A New Carrier Gas Type for Accurate Measurement of N_2O by GC-ECD

The accurate measurement of concentration is the basis for determining emission sources and sinks of nitrous oxide （N2O）. The detection of N2O showed that the presence of carbon dioxide （CO2） biased the N2O response when pure nitrogen （N2） was used as a carrier gas for gas chromatography （GC） equipped with an electron capture detector （GC-ECD）. In this study, laboratory experiments were carried out to explore how the presence of CO2 interferes with the accurate determination of N2O. The aims were to address the extent of the influence to try and explain the underlying mechanism, and to uncover technical options for solving the problem. Three GC carrier gases are discussed： pure nitrogen （DN）; a mixture of argon and methane （AM）; and a high concentration CO2, which was introduced into the ECD cell with a low flow rate based on DN （DN-CO2）. The results show that when DN was used, the existence of CO2 in the ECD cell greatly enhanced the response of N2O, which increased with CO2 content and remained constant when the content reached a limit. Comparisons between the three methods show that the DN method is defective for the accurate determination of N2O. The bias is caused by different electron capture mechanisms of CO2 and N2O and depends heavily on the detector temperature. New GC carrier gas types with make-up gases that can remove the CO2-induced influence, such as the DN-CO2 and DN-CH4 methods reported in this paper, are recommended for the accurate measurement of N2O.

Sulfonic acid-based metal organic framework functionalized magnetic nanocomposite combined with gas chromatography-electron capture detector for extraction and determination of organochlorine

The metal organic framework functionalized with sulfonic acid was combined with magnetic nanoparticles to fabricate a new nanocomposite(denoted as Fe3O4@PDA@Zr-SO3H).By combining with gas chromatography-electron capture detector,the resulting Fe3O4@PDA@Zr-SO3H nanocomposite was successfully used as a high-efficiency adsorbent for pre-concentrating eight organochlorine pesticides from water sample in environment.Apart from the ability of fast separation,the as-prepared Fe3O4@PDA@Zr-SO3H nanocomposite also exhibited high adsorption capacity for organochlorine pesticides.With the use of optimal experimental conditions,the linear relationship can be obtained in the range of 0.05~300μg/L,the correlation coefficient was over 0.9978,and the relative standard deviation was located in 2.5%-7.7%.Moreover,the limit of detection and quantification was between0.005-0.016μg/L and 0.017~0.050μg/L.Finally,the nanocomposite was used for the determination of organochlorine pesticides from environmental water samples,and displayed the recovery of 82%-118%.

The relevance of James Lovelock’s research and philosophy to environmental science and academia

James E.Lovelock,famed for his Gaia hypothesis,which views the Earth as a living integrated and interconnected self-regulating system whose equilibrium comes about from complex energy-based interactions and feedback loops,ultimately sustaining life,passed away at the end of July,2022 at the age of 103.Not only are the adaptive mechanisms of Gaia central to the conversation of environmental homeostasis,they lie at the heart of climate change and global warming.Lovelock is also remembered as the co-inventor of the electron capture detector that eventually allowed for the sensitive detection of chlorofluorocarbons and pesticides.Finally,Lovelock’s free-spirited nature and research independence allow academia to rethink current research’s modus operandi.