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101.
102.
顺序注射在线稀释微量进样技术及其在自动光度法测定水中亚硝酸盐的应用 总被引:1,自引:0,他引:1
以测定环境水样中的亚硝酸盐为例,采用顺序注射技术,提出了一种智能化在线微量进样稀释分析系统(SIA系统).将测定过程中分光光度计输出的模拟电压信号,反馈至顺序注射仪,判断是否需要稀释.当获得的电压信号值小于305 mV(约相当于吸光度值0.8)时,SIA系统进入稀释程序,否则,则进入直接测定程序,两种程序均自动完成.直接测定和稀释测定的线性范围分别为1~50μmol·L-1和50~500μmol·L-1NO2-.分别在NO2-浓度水平为10,200μmol·L-1时作精密度试验,测得相对标准偏差(n=11)依次为0.7%和1.0%.该分析系统特别适合于自动分析过程中被测物质浓度变化较大而需要在线稀释的情况. 相似文献
103.
A chemically modified electrode was successfully fabricated by means of depositing a thin layer of nickel hexacyanoferrate (NiHCF) on an amine adsorbed graphite paraffin wax composite electrode using a new approach. The electrode was further coated with Nafion. The electrochemical characteristics of the modified electrode were studied using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The modified electrode catalyzed dopamine (DA) oxidation in the concentration range of 1.5×10?6 to 1.2×10?3 M without the interference from ascorbic acid (AA). A detection limit of 4.9×10?7 M was obtained for DA in the presence of AA with a correlation coefficient of 0.9972 based on S/N=3. Flow injection analysis was used for the determination of dopamine with excellent reproducible results. The analytical utility of the sensor was evaluated for detection of DA in urine. 相似文献
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《应用有机金属化学》2017,31(11)
A new, simple and cheap dispersive liquid–liquid microextraction (DLLME) procedure was optimized for the preconcentration of trace amounts of Ni(II) as a prior step to its determination by flame atomic absorption spectrometry (FAAS). It is based on the microextraction of nickel, where appropriate amounts of the extraction solvent (CHCl3), disperser solvent (ethanol) and chelating agent, name 5‐[(Z)‐isoxazol‐3‐yl‐diazenyl]‐2‐methyl‐quinolin‐8‐ol (MMD), were firstly synthesized/characterized and used. Various parameters that affect the extraction procedure such as pH, centrifugation rate and time, the chelating agent (MMD) concentration and sampling volume on the recovery of Ni(II) were investigated. The preconcentration of a 20 ml sample solution was thus enhanced by a factor of 80. The resulting calibration graph was linear in the range of 0.24–10 mg L−1 with a correlation coefficient of 0.9998. The limit of detection (3 s/b) obtained under optimal conditions was 1.00 μg L−1. The relative standard deviation for certified reference material determinations was 1.2%. The accuracy of the method was verified by the determination of Ni(II) in the certified reference material of wastewater (Waste water CWW TMD). The proposed procedure was successfully applied to the determination of Ni(II) in some fake jewelry and cosmetics samples. 相似文献
108.
《Biomedical chromatography : BMC》2017,31(10)
Propafenone is a potent antiarrhythmic agent; clinically propafenone has been used for a number of cardiac arrhythmias because it possesses multiple modes of action, via beta adrenergic receptor blockade and calcium antagonistic activity. Propafenone (PPF) exhibits extensive saturable presystemic biotransformation (first‐pass effect) resulting in two active metabolites: 5‐hydroxypropafenone (5‐OH PPF) formed by CYP2D6 and N‐ depropylpropafenone (NDP) formed by both CYP3A4 and CYP1A2 enzymes. A specific and sensitive LC–MS/MS method was developed and validated for quantitation of PPF, 5‐OH PPF and NDP using turboion spray in a positive ion mode. A solid‐phase extraction was employed for the extraction from human plasma. Chromatographic separation of analytes was achieved using an ACE‐5 C8 (50 × 4.6 mm) column with a gradient mobile phase comprising ammonium acetate containing 0.01% TFA in purified water and acetonitrile. The retention times achieved were 1.36, 1.23, 1.24 min and 1.34 min for PPF, 5‐OH PPF, NDP and IS (carbamazepine), respectively. Quantitation was performed by monitoring multiple reaction monitoring transition pairs of m /z 342.30 to m /z 116.20, m /z 358.30 to m /z 116.20, m /z 300.30 to m /z 74.20 and m /z 237.20 to m /z 194.10, respectively. The developed method was validated for various parameters. The calibration curves of PPF and 5‐OH PPF showed linearity from 1 to 500 ng/mL, with a lower limit of quantitation of 1.0 ng/mL and for NDP linearity from 0.1 to 25 ng/mL with a lower limit of quantitation of 0.1 ng/mL. The bias and precision for intra‐ and‐inter batch assays were <10 and 5%, respectively. The developed assay was used to evaluate pharmacokinetic properties of propafenone and its major metabolites in healthy human subjects. 相似文献
109.
Naumih M. Noah Omole Marcells Anas Almalleti Jae Lim Omowunmi A. Sadik 《Electroanalysis》2011,23(10):2392-2399
Pain measurement is commonly required in biomedical and other emergency situations, yet there has been no pain biosensor reported in literature. Conventional approaches for pain measurement relies on Wong‐Baker face diagrams, which are grossly inadequate for situations involving children or unconscious people. We report a label‐free immunosensor for monitoring the pain biomarker cylooxygenase‐2 (COX‐2) in blood. The sensor is based on the concept of metal‐enhanced detection (MED). MED relies on the idea that the immobilization of underpotential deposition (upd) metallic films deposited either as a monolayer or electrostatically held onto a solid gold substrate could significantly amplify bimolecular recognition such as involving antigen‐antibody (Ab‐Ag) interactions. The surface bound Ab‐Ag complex insulates the electrode; causing a decrease in concentration‐dependent redox signals. A linear detection range of (3.64–3640.00)×10?4 ng/mL was recorded with a detection limit of 0.25×10?4 ng/mL, which was 4 orders of magnitude lower than that reported for ELISA for the same biomarker. The immunosensor exhibited selectivity of less than 6 % for potential interferents. 相似文献
110.
The paper covers the main principles of setting up and the function of the Russian system of metrological assurance of analytical
measurements for the production of light alloys and superalloys.
Received: 20 October 1998 / Accepted: 9 November 1998 相似文献