•Size distributions of particles with different component from coal combustion are different.•Non-volatile single particles can be measured by aerosol mass spectrometry (SPAMS) and transmission electron microscopy (TEM).•Number percentages by SPAMS correlate with mass concentrations by ICP-MS.Coal combustion particles (CCPs) are linked to the high incidence of lung cancer in Xuanwei and in Fuyuan, China, but studies on the chemical composition of the CCPs are still limited. Single particle aerosol mass spectrometry (SPAMS) was recently developed to measure the chemical composition and size of single particles in real-time. In this study, SPAMS was used to measure individual combustion particles emitted from Xuanwei and Fuyuan coal samples and the results were compared with those by ICP-MS and transmission electron microscopy (TEM). The total of 38,372 particles mass-analyzed by SPAMS can be divided into 9 groups based on their chemical composition and their number percentages: carbonaceous, Na-rich, K-rich, Al-rich, Fe-rich, Si-rich, Ca-rich, heavy metal-bearing, and PAH-bearing particles. The carbonaceous and PAH-bearing particles are enriched in the size range below 0.56 μm, Fe-bearing particles range from 0.56 to 1.0 μm in size, and heavy metals such as Ti, V, Cr, Cu, Zn, and Pb have diameters below 1 μm. The TEM results show that the particles from Xuanwei and Fuyuan coal combustion can be classified into soot aggregates, Fe-rich particles, heavy metal containing particles, and mineral particles. Non-volatile particles detected by SPAMS could also be observed with TEM. The number percentages by SPAMS also correlate with the mass concentrations measured by ICP-MS. Our results could provide valuable insight for understanding high lung cancer incidence in the area.

•Creatine phosphate disodium salt was analyzed using ESI-QTOF.•A seven-centered rearrangement mechanism was proposed.•D-labeled experiment and DFT calculation support proposed mechanism.•The product ion formed by condensation reaction was detected.Creatine phosphate disodium salt was investigated by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) both in positive- and negative-ion modes. The results indicate that an unusual seven-centered rearrangement mechanism was involved in the whole fragmentation. The positive product ion at m/z 165 is formed through the seven-centered rearrangement from the precursor ions of [M+Na]+ at m/z 278 and further confirmed by D-labeled experiment and DFT calculation. The negative product ion at m/z 190 resulting from the precursor ion [M−Na]− at m/z 232 is formed through the seven-centered rearrangement, accompanied with internal residue loss of a methanediimine molecule. In addition, the processes producing the product ion at m/z 97 from [M−2Na+H]− at m/z 210 also involved a seven-centered rearrangement.

Using the density functional theory combined with the nonequilibrium Green's function, the transport properties of double-walled carbon nanotubes (DWCNTs) and carbon boronitride (CBN) heteronanotubes were investigated. As the hopping length increases, the conductance of DWCNTs shows a dramatic variation that is independent of the intertube space. The transport of the CBN heterojunctions also displays abnormal behavior when the hopping length is changed, which is very different from the behavior of DWCNTs. The currents of the forward in the CBN heterojunctions are about 3–15 times as large as those of the back under lower bias voltages. The negative differential resistance (NDR) effect occurs in the CBN heterojunctions, and the peak-to-valley ratio in the additional NDR regions is about 2–4 for the current–voltage relationship. The hopping length and BN parts have a great influence on the transport of the double-walled nanodevices.

Collision-induced dissociation (CID) of [MaMb(Gly-H)]+ precursors (where Ma = Ag, Cu; Mb = Ag, Cu) results in formation of novel dimetal hydrides, [MaHMb]+ and elimination of MaH in the gas phase. Deuterium labeling studies reveal that the hydride only originates from the CH2 group. Energy-resolved CID of [Ag2(Gly-H)]+ shows that the formation of [Ag2H]+ and the elimination of AgH are two primary dissociation channels, and the latter is always more prevalent than the former. H2 loss, only a minor channel, was also observed. This was confirmed by the correlation of the relative abundance of dimetal hydride with the difference of silver ion affinity between the neutral (Gly-2H) and AgH. Dimetal hydrides are of particular interest due to the three-center two-electron (3c–2e) bond. DFT calculations predict that [Cu2H]+ and [CuAgH]+ have bent structures, while [Ag2H]+ has linear structures. However, bending deformation energies are only 2.6 kcal/mol for [Cu2H]+. Population analysis and atom in molecule (AIM) calculations show that in [Cu2H]+ the metal–metal bond is present, while for [Ag2H]+ there is no metal–metal bond. Energies from high-level theory calculations provide direct evidence to explain why the dimetal radical cation cannot be observed in the CID of the dimetal hydride.

Dispersive liquid–liquid microextraction (DLLME) was coupled with gas chromatography and mass spectrometric detection for the determination of eight phthalate acid esters (PAEs) in soybean milk. Parameters impacting the extraction efficiencies were optimized including organic solvents to extract PAEs from soybean milk, salt concentrations and organic solvents for DLLME. Under the optimal conditions, limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.57–0.79 and 1.90–2.63 ng g−1, respectively. Linearities varied in the range of 1–16000 ng g−1 with the correlation coefficients of 0.9993–0.9998. The precision of the method was 2.9–3.2 in terms of RSD% based on triplicate measurements. The preconcentration factors were in the range of 200–260. The recoveries of eight PAEs were in the range from 79.0 to 110% at three spiked levels. The trace PAEs in five different brands of soybean milk purchased from the market were determined successfully.

•A series of six matrine-type alkaloids was investigated using ESI-MS/MS.•A pair of stereoisomers was unambiguously distinguished using CID and DFT calculations.•Classical fragmentation patterns and radical product ions are of scientific interest.•The protonation site was tentatively identified.A series of six matrine-type alkaloids, including a pair of stereoisomers, was investigated using electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) in positive-ion mode. Protonated molecules were fragmented by collision-induced dissociation (CID) and the products identified. The identity of the major product ions was also supported by deuterium-labeling experiments. It was found that sequential four-centered H rearrangements play a significant role in the fragmentation of the piperidine-ring; the RDA reaction dominates the dissociations for sophocarpine and sophocarpidine; and the McLafferty-type rearrangement occurs with neosophoramine. Interestingly, a pair of stereoisomers matrine and sophoridine, can be unambiguously distinguished using CID, and this characterization was supported by the DFT calculations of the potential energy profiles for protonated matrine and sophoridine before dissociation to the product ion at m/z 152.

•The stability and structure of [CuLn]2+ and [LnH]+ (L = cytidine) were investigated.•The main interaction between the Cu(II) and L for [CuLn]2+ is coordination.•The main interaction between Ls for [LnH]+ is hydrogen bond.•The stability order for [CuLn]2+ is [CuL2]2+ > [CuL]2+ > [CuL4]2+ > [CuL3]2+.•The stability order for [LnH]+ is [L2H]+ > [LH]+ > [L3H]+ > [L4H]+.[CuLn]2+ and [LnH]+ (L = cytidine) with high relative intensity were observed in the gas phase via electronspray of water and methanol solution of Cu(NO3)2 and cytidine. The possible structures and zero-point energies for the most of these complexes were calculated with DFT methods. The results show that coordination is the main interaction between the L and Cu(II) for [CuLn]2+ (n = 1–4), and the hydrogen-bond between the Ls for [LnH]+ (n = 1–4); the structures for [CuLn]2+ are that the Cu(II) coordinate mostly 4 ligands forming the primary order sphere and other ligands just bind loosely with the primary sphere forming the secondary or outer sphere, and [LnH]+ are that the protonated L dimer composes the primary sphere, and the others binding the dimer loosely form the outer sphere; the calculated stability orders are [CuL2]2+ > [CuL]2+ > [CuL4]2+ > [CuL3]2+ and [L2H]+ > [LH]+ > [L3H]+ > [L4H]+ which are luckily consistent quite well with the peak intensity distribution in the mass spectrum.

The complexes of doubly charged cations, [CuLn]2+, [CuL(MeOH)n]2+ and single charged cations, [Cu(L–H)Ln]+, [L+H]+, [L2+H]+, and [B+H]+, etc. (L = cytidine, B = cytosine) were observed via electrospray of water and methanol solutions of Cu(NO3)2 and cytidine. The peak distribution for [CuLn]2+ shows that the [CuL2]2+ and [CuL4]2+ are the highest peaks, then followed by [CuL3]2+, [CuL5]2+, etc.Collision-induced dissociation (CID) of [Cu(L–H)Ln]+(n = 0,1), [CuLn]2+(n = 2–6) and [CuL(MeOH)n]2+(n = 1, 2) was investigated using the ESI-MS/MS instrument, and the structure and thermal energy for the most of these complexes were also calculated with ab initio and DFT methods through Gaussian 09 program. For [Cu(L–H)L0-1]+, the primary dissociation only involved a ribose group, including ribose group lost, ribose side chain and ribose ring broken. The calculation result shows that the deprotonated site for [Cu(L–H)]+ is the N-atom in the amino group of the cytidine base. The inter-ligand proton transfer was observed to dominate the CID of all doubly charged CuII–cytidine complexes, [CuLn]2+ (n = 2–6), and other channels, including charge reduction dissociation, lost neutral ligands were also observed. The protonated cytidine dimer, [L2+H]+, produced in the CID of [CuLn]2+ (n = 4–6), can further break into [L+ H]+ and neutral L, and the structure is proposed to be from the interaction of two cytidinesviahydrogen bonds. The protonated trimeric cytidine was also observed in the dissociation of [CuL6]2+. Three charge reduction dissociation channels were observed in the CID of [CuL(MeOH)]2+. Unlike the CuII–guanosine complex, the radical cation [CuLn]+ was not observed in the CID process of the [CuLn]2+, and the reasons are attributed to the higher ionization energy and proton affinity, which makes the inter-ligand proton transfer more favorable than the electron transfer from ligand to Cu2+.

Gas-phase guanine (G) radical cations were generated by electrospraying a solution of guanosine (L) and Cu(NO3)2. Collision-induced dissociation (CID) for guanine radical cations yielded five competing dissociation channels, corresponding to the elimination neutral molecules of NH3, HCN, H2NCN (HNCNH), HNCO and the neutral radical ˙NCNH, respectively. The primary product ions were further characterized by their relevant fragmentions. Ab initio and density functional theory (DFT) calculations were employed to explain the experimental observations. Ten stable radical cation isomers were optimized and the potential energy surfaces (PESs) for the isomerization processes were explored in detail. Starting with the most stable isomer, the primary dissociation channels of guanine radical cations were theoretically investigated. DFT calculations show that the energy barriers for the eliminations of NH3, HCN, H2NCN (HNCNH), HNCO and ˙NCNH are 397 kJ mol−1, 479 kJ mol−1, 294 kJ mol−1 (298 kJ mol−1), 306 kJ mol−1, and 275 kJ mol−1, respectively. The results are consistent with the energy-resolved CID of guanine radical cation, in which the eliminations of NH3 and HCN are less abundant than the other channels.

Dispersive liquid–liquid microextraction (DLLME) was coupled with gas chromatography and mass spectrometric detection for the determination of eight phthalate acid esters (PAEs) in soybean milk. Parameters impacting the extraction efficiencies were optimized including organic solvents to extract PAEs from soybean milk, salt concentrations and organic solvents for DLLME. Under the optimal conditions, limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.57–0.79 and 1.90–2.63 ng g−1, respectively. Linearities varied in the range of 1–16000 ng g−1 with the correlation coefficients of 0.9993–0.9998. The precision of the method was 2.9–3.2 in terms of RSD% based on triplicate measurements. The preconcentration factors were in the range of 200–260. The recoveries of eight PAEs were in the range from 79.0 to 110% at three spiked levels. The trace PAEs in five different brands of soybean milk purchased from the market were determined successfully.

Gas-phase guanine (G) radical cations were generated by electrospraying a solution of guanosine (L) and Cu(NO3)2. Collision-induced dissociation (CID) for guanine radical cations yielded five competing dissociation channels, corresponding to the elimination neutral molecules of NH3, HCN, H2NCN (HNCNH), HNCO and the neutral radical ˙NCNH, respectively. The primary product ions were further characterized by their relevant fragmentions. Ab initio and density functional theory (DFT) calculations were employed to explain the experimental observations. Ten stable radical cation isomers were optimized and the potential energy surfaces (PESs) for the isomerization processes were explored in detail. Starting with the most stable isomer, the primary dissociation channels of guanine radical cations were theoretically investigated. DFT calculations show that the energy barriers for the eliminations of NH3, HCN, H2NCN (HNCNH), HNCO and ˙NCNH are 397 kJ mol−1, 479 kJ mol−1, 294 kJ mol−1 (298 kJ mol−1), 306 kJ mol−1, and 275 kJ mol−1, respectively. The results are consistent with the energy-resolved CID of guanine radical cation, in which the eliminations of NH3 and HCN are less abundant than the other channels.