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91.
92.
On-line sample-pre-treatment schemes for trace-level determinations of metals by coupling flow injection or sequential injection with ICP-MS 总被引:1,自引:0,他引:1
Within the last decade, the first generation of flow injection (FI) has been supplemented by sequential injection (SI), also termed the second generation, and, recently, by the third generation, i.e., SI-Lab-on-Valve (SI-LOV). As apparent from the literature, FI and/or SI have become dominant as substitutes for labor-intensive, manual, sample-pre-treatment and/or solution-handling procedures prior to analyte detection by inductively coupled plasma mass spectrometry (ICP-MS). The present review presents and discusses the progress of the state of the art in implementing miniaturized FI/SI systems for on-line matrix separation and pre-concentration of trace levels of metals with detection by ICP-MS. It highlights some of the frequently applied on-line, sample-pre-treatment schemes, including solid phase extraction (SPE), on-wall molecular sorption and precipitate/(co)-precipitate retention using a polytetrafluoroethylene (PTFE) knotted reactor (KR), solvent extraction-back extraction and hydride/vapor generation. It also addresses a novel, robust approach, whereby the protocol of SI-LOV-bead injection (BI) on-line separation and pre-concentration of ultra-trace levels of metals by a renewable microcolumn is interfaced to ICP-MS, as conducted in the present authors' group. It discusses the future outlook in this field. 相似文献
93.
研究了利用电感耦合等离子体质谱仪测定无尘产品中的痕量杂质元素氯含量的方法,检测下限0.06 ng/mL,精密度RSD<5%(n=7),回收率93.7%~110.0%。 相似文献
94.
Joanna Gajewiak 《Tetrahedron letters》2006,47(43):7607-7609
Lysophosphatidic acid (LPA) and phosphatidic acid (PA) are potent bioactive lipid mediators of signal transduction and are inactivated by phosphatases. To obtain receptor-isoform selective ligands with neutral phosphomimetic head groups, we performed the stereoselective synthesis of LPA and PA analogues with trifluoromethanesulfonamide and trifluoromethanesulfonamidoxy moieties replacing the phosphomonoester. 相似文献
95.
A microwave-assisted digestion procedure using HNO3, HF, and H2O2 has been developed for analysis of elements in ambient particulate matter (PM). The samples are collected on cellulose filters and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS is calibrated with external standards, and recovery of analytes is tested with NIST SRM 1648 Urban Dust. This method has been used to quantify the airborne concentrations of a large number of elements, including Ag, As, Ba, Be, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Se, Sb, Sr, Ti, Tl, V, and Zn. For the majority of these elements, recovery of the NIST SRM is within 15% of the certified values. 相似文献
96.
马晓国 《广东微量元素科学》1998,5(12):57-58
用电感耦合等离子体原子发射光谱法(ICP-AES0测定了玩具材料中的痕量砷,硒和锑。方法简便快速,回收率为97.5%-102.7%,相对标准偏差小于3%。 相似文献
97.
本文利用电感耦合等离子体原子发射光谱(ICP-AES)多色仪的扫描功能,用C语言编制了Kalman滤波程度软件包,用该软件包对铁基体中26种痕量元素进行了回收率试验,并对标准碳素钢样中13种痕量元素进行了测定,结果表明Kalman滤波完全适用于复杂谱线基体中的多种元素同时分析。 相似文献
98.
Pyrolysis study of fluorinated sol-gel silica 总被引:1,自引:0,他引:1
Fluorinated silica gels at various fluorine content were prepared via sol-gel by hydrolysis of 3,3,3-trifluoropropyltrimethoxysilane
and tetraethoxysilane mixtures. The gels, of nominal stoichiometry Si(CH2CH2CF3)XO(2-X/2)(X=0.1-1), were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS) and N2 adsorption analysis. The thermal stability of the fluorinated samples was investigated by coupling thermogravimetric measurements
with mass spectrometric and gas chromatographic analyses of the evolved gaseous species. The chemical reactions occurring
in the gel matrices during heating were siloxane chain rearrangements involving condensation between residual hydroxyl and
ethoxyl groups in the 100-350°C temperature range, whereas the thermal decomposition of the fluoroalkyl groups were observed
at higher temperatures (450-600°C). The release of the fluoroalkyl moieties also involved C-F/Si-O bond exchanges inside the
siloxane chains, with gas-phase evolution of different fluorinated silicon units.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
99.
《Arabian Journal of Chemistry》2022,15(11):104302
Traditional Chinese medicine (TCM) is the key to unlock treasures of Chinese civilization. TCM and its compound play a beneficial role in medical activities to cure diseases, especially in major public health events such as novel coronavirus epidemics across the globe. The chemical composition in Chinese medicine formula is complex and diverse, but their effective substances resemble “mystery boxes”. Revealing their active ingredients and their mechanisms of action has become focal point and difficulty of research for herbalists. Although the existing research methods are numerous and constantly updated iteratively, there is remain a lack of prospective reviews. Hence, this paper provides a comprehensive account of existing new approaches and technologies based on previous studies with an in vitro to in vivo perspective. In addition, the bottlenecks of studies on Chinese medicine formula effective substances are also revealed. Especially, we look ahead to new perspectives, technologies and applications for its future development. This work reviews based on new perspectives to open horizons for the future research. Consequently, herbal compounding pharmaceutical substances study should carry on the essence of TCM while pursuing innovations in the field. 相似文献
100.
The use of hydride generation coupled with axial view inductively couple plasma atomic emission spectrometry was presented for the determination of selenium in plant samples. The chemical factors affecting potentially the hydride generation efficiency (hydrochloric acid, sodium borohydride and sodium hydroxide concentrations) were assessed through investigation of chemical interference, accuracy and repeatability. The accuracy of measurements was not affected by elements present in high concentration in the plant matrix (K, Ca, Mg, and P). No interference was also observed with transition metals. Using a real sample (maize) with standard additions, decreases of recoveries were sometimes observed for 0.1% (m/v) NaOH, and attained 13.8% in the most unfavourable case. The final accuracy of the method was verified by using two certified reference materials: CRM 402 (white clover) and CRM 279 (sea lettuce). No statistically significant differences were obtained between the measured concentrations and the certified values. The optimized method was found sensitive (detection limit 0.15 μg l−1), reliable and repeatable (R.S.D. between 1.3% and 4.0%). 相似文献