China’s rapid economic growth has resulted in significant environmental side-effects. Therefore, China has beeninterested in reducing her dependence on foreign oil and gas by developing technologies needed for hydrogen, in addition to herincreasing energy mix of nuclear and renewable energy form such as solar and wind power. There are three isotopes of hydrogen,i.e. protium (P or H), deuterium (D), and tritium (T). Both deuterium and tritium are important materials in nuclear fuel cycleindustry. Tritium is one of the critical radioactive nuclides. Planning for and implementing contamination control as a part ofnormal operation and maintenance activities is an important function in any hydrogen facility, especially tritium facility. Thedevelopment of hydrogen isotopes analysis is the key issues in this area. Mass spectrometry (MS) with medium (about 600) andhigh resolution (>1400) is commercially available; however, the routine analysis of hydrogen isotopes is done with low-resolutionMS (<200) in China. This paper summarizes the progress of MS measurement technology for hydrogen isotope abundance inChina, focusing on our lab’s research program and technical status. An analyzing method has been introduced for accurate measurementof tritium abundance in the H-D-T system by low resolution MAT-253 MS. The quotient of compression ratio coefficient isdetermined based on building up equipment for laboratory-scale preparation of secondary standard gases and considering thedifference in sensitivity between hydrogen isotopes. The results show that the measured value is believable in the relative errorrange of 0.8% for gas samples of different tritium abundance.
Two types of glycerolipids [monoacylglycerols (MAG) and cyclitols] were isolated by reversed phase high-performanceliquid chromatography from the MeOH extracts of a marine sponge, and analyzed by fast atom bombardment mass spectrometry(FAB-MS) in positive-ion mode. FAB mass spectra of these compounds included protonated molecules [M+H]+ and abundantsodiated molecules [M+Na]+ from a mixture of m-NBA and NaI. The structures of these compounds were elucidated by FABcollisional-induced dissociation (CID)-tandem mass spectrometry. To find diagnostic ions for their characterization, these lipidswere analyzed by collision-induced dissociation (CID) B/E-linked scan. The CID B/E-linked scan of [M+H]+ and [M+Na]+ precursorions resulted in the formation of numerous characteristic product ions via a series of dissociative processes. The product ionsformed by charge-remote fragmentation (CRF) provided important information for the characterization of the acyl chain structuresubstituted at the glycerol backbone. Some of product ions were diagnostic for the presence of a glycerol backbone and acylchain structure, respectively.
The Korean government has regulated emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)in waste water of manufacturing facilities producing chlorinated compounds since 2009. As this regulation has been reinforcedin 2013 to 50 pg I-TEQ/L, a large sample volume is required for the analysis of trace amounts of PCDD/Fs in waste water. Liquidliquidextraction (LLE) is used to extract PCDD/Fs from aqueous samples. However, its low efficiency makes it inadequate foranalyzing large sample volumes. Here, a disk-type solid-phase extraction (SPE) method was applied to the analysis of dioxin ata part per quadrillion level in waste water. This SPE system contains airtight glass covers with a decompression pump, whichenables continuous semi-automated extraction. Small (0.5 L) and large (7 L) samples were extracted using LLE and SPE methods,respectively. The method detection limits (MDLs) were 0.001-0.25 and 0.015-4.1 pg I-TEQ/L for the SPE and LLE methods,respectively. The concentrations of detected congeners with both methods were similar. However, the concentrations of severalcongeners that were not detected with the LLE method were quantified using the SPE method.
Oxidation products of ceftiofur were formed in hydrogen peroxide solution. The structures of the ceftiofur oxidationproducts were characterized by high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry(HPLC/ESI/MS/MS). The products were identified as compounds oxidized at the sulfur of a cephem ring. For further analysis,an experiment was performed using O18-labeled hydrogen peroxide. Results of the density-functional calculations for six possibleoxidation products were in good agreement with the experimental results.
The purpose of this study is to investigate the in vitro metabolism of hesperetin, a bioflavonoid. Hesperetin was incubatedwith rat liver microsomes in the presence of NADPH and UDP-glucuronic acid for 30 min. The reaction mixture was analyzedby liquid chromatography-ion trap mass spectrometer and the chemical structures of hesperetin metabolites were characterzed basedon their MS/MS spectra. As a result, a total of five metabolites were detected in rat liver microsomes. The metabolites were identifiedas a demethylated metabolite (eriodictyol), two hesperetin glucuronides, and two eriodictyol glucuronides.
Hyperthermal ion/surface collisions of bromotoluene molecular ions were studied using perfluorinated (F-SAM) andhydroxyl-terminated (OH-SAM) self-assembled monolayer surfaces in a tandem mass spectrometer with BEEQ geometry. Theisomers were differentiated by ion abundance ratios taken from surface-induced dissociation (SID). The dissociation rate followedthe order of ortho>meta>para isomers. The peak abundance ratio of m/z 51 to m/z 65 showed the best result to discern theisomers, while the other ratios would effectively serve the same purpose as well. A dissociation channel leading to tolylium ionwas suggested to be responsible for the pronounced isomeric differentiability. The capability of SID to provide high-energy activationwith narrow internal energy distribution may have channeled the reaction into the specific dissociation pathway, also facilitatingsmall difference in reaction rates to be effective in the spectral time window of this experiment. All the molecular ions experiencedreactive collisions with the F-SAM surface leading to transhalogenation products, where a fluorine atom from the surface replacesthe bromine of the projectile. This reactive collision was dependant on the laboratory collision energy occurring in ca. 40~75 eV range.