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81.
Summary Four different techniques to quantify unresolved chromatographic peaks with known spectral features combined with photodiode array detection, are investigated as regards their efficiency for the accurate and precise determination of drugs in the low g-range. The comparison includes peak suppression utilising difference chromatograms, first-order derivative chromatograms, selective chromatograms, generated by the calculation of orthogonal polynomial shares, and the powerful least-squares multicomponent analysis approach. Each of these methods uses UV-spectra taken throughout, the peak. The results presented and conclusions reached should enable the chromatographer to come to a decision about the reasonable use of these options now provided by multichannel detection in HPLC. 相似文献
82.
83.
Badol C Borbon A Locoge N Léonardis T Galloo JC 《Analytical and bioanalytical chemistry》2004,378(7):1815-1827
An automated system for the monitoring of volatile organic compound (VOC) ozone precursors in ambient air is described. The measuring technique consists of subambient preconcentration on a cooled trap followed by thermal desorption and GC/FID analysis. First, the technical development, which permits detection limits below 0.05 ppbv to be reached, proceeded in two steps: (1) the determination of optimum sampling parameters (trap composition and conditioning, outlet split, desorption temperature); (2) the development of a reliable calibration method based on a highly accurate standard. Then, a 4-year field application of the hourly measuring chain was carried out at two urban sites. On the one hand, quality control procedures provided the best VOC identification (peak assignment) and quantification (reproducibility, blank system control). On the other hand, the success and performances of the routine experience (88% of the measurements covered more than 40 target compounds) indicated the high quality and suitability of the instrumentation which is actually applied in several French air quality monitoring networks. Finally, an example of data analysis is presented. Data handling identified important organic compound sources other than vehicle exhaust. 相似文献
84.
本文介绍了栀子油脂中脂肪酸的气相色谱-质谱-计算机联用分析方法。栀子油脂中脂肪酸组成较为简单,主要以软脂酸(38.0%)和亚油酸(53.4%)为主,营养价值高,具有开发利用的价值。 相似文献
85.
86.
Omar El Tall Nicole Jaffrezic‐Renault Monique Sigaud Olivier Vittori 《Electroanalysis》2007,19(11):1152-1159
Boron‐doped Diamond (BDD) electrode has become one of the important tools for heavy metal detection. By studying some analytical parameters of DPASV method, like deposition time and potential in different electrolyte concentrations (acetate buffer), the conditions for detecting very low metal ion levels (Zn, Cd, Pb, and Cu) could be chosen. Diluted electrolyte (0.01 M buffer) was one of the factors favoring low detection and quantification limits, but its quantification range is short in comparison to more concentrated media. For ?1.7 V deposition potential, the detection of single metal at ppb levels was reached in 60 s deposition time. Understanding different metal‐metal interactions shows the limits to the simultaneous determination of heavy metals at BDD. Quantification was possible for the simultaneous determination of Zn, Cd and Pb despite the overlapping of Zn and Cd peaks. The performance of the BDD was compared with that of another C‐based solid electrode: the glassy carbon electrode (without mercury plating). A lower base line current, wider potential range, higher sensitivity (3 to 5 times higher than GC) and longevity of the material were noticed for the BDD. 相似文献
87.
K. H. C. Baser H. R. Nuriddinov T. Ozek B. Demirci N. Azcan A. M. Nigmatullaev 《Chemistry of Natural Compounds》2002,38(1):51-53
The herbal parts of Arischrada korolkowii (Regel et Schmalh.) Pobed. (Lamiaceae) growing in Uzbekistan were hydrodistillated to yield 1.1% of essential oil. The essential oil was analyzed by GC/MS. Eighty eight compounds were characterized representing 98% of the essential oil with 1,8-cineole (29.3%), camphor (9.8%), -caryophyllene (8.5%), bornyl acetate (7.7%), caryophyllene oxide (7.2%), and borneol (5.6%) as the main constituents. 相似文献
88.
89.
Summary To match the need of high efficiency capillary column (plate number N2, Plate height H2 and carrier gas linear velocity U2), a new high efficiency packed column (N1, H1 and U1) at high carrier gas velocity with small capacity factor has been developed in the light of theoretical discussion of factors
effecting the column efficiency utilization ratio. 相似文献
90.
研究开发的一种新型的元素光度检测器主要用于锗、砷、锡和锑的氢化物气相色谱检测,具有高灵敏,高选择性。它是在普通火焰光度检测器的基础上加装了特制的滤光片改制而成的。对锗、砷、锡和锑的检测限分别为3.0×10 ̄(-11)g、7.0×10 ̄(-11)g、7.0×10 ̄(-10)g和1.1×10 ̄(-8)g,相对标准偏差分别为1.8%、2.4%、2.6%和3.0%。 相似文献