The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 speci...The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency （PIE） spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes.展开更多
A new GC/MS method for detection and identification of 19 anabolic steroids in human urine is presented.The procedure involves adsorption and isolation on a macroporous XAD-2 resin,enzymatic hydrolysis,alkaline extrac...A new GC/MS method for detection and identification of 19 anabolic steroids in human urine is presented.The procedure involves adsorption and isolation on a macroporous XAD-2 resin,enzymatic hydrolysis,alkaline extraction,derivatization,GC separation and MS detec- tion.Gas chromatographic-mass spectrometric data illustrate artifacts arising from enzymatic hydrolysis of steroid glucuronides and the structural characterization of their metabolites. Using this method,metabolic studies of these steroids in human urine were made after their ingestion by normal and healthy male volunteers.This method was proven to be suitable for large-scale routine analysis of anabolic steroids and was used successfully in passing the doping control test held by the Medical Commission of the International Olympic Committee.展开更多
The basic difference non-equal interval model GM(1,1) in grey theory was used to fit and forecast data series with non-equal lengths and different inertias, acquired from oil monitoring of internal combustion engines....The basic difference non-equal interval model GM(1,1) in grey theory was used to fit and forecast data series with non-equal lengths and different inertias, acquired from oil monitoring of internal combustion engines. The fitted and forecasted results show that the length or inertia of a sequence affects its precision very much, i.e. the bigger the inertia of a sequence is, or the shorter the length of a series is, the less the errors of fitted and forecasted results are. Based on the research results, it is suggested that short series should be applied to be fitted and forecasted; for longer series, the newer datum should be applied instead of the older datum to be analyzed by non- equalinterval GM(1,1) to improve the forecasted and fitted precision, and that data sequence should be verified to satisfy the conditions of grey forecasting.展开更多
This paper,through mass spectrometric(MS)analysis for nitro compound explosives on a direct analysis in a real‑time time‑of‑flight MS,indicates that even on a high‑resolution MS with accurate mass measurement capabili...This paper,through mass spectrometric(MS)analysis for nitro compound explosives on a direct analysis in a real‑time time‑of‑flight MS,indicates that even on a high‑resolution MS with accurate mass measurement capabilities,there is no guarantee to obtain the unique molecular formula of a compound.By calculating spectra accuracy,highly accurate isotope pattern matching can be conducted to significantly improve performance of compound confirmation or identification.展开更多
基金This work is supported by the National. Natural Science Foundation of China （No.51106146, No.51036007, No.U1232127）, the China Postdoctoral Science Foundation （No.20100480047 and No.201104326）, the Chinese Universities Scientific Fund （No.WK2310000010）, the Anhui Science ＆ Technology Department （No.l1040606Q49）, and the Chinese Academy of Sciences.
文摘The pyrolysis of n-butane and i-butane at low pressure was investigated from 823-1823 K in an electrically heated flow reactor using synchrotron vacuum ultraviolet photoionization mass spectrometry. More than 20 species, especially several radicals and isomers, were detected and identified from the measurements of photoionization efficiency （PIE） spectra. Based on the mass spectrometric analysis, the characteristics of n-butane and i-butane pyrolysis were discussed, which provided experimental evidences for the discussion of decomposition pathways of butane isomers. It is concluded that the isomeric structures of n-butane and i-butane have strong influence on their main decomposition pathways, and lead to dramatic differences in their mass spectra and PIE spectra such as the different dominant products and isomeric structures of butene products. Furthermore, compared with n-butane,i-butane can produce strong signals of benzene at low temperature in its pyrolysis due to the enhanced formation of benzene precursors like propargyl and C4 species, which provides experimental clues to explain the higher sooting tendencies of iso-alkanes than n-alkanes.
文摘A new GC/MS method for detection and identification of 19 anabolic steroids in human urine is presented.The procedure involves adsorption and isolation on a macroporous XAD-2 resin,enzymatic hydrolysis,alkaline extraction,derivatization,GC separation and MS detec- tion.Gas chromatographic-mass spectrometric data illustrate artifacts arising from enzymatic hydrolysis of steroid glucuronides and the structural characterization of their metabolites. Using this method,metabolic studies of these steroids in human urine were made after their ingestion by normal and healthy male volunteers.This method was proven to be suitable for large-scale routine analysis of anabolic steroids and was used successfully in passing the doping control test held by the Medical Commission of the International Olympic Committee.
文摘The basic difference non-equal interval model GM(1,1) in grey theory was used to fit and forecast data series with non-equal lengths and different inertias, acquired from oil monitoring of internal combustion engines. The fitted and forecasted results show that the length or inertia of a sequence affects its precision very much, i.e. the bigger the inertia of a sequence is, or the shorter the length of a series is, the less the errors of fitted and forecasted results are. Based on the research results, it is suggested that short series should be applied to be fitted and forecasted; for longer series, the newer datum should be applied instead of the older datum to be analyzed by non- equalinterval GM(1,1) to improve the forecasted and fitted precision, and that data sequence should be verified to satisfy the conditions of grey forecasting.
文摘This paper,through mass spectrometric(MS)analysis for nitro compound explosives on a direct analysis in a real‑time time‑of‑flight MS,indicates that even on a high‑resolution MS with accurate mass measurement capabilities,there is no guarantee to obtain the unique molecular formula of a compound.By calculating spectra accuracy,highly accurate isotope pattern matching can be conducted to significantly improve performance of compound confirmation or identification.
