质子转移反应质谱用于痕量挥发性有机化合物的在线分析

质子转移反应质谱(PTR-MS)是一种化学电离源质谱技术,专门用于痕量挥发性有机化合物(VOCs)实时在线检测.此技术利用H3O-作化学电离源试剂离子与作为质子接受体的VOCs发生质子转移反应.大气中的O2,N1,CO2等主要成分由于其质子亲和势低于H2O,而不与H3O发生质子转移反应,因此可在大气环境下检测痕量VOC...     

流动注射化学发光发测定葡萄糖

β-D-葡萄糖的检测是临床化学的常规分析项目 .化学发光分析法测定葡萄糖具有线性范围宽、灵敏度高等优点[1～ 3] .我们曾研究了鲁米诺 ( L uminol) -KIO4 -H2 O2 化学发光反应体系[4 ] ,发现 H2 O2 浓度在 2 .0× 1 0 - 7～ 6.0× 1 0 - 4mol/L范围内与发光强度有良好的线性关系 .本文将生成 H2 O2 的葡萄糖 -葡萄糖氧化酶 ( GOD)的酶促反应与鲁米诺 -KIO4 -H2 O2 的化学发光反应相偶合 ,结合流动注射技术 ,建立了一种流动注射化学发光测定葡萄糖的新方法 .方法的线性范围为 0 .6～ 1 1 0 mg/L ,相关系数为 0 .9997,检出限为 0 .0…     

血红蛋白作为过氧化物模拟酶催化测定过氧化氢

研究了牛血红蛋白 (Hemoglobin ,Hb)作为过氧化物模拟酶催化H2 O2 氧化隐性亮绿 (RecessiveBrilliantGreen ,RBG)显色反应的催化特性及反应条件。该体系在pH 5 .73的条件下形成的酶催化产物在 640nm处有最大吸收。体系测定H2 O2 时表观摩尔吸光系数为 7.1 5× 1 0 3L·mol-1·cm-1,测定H2 O2 检测限为 2 .8× 1 0 -6mol L。方法可用于天然水中H2 O2 的测定。     

四羧基铁酞菁催化氧化邻苯二胺测定H2O2

研究了四羧基铁酞菁对H2O2氧化邻苯二胺显色体系的催化特性和反应条件.室温下,体系在pH10.5的硼砂-NaOH缓冲溶液中反应20 min,形成的产物在424 nm处有最大吸收,H2O2在4.69×10-6～2.34×10-mol/L范围内与吸光度呈线性关系,检测限为3.43×10-6mol/L.方法可用于消毒液和雨水...     

离子色谱仪流动注射电导法测定过氧化氢

以H2S03与H2O2反应生成H2SO4产生的电导变化与H202的量呈线性关系为理论依据，根据流动注射原理将现有离子色谱仪进行改装成流动注射仪测定过氧化氢。此方法有很好的重现性，8次进样所得相对标准偏差小于2．6％，所得结果稳定，其检测下限为0．5mg/L，标准曲线的相关系数达0．9995。本实验对某些分析条件，诸如H2SO3的浓度和流速、样品用量及反应管长度等因素进行了探讨。由于实际样品中存在不同离子而具有不同背景电导，因而在测定实际样品时采用经过过氧化氢酶处理的样品作空白，以此消除背景电导的干扰。     

过氧化氢荧光探针的研究进展

过氧化氢(H2 O2)与生命系统中的许多生理和病理过程有关.但是,过量的H2 O2会导致一系列生理疾病,因此,有效地识别和检测H2 O2非常重要.近年来已经报道了许多用于检测生物体系中H2 O2的荧光探针,与传统的检测方法相比,其具有灵敏度高、无创检测及实时成像等优点.本文根据不同的荧光团,评述了近五年H2 O2荧光探...     

流动注射-化学发光法测定水果提取物对羟自由基的清除率

建立了Fe2+-H2O2-亚甲基蓝化学发光体系用于水果对羟自由基清除率的测定。实验发现,在酸性介质中,Fe2+和H2O2在线生成的羟自由基(.OH)与亚甲基蓝反应能产生较强的化学发光,加入水果水提取物可以清除部分羟自由基,使化学发光强度降低。据此,结合流动注射技术,建立了测定水果水提取物对.OH清除率的化学发光新方法。将该方法应用于9种水果水提取物对.OH清除能力的研究,结果满意。     

流动注射激光诱导荧光光度法测定食品中的铁

将流动注射与CCD阵列检测激光诱导荧光装置联用 ,形成连续自动荧光光谱分析系统 ,建立了在 1× 1 0 -3 mol L的HCl溶液中 ,Fe3 催化H2 O2 氧化罗丹明B(RhB)的催化荧光光度测定铁的新方法 ,对反应条件及流动注射各实验参数进行了优化 ,用于食品样品中铁的测定 ,测定结果与原子吸收分光光度法有一致性 ,方法的相对标准差不大于 8.0 % ,加标回收率为 95 .9%～ 1 0 6%。     

基于固定化纳米金增强化学发光双酶传感器测定葡萄糖

研制了一种新型流动注射化学发光（CL）双酶传感器,用于葡萄糖的检测．该传感器将掺杂金纳米粒子（GNPs）的壳聚糖膜包覆在硅烷化试剂预处理的玻璃微珠上,用于吸附固定葡萄糖氧化酶（GOD）和辣根过氧化物酶（HRP）．葡萄糖在GOD的催化下发生氧化反应生成H2O2,生成的H2O2在HRP的催化作用下与鲁米诺发生反应,并产生化学发光信号．实验表明,壳聚糖中掺杂的GNPs不仅能够有效的吸附酶分子并保持其生物活性,还对Luminol-H2O2-HRP化学发光体系具有增敏作用．通过化学发光光谱和紫外光谱表征,详细研究了固定化GNPs增强Luminol—H2O2-HRP体系的化学发光机理．在优化的实验条件下,该传感器对葡萄糖检测的线性范围为0．01～6．0mmol／L,检测限为5．0μmol／L（3σ）．将所建立的方法用于临床血清样品中葡萄糖含量的测定,获得了满意的结果．     

溶胶凝胶法固定反应试剂流动注射化学发光法测定H_2O_2

采用溶胶凝胶技术对 Luminol- Co( ) - H2 O2 体系中的 Co( )和 Luminol试剂进行了固定化 ,并将其用于化学发光法测定 H2 O2 。试验结果表明 ,固定柱的洗脱液中 Co( )的浓度稳定 ,测定的线性范围为 2× 1 0 - 6～ 1× 1 0 - 4 mol·L- 1 ,相关系数大于 0 .997,检出限为 0 .6μmol·L- 1 。1 0次测定的 RSD为 1 .7% ,单次测定能在 1 min内完成。方法成功地用于雨水中 H2 O2 的测定。     

微加工芯片式流通池在顺序注射可更新表面反射光谱检测中的应用

提出了一种以湿法蚀刻技术制备的用于流动注射（FI）或顺序注射（SI）进样可更新表面检测的芯片式流通池,并将此流通池与SI系统及检测器相匹配,用于顺序注射可更新表面（SI－RST）反射光谱法检测。流通池由两片玻璃封接而成,流通池通道蚀刻在玻璃基片上。流通池通过多股双岔光纤分别与光源、检测器相耦合,以实现对微珠表面的反射光谱法检测。将此SI－RST反射光谱法检测系统用于对锌的检测,并测定人发试样中微量锌的含量。     

Determination of Lead(II), Copper(II), Zinc(II), Cobalt(II), Cadmium(II), Iron(III), Mercury(II) using sequential injection extractions

Sequential injection analysis is still dominated by single component analysis. In this proposed robust, economical simple instrumental system seven different metal ions are determined simultaneously using thin-film sequential injection extraction (SIE) with multivariate calibration and multiwavelength detection. Dithizone, in ethanol, is used as extractant and the metal dithizonates’ spectra are generated by a diode array spectrophotometer between 300 and 700 nm. The SI thin-film extraction using water miscible with ethanol works due to the hydrophobic interaction of ethanol with the Teflon wall to create a thin film. A sample frequency of 27 samples per hour was obtained with a sample carry-over of less than 1%. The results of the proposed sequential injection extraction system compare favourably with the results obtained by using standard atomic absorption spectrometry (AAS) methods on conventional extraction samples.     

Sequential injection technique for automation of complex analytical procedures: fluorometric assay of factor thirteen

A non-segmented flow method is used to automate an analysis which involves five different reagents. The fluorometric assay for factor thirteen (FXIII) is performed by the sequential injection analysis (SIA) technique. Two reactions take place in a single fine SIA system to produce the final fluorescing product. Because of its mechanical simplicity and versatility, the sequential injection (SI) technique is shown to be an attractive tool for automation of a complex analytical procedure. In addition to collecting quantitative and kinetic information, the SI system is illustratively used for optimization of the analysis and for obtaining validation information.     

Coupling of sequential injection with liquid chromatography for the automated derivatization and on-line determination of amino acids

The principle of sequential injection (SI) was exploited to develop a fully automated pre-column derivatization procedure combined on-line to liquid chromatography (LC). Using SI-LC derivatization 14 amino acids were determined fluorimetrically in pharmaceuticals with o-phthaldialdehyde (OPA) as the derivatization reagent. The SI system was used for the handling of samples and reagents, on-line mixing and introduction to the LC injection system. Chemical (pH and reagents concentrations) and instrumental variables (sample and reagent volumes, reaction time and flow rate) were optimized to attain the highest reaction yield and detector signal. Reversed phase chromatographic resolution of 14 amino acids was achieved within 35 min using gradient elution. The automated operation of the coupled SI-LC system resulted in very satisfactory performance. The method was applied for the simultaneous determination of amino acids in pharmaceutical formulations.     

Recent Developments in Automated Determinations of Trace Level Concentrations of Elements and On‐Line Fractionation Schemes Exploting the Micro‐Sequential Injection—Lab‐On‐Valve Approach

Abstract

The determination of trace level concentrations of elements, such as metal species, in complex matrices by atomic absorption or emission spectrometric methods often requires appropriate pretreatments comprising separation of the analyte from interfering constituents and analyte preconcentration. In this context sequential injection (SI) and lab‐on‐valve (LOV) schemes have proven themselves as superb vehicles to act as front‐end microanalytical methodologies, particularly when employing solid‐phase extraction (SPE) procedures. In this communication, selected SPE‐procedures in the bead‐renewable fashion are presented as based on the exploitation of micro‐sequential injection (µSI‐LOV) using hydrophobic as well as hydrophilic bead materials. The examples given comprise the presentation of a universal approach for SPE‐assays, front‐end speciation of Cr(III) and Cr(VI) in a fully automated and enclosed setup, and the combination of SPE with fractionation schemes of environmentally interesting solid samples (such as soils or sediments) in order to conduct ecotoxicological studies.     

On-line sample-pre-treatment schemes for trace-level determinations of metals by coupling flow injection or sequential injection with ICP-MS

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.     

Enzymatic in-capillary derivatization for glucose determination by electrophoresis with spectrophotometric detection

The following paper compares several procedures of in-capillary bienzymatic derivatization with regard to glucose determination with the use of glucose oxidase and horseradish peroxidase. The procedures discussed below include continuous contact in the capillary, plug-plug injection, and sequential injection with incubation in the capillary inlet. The reaction of hydrogen peroxide catalyzed by peroxidase was performed using two different substrates. The best results were achieved for nicotinamide adenine dinucleotide, reduced disodium salt (NADH) acting both as a chromogenic reagent and a substrate for peroxidase, while the method employed was sequential injection and incubation at the capillary inlet. The LOD was estimated to be 25 nM with a linear response up to 0.1 microM.     

Sequential injection-bead injection-lab-on-valve coupled to high-performance liquid chromatography for online renewable micro-solid-phase extraction of carbamate residues in food and environmental samples

A sequential injection‐bead injection‐lab‐on‐valve system was hyphenated to HPLC for online renewable micro‐solid‐phase extraction of carbamate insecticides. The carbamates studied were isoprocarb, methomyl, carbaryl, carbofuran, methiocarb, promecarb, and propoxur. LiChroprep^® RP‐18 beads (25–40 μm) were employed as renewable sorbent packing in a microcolumn situated inside the LOV platform mounted above the multiposition valve of the sequential injection system. The analytes sorbed by the microcolumn were eluted using 80% acetonitrile in 0.1% acetic acid before online introduction to the HPLC system. Separation was performed on an Atlantis C‐18 column (4.6×150 mm, 5 μm) utilizing gradient elution with a flow rate of 1.0 mL/min and a detection wavelength at 270 nm. The sequential injection system offers the means of performing automated handling of sample preconcentration and matrix removal. The enrichment factors ranged between 20 and 125, leading to limits of detection (LODs) in the range of 1–20 μg/L. Good reproducibility was obtained with relative standard deviations of <0.7 and 5.4% for retention time and peak area, respectively. The developed method has been successfully applied to the determination of carbamate residues in fruit, vegetable, and water samples.     

Determination of thiamine in pharmaceutical preparations by sequential injection renewable surface solid-phase spectrofluorometry.

Fluorometric determination of thiamine requires the conversion of the analyte to fluorescent thiochrome by hexacyanoferrate(III) oxidation in alkaline solution and the isolation of the produced thiochrome from the reaction medium by solvent extraction. It was observed that thiochrome could be concentrated and separated from the reaction medium by solid-phase extraction. The thiochrome sorpted on the surface of octadecyl-alklylated poly[styrene/divinylbenzene] (C18-PS/DP) microbeads emitted strong fluorescence upon excitation, the maximum excitation and emission wavelengths being 385 nm and 433 nm, respectively. Based on this observation, a sequential injection renewable surface solid-phase spectrofluorometry was developed for the determination of thiamine. A sequential injection system on-line coupled to a chip-based flow-through cell was employed to handle the chemical reaction, bead injection and discharging, and adsorption of thiochrome. Solid-phase fluorometric detection was realized by coupling the chip-based flow-through cell to a spectrofluorometer with a multistrand bifurcated optical fiber. Under the optimized condition, a detection limit of 0.03 microg ml(-1) was achieved at the sample throughput of 30 h(-1) and consumption of 1 mg C18-PS/DP microbeads for each run. Eleven runs of a 2 microg ml(-1) thiamine standard solution gave a relative standard deviation of 1.0%. The developed approach was successfully applied for the determination of thiamine contents in pharmaceutical preparations.     

Accelerated micro-sequential injection in lab-on-valve format, applied to enzymatic assays

The assay cycle of sequential injection (SI) analysis has been greatly accelerated by simultaneously processing two sample injections within the same manifold. This is achieved through micro-miniaturization of the SI system using the lab-on-valve format (LOV), and by optimizing the assay protocol for stopped-flow reaction rate measurements. The approach has been tested on enzymatic assays of glucose and ethanol, but it is, in principle, applicable to all SI reagent-based assays. The average assay time for a single run has been shortened from 200 s to approximately 30 s. Assays were carried out at 22 degree C and 37 degree C using commercially available reagent kits. For glucose, at 22 degree C, the calibration had a linear response (r(2)= 0.9999) for the concentration range of 100-1000 ppm. At 37 degree C, the calibration was linear (r(2)= 0.9996) for 100-600 ppm glucose, but was a second order polynomial curve (r(2)= 0.9996) for 100-1000 ppm. For ethanol, at both 22 degree C and 37 degree C, the calibrations were linear for the concentration range of 50-250 ppm. The r(2) at two temperatures was 0.9994 and 0.9995, respectively. For both the glucose and ethanol assays, the relative standard deviations were below 3%. Factors affecting sampling frequency are discussed. In this work, sequential injection is shown, for the first time, to achieve sampling frequency comparable to flow injection (FI), while retaining the advantages of small reagent consumption (typically microlitres per assay), minimized waste production, full automation of assay protocols, and zero carryover.