A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear reg...A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.展开更多
Thiacloprid is the first-generation neonicotinoid insecticide,which is widely used in modern agriculture.Reference materials are essential for sound measurement and traceability of results in chemical analysis.Pure th...Thiacloprid is the first-generation neonicotinoid insecticide,which is widely used in modern agriculture.Reference materials are essential for sound measurement and traceability of results in chemical analysis.Pure thiacloprid was comprehensively assessed by two orthonormal methods:mass balance(MB) and quantitative nuclear magnetic resonance spectroscopy(qNMR).From MB,its mass fraction value was 998.4 mg/g with the subtraction of structurally related impurities(99.87%),inorganic impurities(0.006 mg/g),water(0.33 mg/g),and volatile organic solvent(0 mg/g).To guarantee sufficient separation of structurally related purity,peak purity of thiacloprid was evaluated by five points of UV spectra.From the qNMR of hydrogen,its mass fraction value was 995.7 mg/g which was traced to the internal standard(methyl sulfone).Finally,the certified value was assigned to 997 mg/g,together with an expanded uncertainty of 3 mg/g(k=2).This high-purity thiacloprid can be applied to routine monitoring in agriculture and the food fields.展开更多
利用六西格玛设计(design for six Sigma,DFSS)方法,通过定量核磁共振碳谱(quantitative carbon nuclear magnetic resonance spectroscopy,^(13)C qNMR)对由11种已知烃类化合物组成的模型油品进行了芳香碳摩尔百分比[C(ar)%,简称芳碳率...利用六西格玛设计(design for six Sigma,DFSS)方法,通过定量核磁共振碳谱(quantitative carbon nuclear magnetic resonance spectroscopy,^(13)C qNMR)对由11种已知烃类化合物组成的模型油品进行了芳香碳摩尔百分比[C(ar)%,简称芳碳率]测定的系统研究,建立了C(ar)%与样品浓度Conc.、弛豫试剂浓度[Cr(acac)_3]和循环延迟D13个参数之间的数学模型,据此模型得到了优化的参数设置:Conc.为180mg/mL,[Cr(acac)_3]为12 mg/mL,D1为10.5 s.按此设置进行了8组验证实验,其结果重现性较好,相对标准偏差(relative standard deviation,RSD)为0.61%;准确性较高,达到99.0%~100.6%.该方法也可用于其它分析测试方法的系统研究,且实验结果对现行油品芳碳率测定标准中相关参数,如[Cr(acac)_3]和D1的设置能够提出补充性建议.展开更多
基金Projects(20775010, 21075011) supported by the National Natural Science Foundation of ChinaProject(2008AA05Z405) supported by the National High-tech Research and Development Program of China+2 种基金Project(09JJ3016) supported by the Natural Science Foundation of Hunan Province, ChinaProject(09C066) supported by the Scientific Research Fund of Hunan Provincial Education Department, ChinaProject(2010CL01) supported by the Foundation of Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation, China
文摘A quantitative structure-spectrum relationship (QSSR) model was developed to simulate 13C nuclear magnetic resonance (NMR) spectra of carbinol carbon atoms for 55 alcohols. The proposed model,using multiple linear regression,contained four descriptors solely extracted from the molecular structure of compounds. The statistical results of the final model show that R2= 0.982 4 and S=0.869 8 (where R is the correlation coefficient and S is the standard deviation). To test its predictive ability,the model was further used to predict the 13C NMR spectra of the carbinol carbon atoms of other nine compounds which were not included in the developed model. The average relative errors are 0.94% and 1.70%,respectively,for the training set and the predictive set. The model is statistically significant and shows good stability for data variation as tested by the leave-one-out (LOO) cross-validation. The comparison with other approaches also reveals good performance of this method.
基金financially supported by the State Administration for Market Regulation(QNBJ202306)the National Natural Science Foundation of China(22004004).
文摘Thiacloprid is the first-generation neonicotinoid insecticide,which is widely used in modern agriculture.Reference materials are essential for sound measurement and traceability of results in chemical analysis.Pure thiacloprid was comprehensively assessed by two orthonormal methods:mass balance(MB) and quantitative nuclear magnetic resonance spectroscopy(qNMR).From MB,its mass fraction value was 998.4 mg/g with the subtraction of structurally related impurities(99.87%),inorganic impurities(0.006 mg/g),water(0.33 mg/g),and volatile organic solvent(0 mg/g).To guarantee sufficient separation of structurally related purity,peak purity of thiacloprid was evaluated by five points of UV spectra.From the qNMR of hydrogen,its mass fraction value was 995.7 mg/g which was traced to the internal standard(methyl sulfone).Finally,the certified value was assigned to 997 mg/g,together with an expanded uncertainty of 3 mg/g(k=2).This high-purity thiacloprid can be applied to routine monitoring in agriculture and the food fields.
文摘利用六西格玛设计(design for six Sigma,DFSS)方法,通过定量核磁共振碳谱(quantitative carbon nuclear magnetic resonance spectroscopy,^(13)C qNMR)对由11种已知烃类化合物组成的模型油品进行了芳香碳摩尔百分比[C(ar)%,简称芳碳率]测定的系统研究,建立了C(ar)%与样品浓度Conc.、弛豫试剂浓度[Cr(acac)_3]和循环延迟D13个参数之间的数学模型,据此模型得到了优化的参数设置:Conc.为180mg/mL,[Cr(acac)_3]为12 mg/mL,D1为10.5 s.按此设置进行了8组验证实验,其结果重现性较好,相对标准偏差(relative standard deviation,RSD)为0.61%;准确性较高,达到99.0%~100.6%.该方法也可用于其它分析测试方法的系统研究,且实验结果对现行油品芳碳率测定标准中相关参数,如[Cr(acac)_3]和D1的设置能够提出补充性建议.
