共查询到20条相似文献,搜索用时 411 毫秒
1.
Robert Koeber R. Niessner Josep Maria Bayona 《Fresenius' Journal of Analytical Chemistry》1997,359(3):267-273
The performance of two liquid chromatography-mass spectrometry (LC/MS) interfacing techniques, thermospray (TSP) and atmospheric
pressure chemical ionization (APCI), for the analysis of benzo[a]pyrene (BaP) metabolites (hydroxy, epoxy and quinone derivatives) was compared. Interface and detection parameters such as
source temperature, eluent composition or flow rate were optimized using negative ion mode. In TSP, the main ions are mostly
[M]-, [M−H2O]- or [M+CH3COO]-, whereas APCI gives mainly the [M]- and [M−H]- ions. Quantification was carried out by flow injection. Calibration graphs were linear in the range of 10 ng to 1000 ng in
TSP and 0.1 ng to 10 ng in APCI. Detection limits were in the range of 1 ng to 20 ng in TSP and 0.002 ng to 0.2 ng in APCI.
The presence of BaP-1,6-dione, BaP-3,6-dione, and BaP-6,12-dione was confirmed in environmental samples of air particulate
matter.
Received: 6 January 1997/Accepted: 18 April 1997 相似文献
2.
D. Barceló 《Chromatographia》1988,25(4):295-299
Summary Positive and negative ion modes (Pl and NI, respectively) have been employed for the characterization of 2,4-dichlorophenol,
2,4,5-trichlorophenol, pentachlorophenol, Linuron and Cyanazine in thermospray (TSP) liquid chromatography-mass spectrometry
(LC-MS). The PI mode showed no response when 200 ng of the different chlorophenols were injected, while for Linuron and Cyanazine
high signals were obtained with [M+NH4]+ and [M+acetic acid]+ ions as base peaks, respectively. With the NI mode, the base peak usually corresponds to the [M−H]− ion, with better sensitivities for the chlorophenols than for the herbicides. The chloride adduct [M+Cl]− ion was also obtained for 2,4,5-trichlorophenol and for Linuron. Although the PI mode is more sensitive than the NI mode
for the two herbicides, the combination of both ionization modes offers complementary structural information for characterizing
such compounds in TSP LC-MS. 相似文献
3.
Brent N. Jewett Louis Ramaley Jan C. T. Kwak 《Journal of the American Society for Mass Spectrometry》1999,10(6):529-536
This paper compares two liquid introduction atmospheric pressure ionization techniques for the analysis of alkyl ethoxysulfate (AES) anionic surfactant mixtures by mass spectrometry, i. e., electrospray ionization (ESI) in both positive and negative ion modes and atmospheric pressure chemical ionization (APCI) in positive ion mode, using a triple quadrupole mass spectrometer. Two ions are observed in ESI(+) for each individual AES component, [M + Na]+ and a “desulfated” ion [M − SO3 + H]+, whereas only one ion, [M − Na]− is observed for each AES component in ESI(−). APCI(+) produces a protonated, “desulfated” ion of the form [M − NaSO3 + 2H]+ for each AES species in the mixture under low cone voltage (10 V) conditions. The mass spectral ion intensities of the individual AES components in either the series from ESI(+) or APCI(+) can be used to obtain an estimate of their relative concentrations in the mixture and of the average ethoxylate (EO) number of the sample. The precursor ions produced by either ESI(+) or ESI(−), when subjected to low-energy (50 eV) collision-induced dissociation, do not fragment to give ions that provide much structural information. The protonated, desulfated ions produced by APCI(+) form fragment ions which reveal structural information about the precursor ions, including alkyl chain length and EO number, under similar conditions. APCI(+) is less susceptible to matrix effects for quantitative work than ESI(+). Thus APCI(+) provides an additional tool for the analysis of anionic surfactants such as AES, especially in complex mixtures where tandem mass spectrometry is required for the identification of the individual components. 相似文献
4.
Low-energy CAD product-ion spectra of various molecular species of phosphatidylserine (PS) in the forms of [M−H]− and [M−2H+Alk]− in the negative-ion mode, as well as in the forms of [M+H]+, [M+Alk]+, [M−H+2Alk]+, and [M−2H+3Alk]+ (where Alk=Li, Na) in the positive-ion mode contain rich fragment ions that are applicable for structural determination.
Following CAD, the [M−H]− ion of PS undergoes dissociation to eliminate the serine moiety (loss of C3H5NO2) to give a [M−H−87]− ion, which equals to the [M−H]− ion of a phoshatidic acid (PA) and give rise to a MS3-spectrum that is identical to the MS2-spectrum of PA. The major fragmentation process for the [M−2H+Alk]− ion of PS arises from primary loss of 87 to give rise to a [M−2H+Alk−87]− ion, followed by loss of fatty acid substituents as acids (RxCO2H, x=1,2) or as alkali salts (e. g., RxCO2Li, x=1,2). These fragmentations result in a greater abundance of [M−2H+Alk−87−R2CO2H]− than [M−2H+Alk−87−R1CO2H]− and a greater abundance of [M−2H+Alk−87−R2CO2Li]− than [M−2H+Alk−87−R1CO2Li]−; while further dissociation of the [M−2H+Alk−87−R2(or 1)CO2Li]− ions gives a preferential formation of the carboxylate anion at sn-1 (R1CO2−) over that at sn-2 (R2CO2−). Other major fragmentation process arises from differential loss of the fatty acid substituents as ketenes (loss of Rx′CH=CO, x=1,2). This results in a more prominent [M−2H+Alk−R2′CH=CO]− ion than [M−2H+Alk−R1′CH=CO]− ion. Ions informative for structural characterization of PS are of low abundance in the MS2-spectra of both the [M+H]+ and the [M+Alk]+ ions, but are abundant in the MS3-spectra. The MS2-spectrum of the [M+Alk]+ ion contains a unique ion corresponding to internal loss of a phosphate group probably via the fragmentation processes involving
rearrangement steps. The [M−H+2Alk]+ ion of PS yields a major [M−H+2Alk−87]+ ion, which is equivalent to an alkali adduct ion of a monoalkali salt of PA and gives rise to a greater abundance of [M−H+2Alk−87−R1CO2H]+ than [M−H+2Alk−87−R2CO2H]+. Similarly, the [M−2H+3Alk]+ ion of PS also yields a prominent [M−2H+3Alk−87]+ ion, which undergoes consecutive dissociation processes that involve differential losses of the two fatty acyl substituents.
Because all of the above tandem mass spectra contain several sets of ion pairs involving differential losses of the fatty
acid substituents as ketenes or as free fatty acids, the identities of the fatty acyl substituents and their positions on
the glycerol backbone can be easily assigned by the drastic differences in the abundances of the ions in each pair. 相似文献
5.
A method for the determination of theophylline (TH), without derivatization, in serum by isotope dilution mass spectrometry
using labelled [1, 3-15N2-2-13C]theophylline (LTH) as internal standard is described. After deproteinization, the analyte is directly injected into a high
performance liquid chromatography – mass spectrometer operating with atmospheric-pressure chemical-ionization (APCI HPLC/MS).
The concentrations of TH in sera measured by APCI HPLC/MS are compared with results from gas chromatography – isotope dilution
mass spectrometry (GC-ID/MS), high performance liquid chromatography (HPLC) and fluorescence polarization immunoassay (FPIA).
The accuracy, precision and recovery of the APCI HPLC/MS and GC-ID/MS methods are discussed. The coefficient of variation
(CV) determined from duplicate samples was less than 2%. The detection limit was 10 ng/ml at a signal-to-noise ratio of 3:1.
Received: 17 January 1996/Revised: 26 March 1996/Accepted: 5 April 1996 相似文献
6.
Two carbonyl compounds, nabumetone and testosterone, were derivatized with pentafluorophenyl hydrazine (PFPH) and analyzed by atmospheric-pressure chemical-ionization mass spectrometry. The PFPH derivatives underwent dissociative electron capture in negative-ion APCI (ECAPCI) and gave intense [M–20]– ions in the mass spectra. In positive-ion APCI, the PFPH derivatives underwent efficient protonation and gave intense [M+H]+ ions in the mass spectra. In CID, the major product ions of the [M–20]– ions in ECAPCI corresponded to the partial moiety of PFPH. In contrast, the major product ions of [M+H]+ corresponded to the partial moiety of the analyte. By using selected reaction monitoring (SRM) detection, low pg of nabumetone (1 pg) and testosterone (7 pg) could be detected in both ECAPCI and positive-ion APCI. In comparison with the detection limits (SRM) of the underivatized analytes, use of the PFPH derivatives resulted in 2500-fold and 35-fold sensitivity enhancements for nabumetone and testosterone, respectively. The PFPH derivatives were applied to the analysis of nabumetone and testosterone in human plasma by both ECAPCI and positive-ion APCI and were found to enable detection of 0.1 ng mL–1 nabumetone in spiked plasma. For testosterone, endogenous testosterone in female plasma was detected in both ECAPCI and positive-ion APCI. 相似文献
7.
As part of a mass spectrometric investigation of the binding properties of sulfonamide anion receptors, an atmospheric pressure
chemical ionization mass spectrometric (APCI-MS) method involving direct infusion followed by thermal desorption was employed
for identification of anionic supramolecular complexes in dichloromethane (CH2Cl2). Specifically, the dansylamide derivative of tris(2-aminoethyl)amine (tren) (1), the chiral 1,3-benzenesulfonamide derivatives of (1R,2S)-(+)-cis-1-amino-2-indanol (2), and (R)-(+)-bornylamine, (3), were shown to bind halide and nitrate ions in the presence of (n−Bu)4N+X− (X− = Cl−, NO3−, Br−, I−). Solutions of receptors and anions in CH2Cl2 were combined to form the anionic supramolecular complexes, which were subsequently introduced into the mass spectrometer
via direct infusion followed by thermal desorption. The anionic supramolecular complexes [M+X]−, (M=1–3, X−=Cl−, NO3−, Br−, I−) were observed in negative mode APCI-MS along with the deprotonated receptors [M−H]−. Full ionization energy of the APCI corona pin (4.5 kV) was necessary for obtaining mass spectra with the best signal-to-noise
ratios. 相似文献
8.
M. V. Muftakhov R. V. Khatymov V. A. Mazunov V. N. Odinokov I. V. Galyautdinov 《Russian Chemical Bulletin》2000,49(4):713-716
The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative
ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by
the elimination of H2O and H2 molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH2O].− (n=1–3) and [M−H2−nH2O].− (n=0−3) ions that are generated exclusively by the rearrangement.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000. 相似文献
9.
Zhaoxiang Wu Francisco A. Fernandez-Lima David H. Russell 《Journal of the American Society for Mass Spectrometry》2010,21(4):522-533
Matrix assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) and theoretical calculations
[density functional theory (DFT)] were utilized to investigate the influence of cysteine side chain on Cu+ binding to peptides and how Cu+ ions competitively interact with cysteine (−SH/SO3H) versus arginine. Results from theoretical and experimental (fragmentation reactions) studies on [M+Cu]+ and [M+2Cu−H]+ ions suggest that cysteine side chains (−SH) and cysteic acid (−SO3H) are important Cu+ ligands. For example, we show that Cu+ ions are competitively coordinated to the −SH or SO3H groups; however, we also present evidence that the proton of the SH/SO3H group is mobile and can be transferred to the arginine guanidine group. For [M+2Cu−H]+ ions, deprotonation of the −SH/SO3H group is energetically more favorable than that of the carboxyl group, and the resulting thiolate/sulfonate group plays
an important role in the coordination structure of [M+2Cu−H]+ ions, as well as the fragmentation patterns. 相似文献
10.
Gao J Owen BC Borton DJ Jin Z Kenttämaa HI 《Journal of the American Society for Mass Spectrometry》2012,23(5):816-822
Saturated and unsaturated, linear, branched, and cyclic hydrocarbons, as well as polyaromatic and heteroaromatic hydrocarbons,
were successfully ionized by atmospheric pressure chemical ionization (APCI) using small hydrocarbons as reagents in a linear
quadrupole ion trap (LQIT) mass spectrometer. Pentane was proved to be the best reagent among the hydrocarbon reagents studied.
This ionization method generated different types of abundant ions (i.e., [M + H]+, M+•, [M – H]+ and [M – 2H]+ •), with little or no fragmentation. The radical cations can be differentiated from the even-electron ions by using dimethyl
disulfide, thus facilitating molecular weight (MW) determination. While some steroids and lignin monomer model compounds,
such as androsterone and 4-hydroxy-3-methoxybenzaldehyde, also formed abundant M+• and [M + H]+ ions, this was not true for all of them. Analysis of two known mixtures as well as a base oil sample demonstrated that each
component of the known mixtures could be observed and that a correct MW distribution was obtained for the base oil. The feasibility
of using this ionization method on the chromatographic time scale was demonstrated by using high-performance liquid chromatography
(HPLC) with hexane as the mobile phase (and APCI reagent) to separate an artificial mixture prior to mass spectrometric analysis. 相似文献
11.
A method for the identification and quantification of underivatised steryl sulphates in invertebrates by liquid chromatography
(LC) coupled with tandem mass spectrometry (MS) involving a single cleanup step has been developed. Negative electrospray
ionisation and positive and negative atmospheric-pressure chemical ionisation (APCI) spectra of steryl sulphate showed pseudomolecular
ions ([M+H–H2SO4]+or [M–H]−). Collision-induced dissociation (CID) was efficient only in positive APCI. LC-MS in negative APCI was least susceptible
to interference and possible differences in response factors. The detection limits (signal-to-noise ratio of 3) based on cholest-5-enyl-3-sulphate
in positive and negative APCI modes are 3.66 and 0.73 pmol μL−1, respectively. Calibration plots and response factors for cholest-5-enyl-3-sulphate relative to the internal standard, cholecalciferyl-3-sulphate,
in both positive and negative polarities, were linear in the concentration range from 1.22 to 16.4 pmol μL−1 with good coefficients of determination (R
2>0.98). It is suggested that the structure elucidation of steryl sulphates is best achieved in CID positive APCI mode, whereas
their quantification should be carried out using negative APCI. 相似文献
12.
A new method for the analysis of cyclic peptides (Pseudostellarins) in traditional Chinese medicine, Pseudostellaria heterophylla (Miq.) Pax, was established by high performance liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry
(HPLC–APCI–MS). The real samples were separated by a reversed-phase C18 column using a binary eluent under gradient conditions. Six cyclic peptides were isolated and detected with a DAD detector.
The Pseudostellarins components were identified by APCI–MS in a negative mode. In the negative ion APCI mode, the best sensitivity
and the lowest detection limit for Pseudostellarins were obtained by using a mobile phase consisting of acetonitrile and pure
water. The APCI spectra were characterized by [M-H]− peak. The parent ions [M-H]− with highest intensity was used for quantification of one cyclic peptide-Pseudostellarin B. 相似文献
13.
Zhaoxiang Wu Francisco A. Fernandez-Lima Lisa M. Perez David H. Russell 《Journal of the American Society for Mass Spectrometry》2009,20(7):1263-1271
The dinuclear copper complex (α-cyano-4-hydroxycinnamic acid (CHCA) copper salt (CHCA)4Cu2), synthesized by reacting CHCA with copper oxide (CuO), yields increased abundances of [M + xCu − (x−1)H]+ (x = 1–6) ions when used as a matrix for matrix-assisted laser desorption ionization (355 nm Nd:YAG laser). The yield of
[M + xCu − (x−1)H]+ (x = 1∼6) ion is much greater than that obtained by mixing peptides with copper salts or directly depositing peptides onto
oxidized copper surfaces. The increased ion yields for [M + xCu − (x−1)H]+ facilitate studies of biologically important copper binding peptides. For example, using this matrix we have investigated
site-specific copper binding of several peptides using fragmentation chemistry of [M + Cu]+ and [M + 2Cu − H]+ ions. The fragmentation studies reveal interesting insight on Cu binding preferences for basic amino acids. Most notable
is the fact that the binding of a single Cu+ ion and two Cu+ ions are quite different, and these differences are explained in terms of intramolecular interactions of the peptide-Cu ionic
complex. 相似文献
14.
Summary This paper describes the fragmentation patterns and the GC-MS quantitation possibilities of the trimethylsilyl derivatives
of thirty-one aromatic carboxylic acids, using ion trap detection (ITD). Sixteen aralkyl carboxylic acids, including those
containing a saturated aliphatic side chain {phenylacetic, 2-phenylbutyric, phenylglycolic (mandelic acid), β-phenyllactic,
3-hydroxyphenylacetic, β-phenylpyruvic and 3-(4-hydroxyphenyl)-propionic acids} and those with an unsaturated aliphatic side
chain {cinnamic, 2-hydroxycinnamic (o-coumaric), 4-methoxycinnamic, 3-hydroxycinnamic (m-coumaric), 4-hydroxycinnamic (p-coumaric),
4-hydroxy-3-methoxycinnamic (ferulic acid), 3,4-dihydroxycinnamic (caffeic), and 4-dihydroxy-3,5-dimethoxycinnamic (sinapic)
acids}, as well as, the fifteen hydroxy(methoxy) benzoic acids {benzoic, 2-hydroxybenzoic (salicylic), 3-hydroxybenzoic, 4-hydroxybenzoic,
3,5-dimethoxybenzoic, 3,4-dimethoxybenzoic (veratric), 2,6-dihydroxybenzoic (γ-resorcylic), 3-methoxy-4-hydroxybenzoic (vanillic),
2,5-dihydroxybenzoic (gentisic), 2,4-dihydroxybenzoic (β-resorcylic), 3,4-dihydroxybenzoic (protocatechuic), 3,5-dihydroxybenzoic
(α-resorcylic), 2,4,5-trimethoxybenzoic (asaronic), 3,5-dimethoxy-4-hydroxybenzoic (syringic) and 3,4,5-trihydroxybenzoic
(gallic) acids}, provided distinct fragmentation characteristics that were very useful for their identification and simultaneously
quantitation. Based on 1–20 ng amounts of acids, very informative ions of high mass with considerable intensities ([M+TMS]+, [M+1]+),
, ([M−CH3]+) were obtained. In the case of the cinnamic acid derivatives, several odd electron fragments are formed by the loss of CO,
HCHO and/or Si(CH3)4 molecules. In the case of benzoic acids the molecular ion
proved to be abundant in three, the [M−CH3]+ ion in nine cases out of fifteen. The special MacLafferty rearrangement product ([C6H5Si(CH3)2]+) was obtained in different yields. In addition to the TIC values, at least three, and in most cases four, selective fragment
ions could be utilized for quantitation. The reproducibility of the data in the concentration range of 1–20 ng acids proved
to be between 1.2 and 13.0% (R.S.D.).
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997 相似文献
15.
Negative-ion low-energy collisionally activated dissociation (CAD) tandem mass spectrometry of electrospray-produced ions permits structural characterization of phosphatidylglycerol (PG). The major ions that identify the structures arise from neutral loss of free fatty acid substituents ([M − H − R x CO2H]−) and neutral loss of the fatty acids as ketenes ([M − H − R′ x CH = C = O]−), followed by consecutive loss of the glycerol head group. The abundances of the ions arising from neutral loss of the sn-2 substutient as a free fatty acid ([M − H − R2CO2H]−) or as a ketene ([M − H − R′2CH = C = O]−) are greater than those of the product ions from the analogous losses at sn-1. Nucleophilic attack of the anionic phosphate site on the C-1 or the C-2 of the glycerol to which the carboxylates attached expels the sn-1 (R1CO2−) or the sn-2 (R2CO2−) carboxylate anion, resulting in a greater abundance of R2COO− than R1COO−. These features permit assignments of fatty acid substituents and their position in the glycerol backbone. The results are also consistent with our earlier findings that pathways leading to those losses at sn-2 are sterically more favorable than those at sn-1. Fragment ions at m/z 227, 209 and 171 reflect the glycerol polar head group and identify the various PG molecules. Both charge-remote fragmentation (CRF) and charge-drive fragmentation (CDF) processes are the major pathways for the formation of [M − H − R x COOH]− ions. The CRF process involves participation of the hydrogen atoms on the glycerol backbone, whereas the CDF process involves participation of the exchangeable hydrogen atoms of the glycerol head group. The proposed fragmentation pathways are supported by CAD tandem mass spectrometry of the analogous precursor ions arising from the H-D exchange experiment, and further confirmed by source CAD in combination with tandem mass spectrometry. 相似文献
16.
V. I. Kadentsev N. G. Kolotyrkina A. A. Stomakhin O. S. Chizhov 《Russian Chemical Bulletin》1997,46(7):1261-1263
Specific features of the interaction between trimethylsilyl ions and methyl (methyl-α-d-galactopyranoside)uronate and its methyl ethers were revealed. It was shown that a hydrogen atom is generated when the trimethylsilyl
ion is located at hydroxyl group. This atom migrates over the methoxy and hydroxyl groups toward the glycoside methoxy group,
resulting in the formation of [Me+SiMe3−MeOH]+ ions.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1317–1319, July, 1997. 相似文献
17.
Frański R Gierczyk B Schroeder G 《Journal of the American Society for Mass Spectrometry》2009,20(2):257-262
The loss of X· radical from [M + Cu + X]+ ions (copper reduction) has been studied by the so called in-source fragmentation at higher cone voltage (M = crown ether
molecule, X− = counter ion, ClO4−, NO3−, Cl−). The loss of X· has been found to be affected by the presence/lack of aromatic ring poor/rich in electrons. Namely, the loss of X· occurs with lower efficiency for the [NO2-B15C5 + Cu + X]+ ions than for the [B15C5 + Cu + X]+ ions, where NO2-B15C5 = 3-nitro-benzo-15-crown-5, B15C5 = benzo-15-crown-5. A reasonable explanation is that Anion-π interactions prevent the loss of X· from the [NO2-B15C5 + Cu + X]+ ions. The presence of the electron-withdrawing NO2 group causes the aromatic ring to be poor in electrons and thus its enhances its interactions with anions. For the ion containing
the aromatic ring enriched in electrons, namely [NH2-B15C5 + Cu + ClO4]+ where NH2-B15C5 = 3-amino-benzo-15-crown-5, the opposite situation has been observed. Because of Anion-π repulsion the loss of X· radical proceeds more readily for [NH2-B15C5 + Cu + X]+ than for [B15C5 + Cu + X]+. Iron reduction has also been found to be affected by Anion-π interactions. Namely, the loss of CH3O· radical from the ion [B15C5 + Fe + NO3 + CH3O]+ proceeds more readily than from [NO2−B15C5 + Fe + NO3 + CH3O]+. 相似文献
18.
A new method is described for simultaneous determination of 3-methylindole (3MI) and indole in porcine adipose tissue. Sample preparation included liquid–liquid extraction with n-hexane and 75% aqueous acetonitrile. The acetonitrile extracts were analysed by liquid chromatography–mass spectrometry (LC–MS) using atmospheric pressure chemical ionization (APCI) with selective ion monitoring of protonated ions [M + H]+. This method showed excellent linearity over the concentration range tested (from 2 to 500 ng mL−1 for 3MI and from 1 to 500 ng mL−1 for indole) and good accuracy (recovery of 92 ± 10% for 3MI and 91 ± 10% for indole). This new LC–MS method was compared with traditional colorimetric method for 3MI equivalent. Additionally, the correlation between 3MI concentrations in adipose tissue and plasma was studied. The described LC–MS method can be used to quantify 3MI and indole in porcine adipose tissue in various endocrinological or meat science studies. 相似文献
19.
Mobolanle Adegboyega Olatunji Godwin A. Ayoko Florence O. Ohiani 《Transition Metal Chemistry》1994,19(2):253-256
Summary The stoichiometries, kinetics and mechanisms of oxidation of (NH2)2CS (1) and (Me2N)2CS (2) to the corresponding disulphides by CoIIIM (M = W12O40
∞-) in aqueous HC1O4 were investigated. The reaction with (1) follows the empirical rate law- d[oxidant] = k[reductant][oxidant] where k = 12.5 ± 0.3 m−1 s−1 at 25° C, while that with (2) follows the equation- d[oxidant] = a + b [reductant] [reductant] [oxidant] where a = 5.4 × 104 M−1s−1 and b = 3.3 × 106M−2 s−1 at 25° C. Free radicals are important in the reactions and possible reaction mechanisms are suggested and discussed. 相似文献
20.
Feng Zhang Xing Liu Jian Zhou Xian-Hong Yin Jun He 《Monatshefte für Chemie / Chemical Monthly》2011,22(1):763-768