二乙基二硫代氨基甲酸钠流动注射萃取分光光度法测定矿石中微量铜的研究

本文对二乙基二硫代氨基甲酸钠(铜试剂)-四氯化碳流动注射莘取分光光度法测定矿石中微量铜进行了研究。与手工萃取法相比,本法最大特点是大量Mn~(2+)无干扰。方法操作简便、快速、可靠、毒性小;进样频率为20次/小时,RSD为3.5％。线性范围为O～1.28μg/ml。方法用于测定矿石中微量铜,结果满意。     

氯化钠-二乙基二硫代氨基甲酸钠-丙醇体系萃取分离铜

研究了氯化钠－二乙基二硫代氨基中甲酸钠－丙醇体系萃取铜的行为及丙醇水溶液分相条件的选择。实验表明,丙醇作为萃取溶剂,能萃取中性螯合物。在ＥＤＴＡ存在下,调节ｐＨ５－ｐＨ１０,该体系能使Ｃｕ６２＋从常见元素Ｆｅ＾３＋,Ｃｏ＾２＋,Ｎｉ＾２＋,Ａｌ＾３＋等离子的混合液中分离出来。     

吐温-80-DDTC胶束增溶吸光光度法测定饮料中微量铜

利用非离子表面活性剂的胶束增溶增敏作用,研究和建立了吐温-80?DDTC水相体系中直接测定饮料中Cu(Ⅱ)的方法。在表面活性剂吐温-80存在下,于pH 10.0碱性介质中,Cu(Ⅱ)与铜试剂(DDTC)形成灵敏度高的棕黄色络合物。铜含量在0.028~4.70 mg.L-1范围内遵守比耳定律,表观摩尔吸光系数为1.32×103L.mol-1.cm-1,检出限为0.01 mg.L-1,相对标准偏差为1.04%~1.67%,回收率为96.1%~101.7%,测定结果与有机溶剂萃取法一致。     

异丙醇在镉试剂与铜(Ⅱ)反应中的增敏作用

在铜(Ⅱ)与镉试剂的显色反应体系(即在含一定量铜(Ⅱ)及50g·L~(-1)吐温-80溶液0.5mL,pH 9.6硼砂-氢氧化钠缓冲溶液2.0mL和0.5mg·L~(-1)镉试剂1.0mL的混合溶液)中加入异丙醇4.0mL,加水定容至25mL,于反应20min后在498nm波长处测其吸光度。试验表明:加入异丙醇使铜(Ⅱ)与镉试剂所生成的络合物的吸光度增高约30%。此新反应体系的表观摩尔吸光率达1.23×10~5L·mol~(-1)·cm~(-1),铜(Ⅱ)质量浓度在0.28mg·L~(-1)以内与相应吸光度呈线性关系。测得方法的检出限(3s/k)为6.7×10~(-3)mg·L~(-1)。应用此方法分析了两个水样,并以此为基体用标准加入法做回收试验,测得平均回收率为98.2%,测定值的相对标准偏差(n=7)小于1.5%。     

乙酰丙酮缩邻氨基苯酚对铜的萃取性能及萃取光度法

乙酰丙酮缩邻氨基苯酚对铜的萃取性能及萃取光度法＊唐丽素刘春元龙云飞周建军（湘潭师范学院化学系湖南湘潭４１１１００）关键词乙酰丙酮缩邻氨基苯酚铜（Ⅱ）萃取分光光度法中图分类号Ｏ６５７．３２对铜的萃取分离已做了大量的研究工作，并在湿法冶金工业获得了应用［...     

室温离子液体协同增敏浊点萃取分光光度法测定痕量镉

本文建立了离子液体协同增敏浊点萃取-紫外可见分光光度法测定痕量镉的方法。离子液体和二硫代氨基甲酸钠(DDTC)分别用作增敏剂和络合剂,离子液体的加入能使测定镉的方法灵敏度提高3.2倍。非离子表面活性剂TritonX-100用作提取剂,当样品体系的温度高于TritonX-100的浊点温度时,镉与DDCT形成的络合物被萃取到TritonX-100中,经相分离紫外可见分光光度计检测。考查了离子液体,DDTC和TritonX-100的浓度、溶液酸度、干扰离子等实验条件对浊点萃取效率的影响。在最优化的实验条件下,测量镉的线性范围为1～100 ng·mL-1,方法的检出限为0.1 ng·mL-1,相对标准偏差RSD为4.3%,富集系数为96。该方法应用于测定于水样中的痕量镉具有满意的效果。     

分光光度法研究水-乙醇体系析相萃取分离和富集PdBr_4~(2-)

用可见分光光度法研究了水-乙醇体系析相萃取分离和富集PdBr42-的行为及与一些金属离子分离的条件.结果表明,(NH4)2SO4能使乙醇的水溶液分成两相,在分相过程中,Pd(Ⅱ)与KBr生成的PdBr42-与质子化乙醇(C2H5OH2+)形成的缔合物[PdBr42-][C2H5OH2+]2能被乙醇相完全萃取.当乙醇、KBr和(NH4)2SO4分别为30%、6.0×10-3 mol/,L、0.3 g/mL,pH 3时,PdBr42-的萃取率达到98.6%以上,Fe(Ⅲ),Al(Ⅲ),Cr(Ⅲ),Ag(Ⅰ),Cu(Ⅱ),Ni(Ⅱ),Zn(Ⅱ),Co(Ⅱ),Mn(Ⅱ),V(Ⅴ),U(Ⅵ),Pb(Ⅱ),Ru(Ⅲ),Rh(Ⅲ)和Hg(Ⅱ)基本不被萃取,实现了Pd(Ⅱ)与上述金属离子的分离.     

丙氨酸增敏催化动力学光度法测定痕量铜(Ⅱ)

在pH=4.7的HAc-NaAc缓冲溶液中,以丙氨酸为增敏剂,铜(Ⅱ)能催化过氧化氢氧化依文思蓝使其褪色,据此建立了测定痕量铜(Ⅱ)的新催化动力学光度法。研究了该指示反应的最佳条件,并测得其表观活化能和反应速率常数分别为12.29kJ/mol和3.25×10-4s-1。在优化条件下,铜(Ⅱ)在0.008～0.120μg/mL浓度范围内与△A呈良好的线性关系,相关系数r=0.9999,检出限为5.75×10-9g/mL。方法应用于不同水样、茶叶及几种新鲜蔬菜中痕量铜的分析,相对标准偏差(RSD)小于0.61%,回收率在96.0%～105%之间。     

分光光度法研究水-乙醇体系析相萃取分离和富集PdBr2-4

用可见分光光度法研究了水-乙醇体系析相萃取分离和富集PdBr42-的行为及与一些金属离子分离的条件.结果表明,(NH4)2SO4能使乙醇的水溶液分成两相,在分相过程中,Pd(Ⅱ)与KBr生成的PdBr42-与质子化乙醇(C2H5OH2+)形成的缔合物[PdBr42-][C2H5OH2+]2能被乙醇相完全萃取.当乙醇、K...     

Ligandless-dispersive liquid-liquid microextraction of trace amount of copper ions

In the present work, a new ligandless-dispersive liquid-liquid microextraction (LL-DLLME) method has been developed for preconcentration trace amounts of copper as a prior step to its determination by flame atomic absorption spectrometry. In the proposed approach 1,2-dicholorobenzene and ethanol were used as extraction and dispersive solvents, respectively. Some factors influencing on the extraction efficiency of copper and its subsequent determination were studied and optimized, such as the extraction and dispersive solvent type and volume, pH of sample solution, extraction time and salting out effect. Under the optimal conditions, the calibration curve was linear in the range of 1.0 ng mL⁻¹-0.6 μg mL⁻¹ of copper with R² = 0.9985. Detection limit was 0.5 ng mL⁻¹ in original solution (3S_b/m) and the relative standard deviation for seven replicate determination of 0.2 μg mL⁻¹ copper was ±1.4%. The proposed method has been applied for determination of copper in standard and water samples with satisfactory results.     

Solid phase extraction of trace amount of Cu(II) using functionalized-graphene

A novel and selective method for the fast determination of trace amounts of Cu(II) ions in water samples has been developed. The first organic-solution-processable functionalized-graphene (SPF-Graphene) hybrid material with porphyrins, porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10, 15, 20-triphenyl porphyrin and its photophysical properties including optical (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) were used as absorbent for extraction of Cu(II) ions by solid phase extraction method. The complexes were eluted with HNO₃ (2 M) 10% (vol/vol) methanol in acetone and determined the analyte by flame atomic absorption spectrometry. The procedure is based on the selective formation of Cu(II) at optimum pH by elution with organic eluents and determination by flame atomic absorption spectrometry. The method is based on complex formation on the surface of the ENVI-18 DISK? disks modified porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10,15,20-triphenyl porphyrin (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution is efficient and quantitative. The effect of potential interfering ions, pH, TPP-NHCO-SPFGraphene, amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to about 1000 mL providing a preconcentration factor of 600. The maximum capacity of the disks was found to be 398 ± 3 μg for Cu²⁺. The limit of detection of the proposed method is 5 ng per 1000 mL. The method was applied to the extraction and recovery of copper in different water samples.     

Microviscosity of ions and salting-out in the extraction of rare-earth and transplutonium elements

A chemical procedure has been developed for the separation of U, Th, Fe, Sc, Na, Ta and Mo, which interfere in neutron activation analysis of the lanthanide elements in rocks. This methods in based on the extraction of interferents, before irradiation of the samples, using a solution of tetracycline in benzyl alcohol. The lanthanide elements remain in the aqueous phase and are coprecipitated with calcium oxlate or ferric hydroxide for irradiation and subsequent determination by gamma-ray spectrometry. Conditions for the separation of these interferences are examined determining the extraction curves. The chemical separation procedure was applied in the analysis of lanthanides in geological materials and the results showing the accuracy and the reproducibility of the method are presented. The sensitivity for all the lanthanides was determined.     

The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid–liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C₄mim][Br]) and tri-sodium citrate (Na₃Cit) are taken. The apparent molar volume of transfer of [C₄mim][Br] from water to aqueous solutions of Na₃Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C₄mim][Br] from water to aqueous solutions of Na₃Cit have negative values. The effects of temperature and the addition of Na₃Cit and [C₄mim][Br] on the liquid–liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na₃Cit triggers a salting-out effect, leading to significant upward shifts of the liquid–liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of entropy and enthalpy are the driving forces for biphasic formation.     

The salting-out effect and phase separation in aqueous solutions of sodium phosphate salts and poly(propylene glycol)

Phase diagrams and liquid–liquid equilibrium (LLE) data of the aqueous poly(propylene glycol) (PPG) + di-sodium hydrogen phosphate and PPG + tri-sodium phosphate two-phase systems have been determined experimentally at 298.15, 303.15, 308.15, 313.15 and 318.15 K. The effects of temperature and charge on the anion of electrolyte on the binodal curves and tie-lines have been studied and it was found that an increasing in temperature and charge on the anion caused the expansion of two-phase region. The results show that the effect of charge on the anion of electrolyte on the binodal curves becomes smaller by increasing temperatures. It was also found that the concentration of salt, which is in equilibrium with a certain concentration of PPG, decreases by increasing temperature. Based on cloud point values, the energetics of the clouding process has been estimated and it was found that entropy increase is the driving force for biphasic formation.     

Solid phase extraction of trace amount of mercury from natural waters on silver and gold nanoparticles

Silver (Ag) and gold (Au) nanoparticles impregnated in nylon membrane filters have been proposed as a new solid phase for preconcentration of mercury from natural waters. Water samples were treated with KMnO₄ to convert all mercury species to inorganic Hg²⁺ and this was followed by the reduction of Hg²⁺ with NaBH₄ to elemental Hg⁰. The determination of Hg was carried out by thermal evaporation of mercury from membrane filters using Zeeman mercury analyzer RA–915+ (Lumex, Russia). This process does not involve any additional sample treatment and sharply reduces risk of samples contamination. The limit of detection (LOD) was found to be 0.04 ng (absolute mass). Relative LOD was 0.4 ng L⁻¹ for 100 mL of water. The method was validated through the analysis of CRM NRCC Tort–2 (Lobster hepatopancreas) and the found value (0.30 ± 0.07 μg g⁻¹) was in good agreement with the certified value (0.27 ± 0.06 μg g⁻¹). High efficiency of Hg accumulation from aqueous phase to membrane filters can be attributed to a large surface area of nanoparticles.     

Polarographic determination of copper(II) after salting-out extraction as thiocyanate in acetonitrile

Summary A simple and sensitive extraction-polarographic method for the determination of copper(II) by use of acetonitrile as solvent is described. The copper(II) complex formed in aqueous solution can be quantitatively extracted into acetonitrile, in which the complex is reduced to give a polarographic wave withE _1/2–0.58 Vvs. SCE. Linear calibration curves for copper(II) are obtained by the dc, ac and differential pulse polarographic methods. Foreign ions such as Hg(II), Bi, Pb(II), Zn and Ni have no effect even in 20-fold amount relative to copper(II), but a 10-fold ratio of Sn(II) does interfere.

---

Zusammenfassung Ein einfaches und empfindliches Verfahren zur Extraktion von Kupfer (II) mit Acetonitril und darauf folgende polarographische Bestimmung wurde beschrieben. Der in wäßriger Lösung entstandene Cu(II)-Komplex läßt sich mit Acetonitril quantitativ extrahieren. Er wird dann reduziert und gibt eine polarographische Welle mit dem Halbwellenpotential E_1/2=–0,58 V gegen eine gesättigte Kalomelelektrode. Lineare Eichkurven für Kupfer(II) ergaben sich mit Gleichstrom-, Wechselstrom- und Differential-Puls-Polarographie. Fremdionen wie Hg(II), Bi, Pb(II), Zn und Ni beeinflussen das Ergebnis auch in 20fachem Überschuß nicht, wohl aber stört Sn(II) in 10facher Menge.

     

Studies on synthesis and application of XAD-4-salen chelate resin for separation and determination of trace elements by solid phase extraction

The use of chemically modified XAD-4-salen chelating resin had been studied for the separative concentration of metal ions from an aqueous solution. XAD-4-salen was synthesized by diazonium coupling reaction of salen[N,N′-bis(salicylidene)ethylenediamine] and Amberlite XAD-4 resin. The distribution coefficient at various pH values and adsorption capacities were obtained with respect to Cu(II), Pb(II) and Bi(III). Trace elements were pre-concentrated on the synthesized XAD-4-salen by batch method for atomic absorption spectrometric determination. Some conditions, such as the pH of aqueous solution, amount of XAD-4-salen, kinds and concentration of acids were optimized for the analytical application of XAD-4-salen. For the pre-concentration of metal ions, the pH of the aqueous solution was adjusted to approximately 5.5, and then it was stirred 30 min after the addition of 50 mg of pulverized XAD-4-salen. The adsorbed metal ions were desorbed by 10 mL of 1.0 M HNO₃. The desorption efficiency of Bi(III) was enhanced by the addition of 30 mg/L of Pd(II). The addition of Pd(II) as a matrix modifier could improve the reproducibility and sensitivity in the Atomic Absorption Spectroscopy (AAS) determination of volatile lead and bismuth. In the present study, this procedure has been applied for the determination of Cu(II), Pb(II) and Bi(III) in real samples of five kinds of river water, using a standard calibration curve method. Recoveries of 85–120% were obtained in the spiked samples in which given amount of analytes were added.     

Organic-solvent-free systems with phase separation as efficient and safe systems for extraction of metal ions

The possibilities of using organic-solvent-free extraction systems with phase separation, based on antipyrine derivatives, are examined. Ionic associates with tin(II) and tin(IV) anionic complexes and mixed chelates of indium with antipyrine and sulfosalicylic acid are extracted into the organic phase. The suggested systems show promise for the recovery and determination of macro- and microamounts of indium, tin(II), and tin(IV) ions.     

Coupling of flow injection wetting-film extraction without segmentation and phase separation to flame atomic absorption spectrometry for the determination of trace copper in water samples

A flow injection wetting-film extraction system without segmentor and phase separator has been coupled to flame atomic absorption spectrometry for the determination of trace copper. Isobutyl methyl ketone (MIBK) was selected as coating solvent and 8-hydroxyquinoline (oxine) as the chelating reagent. By switching of a 8-channel valve and alternative initiation of two peristaltic pumps, MIBK, sample solution containing copper chelate of oxine, and air-segment sandwiched eluting solution (1.0 mol l⁻¹ nitric acid) were sequentially aspirated into an extraction coil made of PTFE tubing of 360 cm length and 0.5 mm i.d. The formation of organic film in the wall of the extraction coil, extraction of the copper chelate into the organic film and back-extraction of the analyte into the eluting solution occurred consecutively when these zones aspirated into the extraction coil were propelled down the extraction coil by a carrier solution at a flow rate of 2 ml min⁻¹. After leaving the extraction coil, the concentrated zone was transported to the nebulizer at its free uptake rate for atomization. Under the optimized conditions, an enrichment factor of 43 and a detection limit of 0.2 μg l⁻¹ copper were achieved at a sample throughput rate of 30 h⁻¹. Eleven determinations of a standard copper solution of 60 μg l⁻¹ gave a relative standard deviation of 1.5%. Foreign ions possibly present in tap water and natural water did not interfere with the copper determination. The developed method has been successfully used to the determination of copper content of tap water and river water.