The mass of oligonucleotides was quantitated by liquid chromatography-isotope dilution mass spectrometry.The uncertainty was calculated.This could provide information for the further quantitative measurement and utili...The mass of oligonucleotides was quantitated by liquid chromatography-isotope dilution mass spectrometry.The uncertainty was calculated.This could provide information for the further quantitative measurement and utilization of DNA.展开更多
The status of PCDDs and PCDFs content in retail foods from a certain area by Isotope Dilution HRGC-HRMS was surveyed and the local population PCDD/Fs exposure from diverse foods and health risk was evaluated.PCDD/Fs w...The status of PCDDs and PCDFs content in retail foods from a certain area by Isotope Dilution HRGC-HRMS was surveyed and the local population PCDD/Fs exposure from diverse foods and health risk was evaluated.PCDD/Fs was extracted from samples by Soxhlet extraction,concentrated and purified by FMS column chromatograph,carbon column enrichment.Confirmation and quantitative analysis at pg/g level of PCDD/Fs was performed by HRGC/HRMS using multiple ion detection mode(MID).TEQ concentration was calculated by WHO-TEF multiplying by concentration of seventeen PCDD/Fs congener.Median of PCDD/Fs concentration for fish,livestock,poultry,egg,vegetable oil,milk,vegetable totally 100 samples for ten diverse foods didn’t exceed the limit standards by EU.The level of PCDD/Fs for different food in the certain area was lower or comparable to the data reported by developed country in the world.The total weekly intake and monthly intake for local population or national population was 3.44,14.8 WHO-TEQ/kg BW and 1.5,6.42 pg WHO-TEQ/kg BW respectively,the value was lower than the Tolerable Weekly Intake of 14 pg WHO TEQ/kg BW for PCDDs,PCDFs and dioxin-like PCBs established by EU Scientific Committee for Food.The dietary PCDD/Fs intake for local people was higher than national population.And animal food was the dominant contributor to the total dietary intake,which accounted for more than 70 percent.These levels of consumption of diverse food containing typical levels of PCDD/Fs doesn’t present a risk to the health of the local population.But integrative dietary intake could be evaluated including of PCBs intake for population in the future.展开更多
Adenosine 5′-monophosphate in powdered milk was quantitated by liquid chromatography-isotope dilution mass spectrometry.The uncertainty was calculated.This could provide information for the further quantitative measu...Adenosine 5′-monophosphate in powdered milk was quantitated by liquid chromatography-isotope dilution mass spectrometry.The uncertainty was calculated.This could provide information for the further quantitative measurement and utilization of 5′-nucleotide acid as food additive.展开更多
Three series of laboratory vaporization experiments were conducted to investigate the carbon isotope fractionation of low molecular weight hydrocarbons（LMWHs）during their progressive vaporization.In addition to the ...Three series of laboratory vaporization experiments were conducted to investigate the carbon isotope fractionation of low molecular weight hydrocarbons（LMWHs）during their progressive vaporization.In addition to the analysis of a synthetic oil mixture,individual compounds were also studied either as pure single phases or mixed with soil.This allowed influences of mixing effects and diffusion though soil on the fractionation to be elucidated.The LMWHs volatilized in two broad behavior patterns that depended on their molecular weight and boiling point.Vaporization significantly enriched the ^13C present in the remaining components of the C6–C9 fraction,indicating that the vaporization is mainly kinetically controlled;the observed variations could be described with a Rayleigh fractionation model.In contrast,the heavier compounds（n-C10–n-C12）showed less mass loss and almost no significant isotopic fractionation during vaporization,indicating that the isotope characteristics remained sufficiently constant for these hydrocarbons to be used to identify the source of an oil sample,e.g.,the specific oil field or the origin of a spill.Furthermore,comparative studies suggested that matrix effects should be considered when the carbon isotope ratios of hydrocarbons are applied in the field.展开更多
文摘The mass of oligonucleotides was quantitated by liquid chromatography-isotope dilution mass spectrometry.The uncertainty was calculated.This could provide information for the further quantitative measurement and utilization of DNA.
文摘The status of PCDDs and PCDFs content in retail foods from a certain area by Isotope Dilution HRGC-HRMS was surveyed and the local population PCDD/Fs exposure from diverse foods and health risk was evaluated.PCDD/Fs was extracted from samples by Soxhlet extraction,concentrated and purified by FMS column chromatograph,carbon column enrichment.Confirmation and quantitative analysis at pg/g level of PCDD/Fs was performed by HRGC/HRMS using multiple ion detection mode(MID).TEQ concentration was calculated by WHO-TEF multiplying by concentration of seventeen PCDD/Fs congener.Median of PCDD/Fs concentration for fish,livestock,poultry,egg,vegetable oil,milk,vegetable totally 100 samples for ten diverse foods didn’t exceed the limit standards by EU.The level of PCDD/Fs for different food in the certain area was lower or comparable to the data reported by developed country in the world.The total weekly intake and monthly intake for local population or national population was 3.44,14.8 WHO-TEQ/kg BW and 1.5,6.42 pg WHO-TEQ/kg BW respectively,the value was lower than the Tolerable Weekly Intake of 14 pg WHO TEQ/kg BW for PCDDs,PCDFs and dioxin-like PCBs established by EU Scientific Committee for Food.The dietary PCDD/Fs intake for local people was higher than national population.And animal food was the dominant contributor to the total dietary intake,which accounted for more than 70 percent.These levels of consumption of diverse food containing typical levels of PCDD/Fs doesn’t present a risk to the health of the local population.But integrative dietary intake could be evaluated including of PCBs intake for population in the future.
文摘Adenosine 5′-monophosphate in powdered milk was quantitated by liquid chromatography-isotope dilution mass spectrometry.The uncertainty was calculated.This could provide information for the further quantitative measurement and utilization of 5′-nucleotide acid as food additive.
基金financially supported by the National ‘‘863’’ Project (Grant No. 2012AA0611401)the program of the Chinese Academy of Sciences (Grant No. KZCX2-YW-JC103)
文摘Three series of laboratory vaporization experiments were conducted to investigate the carbon isotope fractionation of low molecular weight hydrocarbons（LMWHs）during their progressive vaporization.In addition to the analysis of a synthetic oil mixture,individual compounds were also studied either as pure single phases or mixed with soil.This allowed influences of mixing effects and diffusion though soil on the fractionation to be elucidated.The LMWHs volatilized in two broad behavior patterns that depended on their molecular weight and boiling point.Vaporization significantly enriched the ^13C present in the remaining components of the C6–C9 fraction,indicating that the vaporization is mainly kinetically controlled;the observed variations could be described with a Rayleigh fractionation model.In contrast,the heavier compounds（n-C10–n-C12）showed less mass loss and almost no significant isotopic fractionation during vaporization,indicating that the isotope characteristics remained sufficiently constant for these hydrocarbons to be used to identify the source of an oil sample,e.g.,the specific oil field or the origin of a spill.Furthermore,comparative studies suggested that matrix effects should be considered when the carbon isotope ratios of hydrocarbons are applied in the field.
