On-line Separation and Preconcentration for Histamine Determination in Fish Meal Using Cation-Exchanger Resin

FI system was used for the determination of histamine. A mini-column filled with amberlite resin （weak cation exchanger） was introduced to the flow system. A 200 laL of the sample was injected into the carrier stream through the injection valve. The merged streams were passed through a quartz flow cell in a spectrophotometer connected to recorder. Under the optimum conditions, the calibration curve was linear in the range 0.02-1.5 μg mL^-1 of histamine using the peak height as an analytical signal, while the detection limit was 0.01 μg mL^-1. The precision and accuracy of the method were studied depending upon the values of the relative standard deviation and relative error percentage. The selectivity of the method was investigated by studying the effect of interference from other species accompanied with histamine in fish meal. Under the optimum conditions, the system was used for on line separation, preconcentration of histamine. The proposed method was applied for the determination of histamine in fish meal. The results were compared with the standard method and a good agreement between the results was obtained.

Sequential injection spectrophotometric determination of nanomolar nitrite in seawater by on-line preconcentration with HLB cartridge

The unstable state of nitrite results in its very low concentration in seawater, which is below the limit of detection （LOD） of conventional techniques of analysis. Some sensitivity-enhanced methods have been proposed for the determination of nitrite at nanomolar level to illustrate the role of nitrite in the marine nitrogen cycle. However, most of previous reports are not widely accepted, because of their complexity and cost equipment or intensive labor requirement. In this study, a simple automatic system for the determination of nanomolar level nitrite using on-line preconcentration with spectrophotometric detection was described..An Oasis HLB cartridge was adopted to quantitatively enrich the pink-colored azo compound, formed from nitrite via Griess reaction. The cartridge was rinsed with water and ethanol （volume fraction is 55%, the same below）, in turn, then eluted by an eluent containing 50% ethanol and 0.25 M（mol/dm^3） H2SO4, and determined at 543 nm with a 2 cm path-length flow cell. Under the optimized experimental conditions, the calibration curve showed a good linearity in the range of 1.4 85.7 aM, and the LOD （3a） was estimated to be 0.5 nM. The relative standard deviations of 7 measurements were 4.0% and 1.0% for the samples spiked at 7.1 and 28.6 nM, respectively. The recoveries for the different natural water samples were between 92.2%-108.4%. Each HLB cartridge could be reused for at least 50 times. As compared with other SPE methods, the advantages of this method included the free of interference from salinity variation and less sample consuming. The results of the application of the proposed method to natural water showed good agreement with liquid waveguide capillary cell detection method.

Flow-Injection Microcolumn on-Line Preconcentration for theDetermination of Chromium(Ⅵ)

A rapid and sensitive on-line preconcentration method for spectrophotometric determination of chromium (VI) in nature water is described. Preconcentration and determination are based on (i) the quantitative and fast adsorption of chromium (VI) on the high surface area nanometer-size TiO2 (anatase) powders, which prepared by a sol-gel method from hydrolysis of TiCI4 and (ii) the quantitative and reproducible elution of Cr (VI) by 2. 0 mol. L-1 HCI. A mini-column system for preconcentration is developed, Cr(VI)on the mini-column is eluted and merged with a stream water and DPCB (1, 5-diphenylcarbazide ) as the chromogenic reagent. The Proposed system permits throughputs of 6 sample h--l (0. 001 μg mL-1 Cr(VI) ) or 20 sample h-1 (0. 1 μg mL-1Cr (VI) . The preconcentration factor is 55. The detection limit is 0. 8 ng·mL-1 Cr(VI). The reproducibility is satisfactory with a relative standard deviation of less than 3. 35% (0. Of μg'mL-1Cr (VI), n = 5).

Separation,preconcentration and determination of Pb(Ⅱ) in water samples using microcrystalline triphenylmethane loaded with quinolin-8-olate

This paper described a novel method for the preconcentration of Pb（II） using microcrystalline triphenylmethane loaded with quinolin-8-olate prior to the determination by flame atomic absorption spectrometry. Pb（II） could be enriched by controlling appropriate condition. The preconcentration factor could reach to 200 and the detection limit of Pb（II） was 0.074 μg/L. The recovery was in a range of 93.5-103% with relative standard deviation of 1.0-2.2%. The proposed method had been successfully applied to the determination of trace Pb（U） in various water samples with satisfactory result.

Cobalt Determination by Means of Flow Injection On-line Sorbent Preconcentration-Flame Atomic Absorption Spectrometry with 1-Nitroso-2-naphthol as a Complexing Reagent

The suitability of 1-nitroso-2-naphthol(NN) as a complexing agent for on-line preconcentration of cobalt eluted on the C_(18) microcolumn by means of the FI-FAAS system was tested. Various parameters affecting the complex formation and its elution were optimized. A 2.3×10^(-3) mol/L reagent solution and the aqueous sample solution acidified with 0.1% (volume fraction) nitric acid were on-line mixed (6.4 mL/min) on a reaction coil set at (65±1)℃ and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3—4 with HNO_3(1 mol/L) or NaOH(1 mol/L). The adsorbed complexes in the microcolumn were eluted into the nebulizer of FAAS in 10 s with ethanol acidified with 1% HNO_3(3.0 mL/min). A good precision(1.6% for 100μg/L Co(Ⅱ), n=10), a high enrichment factor 17.2, with detection limit (3σ) 3.2μg/L, and sample throughput (90 h^(-1)) were obtained. The method was applied to the certified reference materials(CRMs), NBS-362 and NBS-364, for the determination of cobalt and the results were in good agreement with the certified values.

PMOXA/PAA Brushes toward on-Line Preconcentration for BSA in Capillary Electrophoresis

In this work, a binary-mixed-brushes-coated (BBC) capillary with switchable protein adsorption/desorption properties was developed and applied for on-line preconcentration of proteins. Firstly, amine-terminated poly(2-methyl-2-oxazoline)(PMOXA-NH2) and thiolterminated poly(acrylic acid)(PAA-SH) were synthesized by using cationic ring-opening polymerization (CROP) and reversible addition fragmentation chain transfer (RAFT) polymerization, respectively. Then, the BBC capillary based on poly(2-methyl-2-oxazoline)(PMOXA) and poly(acrylic acid)(PAA) was prepared by sequentially grafting of PMOXA-NH2 and PAA-SH onto fused-silica capillary inner surface through poly(dopamine)(PDA) as an anchor. The obtained PMOXA/PAA coating formed on the capillary or capillary's raw material was characterized in terms of the thickness, surface chemical composition by using scanning electron microscope (SEM) and X-ray photoelectron spectrum (XPS). The switchable protein adsorption/desorption performance of the BBC capillary was investigated by using fluorescence microscope under di erent solutions with certain pH and ionic strength(I). The results showed that bovine serum albumin (BSA) could be adsorbed on BBC capillary at pH=5.0 (I=10^-5 mol/L), and then the adsorbed BSA could be released at pH=9.0 (I=0.1 mol/L). This switchable protein adsorption/desorption property of coated capillary was then used to preconcentrate proteins on-line for increasing the detection sensitivity of BSA in capillary electrophoresis (CE). With this method, a sensitivity enhancement factor (SEF) more than 5000 for BSA detection was obtained.

Octa-<i>O</i>-Methoxy Resorcin [4] Arene Amberlite XAD-4 Polymeric Chelating Resin for Solid Phase Extraction, Preconcentration, Separation and Trace Determination of Ni(II), Cu(II), Zn(II) and Cd(II) Ions

Synthetic resin, Amberlite XAD-4 was linked covalently with the third generation supramolecule, octa-O-methoxy resorcin [4] arene through -N=N-group to form chelating resin, which has been characterized and effectively used for the separation and preconcentration of metal ions such as Ni(II), Cu(II), Zn(II) and Cd(II). Critical parameters such as pH, flow rate, sorption capacity, breakthrough studies, distribution coefficient, preconcentration factor, concentration of eluting agents responsible for quantitative extraction of metal ions were optimized. The synthesized resin showed good binding affinity towards Ni(II), Cu(II), Zn(II) and Cd(II) under selective pH conditions. Good breakthrough capacity and fast exchange kinetics of the resin lead to effective separation of metal ions from their binary and ternary mixture by column method on the basis of pH and eluting agents. The resin could be reused for about 8 -10 cycles. The proposed method having the analytical data with the relative standard deviation (RSD) 2% and with recoveries of analytes higher than 98%, reflects upon the reproducibility and reliability of the method which has been successfully applied in the separation and determination of Ni(II), Cu(II), Zn(II) and Cd(II) ions in synthetic, natural and ground water samples.

PRECONCENTRATION OF TRACE ZINC IN SEAWATER ON CPPI RESIN BY FIA AND ON-LINE DETECTION BY ICP-AFS

A quite new type of chelating resin Carboxymethylated Polyethylenimine-Polymethylenepolyphenylene Isocyanate(CPPI)is used for the preconcentration of Zn from high salt water such as seawater. The preconcentration is controlled through the technique of Flow Injection Analysis(FIA).The concentrated sample solution is then directly transferred to an Inductively Coupled Plasma-Atomic Fluorescence Spectrometer(ICP-AFS)for determination.The detection limit of Zn by the technique is about 0.06 ppb.

DETERMINATION OF ANTIMONY IN WATER SAMPLES BY FLOW-INJECTION HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY WITH ON-LINE ION-EXCHANGE COLUMN PRECONCENTRATION

On-line ion-exchange separation and preconcentration were combined with flow-injection hydride generation atomic absorption spectrometry (HGAAS) to determine ultra-trace amounts of antimony in water samples. Antimony(Ⅲ) was preconcentrated on a micro-column packed with CPG-8Q chelating ion-exchanger using time-based sample loading and eluted by 4 mol l^(-1) HCl directly into the hydride generation AAS system. A detection limit (3σ) of 0.0015μg l^(-1) Sb(Ⅲ) was obtained on the basis of a 20 fold enrichment and with a sampling frequency of 60h^(-1). The precision was 1.0% r.s.d.(n=11) at the 0.5μg l^(-1) Sb(Ⅲ) level. Recoveries for the analysis of antimony in tap water, snow water and sea water samples were in the range 97-102%.

Microfluidic Analytical System with On-Line Luminol Chemiluminescence Detection Based on Annular Flow of Phase Separation Multiphase Flow

Microfluidic analytical system was developed based on annular flow of phase separation multiphase flow with a ternary water-hydrophilic/hydrophobic organic solvent solution. The analytical system was combined with on-line luminol chemiluminescence detection for catechin analysis. The water (10 mM phosphate buffer, pH 7.3)-acetonitrile-ethyl acetate mixed solution (3:8:4, volume ratio) containing 60 μM luminol and 2 mM hydrogen peroxide as a carrier was fed into the capillary tube (open-tubular fused-silica, 75 μm inner diameter, 110 cm effective length) at a flow rate of 1.0 μL·min-1. The carrier solution showed stable chemiluminescence as a baseline on the flow chart. Eight catechins were detected as negative peaks for their antioxidant potential with different detection times. The system was applied to analyze the amounts of catechin in commercially available green tea beverages.

Chemical Selectivity of Laser Ion Source for on-Line Mass Separator

Thulium(Tm)atoms are resonantly ionized in a hot tube by stepwise excitations us-ing three dye lasers pumped by a series of copper vapor pulsed at a 10 kHz rate.The chemicalselectivity of the laser ion source is measured as a function of temperature of the tubes made ofTa,Nb-Zr and TaC.The chemical selectivity rises from 50 to 10000 with decreasing tube temp-erature and strongly depends on the tube material.A chemical selectivity of about 10000 withhigh efficiencies is obtained with the Nb-Zr and TaC tubes.Such a laser ion source can be usedin on-line mass separator to obtain isobarically pure ion beams.

Iodine Determination by Microwave Plasma Torch Atomic Emission Spectrometer Coupled with Online Preconcentration Vapor Generation Technique

This article focuses on iodine determination by microwave plasma torch atomic emission spectrometry （MPT-AES） coupled with online preconcentration vapor generation method. A new desolvation device, multistrand Nafion dryer, was used as the substitute for condenser desolvation system. Some experimental conditions, such as preconcentration time, acidity of sample solution, rinsing solution acidity and dynamic linear range were investigated and optimized. The new desolvation system eliminates the problem of decreasing emission intensity of I（I） 206.238 nm line with the increase of working time on a conventional condenser desolvation system, thus greatly improving the reproducibility.

预选抛废技术发展现状

随着我国矿产资源的不断开发与利用,天然高品位矿石资源逐步减少,低品位矿石成为目前我国矿产资源的主要来源,因此,预选抛废成为一个必要的选矿环节。重点阐述了人工拣选抛废、光电选抛废、磁选抛废、重选抛废以及浮选抛废五种抛废技术,并介绍了不同技术在预选抛废时使用的设备和工作原理,指出了各种预选抛废技术的优缺点,为预选抛废技术能进一步工业应用提供了一定借鉴意义。

含铟粉尘的处理工艺现状与展望

含铟粉尘是金属冶炼流程产生的固体废弃物之一,包含锌、钾、铝、铁、铟、铅、镉等金属,是回收稀有金属铟的重要原料。针对现阶段含铟粉尘回收铟过程中存在的分散损失严重、回收率低、处理难度大等问题,本文以含铟粉尘回收铟的全流程处理工艺为主线,对含铟粉尘处理过程中火法预处理、湿法浸出、富集分离等环节的常用技术和工艺进行对比分析,探究不同工艺的独特机理和处理流程,同时讨论不同工艺的特点和局限性,指出现阶段各工序工业生产中存在的问题;重点综述铟湿法浸出和富集分离提取两个环节的技术进展,并基于现阶段工业粉尘“无害化、减量化、资源化”的处理目标与发展趋势,提出未来含铟粉尘综合回收处理的新思路,为实现含铟粉尘中铟等高附加值元素回收利用提供参考。

基于色选法的钨矿石分选技术

针对石英脉型钨矿中石英矿无法被分选利用以及原矿分选效率低的问题,采用色选法研究钨矿石分选技术。介绍韶关地区石英脉型钨矿的矿石性质,指出伴生石英矿与花岗岩废石之间存在的显著分选差异性;对色选机的组成和色选法原理进行分析,利用图像采集系统提取矿石表面颜色;基于RGB颜色空间模型描述矿石颜色,通过计算比较矿石颜色空间距离,精准区分有用矿石与伴生石英矿和花岗岩废石;构造适合原矿分选的色选机,随机选取15~22 mm原矿样本进行试验。结果表明:钨矿分选技术能够有效分选含钨矿石、石英矿石和花岗岩废石,可大幅度提高分选效率和分选矿石量,分选量超过2500 kg/h,分选精准度超过99%,经济效益和社会效益显著。

Preconcentration and separation of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-4-(2-pyridyl-azo)-resorcinol

This paper reports a simple and highly selective method for preconcentrating and separating of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-4-(2-pyridylazo)-resorcinol (ABPR·SG). ABPR·SG is stable in solution from 6 mol/L HCl to pH 7.0 and in common organic solvents. The maximum adsorptive capacity of Pd(II) on ABPRSG is 362 μmol/g. After preconcentrating and separation by using ABPR·SG column, Pd(II) and Pt(IV) of μg/L level in artificial water samples can be measured reliably by common spectrophotometer. The maximum concentration factors of Pd(II) and Pt(IV) on ABPR·SG column are 143 and 125 respectively. The chromatographic column packed with ABPR·SG can be reused. The method is simple and efficient.

四川某低品位稀土尾矿回收稀土实验研究

这是一篇矿物加工工程领域的论文。本研究以四川某稀土尾矿为研究对象,通过工艺矿物学研究表明尾矿中稀土金属成分的分布矿物较一致,主要存在矿物为氟碳铈矿及氟碳钙铈矿。由于样品中稀土品位较低,仅为1.06%,采用重选工艺对尾矿中的稀土矿物进行预富集,以达到降低选矿成本的目的。对预富集的产品开展浮-磁工艺研究,捕收剂采用自主研发的植物基部分取代氨基苯环的绿色高效药剂RF802,抑制剂采用水玻璃,经一粗三精一扫的浮选工艺和强磁选工艺,可获得REO品位为53.63%、回收率为70.54%的稀土精矿,实现了该低品位稀土尾矿中稀土矿物的有效回收利用。

钨矿预选抛废技术研究进展

我国钨矿资源具有优质资源消耗快、低品位矿石占比多的特点。近几年,随着优质钨矿资源储量的日益减少,低品位和复杂难选矿石的经济开发和高效利用愈发迫切。如何合理选择和利用预选抛废技术是实现钨矿绿色开发、高效分选的关键。分析了钨矿预选抛废的必要性,详细阐述了人工拣选、重选法预选、磁选法预选以及智能光电预选的技术原理和特点,总结了钨预选抛废的研究与应用进展。分析认为,矿石性质、粒度分布等条件是选择适宜预选方法的关键;工艺及设备的优化和改进是今后传统预选方法的重要研究方向;智能光电预选会成为未来钨矿预选的热门选择。最后对钨矿预选未来的发展进行了总结和展望,以期为未来钨矿预选抛废技术的研究和应用提供参考。

预富集技术研究进展

预富集技术主要是根据矿石矿物与脉石矿物在某种特性上的差异,利用光电选、重选、磁选、浮选及化学选等工艺提高矿石矿物入选品位,预先抛弃部分脉石矿物,从而为后续分选作业创造有利条件。概述了预富集技术的研究现状,从光电选、重选、磁选、浮选、化学选以及联合工艺等方面介绍了预富集技术在选矿领域的研究及应用,分析了各种预富集技术的优缺点,并指出采用联合工艺进行预富集是实现低贫矿石和废石资源综合利用的重要技术手段。

稀土萃取分离氯化铵废水处理工艺探究

为了解决稀土萃取分离产生的氯化铵废水需处理的紧迫性,根据稀土废水构成,从工艺原理及适用范围方面综合比较蒸发结晶法、多效蒸发法、折点氯化法、氨吹脱法、磷酸铵镁法、MVR蒸发等工艺的优缺点,结果显示采用三效蒸发蒸汽成本<125.56元/t,并适用于1万t/a以下稀土萃取分离企业。查阅电渗析、离子交换、生物处理、SBR工艺等尚未应用推广的处理方案;提出了预处理+预浓缩+三效的组合方案。结果表明:组合方案既降低能耗,又实现氨氮处理,同时氨氮和水资源得到回收利用,副产氯化铵形成新盈利点,用于化肥工业原材料。