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1.
The reactions of hydroxyl radical, hydrogen atom and hydrated electron intermediates of water radiolysis with N-isopropylacrylamide (NIPAAm) were studied by pulse radiolysis in dilute aqueous solutions. OH, H and e aq− react with NIPAAm with rate coefficient of (6.9±1.2)×10 9, (6.6±1)×10 9, and (1.0±0.2)×10 10 mol −1 dm 3 s −1. In OH and H radical addition to the double bond mainly -carboxyalkyl type radicals form, (OHCH 2CH √C(N- i-C 3H 7)O and CH 3CH √C(N- i-C 3H 7)O). In reaction of e aq− oxygen atom centered radical anion is produced (CH 2CHC √(N- i-C 3H 7)O −), the anion undergoes reversible protonation with p Ka=8.7. There is also an irreversible protonation on the β-carbon atom that produces the same radical as forms in H atom reaction (CH 3CH √C(N- i-C 3H 7)O). The -carboxyalkyl type radicals at low NIPAAm concentration (0.1–1 mmol dm −3) mainly disappear in self-termination reactions, 2 kt,m=8.4×10 8 mol −1 dm 3 s −1. At higher concentrations the decay curves reflect the competition of the self-termination and radical addition to monomer (propagation). The termination rate coefficient of oligomer radicals containing a few monomer units is 2 kt≈2×10 8 mol −1 dm 3 s 1. 相似文献
2.
The one-electron oxidation of Mitomycin C (MMC) as well as the formation of the corresponding peroxyl radicals were investigated by both steady-state and pulse radiolysis. The steady-state MMC-radiolysis by OH-attack followed at both absorption bands showed different yields: at 218 nm G i (-MMC) = 3.0 and at 364 nm G i (-MMC) = 3.9, indicating the formation of various not yet identified products, among which ammonia was determined, G(NH 3) = 0.81. By means of pulse radiolysis it was established a total κ (OH + MMC) = (5.8 ± 0.2) × 10 9 dm 3 mol −1 s −1. The transient absorption spectrum from the one-electron oxidized MMC showed absorption maxima at 295 nm (ε = 9950 dm 3 mol −1 cm t-1), 410 nm (ε = 1450 dm 3 mol −1 cm −1) and 505 nm ( ε = 5420 dm 3 mol −1 cm −1). At 280–320 and 505 nm and above they exhibit in the first 150 μs a first order decay, κ 1 = (0.85 ± 0.1) × 10 3 s −1, and followed upto ms time range, by a second order decay, 2κ = (1.3 ± 0.3) × 10 8 dm 3 mol -1 s −1. Around 410 nm the kinetics are rather mixed and could not be resolved. The steady-state MMC-radiolysis in the presence of oxygen featured a proportionality towards the absorbed dose for both MMC-absorption bands, resulting in a Gi (-MMC) = 1.5. Among several products ammonia-yield was determined G(NH3) = 0.52. The formation of MMC-peroxyl radicals was studied by pulse radiolysis, likewise in neutral aqueous solution, but saturated with a gas mixture of 80% N2O and 20% O2. The maxima of the observed transient spectrum are slightly shifted compared to that of the one-electron oxidized MMC-species, namely: 290 nm (ε = 10100 dm3 mol−1 cm−1), 410 nm (ε = 2900 dm3 mol−1 cm−1) and 520 nm (ε = 5500 dm3 mol−1 cm−1). The O2-addition to the MMC-one-electron oxidized transients was found to be at 290 to 410 nm gk(MMC·OH + O2) = 5 × 107 dm3 mol−1 s−1, around 480 nm κ = 1.6 × 108 dm3 mol−1 s−1 and at 510 nm and above, κ = 3 × 108 dm3 mol−1 s−1. The decay kinetics of the MMC-peroxyl radicals were also found to be different at the various absorption bands, but predominantly of first order; at 290–420 nm κ1 = 1.5 × 103 s−1 and at 500 nm and above, κ = 7.0 × 103 s−1. The presented results are of interest for the radiation behaviour of MMC as well as for its application as an antitumor drug in the combined radiation-chemotherapy of patients. 相似文献
3.
Reactions of OH radicals and some one-electron oxidants with 2-aminopyridine (2-AmPy) and 3-aminopyridine (3-AmPy) were studied in aqueous solutions using pulse radiolysis technique. The OH adduct of 2-AmPy at pH 9 has an absorption maximum at 360 nm along with a weak absorption band in the visible region and was found to be reactive with oxygen. The rate constant for its reaction with O 2 was determined to be 1.0×10 8 dm 3 mol −1 s −1. At pH 4 also, the OH adduct of 2-AmPy has an absorption band at 360 nm. However, there are differences in the absorption at other wavelengths. From the plot of ΔOD vs. pH at 340 nm, the p Ka of the OH adduct was determined to be 6.5. Among the specific oxidants, only SO 4−√ radicals were able to oxidize 2-AmPy. In the case of 3-aminopyridine (3-AmPy), the transient species formed by OH radical reaction at pH 9 has an absorption maximum at 410 nm with shoulder bands on both the sides. Its absorption spectrum at pH 4 was different indicating the existence of a p K value for the OH adduct. p Ka of 3-AmPy-OH radical adduct species was evaluated to be 5.7. This adduct species was also found to be reactive with oxygen ( k=7.6×10 6 dm 3 mol −1 s −1). Specific one-electron oxidants like N 3√, Br 2−√ C 2−√ and SO 4−√ were able to oxidize 3-AmPy indicating that it is easier to oxidize 3-AmPy as compared to 2-AmPy. 相似文献
4.
The reactions of two triphenyl methane (TPM) dyes—crystal violet (CV +) and malachite green (MG +)—with N 3• and OH • radicals were studied by pulse radiolytic kinetic spectrophotometry. The rate constants for the reaction of the cationic dyes (D +) with N 3• are (9.0±0.6)×10 9 and (3.0±0.2)×10 9 dm 3 mol −1 s −1 respectively and those for the reaction with OH • are obtained as (8.0±0.6)×10 9 and (1.1±0.1)×10 9 dm 3 mol −1 s −1 respectively. The transient spectra resulting from the oxidation of the dyes were characterized. The time-resolved spectra indicate that the reaction with OH • radicals initially generates an adduct which subsequently dissociates to form the radical dication D •2+. The D •2+ species decay by further reaction with the parent dye. 相似文献
5.
The self-termination rates of the benzyl radical (C 6H 5---CH 2√) and para-substituted benzyl radicals (X---C 6H 4---CH 2√) were studied in aqueous solutions. The Arrhenius parameters and activation energies were determined in the temperature range 275.5–328 K. The kinetic activation energies of these radicals were close to the dynamic activation energy of the solvent, indicating that the termination rate is controlled by diffusion. The values for the rate constants (2 kt (10 9 dm 3 mol −1 s −1)) and the activation energies ( E (kJ mol −1)) were 5.94±0.52 and 14.69±0.61 for CH 3O---C 6H 4---CH 2√, 4.52±0.2 and 17.65±1.16 for CH 37z.sbnd;C 6H 4---CH 2√, 3.07±0.45 and 17.58±0.97 for H---C 6H 4---CH 2√, 4.13±0.81 and 19.10±1.20 for Cl---C 6H 4---CH 2√ and 4.17±0.44 and 14.62±0.52 for NO 2---C 6H 4---CH 2√. 相似文献
6.
Excitation of solutions of Fe(bipy) 2(CN) 2 by a 266-nm laser pulse produces a hydrated electron and the oxidized complex, Fe(bipy) 2 (CN) 2+, in the primary photochemical step, in homogeneous aqueous solution as well as in aqueous solutions containing cetyltrimethylammonium bromide (CTAB) or sodium dodecyl sulfate (SDS) micelles. In all cases nascent hydrated electrons react with ground state Fe(bipy) 2(CN) 2 to form Fe(bipy) 2(CN) 2−, and comparison of the decay constants in the three media (H 2O: k = 2.8 × 10 10 M −1 s −1; CTAB: k = 2.9 × 10 10 M −1 s −1; SDS: k = 5.5 × 10 9 M −1 s −1), shows that the reaction is essentially unaffected by CTAB micelles but is much slower in SDS solution. Similar micellar effects were found for the back reaction between e aq− and Fe(bpy) 2(CN) 2+. Rate constants for the scavenging of the photogenerated hydrated electrons by methyl viologen (MV 2+) cations and NO 3− anions were measured in the three systems, and the results indicate that for scavenging by MV 2+ the rate constants are decreased in the micelle systems ( k in H 2O, 8.4 × 10 10; CTAB, 3.5 × 10 10 and SDS, 1.58 × 10 10 M −1 s −1), whereas for NO 3− the CTAB micelle decreases while the SDS micelle enhances the scavenging compared to water solution ( k in H 2O, 8.3 × 10 9; CTAB, 7 × 10 8; and SDS, 2.05 × 10 10 M −1 s −1). For the comproportionation reaction between Fe(bipy) 2(CN) 2+ and Fe(bipy) 2(CN) 2− both micelles reduce the rate ( k in H 2O, 3.3 × 10 10; CTAB, 2.3 × 10 10; and SDS, 1.05 × 10 10 M −1s −1), but while the reaction of Fe(bipy) 2(CN) 2+ with MV + is increased in CTAB compared to water, it is slowed in SDS ( k in H 2O, 2.4 × 10 10; CTAB, 8.9 × 10 10; and SDS, 1.8 × 10 10 M −1s −1). All effects observed in these microheterogeneous systems can be uniformly interpreted in terms of Coulombic interactions between the actual reactants and the charged surface of the micelles. 相似文献
7.
Pulse radiolysis of epicatechin in aqueous solution has been done to investigate the reactions of epicatechin derived phenoxy radical (EpO) at neutral pH. EpO was generated by N 3 reacting toward EpOH, the rate constant was measured to be 3 × 10 8 dm 3 mol −1 s −1. The biomolecular termination of EpO is rather slow ((2 k < × 10 6 dm 3 mol −1 s −1) and results in products exhibiting strong visible absorption around 450 nm. No reactions have been observed for EpO with O 2 and O 2 in the time scale of pulse radiolysis (0.01 s), suggesting the bimolecular rate constant are less than 10 4 and 5 × 10 6 dm 3 mol −1 s −1, respectively. 相似文献
8.
Pulse radiolysis technique has been employed to study the reactions of oxidizing ( √OH, N 3√) and reducing radicals (e −aq, CO 2√−, acetone ketyl radical) with 2-hydroxy-3-methoxybenzaldehyde ( o-vanillin) at different pH. Hydroxyl radicals react mostly by addition reaction forming radical adducts (λ max=420 nm) and the oxidation is only a minor process even in the alkaline region. The reaction with azide radicals produced phenoxyl radicals (λ max=340 nm), which are formed on fast deprotonation of solute radical cation. Using PMZ √+/PMZ and ABTS √−/ABTS 2− as the reference couple, different methods are employed to determine the one-electron reduction potential of o-vanillin and the average value is estimated to be 1.076±0.004 V vs. NHE at pH 6. The phenoxyl radicals of o-vanillin were able to oxidize ABTS 2− quantitatively. The e aq− is observed to react with o-vanillin with rate constant value of 2×10 10 dm 3 mol −1 s −1. CO 2√− and acetone ketyl radical are also observed to react with o-vanillin by electron transfer mechanism and showed the formation of transient absorption bands with λ max at 350 and 390 nm at pH 4.5 and 9.7, respectively. The p Ka of the one-electron reduced species was determined to be 8.1. The results indicate that the aldehydic group is the most preferred site for electron addition. 相似文献
9.
The rate constants at which oxidizing and reducing radicals react with the dinuclear iron(III) complex Fe 2O(ttha) 2− were measured in neutral aqueous solution. The rate constants for reduction of the complex by ·CO 2.− CH 3.CHOH and O 2.− were found to be comparable with rate constants previously measured in mononuclear iron(III) polyaminocarboxylate systems. Fe 2O(ttha) 2− reacts slowly with O 2.− ( k8 = (1.2 ± 0.2) × 10 4 dm 3 mol −1 s −1) and, hence, is a relatively poor catalyst for the dismutation of superoxide radical. The hydrated electron reduces the complex at a diffusion-controlled rate in a process which consumes one proton: e aq− + Fe 2O(ttha) 2− → Fe 2III,IIO(ttha) 3− The reduction by carbon-centered radicals produces a (III,II) mixed-valence complex with an absorption spectrum different from that of the Fe 2(II,III) species produced from reduction by the hydrated electron. The oxidizing radicals .OH and ·CO 3− appear to act as reductants of the complex via ligand oxidation rather than by oxidation of the Fe 2IIIO core to Fe 2III,IVO. In the former case ligand attack appears to occur mainly at the methylene carbon of a glycinate group. The decarboxylation product, CO 2, was detected by its aquation reaction in the presence of a pH sensitive dye, bromthymol blue. 相似文献
10.
Using N •3 species as specific electron acceptor a defined ascorbate radical: AH •↔A •−+H + (λ max=360 nm, =3400 dm 3 mol −1 cm −1) is observed. The attack of DMSO •+ on vit.E results in a vit.E • radical ( k=1×10 9 dm 3 mol −1 s −1; λ max=425 nm, =2400 dm 3 mol −1 cm −1; 2 k=4.7×10 8 dm 3 mol −1 s −1). Vit.E-acetate leads to the formation of a radical cation (vit.E-ac •+). β-carotene reacts also with DMSO •+ forming a radical cation, β-car •+ ( k=1.75×10 8 dm 3 mol −1 s −1; λ max=942 nm, =14 600 dm 3 mol −1 cm −1), which probably leads to the formation of a dimer radical cation, (β-car) •+2 ( k=2.5×10 7 dm 3 mol −1 s −1). Using E.coli bacteria (AB1157) as a model system in vitro it was found that all three vitamins are rather efficient radiation protecting agents. They can also increase the activity of cytostatica, e.g., mitomycin C (MMC), by electron transfer process. The mixture of vit.E-ac and β-car acts contradictory, but adding vit.C to it a strong cooperative enhancement of the MMC activity is observed once again. A relationship between the pulse radiolysis and the radiation biological data is found and discussed. A possible explanation of the previously reported trials concerning the role of vit.E and β-car on the increased occurence of lung and other types of cancer in smokers and drinkers is presented. 相似文献
11.
The generality of a two-electron reduction process involving an
mechanism has been established for M 3(CO) 12 and M 3(CO) 12− n(PPh 3) n (M = Ru, Os) clusters in all solvents. Detailed coulometric and spectral studies in CH 2Cl 2 provide strong evidence for the formation of an ‘opened’ M 3(CO) 122− species the triangulo radical anions M 3(CO) 12−· having a half-life of < 10 −6 s in CH 2Cl 2. However, the electrochemical response is sensitive to the presence of water and is concentration dependent. An electrochemical response for “opened” M 3(CO) 122− is only detected at low concentrations < 5 × 10 −4 mol dm −3 and under drybox conditions. The electroactive species ground at higher concentrations and in the presence of water M 3(CO) 112− and M 6(CO) 182− were confirmed by a study of the electrochemistry of these anions in CH 2Cl 2; HM 3(CO) 11− is not a product. The couple [M 6(CO) 18] −/2− is chemically reversible under certain conditions but oxidation of HM 3(CO) 11− is chemically irreversible. Different electrochemical behaviour for Ru 3(CO) 12 is found when [PPN][X] (X = OAc −, Cl −) salts are supporting electrolytes. In these solutions formation of the ultimate electroactive species [μ-C(O)XRu 3(CO) 10] − at the electrode is stopped under CO or at low temperatures but Ru 3(CO) 12−· is still trapped by reversible attack by X presumably as [η 1-C(O)XRu 3(CO) 11] −. It is shown that electrode-initiated electron catalysed substitution of M 3(CO) 12 only takes place on the electrochemical timescale when M = Ru, but it is slow, inefficient and non-selective, whereas BPK-initiated nucleophilic substitution of Ru 3(CO) 12 is only specific and fast in ether solvents particulary THF. Metal---metal bond cleavage is the most important influence on the rate and specificity of catalytic substitution by electron or [PPN]-initiation. The redox chemistry of M 3(CO) 12 clusters (M = Fe, Ru, Os) is a consequence of the relative rates of metal---metal bond dissociation, metal-metal bond strength and ligand dissociation and in many aspects resembles their photochemistry. 相似文献
12.
The photoinduced electron transfer reactions of the triplet state of rose bengal (RB) and several electron donors were investigated by the complementary techniques of steady state and time-resolved electron paramagnetic resonance (EPR) and laser flash photolysis (LFP). The yield of radicals varied with the light fluence rate, RB concentration and, in particular, the electron donor used. Thus for L-dopa (dopa, dihydroxyphenylalanine) only 10% of RB anion radical (RB√−) was produced, with double the yield observed with NADH (NAD, nicotinamide adenine dinucleotide) as quencher and more than three times the yield observed with ascorbate as quencher. Quenching of the RB triplet was both reactive and physical with total quenching rate constants of 4 × 10 8 mol −1 dm 3 s −1 and 8.5 × 10 8 mol −1 dm 3 s −1 for ascorbate and NADH respectively. The rate constant for the photoinduced electron transfer from ascorbate to RB triplet was 1.4 × 10 8 mol −1 dm 3 s −1 as determined by Fourier transform EPR (FT EPR). FT EPR spectra were spin polarized in emission at early times indicating a radical pair mechanism for the chemically induced dynamic electron polarization. Subsequent to the initial electron transfer production of radicals, a complex series of reactions was observed, which were dominated by processes such as recombination, disproportionation and secondary (bleaching) reactions. It was observed that back electron transfer reactions could be prevented by mild oxidants such as ferric compounds and duroquinone, which were efficiently reduced by RB√−. 相似文献
13.
The oxidation reaction of 2-aminophenol (OAP) to 2-aminophenoxazin-3-one (APX) initiated by 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) has been investigated in methanol at ambient temperature. The oxidation of OAP was followed by electronic spectroscopy and the rate constants were determined according to the rate law −d[OAP]/d t= kobs[OAP][TEMPO]. The rate constant, activation enthalpy and entropy at 298 K are as follows: kobs (dm 3 mol −1 s −1)=(1.49±0.02)×10 −4, Ea=18±5 kJ mol −1, Δ H‡=15±4 kJ mol −1, Δ S‡=−82±17 J mol −1 K −1. The results of oxidation of OAP show that the formation of 2-aminophenoxyl radical is the key step in the activation process of the substrate. 相似文献
14.
Free radical reactions of dehydrozingerone (DZ), a methoxy phenol, were studied at dfferent pHs with a variety of oxidants using nanosecond pulse radiolysis technique. Hydroxyl radical (OH) reaction with the phenolic form at pH 6 led mainly to the formation of an OH-adduct absorbing at 460 nm in addition to a minor oxidation product. On the other hand, at pH 10 with the deprotonated phenoxide ion, the only reaction observable was oxidation generating a phenoxyl radical absorbing at 360 nm. HPLC analysis indicated formation of two different products at pH 6 from addition and oxidation reactions, whereas at pH 10, only the oxidation product was detectable. Reactions of more specific secondary oxidizing radicals, N3√, Br√, Br −2√ and Tl(II) with DZ gave rise to the phenoxyl radical over the entire pH range. DZ in the phenoxide ion form reacted with nitrogen dioxide and trichloromethyl peroxyl radicals with rate constants 6×10 8 and 8.8×10 8 dm 3 mol −1 s −1 respectively leading to the phenoxyl radicals. The DZ phenoxyl radical reacted with trolox C (an analogue of -tocopherol) with a rate constant of 8.3×10 7 dm 3 mol −1 s −1. One electron reduction potential of the DZ phenoxyl radical at pH 6 was determined to be +1.1 V vs NHE using N3√/N −3 as the standard couple. 相似文献
15.
The three cyanocuprate(I) complexes, Cu(CN) 2−, Cu(CN) 32−, and Cu(CN) 43−, photoeject electrons with high efficiency when excited in aqueous solution by 266 nm laser pulses of 7 ns duration with quantum yields of 0.37±0.06, 0.224±0.021, and 0.240±0.005, for Cu(CN) 2− (at 2 M ionic strength), Cu(CN) 32−, and Cu(CN) 43− (both measured at 1 M ionic strength). Along with hydrated electrons, two transient intermediates, absorbing at 460 and 340 nm, respectively, form consecutively after excitation through bimolecular reactions with ground-state Cu(I) in solutions of Cu(CN) 2−, and Cu(CN) 32−, but not in Cu(CN) 43−. All photoprocesses are essentially monophotonic. A mechanism is proposed that suggests the formation of a dinuclear excited-state complex such as an excimer. 相似文献
16.
The far-UV (193 nm) laser flash photolysis of nitrogen-saturated isooctane solutions of 1,1-dimethylsiletane allows the direct detection of 1,1-dimethylsilene as a transient species, which (at low laser intensities) decays with pseudo-first-order kinetics (τ 10 μs) and exhibits a UV absorption spectrum with λ max 255 nm. Characteristic rapid quenching is observed for the silene with methanol ( kMcOH = (4.9 ± 0.2) × 10 9 M −1 s −1), tert-butanol ( kBuOH = (1.8 ± 0.1) × 10 9 M −1 s −1) and oxygen ( kO2 = (2.0 ± 0.5) × 10 8 M −1 s −1). The Arrhenius activation parameters for the reaction with methanol have been determined to be Ea = −2.6 ± 0.6 kcal mol −1 and log A = 7.7 ± 0.3. 相似文献
17.
Low-temperature heat capacities of the complex Zn(Thr)SO 4·H 2O (s) have been precisely measured with a small sample adiabatic calorimeter over the temperature range from 78 to 373 K. The initial dehydration temperature of the complex ( Td=325.50 K) has been obtained by analysis of the heat-capacity curve. The experimental values of molar heat capacities have been fitted to a polynomial equation by least square method. The standard molar enthalpy of formation of the complex has been determined from the enthalpies of dissolution (Δ dHmΘ) of [ZnSO 4·7H 2O (s) +Thr (s)] and Zn(Thr)SO 4·H 2O (s) in 100 ml of 2 mol dm −3 HCl solvent as: Δ fHm,Zn(Thr)SO4·H2OΘ=−2111.7±3.4 kJ mol −1. These experiments were made by using an isoperibol solution calorimeter at 298.15 K. 相似文献
18.
The one-electron reduction of 4,7-phenanthroline (P) in aqueous solutions at neutral pH has been further studied by pulse radiolysis. The spectral and kinetic properties of the transient formed due to the reaction of 4,7-phenanthroline with hydrated electron were investigated. The transient absorption spectrum obtained 5μs after the pulse exhibits a broad band with a λ max at 420 nm. The λ max is 10 nm blue shift compared with the absorption spectrum obtained at pH 2.9 where the reactant was the protonated form. The bimolecular'rate constant of the reaction of 4,7-phenanthroline with hydrated electron was 0etermined to be (2.2±0.1)×10 10 dm 3 mol −1 s −1. It was found that the decay of the transient was mainly following a first-order kinetics. The first-order decay rate constant was determined to be (1.25±0.1)×10 4s −1. 相似文献
19.
Automated sequential injection (SIA) method for chemiluminescence (CL) determination of nonsteroidal anti-inflammatory drug indomethacin (I) was devised. The CL radiation was emitted in the reaction of I (dissolved in aqueous 50% v/v ethanol) with intermediate reagent tris(2,2′-bipyridyl)ruthenium(III) (Ru(bipy) 33+) in the presence of acetate. The Ru(bipy) 33+ was generated on-line in the SIA system by the oxidation of 0.5 mM tris(2,2′-bipyridyl)ruthenium(II) (Ru(bipy) 32+) with Ce(IV) ammonium sulphate in diluted sulphuric acid. The optimum sequence, concentrations, and aspirated volumes of reactant zones were: 15 mM Ce(IV) in 50 mM sulphuric acid 41 μL, 0.5 mM Ru(bipy) 32+ 30 μL, 0.4 M Na acetate 16 μL and I sample 15 μL; the flow rates were 60 μL s −1 for the aspiration into the holding coil and 100 μL s −1 for detection. Calibration curve relating the intensity of CL (peak height of the transient CL signal) to concentration of I was curvilinear (second order polynomial) for 0.1–50 μM I ( r = 0.9997; n = 9) with rectilinear section in the range 0.1–10 μM I ( r = 0.9995; n = 5). The limit of detection (3 σ) was 0.05 μM I. Repeatability of peak heights (R.S.D., n = 10) ranged between 2.4% (0.5 μM I) and 2.0% (7 μM I). Sample throughput was 180 h −1. The method was applied to determination of 1 to 5% of I in semisolid dosage forms (gels and ointments). The results compared well with those of UV spectrophotometric method. 相似文献
20.
Putative free-radical intermediates in drug action can be studied by radiolysis of model systems containing low concentrations of drug and much higher concentrations of other solutes to scavenge the primary water radicals and convert them into appropriate oxidants or reductants. The need to employ high ionic solute concentrations (typically >10 mmol dm −3) represents a challenge for the high-performance ion chromatographic detection of drug-derived ions (typically, <50 μmol dm −3). Constraints on the chromatographic method chosen are illustrated with examples of the application of high-performance ion chromatography (HPIC) to radiation chemistry studies in the oxidative decar☐ylation of the anti-tumour drugs flavone-8- and xanthenone-4-acetic acids and structurally related aromatic car☐ylic acids (CO 2 in the form of CO 32−), the oxidative denitrification of nitric oxide precursor molecules (NO in the form NO 2−/NO 3−) and the generation of SO 42− from novel thiol-based (perthiol) drugs. 相似文献
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