD was lower and more sensitive than that by GC-FID , which also shows that HPLC-DAD has more advantages for the detection of low content samples.展开更多
为探究直接复热、水浴复热、微波复热和汽蒸复热方式对川菜回锅肉风味的影响,该研究以智能感官技术中的电子鼻和电子舌与氨基酸分析仪和顶空气相色谱-离子迁移谱(HS-GC-IMS)相结合,对回锅肉在4种复热方式处理下的风味特征进行了系统分...为探究直接复热、水浴复热、微波复热和汽蒸复热方式对川菜回锅肉风味的影响,该研究以智能感官技术中的电子鼻和电子舌与氨基酸分析仪和顶空气相色谱-离子迁移谱(HS-GC-IMS)相结合,对回锅肉在4种复热方式处理下的风味特征进行了系统分析。结果表明,电子鼻和电子舌能有效识别回锅肉的香气与口感特征;其中微波复热显著提升了回锅肉的营养价值。该研究共检测到17种游离氨基酸,经微波复热处理后的回锅肉总游离氨基酸含量达到最高值(202.08±6.68)mg/g。偏最小二乘判别分析(partial least squares discriminant analysis,PLS-DA)模型显示直接复热与汽蒸复热之间的风味差异最显著,根据变量重要性投影(variable importance in projection,VIP)值,筛选出22种关键差异香气物质,包括1-戊烯-3-醇、顺-2-戊烯醇等,可作为区分不同复热方式回锅肉香气特征的挥发性标志物。该研究为回锅肉的复热方式提供了重要理论依据,并为进一步探究不同复热方式对回锅肉风味的影响提供了数据支持。展开更多
文摘A GC-MS method for the confirmation of benzthiazide is reported for the first time. This method is based on, the main decomposed product of the methylated derivative and provides a reliable detection of this drug. The detection limit of the method is 1.0 ng with selected ion monitoring.
基金supported by the Special Fund for Environmental Research in the Public Interest(No.201009001)the National Natural Science Foundation of China(No.41075094,21177140 and 40830101)the National Basic Research and the Development Program(973)of China(No.2010CB732304)
文摘Gas chromatography equipped with an electron capture detector （GC-ECD） has been widely used for measuring atmospheric N2O,but nonlinear response and the influence of atmospheric CO2 have been recognized as defects for quantification.An original GCECD method using N 2 as carrier gas was improved by introducing a small flow rate of CO2 makeup gas into the ECD,which could well remedy the above defects.The N2O signal of the improved method was 4-fold higher than that of the original method and the relative standard deviation was reduced from 〉 1% to 0.31%.N2O concentrations with different CO2 concentrations （172.2×10-6-1722×10-6mol/mol） measured by the improved GC-ECD method were in line with the actual N2O concentrations.However,the N2O concentrations detected by the original method were largely biased with a variation range of-4.5%～7%.The N2O fluxes between an agricultural field and the atmosphere measured by the original method were greatly overestimated in comparison with those measured by the improved method.Good linear correlation （R2=0.9996） between the response of the improved ECD and N2O concentrations （93×10-9-1966×10-9mol/mol） indicated that atmospheric N2O could be accurately quantified via a single standard gas.Atmospheric N2O concentrations comparatively measured by the improved method and a high precision GC-ECD method were in good agreement.
文摘The methods of determination of 6-methyl coumarin in cosmetics by HPLC-DAD and GC-FID were compared. The positive samples were confirmed by GC-MS. Methanol was used to extract 6-methyl coumarin from cosmetics. The chromatographic conditions of the two methods were optimized and the samples were determined. The recovery, precision, correlation coefficient, detection limit and quantitative limit of the two methods were compared. The results showed that the linear relationship between the two methods was good. The percentage recovery of standard addition by HPLC-DAD was 92.20%~102.80%, by RSD was 0.77%~2.00%;the detection limit was 0.05 mg/kg, the quantitative limit was 0.17 mg/kg. The percentage recovery of standard addition by GC-FID was 97.30%~103.28%, by RSD was 0.47%~4.87%;the detection limit was 1.3 mg/kg, the quantitative limit was 5.0 mg/kg. The detection limit by HPLC-DAD was lower and more sensitive than that by GC-FID , which also shows that HPLC-DAD has more advantages for the detection of low content samples.
文摘为探究直接复热、水浴复热、微波复热和汽蒸复热方式对川菜回锅肉风味的影响,该研究以智能感官技术中的电子鼻和电子舌与氨基酸分析仪和顶空气相色谱-离子迁移谱(HS-GC-IMS)相结合,对回锅肉在4种复热方式处理下的风味特征进行了系统分析。结果表明,电子鼻和电子舌能有效识别回锅肉的香气与口感特征;其中微波复热显著提升了回锅肉的营养价值。该研究共检测到17种游离氨基酸,经微波复热处理后的回锅肉总游离氨基酸含量达到最高值(202.08±6.68)mg/g。偏最小二乘判别分析(partial least squares discriminant analysis,PLS-DA)模型显示直接复热与汽蒸复热之间的风味差异最显著,根据变量重要性投影(variable importance in projection,VIP)值,筛选出22种关键差异香气物质,包括1-戊烯-3-醇、顺-2-戊烯醇等,可作为区分不同复热方式回锅肉香气特征的挥发性标志物。该研究为回锅肉的复热方式提供了重要理论依据,并为进一步探究不同复热方式对回锅肉风味的影响提供了数据支持。
