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111.
SDE-GC-ECD分析水体中有机氯农药 总被引:4,自引:0,他引:4
运用单滴溶剂萃取-气相色谱-微池电子捕获检测器(SDE—GC—μECD)联用技术对水体中有机氯农药进行了分析,优化了影响单滴溶剂萃取的多种因素。该方法除了对P,P′-DDD的线性范围在0.4~4ng/mL之间外,其余的七种目标物(α-666,β-666,γ-666,δ-666,P,P′-DDE,0,P′-DDT,P,P′-DDT)线性范围均在0.04~4.0ng/mL之间,相关系数为0.9976~0.9999,回收率范围为83.3%~96.1%,相对标准偏差为2.1%~7.8%。与传统的液液萃取相比,单滴溶剂萃取不仅准确度、精密度相当,而且还具有省时、省溶剂的优点。 相似文献
112.
M. Piñeiro-Iglesias M. Miñones-Vázquez E. Vázquez-Blanco S. Muniategui-Lorenzo P. López-Mahía D. Prada-Rodríguez 《Chromatographia》2002,56(7-8):483-488
Summary The aim of this work is to establish the best conditions for concentration and purification steps in the trace analysis of
aliphatic and polycyclic aromatic hydrocarbons (PAH) from atmospheric particulate matter by gas chromatography-flame ionisation
detection (GC-FID) and high performance liquid chromatography with ultraviolet and fluorescence detection (HPLC-UV-FL). The
best results for the more volatile compound were obtained with a combination of rotary evaporation and a stream of nitrogen
(near to 100% for aliphatic hydrocarbons and from 70 to 105% for PAH). Two types of solid phase extraction (SPE)cartridges
(Supelclean
tm
LC-Silica SPE tubes and Sep-Pak? Plus silica cartridges) and glass column were examined for the purification and fractionation step. Blank chromatograms of
both types of cartridges analysed by GC-FID made this study difficult, because a PSS (programmed split-splitless) injector
was employed thereby increasing the sensitivity. This problem was not observed in the HPLC-UV-FL blank chromatograms of these
cartridges. Glass columns filled with silica and alumina were chosen because no interference was found in the GC-FID blank
chromatograms and the best recoveries in the fractionation of both aliphatic hydrocarbons and PAH were achieved. This is especially
important when aliphatic hydrocarbons concentrations are lower than 1 μg mL−1. Finally, the selected conditions were applied to the analysis of hydrocarbons in real atmospheric particulate samples. 相似文献
113.
Summary This paper reports the qualitative and quantitative effects of the column pressure drop on the retention of lipid components in a serially coupled capillary column SFC system. The contribution of the pressure drop consists of two components, the density effect and the flow effect. The magnitude of the flow effect,i. e. the change in retention which results from changes in the flow-rate when column pressures are changed, is determined by the difference in single column analyte k values. The effect will be positive compared with the uncorrected retention values when the column with largest k value is closest to the injector. With the columns in reversed order, the effect will be negative. The contribution from the density effect always resulted in larger coupled column k values and was in most instances of more significance than the flow effect component. Values calculated with and without pressure drop correction have been compared and it has been shown that for most of the eighteen model lipid compounds investigated, the deviations from the experimental retention factors were smaller when pressure drop corrections were made. 相似文献
114.
115.
Summary A method for determining histamine in wine by precolumn derivatization with PITC (phenylisothiocyanate) with reversed-phase HPLC and UV detection is reported. Histamine can be determined together with the 24 amino acids within 40 min, or separately in a shorter time (less than 4 min) if a prior solid phase extraction clean-up is used. 相似文献
116.
Anna Rizzolo Patrizia Lombardi Maristella Vanoli Stefano Polesello 《Journal of separation science》1995,18(5):309-314
Capillary GC/sensory analysis was used to judge if dynamic headspace on sliced pulp and on intact fruit, and solvent extraction could collect the “character impact” and the “contributory” aroma compounds in peaches. Capillary GC/sensory data showed that the headspace techniques selectively recovered the “contributory” volatile compounds, which are strictly related to the characteristic odor of the various peach cultivars, whereas solvent extraction better quantified the “character impact” compounds (lactones). 相似文献
117.
118.
Summary The application of capillary SFC for SIMDIST investigations of paraffins and waxes is reported. Pressure, density and temperature of the mobile phase are optimized to obtain high chromatographic resolution of complex mixtures of industrial products. Isothermal linear pressure programming and asymptotic pressure and density programming are used in the range from 15 to 35 MPa in the isothermic mode above 100°C. SFC chromatograms of natural and synthetic paraffins, microcrystalline wax and candle wax are compared. The retention behaviour of paraffin mixtures and waxes has been investigated on methyl/phenyl and biphenyl capillary columns. The polarity of the stationary phases influences the absolute retention time more than it influences the chromatographic resolution. 相似文献
119.
催化裂化USY/ZnO/Al2O3脱硫添加剂的高温水热失活 总被引:3,自引:0,他引:3
对USY/ZnO/Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察,发现老化后添加剂的脱硫性能大幅度下降.采用XRD和IR等技术对USY/ZnO/Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究.结果表明,在高温下,ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石,从而造成USY晶体结构崩塌,转变成无定形状态.在ZnO含量较高的条件下,ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应,生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构.这一方面使添加剂失去了可形成硫化物吸附中心的ZnO,另一方面破坏了硫化物的裂化活性组分USY,从而造成添加剂脱硫性能下降甚至失去脱硫活性.ZnO对USY的破坏作用主要与温度有关.在USY/ZnO/Al2O3体系中,ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离,单纯的高温条件对添加剂的破坏不显著,而水蒸气可以促进ZnO的移动,有利于ZnO与USY的接触,因此在高温和有水蒸气存
在的条件下添加剂的结构易遭到破坏. 相似文献
120.
Ning Li Chunhui Deng Ning Yao Xizhong Shen Xiangmin Zhang 《Analytica chimica acta》2005,540(2):317-323
In the study, we developed a simple, rapid, sensitive, and inexpensive method for determination of the disease biomarkers of acetone, hexanal and heptanal in human blood. For the first time, derivatization of carbonyls with O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine (PFBHA) was combined with headspace single-drop microextractin (HS-SDME) and gas chromatography-mass spectrometry (GC–MS) and applied to the analysis of acetone, hexanal, and heptanal in human blood. At first, acetone, hexanal and heptanal in blood were derivatized with PFBHA and formed oximes in several seconds. Sequentially, the oximes were headspace extracted and concentrated by a microdrop solvent. Finally, the extracted oximes were analyzed by GC–MS. HS-SDME conditions and method validations were studied. Due to needing of only 2 μl organic solvent, short extraction time of 8 min, and simple operation, derivatization-HS-SDME was shown to be a rapid, simple, and inexpensive technique for analysis of acetone, hexanal, and heptanal in human blood. Moreover, it had low detection limit values from 0.24 to 0.62 nM, and good reproducibility (R.S.D. less than 12%). 相似文献