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91.
The determination of chlorine with o-tolidine in greywater has been studied, and a batch method and a sequential injection method have been proposed. It was found that the reaction of o-tolidine with chlorine was slower in a greywater matrix. Grey water samples must be filtered before analysis, or alternatively, a blank of sample must be measured. The samples are very unstable, and after 2 h of storage in dark conditions at 4 degrees C the chlorine concentration can diminish. The standard addition method, in some samples gave unsatisfactory results as a consequence of matrix effects. It was concluded that samples with a total organic carbon (TOC) higher than 60 mgCl(-1) can not be accurately analysed using these methods. However, samples with a TOC lower than 60 mgCl(-1) gave 100+/-3% recoveries. The linear range of the methods was 0-3.0 and 0-5.0 mgCl(2)l(-1), and the limit of quantification 0.2 and 0.5 mgCl(2)l(-1), for the batch method and the sequential injection method, respectively. This is the first paper devoted to grey water from the analytical chemistry point of view. 相似文献
92.
M. A. G. Calderon F. Simonet 《International Journal of Infrared and Millimeter Waves》1985,6(7):605-628
The feasibility of a swept microwave reflectometer, with one antenna only, for plasma electron density measurement is studied. Experimental results obtained in the laboratory by simulating the plasma with a metallic mirror are presented.Permanent address Departamento de Electromagnetismo Facultat de Ciencas-Universitad de Santander Avda los Castros s/n Santander-Spain 相似文献
93.
Macías FA Varela RM Simonet AM Cutler HG Cutler SJ Dugan FM Hill RA 《The Journal of organic chemistry》2000,65(26):9039-9046
The structures of four new, naturally occurring bioactive spiroditerpenoids, (+)-breviones B, C, D, and E, potential allelopathic agents, have been determined from extracts of semisolid fermented Penicillium brevicompactum Dierckx. The structures display the novel breviane spiroditerpenoid skeleton. Structure elucidation was performed by chemical transformations and by homo- and heteronuclear 2D-NMR spectral data. On the basis of combined studies of the theoretical conformations and NOEDIFF data, their relative stereochemistry is proposed. A mixed biogenesis for this novel family of spiroditerpenoids is tendered. The levels of activity shown by breviones B, C, and E in the etiolated wheat coleoptiles bioassay, especially breviones E (100% inhibition) and C (80% inhibition) both at 10(-4) M, suggest them as lead compounds for new agrochemicals. 相似文献
94.
95.
This work describes an efficient in-line extraction-preconcentration unit coupled to the electrophoretic capillary based on a liquid-phase microextraction (LPME) process, which can be directly assembled to the cartridge of the commercial CE equipment. The unit permits analyte extraction, preconcentration and electrophoretic separation to be automatically performed in the commercial CE equipment without the need for additional hardware or software. This new approach was usefully used for the separation and determination of nonsteroidal anti-inflammatory drugs in human urine permitting at least to analyze 30 consecutive real samples. The LODs were lower than 2 microg/L and the reproducibility, expressed as RSD, was 3.1% for the same unit and only 4.8% between different units. 相似文献
96.
Macías FA Guerra JO Simonet AM Nogueiras CM 《Magnetic resonance in chemistry : MRC》2007,45(7):615-620
A careful NMR analysis, especially 1D TOCSY and 1D ROESY, of two refined saponin fractions allowed us to determine the structures of four new saponins from a polar extract of the Agave brittoniana Trel. spp. Brachypus leaves. A full assignment of the 1H and 13C spectral data for these new saponins, agabrittonosides A-D (1-4), and one previously known saponin, karatavioside A (5) is reported. Their structures were established using a combination of 1D and 2D (1H, 1H-COSY, TOCSY, ROESY, g-HSQC, g-HMBC and g-HSQC-TOCSY) NMR techniques and ESI-MS. Moreover, the work represents a new approach to structural elucidation of saponins in refined fractions by NMR investigations. 相似文献
97.
Maël Nicolas Bruno Fabre Jean-Franois Pilard Jacques Simonet 《Journal of heterocyclic chemistry》1999,36(4):1105-1106
The synthesis of 3-vinylthiophene was efficiently achieved in two steps. 3-(2-bromoethyl)thiophene prepared from 3-(2-ethanol)thiophene was converted to the title compound (70% overall yield) using tetraglyme as a solvent and 1,8-diazabicyclo[5.4.0]undec-7-ene as a base. 相似文献
98.
99.
RE Tribble A Azhari HL Clark CA Gagliardi Y-W Lui AM Mukhamedzhanov A Sattaroy X Tang L Trache V Burjan J Cejpek V Kroha S Piskor J Vincour F Carstoiu 《Pramana》1999,53(3):585-594
S-factors for direct capture reactions can be found at astrophysical energies from asymptotic normalization coefficients which
provide the normalization of the tail of the overlap function. For example the overlap for 8B → 7Be+p defines the S-factor for 7Be (p, γ)8B. Peripheral transfer reactions offer a technique to determine these asymptotic normalization coefficients. As a test of
the technique, the 16O(3He, d)17F reaction has been used to determine asymptotic normalization coefficients for transitions to the ground and first excited
states of 17F. The S-factors for 16O(p, γ)17F calculated from these 17F → 16O+p asymptotic normalization coefficients are found to be in very good agreement with recent measurements. Following the same
technique, the 10B(7Be, 8B)9Be and 14N(7Be, 8B)13C reactions have been used to measure the asymptotic normalization coefficient for 7Be(p, γ)8B. This result provides an indirect determination of S
17(0). 相似文献
100.
AM Cardoso SM Alexandre CM Barros AJ Correia NM Nibbering 《Rapid communications in mass spectrometry : RCM》1999,13(19):1885-1888
The collision-induced dissociation (CID) of deprotonated arylalkylamines of general formula R(1)C(6)H(4)CHR(2)CH(2)NR(3)(2) (where R(1) = H, OH, F or NO(2); R(2) = H or OH; R(3) = H or CH(3)) generated by negative chemical ionization with H(2)O and D(2)O as ionizing reagents, is discussed. The negative chemical ionization mass spectra show that, in the absence of a hydroxy group in the aromatic ring, deprotonation takes place at the benzylic position whereas the proton is lost from the OH group when present. The nitro compound forms only M(-.) ions. The CID spectra of the deprotonated molecules show that fragmentations are strongly dependent on the structural features of the molecules, namely the presence or absence of substituents in the aromatic ring or aliphatic chain. Copyright 1999 John Wiley & Sons, Ltd. 相似文献