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61.
《Analytical letters》2012,45(3):669-681
Abstract The development of a novel on-line derivatisation scheme is described. the scheme involves use of a conducting polymeric material into which the derivatising agent is incorporated. the properties of the polymer enable electrochemical controlled release of the reagent into flowing solutions. 相似文献
62.
Yong Yang Su Zhi Ming Li Hong Bo Dong Guo Qing Zhou Li Hua Zhai Jiang Xu 《International journal of environmental analytical chemistry》2013,93(5):473-483
An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between 159?Tb and 174?Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of 159?Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10?mL?min?1 to 100?mL?min?1, the ratio of 159?Tb ion count to 174?Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of 159?Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG. 相似文献
63.
Isothermal vapor–liquid equilibrium (VLE) and excess enthalpy (HE) data were measured for binary systems required for the design of reactive distillation processes for the methyl acetate production. The isothermal P–x data were measured with the help of a computer-operated static apparatus. A commercial isothermal flow calorimeter was used for the determination of the heats of mixing. Temperature-dependent interaction parameters for the UNIQUAC model were fitted simultaneously to the experimental data from this work and other authors. 相似文献
64.
P. Guinebault C. Dubruc A. Haddouche C. Colafranceschi G. Bianchetti 《Chromatographia》1988,26(1):377-382
Summary In order to follow levels of S-Carboxymethyl-L-cysteine in biological fluids for a period as long as three half-lives after drug administration during pharmacokinetic studies, an improved method for its determination had to be developed. Like the previous one, this method uses a protein precipitation step followed by an O-Phthalaldehyde derivatization step and then an HPLC on-line clean-up. This latter was obtained by means of a switching valve system, including a Nucleosil CN 5 m (3 cm × 4.6 mm i.d.) precolumn and a Spherisorb ODS 5 m (15 cm×4.6 mm i.d.) analytical column. The sensitivity limit was improved to 0.1 g/ml in plasma samples and 0.2 g/ml in urine samples.This method was applied in studies comparing single (0.75 g) and repeated (0.75 g tid) oral administration of the drug to 30 elderly patients and 20 healthy volunteers. Results showed that the half-life was 40% longer in elderly patients than in healthy volunteers, and that area under the plasma concentration versus time curve (AUC) values in elderly patients were twice those obtained with young subjects. 相似文献
65.
Tellez MR Khan IA Schaneberg BT Crockett SL Rimando AM Kobaisy M 《Journal of chromatography. A》2004,1025(1):51-56
A new method involving concurrent solid-phase microextraction combined with continuous hydrodistillation of essential oil was developed. This new methodology allowed for the detection by GC-MS of very small amounts of a diagnostic peak for the authentication of Ephedra sinica, in a short period of time and using only small sample sizes. This diagnostic peak was identified as 4-vinylanisole, and elucidated from the chromatographic profile allowed for the identification of a sample as E. sinica among other species investigated in this study. To the best of our knowledge this is the first report on using continuous solid-phase microextraction coupled to hydrodistillation for the investigation of essential oil components, and the first report of 4-vinylanisole as a marker compound for E. sinica. A total of 46 collections representing 21 species of Ephedra were studied. 相似文献
66.
67.
P. Karvonen T. Sonoda I. D. Moore J. Billowes A. Jokinen T. Kessler H. Penttilä A. Popov B. Tordoff J. Äystö 《The European physical journal. Special topics》2007,150(1):283-284
The ion guide technique was developed in Jyv?skyl? during the early 1980's. In the ion guide the reaction recoil products
are stopped and thermalized in high purity helium gas where they remain ionic due to high ionization potential of helium atoms.
Different designs of ion guide exist for light-ion induced fusion reactions, for heavy-ion induced fusion and for proton induced
fission. Although the IGISOL method is fast and universal it is chemically unselective and in many cases relatively inefficient.
In order to address these deficiencies in the technique, a new laser ion source project, FURIOS (Fast Universal Resonant laser
Ion
Source), commenced in 2004. In addition, resonance ionization spectroscopy has been tested off – line within a sextupole ion
beam
guide. 相似文献
68.
69.
An integrated solid-phase spectrophotometry/flow injection analysis (FIA) method is proposed for the determination of the
synthetic colorant matter Ponceau 4R (P4R) in the presence of its unsulfonated derivative 2-hydroxy-1-[(naphthalenyl)azo]
naphthalene (N2N). The procedure is based on the measurement of P4R at λ = 508, followed by retention and preconcentration
of the low level concentration of N2N on a C18 silica gel minicolumn and subsequent measurement of the absorbance of N2N at λ = 508 nm after its elution. The applicable
concentration range, the detection and the relative standard were the following: for P4R, from 0.30 to 20.0 mg/L; 0.052 mg/L
1.1%; and for N2N, between 0.020 to 3.0 mg/L 0.003 mg/L and 1.1%. The method was applied to the determination of small amounts
of N2N present in P4R in food and cosmetic products. Percentages of recovery between 95 and 105% were obtained in all instances.
The method was applied satisfactorily to the determination of the compounds P4R and N2N in samples of sweets and cosmetic
products when compared to results offered by a HPLC reference method.
Received April 5, 2001. Revision July 25, 2001. 相似文献
70.
二氧化钛紫外光在线消解测定COD的研究 总被引:1,自引:0,他引:1
以TiO2-K2Cr2O7协同光催化氧化体系为基础,结合流动注射分析方法建立了一种快速测定水样中化学需氧量(COD)的简便方法.该方法测试速度快,不需有毒、昂贵的试剂,具有广阔的应用前景.COD含量在10~100mg·L^-1和100~1000mg·L^-1范围内,吸光度与COD含量均呈良好的线性关系;测定30mg·L^-1和300mg·L^-1的COD标准溶液,RSD≤5.1%(n=7);将本系统应用于实际环境水样测定,与国家标准分析方法测定结果相符. 相似文献