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131.
Henri Nouws Cristina Delerue-Matos José Lima E. Manuela Garrido Pieter Vincke Noel Maes 《International journal of environmental analytical chemistry》2013,93(2):69-76
The electrochemical behaviour of the herbicide Asulam was studied by cyclic and square wave voltammetry. Asulam may be irreversibly oxidised at a glassy carbon electrode. Maximum currents were obtained at pH = 1.9 in aqueous electrolyte solution. Based on the electrochemical behaviour of Asulam, two analytical methodologies were developed for its determination in water samples, using square wave voltammetry (SWV) and flow injection analysis (FIA) coupled with an amperometric detector. Limits of detection of 7.1 2 10 m 6 mol L m 1 and 1.2 2 10 m 8 mol L m 1 for SWV and FIA respectively, were achieved. Repeatability was calculated by assessing the relative standard deviation (%) for 10 consecutive determinations of one sample. The found values were 2.1% for SWV and 5.0% for FIA. Validation of the results provided by SWV and FIA methodologies was performed by comparison with results from an HPLC-DAD technique. Good relative deviations were found (< 5%). Recovery trials were performed to assess the accuracy of the results and the obtained values were between 84% and 107% for both methods. 相似文献
132.
Díez D Benéitez MT Marcos IS Garrido NM Basabe P Sanz F Broughton HB Urones JG 《Organic letters》2003,5(23):4361-4364
[reaction: see text] Several chiral building blocks have been obtained easily in large quantities from an epoxysulfone (9) that could be obtained in both enantiomeric forms from accessible starting materials. 相似文献
133.
Polubarinova-Kochina's analytical differential equation methodis used to determine the pseudo-steady-state solution to problemsinvolving the freezing (solidification) of wedges of liquidwhich are initially at their fusion temperature. In particular,we consider four distinct problems for wedges which are: freezingwith the same constant boundary temperature, freezing with thesame constant boundary heat fluxes, freezing with distinct constantboundary temperatures and freezing with distinct constant fluxesat the boundaries. For the last two problems, a Heun's differentialequation with an unknown singularity is derived, which in bothcases admits a particularly elegant simple solution for thespecial case when the wedge angle is . The moving boundariesobtained are shown pictorially. 相似文献
134.
Garrido Frenich A Martínez Galera M Gil García MD Martínez Vidal JL Muñoz de la Peña A Salinas F 《Talanta》1998,46(6):1329-1340
Multi-wavelength detectors offer improved detection capabilities for liquid chromatographic methods, but require multivariate approaches to utilise all the available information. The photodiode-array detector in high-performance liquid chromatography (HPLC) generates a three-dimensional data matrix, which is conventionally presented as an isometric projection or a contour plot. In this work, a new graphical technique is described for improving the quantitative results obtained from HPLC, using the available spectrochromatographic information in both the time and wavelength domains. The technique consists of performing cross-sections through the data matrix to obtain the maximum analytical information for each of the analytes. Hence, the resolution of overlapping peaks and the sensitivity in the determination are optimised. In order to demonstrate the validity and simplicity of the approach, the method has been applied to the resolution of synthetic mixtures of iprodione, procymidone and chlorothalonil. Also, the method has been satisfactorily applied to the simultaneous determination of the pesticides in environmental groundwater samples. 相似文献
135.
Alves GA Amato S Anjos JC Appel JA Astorga J Bernard T Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Gay C Green DR Jedicke R Karchin PE Kwan S Lueking LJ de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1994,72(6):812-815
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A 13 amino acid sequence, CRVARGDWNDNYC, originated from disintegrin eristostatin, was introduced into an inactive human proinsulin
molecule between the B29 and A2 sites to replace proinsulin C-peptide by molecular cloning techniques. The constructed Arg-Gly-Asp
(RGD)-proinsulin gene was cloned into a temperature-inducible vector pBV220 and expressed in Escherichia coli. The expressed RGD-proinsulin was refolded and purified by Sephadex G50 and DEAE-Sephadex A25 separations. The chemical identity
was confirmed by both amino acid composition and mass spectrometry analyses. This RGD-proinsulin showed an inhibitory activity
of adenosine 5′-diphosphate-induced human platelet aggregation with an IC50 value of 200 nM. Its insulin receptor binding activity remained as low as 0.03% with native insulin as a control, and its insulin immune
activity retained 27.6% compared with proinsulin. 相似文献
140.
A procedure is reported for the kinetic determination of iodate/periodate mixtures based on the reduction of these anions by the iron(II)/dipyridylglyoxal dithiosemicarbazone complex in an acidic medium. The reaction is monitored spectrophotometrically at 410 nm (absorption maximum of the iron(III) complex formed). Mixtures of these anions at μg ml?1 levels for iodate/periodate ratios from 5:1 to 1:4 can be determined with a r.s.d, of ca. 3%. Molybdate is used to mask periodate to allow iodate to be determined alone. The sum of both anions is obtained in the absence of molybdate. Chromate, hypochlorite and hexacyanoferrate(III) interfere seriously. 相似文献