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11.
Taylor MJ Keenan GA Reid KB Fernández DU 《Rapid communications in mass spectrometry : RCM》2008,22(17):2731-2746
The utility of ultra-performance liquid chromatography/orthogonal-acceleration time-of flight mass spectrometry (UPLC/TOFMS) for the rapid qualitative and quantitative analysis of 100 pesticides targeted in strawberry was assessed by comparing results with those obtained using a validated in-house UPLC tandem mass spectrometry (MS/MS) multi-residue method. Crude extracts from retail strawberry samples received as part of the 2007 annual UK pesticide residues in food surveillance programme were screened for the presence of pesticide residues using UPLC/TOFMS. Accurate mass measurement of positive and negative ions allowed their extraction following 'full mass range data acquisition' with negligible interference from background or co-eluting species observed during UPLC gradient separation (in a cycle time of just 6.5 min per run). Extracted ion data was used to construct calibration curves and to detect and identify any incurred residues (i.e. pesticides incorporated in or on the test material following application during cultivation, harvest and storage). Calibration using matrix-matched standards was performed over a narrow concentration range of 0.005-0.04 mg kg(-1) with determination coefficients (r2) > or =0.99 for all analytes with the exception of malathion/fenarimol/fludioxanil (r2 = 0.98), quassia/pymetrazine (r2 = 0.97) and fenthion sulfone (r2 = 0.95). Residues found in selected samples ranged from 0.025-0.28 mg kg(-1) and were in excellent agreement with results obtained using UPLC/MS/MS. Mass measurement accuracies of < or =5 ppm were achieved consistently throughout the separation, mass range and concentration range of interest thus providing the opportunity to obtain discrete elemental compositions of target ions. 相似文献
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Adamczyk K Candelaresi M Kania R Robb K Bellota-Antón C Greetham GM Pollard MR Towrie M Parker AW Hoskisson PA Tucker NP Hunt NT 《Physical chemistry chemical physics : PCCP》2012,14(20):7411-7419
The ultrafast equilibrium fluctuations of the Fe(III)-NO complex of a single point mutation of Myoglobin (H64Q) have been studied using Fourier Transform 2D-IR spectroscopy. Comparison with data from wild type Myoglobin (wt-Mb) shows the presence of two conformational substates of the mutant haem pocket where only one exists in the wild type form. One of the substates of the mutant exhibits an almost identical NO stretching frequency and spectral diffusion dynamics to wt-Mb while the other is distinctly different in both respects. The remarkably contrasting dynamics are largely attributable to interactions between the NO ligand and a nearby distal side chain which provides a basis for understanding the roles of these side chains in other ferric haem proteins. 相似文献
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Mattia Russo Kirsty E. McGhee Tersilla Virgili David G. Lidzey Giulio Cerullo Margherita Maiuri 《Molecules (Basel, Switzerland)》2022,27(20)
Molecular dyes are finding more and more applications in photonics and quantum technologies, such as polaritonic optical microcavities, organic quantum batteries and single-photon emitters for quantum sensing and metrology. For all these applications, it is of crucial importance to characterize the dephasing mechanisms. In this work we use two-dimensional electronic spectroscopy (2DES) to study the temperature dependent dephasing processes in the prototypical organic dye Lumogen-F orange. We model the 2DES maps using the Bloch equations for a two-level system and obtain a dephasing time T2 = 53 fs at room temperature, which increases to T2 = 94 fs at 86 K. Furthermore, spectral diffusion processes are observed and modeled by a combination of underdamped and overdamped Brownian oscillators. Our results provide useful design parameters for advanced optoelectronic and photonic devices incorporating dye molecules. 相似文献
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Adams CJ Anderson KM Baber RA Connelly NG Kandiah M Orpen AG 《Dalton transactions (Cambridge, England : 2003)》2004,(20):3353-3359
The nominally square-planar coordination of the d(8) complexes [MClL(1)L(2)(p-XC(6)H(4)NNNHC(6)H(4)X-p)](M = Rh, L(1)= L(2)= CO, X = H, Me, Et or F; M = Ir, L(1)= L(2)= CO, X = Me; M = Pd or Pt, L(1)= Cl, L(2)= PPh(3), X = Me; M = Pd, L(1)L(2)=eta(3)-C(3)H(5), X = Me), with the triazene N-bonded via the imine group, is supplemented by an axial M...H-N interaction involving the terminal amino group. 相似文献
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Adams CJ Anderson KM Connelly NG Harding DJ Orpen AG Patron E Rieger PH 《Chemical communications (Cambridge, England)》2002,(2):130-131
The d2/d3 redox pair [WF2(PhC identical to CPh)Tp']z [z = +1 or 0, Tp' = hydrotris(3,5-dimethylpyrazolyl)borate] is the missing link in a 'redox family tree' relating the d6 tricarbonyls [M(CO)3L]- to the d2 trihalides [MX3L] (M = Mo or W, L = Cp or Tp') by a series of stepwise reactions involving sequential one-electron oxidation followed by ligand substitution. 相似文献
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Kirsty G. Gaw Alexandra M. Z. Slawin Martin B. Smith 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract Whereas the number of functionalised tertiary phosphines, and to a lesser extent phosphites, has flourished in recent years, related systems bearing one (or more) P-N bonds are poorly developed. Here we describe a facile synthetic route to some new, potentially hemilabile, P,O-hybrids. These ligands are of particular interest for use in catalysis[1] and also as suitable precursors for further functionalisation. 相似文献
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Robert K. Henderson David D. MaCnicol Kirsty L. McCormack Stuart J. Rowan Dmitrii S. Yufit 《Supramolecular chemistry》2013,25(2):27-32
Abstract The title compound 1, prepared by reaction of decafluorobenzophenone 5 with PhSNa in DMEU, forms a 1:1 adduct with DMF; in this adduct the molecule's central V-shaped twin core possesses approximate C 2 symmetry, though this does not extend to the molecular periphery owing to the ababababab side-chain orientational distribution [a, above core benzene plane; b, below]. The adduct crystallizes in the monoclinic space group P2 1/c with a = 16.559(3), b = 23.233(5), c = 18.640(4), Å, β = 114.49(3)° and Dc = 1.363 gcm?3 for Z = 4. The refinement is based on 4621 observed reflections and gives a final R value of 0.069. 相似文献
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A reversed-phase HPLC method has been developed which enables separation of the three components of a closed-loop insulin delivery system, namely concanavalin A methacrylamide (Con A-MA), dextran methacrylate (Dex-MA) and bovine insulin. The analysis of Con A-MA represents a significant challenge due to the formation of multiple conformations on contact with the chromatographic surface and the mobile phase. The extent of conformational change is shown to be dependent on a number of parameters: column temperature, mobile phase pH, contact time with the chromatographic surface, salt type and concentration and the organic modifier. By manipulation of these variables, protein denaturation can be minimised and recovery improved. 相似文献
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Griffiths J. D.; Price-Lloyd N.; Smithies M.; Williams J. 《IMA Journal of Management Mathematics》2006,17(3):277-288
** Email: griffiths{at}cardiff.ac.uk Activities in an intensive care unit (ICU) at a major teachinghospital are modelled by means of a queue-theoretic approach.Using data supplied by the ICU relating to the admissions process,the bed availability and the length of stay of patients, itwas possible to fit theoretical distributions to the observedarrival and service distributions.Queueing equations relevant to a multi-channel system havingrandom arrivals and hyper-exponential service times for eachchannel are set up, and solved iteratively. Results obtainedmatch well with observations, and the model is then utilisedto investigate several what if? scenarios. Referenceis made to a simulation model developed in conjunction withthe queueing model. 相似文献