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161.
采用气相色谱法,建立了同时检测食品工业用大孔吸附树脂中的苯、1,2-二氯乙烷、甲苯、邻二甲苯、间二甲苯、对二甲苯、氯苯、苯乙烯、二乙烯苯、丙烯腈、甲基丙烯酸甲酯等11种有机残留物的方法。色谱柱为DB-WAX毛细柱,检测器为氢火焰离子化检测器,该方法的专属性强,在所考察的浓度范围内线性相关系数均在0.99以上,最低检出限为0.002~0.008μg/mL,样品加标回收率为72.4~104.7%,稳定性、精密度和重现性的RSD分别为1.68~5.26%、1.57~6.83%、2.91~9.62%。本方法具有简便易行、准确、稳定、快速等特点。 相似文献
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Bernd Schröder Luís M.N.B.F. Santos Isabel M. Marrucho João A.P. Coutinho 《Fluid Phase Equilibria》2010
The methodology for the prediction of aqueous solubilities of solid organic compounds, and their temperature dependence, based on the Conductor-like Screening Model for Real Solvents (COSMO-RS/COSMOtherm) procedure, is presented and evaluated. The predictive capability of the quantum chemistry based program and the applied methodology was tested on the most common solid carboxylic acids. From the temperature dependence of the solubilities, the mean apparent enthalpies of solution were derived. The results obtained for a set of 27 carboxylic acids, consisting of aromatic carboxylic acids, dicarboxylic acids, as well as hydroxycarboxylic acids, are in good agreement with the experimental solubility data and their dependence with the temperature. The mean apparent enthalpies of solution, although of the same order of magnitude of the experimentally values, seem to be systematically underestimated. 相似文献
164.
The solubilities of three cinnamic acid esters, namely, methyl ferulate, methyl p-coumarate, and methyl sinapate, have been measured in mixed solvent systems of tert-butanol with 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM][PF6]), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF4]) and 1-methyl-3-octyl-imidazolium tetrafluoroborate ([OMIM][BF4]) at 303.15 and 321.15 K, and in mixed solvent systems of ethyl acetate with [BMIM][BF4] and [OMIM][BF4] at 303.15 K. In eight cases, out of the 22 data sets, an additive behaviour of the solubility was observed, positive deviations from additivity were observed in six cases, a positive synergistic effect in five cases, and, finally, negative deviations from additivity in the remaining three cases. Prediction of the solubilities of the solutes in the various ternary systems was performed with the NRTL and UNIQUAC activity coefficient models. The binary interaction parameters of the models between solute and solvent molecules were taken from the literature. When the parameters between the solvent molecules are fitted to literature data, satisfactory predictions are not always obtained. On the other hand, very good predictions are obtained when only one of the two interaction parameters between the two solvent molecules is fitted to one single point of the solubility isotherm and the other interaction parameter is set equal to zero. 相似文献
165.
Mark E. Erupe Allegra Liberman-Martin Philip J. Silva Quentin G.J. Malloy Naomi Yonis David R. Cocker III Kathleen L. Purvis-Roberts 《Journal of chromatography. A》2010,1217(13):2070-2073
An ion chromatography method with non-suppressed conductivity detection was developed for the simultaneous determination of methylamines (methylamine, dimethylamine, trimethylamine) and trimethylamine-N-oxide in particulate matter air samples. The analytes were well separated by means of cation-exchange chromatography using a 3 mM nitric acid/3.5% acetonitrile (v/v) eluent solution and a Metrosep C 2 250 (250 mm × 4 mm i.d.) separation column. The effects of the different chromatographic parameters on the separation were also investigated. Detection limits of methylamine, dimethylamine, trimethylamine, and trimethylamine-N-oxide were 43, 46, 76 and 72 μg/L, respectively. The relative standard deviations of the retention times were between 0.42% and 1.14% while the recoveries were between 78.8% and 88.3%. The method is suitable for determining if methylamines and trimethylamine-N-oxide are a significant component of organic nitrogen aerosol in areas with high concentration of these species. 相似文献
166.
In this paper, two novel kinds of organic–inorganic monomer, SUA-APEMS and SUA-APS, have been achieved by modifying 5-sulfosalicylic acid (SUA) with 3-aminopropyl-methyl-diethoxylsilane (APEMS) and 3-aminopropyl trimethoxysilane (APS). These two organic–inorganic monomers were used as multi-functional bridged components, which can coordinate to metal ions (Tb3+/Eu3+/Zn2+) with carbonyl groups, strongly absorb ultraviolet and effectively transfer energy to metal ions through their triplet excited state, as well as involve in the sol–gel process with inorganic host precursor tetraethoxysilane (TEOS), resulting two series of molecular hybrid materials (named as SUA-APEMS/APS-RE) with double chemical bond (RE(Zn)–O coordination bond and Si–O covalent bond). The effective intra-molecular energy transfer process gives rise to the characteristic emission of metal ions and the chemical bond make the hybrid materials owning better properties. 相似文献
167.
Vesna Vasić Katarina Krinulović Danijela Krstić Tatjana Momić Anica Horvat 《Monatshefte für Chemie / Chemical Monthly》2004,135(5):605-614
Summary. The possibility of using synaptic plasma membrane (SPM) enzymes Na+/K+-ATPase and Mg2+-ATPase, isolated from rat brain, as a biological component of multi-response sensing system for detection of different compounds (alkaline and heavy metal salts, organic compounds) was studied. The method is based on the spectrophotometric determination of inorganic ortho-phosphate (Pi) that serves as a measure of the enzymatic activity in the presence of various analytes. The concentration of Pi, liberated by enzyme catalysed hydrolysis of adenosinetriphosphate (ATP), was followed spectrophotometrically, by single exposure to analytes or in the mixture. Pi was dose dependent on the analyte concentration. Alkaline elements (Na, K, Mg), heavy metals (Pb, Cd, Hg, Cu, Fe, Co, Zn), toxic organic compounds (pyridine, urea, chlorpyrifos), and some drugs (digoxin, gitoxin) showed diverse effects, inducing the inhibition or stimulation of the enzymes activity. Development of simple test method for simultaneous detection of the investigated analytes based on the variation of medium assay composition was discussed. 相似文献
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170.
《Electroanalysis》2004,16(22):1837-1842
Electronic sensor technology remains of widespread and intense interest. There are compelling needs to detect chemical species ranging from small molecules dispersed in the gas phase to complex biopolymers in aqueous solution. This review describes some recent advances in three main areas: chemically sensitive resistors (chemiresistors, CRs) including inorganic and organic based devices, field effect transistors (FETs) with semiconducting layers and/or gates with chemical sensitivity, and sensors based on the differential conductivity of nanotubes and nanowires. Results reported in the last two to three years are emphasized, highlighting some current trends in the development of sensors for applications such as diagnostics, process monitoring, and security. 相似文献