借4-(2-噻唑偶氮)间苯二酚螯合物和反相高压液相色谱法以分离和测定钒、钴和铬

研究了V(Ⅴ)、Co(Ⅱ)和Cr(Ⅲ)的TAR螯合物的柱前衍生条件和反相高压液相色谱分离条件,并提出了同时测定ppb级的此三元素的新方法.于Zorbax ODS柱上,用含0.05mol·dm~(-3)Li_2SO_4和0.01mol·dm~(-3)HOAc-NaOAc(pH 6.0)的46∶54甲醇-水(v/v)溶液作流动相(0.7mL/min),可于15min内将此三螯合物分离并检测(525nm)完毕.此方法快速、经济、灵敏选择性好.     

反相高效液相色谱测定钴和镍的1-(5-溴-2-吡啶偶氮)-2-萘酚-6-磺酸螯合物

研究了1-(5-溴-2-吡啶偶氮)-2-萘酚-6-磺酸与钴(Ⅱ)和镍(Ⅱ)之螯合物的衍生和液相色谱分离条件。于Zorbax ODS柱上,用含0.01mol/L HAC-NaAc(pH 5.5)的乙腈-四氢呋喃-水(24:5:71,V/V)作流动相,流速0.7ml/min淋洗,于570nm检测。本方法已用于镍矿、催化剂回收液和人发样品的分析。     

锑对在硫酸溶液中形成的阳极Pb(Ⅱ)氧化物膜的半导体性质的影响Ⅲ. 交流阻抗法研究阳极Sb~2O~3膜

应用交流阻抗方法研究锑在0.005mol.dm^-^3SO~4+0.5mol.dm^-^3Na~2So~4溶液(30℃)中以0.9V(vs.Hg/Hg~2SO~4/0.005mol.dm^3SO~4)生长3h的阳极Sb~2O~3膜的半导体性质.从Mott-schottky曲线可知.此膜 为n型半导体.平带电位为-0.34v(vs.Hg/Hg~2SO~4/0.005mol.dm^-^3SO~4).施主密度为4.0×19^1^9cm^-^3.讨论了锑增加铅锑合金极PbⅡ氧化物膜施主密度的原因.     

2-(2-噻唑偶氮)-对-甲酚螯合物反相高效液相色谱同時分离测定镍、钴的研究——合金中微量钴和镍的测定

本文研究了2-(2-噻唑偶氮)-对-甲酚(TAC)与镍(Ⅱ)、钴(Ⅱ)螯合物的柱前衍生条件和液相色谱的分离条件。于KYWG-C_(18)柱上,用含有0.03mol/L KH_2PO_4-Na_2HPO_4(pH7.77)和2.5×10~(-4)mol/L TAC的甲醇-四氢呋喃-水(40∶10∶50 V/V)混合液为流动相,流速为1.0mL/min。于580nm处检测。该法用于四种标准合金中镍和钴的测定,回收率在98%～101.5%之间。Ni(Ⅱ)和Co(Ⅱ)的检出限(信噪比为2∶1)分别为0.2ng和1.5ng。建立了同时测定镍,钴的高灵敏、高选择性,快速的HPLC-光度法。     

2-(2-噻吩偶氮)-5-二乙氨基酚反相液相色谱法分离测定铜(Ⅱ)、钴(Ⅱ)、镍(Ⅱ)

本文以2-(2-噻吩偶氮)-5-二乙氨基酚(简称TADAP)作柱前显色剂,反相色谱法分离测定铜(Ⅱ)、钴(Ⅱ)、镍(Ⅱ)离子。用含有1.5×10~(-4)mol/L的TADAP,0.1mol/L氯化锂和0.1mol/L乙酸盐(pH4)的甲醇(60％)-水(40％)溶液作为流动相,流量为0.9ml/min,紫外-可见检测器检测波长为545nm。在此条件下,铜(Ⅱ)、钴(Ⅱ)、镍(Ⅱ)螯合物得到最佳分离,并定量测定了茶叶中铜、钴、镍的含量,与原子吸收分光光度法测定,得到一致的结果。     

双(2-羟乙基)二硫代氨基甲酸铵为螯合剂的液相色谱电化学检测重金属离子的研究

本文在自行合成水溶性螯合剂双(2-羟乙基)二硫代氨基甲酸铵基础上,研究其与镉(Ⅱ),铅(Ⅱ),钴(Ⅱ),镍(Ⅱ),铜(Ⅱ),汞(Ⅱ)之螯合物的液相色谱分离条件。于Nucleosil C_(18)柱上,用合0.05mol/L K_2HPO_4(pH=6.0)和0.01mol/L TBAP的甲醇-水(40:60,V/V)做流动相,流速0.8ml/min淋洗,于电位为+0.90V(vs.SCE)检测。对十七种元素做了干扰实验,除As对Ni峰,Se对Cu峰有干扰外,其它元素均无干扰。大量Co存在不影响Ni的测定。     

铁、钴和镍的2-(6-溴-2-苯并噻唑偶氮)-5-二乙氨基苯酚螯合物的高效液相色谱研究

分别于Shim-pack PNH_2和Zorbax CN柱上,研究了Fe(Ⅱ)、Co(Ⅱ)和Ni(Ⅱ)与6-Br-BTADAP之螯合物的HPLC分离条件;提出了于Shim-pack PNH_2柱上,用环己烷-乙酸乙酯-异丙醇(48:40:12,V/V)作流动相(1.0m/min)的HPLC同时测定此三元素的新方法。校正曲线之线性范围是0.025～4.0ppm Fe(Ⅱ)、0.1～2.0ppm Co(Ⅱ)和0.05～2.5ppm Ni(Ⅱ),其绝对检出限分别是0.61、0.40和0.20ng。异离子:Cd(Ⅱ)、Cu(Ⅱ)、Hg(Ⅱ)、Mn(Ⅱ)、Pb(Ⅱ)、Zn(Ⅱ)和Fe(Ⅱ),无干扰。本方法已应用于实际样品的分析。     

4,7-(氯磺酸基苯基)-1,10-菲啰啉-2,9-二羧酸-铕标记甲胎蛋白抗体

在合成BCPDA基础上 ,对甲胎蛋白抗体与BCPDA连接及与铕离子螯合条件进行了研究。BCPDA与甲胎蛋白抗体反应后 ,分离纯化最佳淋洗液为pH 9.1的 0 .1mol/L碳酸盐缓冲溶液 ,BCPDA用量为甲胎蛋白抗体量 (mol)的 12 0～ 16 0倍 ;反应时间为 30min。讨论了Eu3 + BCPDA AFP抗体螯合物的荧光光谱 ,最佳温育时间为6 0min ,体系pH值为 7.8的Tris HCl溶液。当Eu3 + 浓度为 10 -6mol/L时 ,BCPDA的检出限为 4 .3× 10 -11mol/L。     

离子色谱-紫外检测法分离测定吡啶离子液体阳离子

建立了用离子色谱-紫外检测法分离测定3种吡啶离子液体阳离子(N-乙基吡啶、N-丁基吡啶和N-丁基四甲基吡啶)的方法。采用磺酸型阳离子交换柱,以乙二胺-柠檬酸-乙腈为流动相,考察了流动相和色谱柱温度对离子保留的影响,探讨了保留规律。实验发现,吡啶阳离子的保留过程是放热过程。优化的色谱条件为：流动相是0.2 mmol//L乙二胺-0.3 mmol//L柠檬酸-0.5%(v/v)乙腈(pH 4.2),流速1.0 mL/min,柱温30℃。在此条件下可以基线分离3种吡啶阳离子。所测阳离子的检出限(S/N=3)分别为0.01、0.01、0.02 mg/L,峰面积的相对标准偏差(n=5)小于0.8%。将此方法应用于分析实验室合成的吡啶离子液体样品,加标回收率在96.3%～103.7%之间。本方法准确、可靠、快速,具有较好的实用性。     

硫酸铵-溴化钾铵-正丙醇体系萃取分离和富集锗的研究

研究了硫酸铵-溴化钾铵-正丙醇体系萃取分离和富集锗的行为及与一些金属离子分离的条件.硫酸铵能使正丙醇的水溶液分成两相,在分相过程中,Ge4+与KBr生成(GeBr62-),并与质子化正丙醇(C3H7OH2+)形成缔合物[GeBr62-][C3H7OH2+]2,此缔合物能被正丙醇相完全萃取.当正丙醇、KBr和硫酸铵的浓度分别为30％(V/V)、7.0×10-3mol/L、0.20g/mL时,(GeBr62-)的萃取率达到97.7％以上,而Ni2,Pb2,Cr3+,Co2,Fe3+,Al3+,Mg2+,Ag+,Bi3+,CH2,W(Ⅵ)和V(Ⅴ)基本不被萃取,实现了Ge4+与上述金属离子的分离.     

Reversed-phase ion-pair high performance liquid chromatographic determination of Co(III)-, Ni(II)-, V(V)- and Fe(III)-2-(2-benzothiazolylazo)-5-(3-sulforpropyl)aminophenol chelates

The separation and determination of Co(III), Ni(II), V(V) and Fe(III) chelates with 2-(2-benzothiazolylazo)-5-(3-sulfopropyl)aminophenol (BTASPAP) by reversed-phase ion-pair HPLC was investigated. In the presence of the oxidant potassium iodate, BTASPAP reacts with Co(III), Ni(II), V(V) and Fe(III) to form stable, negatively charged, water-soluble chelates. The chelates were separated on a C(18) siloxane bonded phase and eluted within 7 min with acetonitrile-acetate-water (36:1:63 v/v) containing 0.2 mol 1(-1) acetic acid-sodium acetate buffer (pH 3.0) and 1.0 mmol 1(-1) tetrabutylammonium bromide. The detection limits of Co(III), Ni(II), V(V) and Fe(III) at 565 nm are 0.3, 0.8, 0.3 and 1.0 ng (signal-to-noise ratio = 2), respectively. The method was applied to the determination of Co, Ni, V and Fe in four samples of standard alloys.     

Determination of trace amounts of vanadium in air samples with 2-(8-quinolylazo)-5-N,N-diethylaminophenol by reversed-phase liquid chromatography

A reversed-phase liquid chromatographic method for the determination of trace amounts of vanadium is described. Metal ions are converted into 2-(8-quinolylazo)-5-N,N-diethylaminophenol chelates in an off-line system. The chelates are injected onto a Zorbax CN column and separated with an aqueous acetonitrile mobile phase containing no chromogenic reagent. Unter these conditions, only vanadium(V) is spectrophotometrically detected at 540 nm among the metal ions Al(III), Ba(II), Ca(II), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Ga(III), Hg(II), Mg(II), Mn(II), Ni(II), Pb(II), V(V) and Zn(II). Amounts of 8.0–200 pg of vanadium(V) in 100-μl injections can be determined without interference from 10-fold molar excesses of many cations. At 0.001 a.u.f.s., the detection limit (twice the peak-to-peak noise) for vanadium(V) is 8.0 pg in 100 μl of injected solution and the relative standard deviation at 120 pg of vanadium(V) in a 100-μl injection is 3.5%. The proposed method is applied to the determination of vanadium in rain water and airborne particulates.     

Reversed-phase ion-pair partition liquid chromatography of chelates with 2-(3,5-dibromo-2-pyridylazo)-5-[N-ethyl-N-(3-sulphopropyl) amino] phenol and analogues

The ion-pair reversed-phase chromatography of some transition metal chelates with 2-(3,5-dibromo-2-pyridylazo)-5-[N-ethyl-N-(3-sulphopropyl)amino]phenol (3,5-diBr-PAESPAP) was studied. 3,5-DiBr-PAESPAP and its V(V), Cr(III), Fe(II), Co(III) and Ni(II) chelates were retained on and the copper (II), zinc(II) and cadmium(II) chelates dissociated in an ODS column using acetonitrile/water (37+63, v/v) (pH 7.0) containing 0.01 M acetate, 0.01 M 3-(N-morpholino)propanesulphonate buffer (pH 7.0) and 0.05 M Na⁺ as mobile phase. The chromatograms of 3,5-diBr-PAESPAP chelates were compared with those of the chelates with 2-(3,5-dibromo- 2-pyridylazo)-5-[N-(3-sulphopropyl)amino]phenol (3,5-diBr-PASPAP),2-(5-bromo-2- pyridylazo)-5-[N-(3-sulphopropyl)amino]phenol and 2-(5-bromo-2-pyridylazo)-5-[N-propyl-N- (3-sulphopropyl)amino] phenol. With 3,5-diBr-PAESPAP the Fe(II) and Ni(II) chelates were not resolved, but resolution was achieved with 3,5-diBr-PASPAP. The calibration graphs were linear over the ranges 2.0–10.0 ng (10-μl injection) of Fe, Ni and Co and for 20–100 ng (10-μl injection) for V with 3,5-diBr-PAESPAP and 3,5-diBr-PASPAP.     

Studies on oxovanadium(IV), Cr(III), Co(II), Ni(II), and Cu(II) chelates of some bisketimino ligands

The oxovanadium(IV), Cr(III), Ni(II), Co(II), and Cu(II) chelates of some bisketimino Schiff-base ligands (H₂L) obtained by condensation of 4-butyryl-3-methyl-1-phenyl-(or-1,3-diphenyl)-2-pyrazolin-5-ones with thiourea were synthesized and characterized by elemental analyses and thermogravimetric analyses, molar conductivities, magnetic susceptibility measurements, mass, infrared, and electronic spectroscopies. Ligand field parameters, such as splitting energy, Racah parameter, spin–orbit coupling constant, and covalency parameter of the Cr(III), Ni(II), and Co(II) chelates were calculated by band-fitting methods. Based on these studies, tetragonally distorted octahedral environment around OV(IV) and Cu(II) and octahedral Cr(III), Ni(II), and Co(II) have been proposed.     

Micellar chromatographic separation of vanadium(V) chelate with 2-(2-thiazolylazo)-5-dimethylaminophenol

Summary In reversed phase—high performance liquid chromatography for metal chelates with 2-(2-thiazolylazo)-5-dimethylaminophenol, an aqueous non-ionic surfactant solution is used as a mobile phase. Among V(V), Fe(III), Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Mn(II), and Al(III), only the V(V) chelate gave a resolved peak by using 0.8% w/w poly(oxyethylene)_n-4-nonylphenyl ether (n=20) solution buffered at pH 3.8. V(V) can be selectively separated and sensitively determined.     

Determination of cadmium, zinc, nickel and cobalt in tobacco by reversed-phase high-performance liquid chromatography with 2-(8-quinolylazo)-4,5-diphenylimidazole as a chelating reagent.

A sensitive and selective method has been developed for the simultaneous determination of cadmium, zinc, nickel and cobalt. The method is based on the chelation of metal ions with 2-(8-quinolylazo)-4,5-diphenylimidazole (QAI) and the subsequent reversed-phase (RP) high-performance liquid chromatographic separation and spectrophotometric detection of the metal chelates. The chelates were separated on an RP column with acetonitrile-water containing ethylenediamine tetraacetic acid and sodium acetate (pH 7.5). Though Zn(II) and Cd(II) chelates with azo compounds were generally labile in the RP column, these chelates with QAI were successfully detected. When analyses were carried out at 575 nm and at 0.001 absorbance unit full scale, the peak height calibration curves were linear up to 2.0 ng for Cd(II), 2.4 ng for Zn(II), 0.14 ng for Ni(II) and 0.72 ng for Co(II) in 100-microL injections, respectively; the detection limits (3sigma, three times of the standard deviation for the blank signal) for Cd(II), Zn(II), Ni(II) and Co(II) were 4.8, 24, 2.4 and 7.2 pg in 100 microL of injected solution, respectively. The proposed method was successfully applied to the analysis of tobacco without any preliminary concentration or separation.     

Pre-column chelation liquid chromatographic separation and determination of trace V,Cu, Co,Pd, Fe and Ni

Conditions for the separation by reversed-phase liquid chromatography (LC) of V(V), Cu(II), Co(III), Pd(II), Fe(III) and Ni(II) chelates with 2-(5-bromopyridylazo)-5-diethylaminophenol (5-Br-PADAP) were studied. Six species of metal chelates were separated successfully with methanol-acetonitrile-water (72:12:16, v/v/v) containing 0.13 M NaCl and 0.29 mM cetyltrimethylammonium bromide (pH 5.0) as the mobile phase on a Nucleosil C₁₈ (5 μm) column (250 × 4 mm i.d.).The conditions of the determination of these metal chelates are discussed. A simple and rapid method for the determination of trace amounts of V(V), Cu(II), Co(III), Pd(II) and Ni(II) simultaneously by reversed-phase LC has been developed. The detection limits are 5 × 10^?12, 1 × 10^?10, 3 × 10^?11, 5.3 × 10^?9 and 2 × 10^?10 g, respectively. The method is applied to the determination of these metals in natural waters and mineral samples.     

Preparation and Study of Decavanadate-Pillared Hydrotalcite-like Anionic Clays Containing Cobalt and Chromium

Hydrotalcite-like compounds containing Co(II) and Cr(III) in the brucite-like layers have been prepared. The interlayer anion was carbonate or decavanadate. The chemical formulas of the samples are [Co(0.65)Cr(0.35)(OH)(2)] (CO(3))(0.175).1.22H(2)O (sample CoCrC) and [Co(0.61)Cr(0.39)(OH)(2)](V(10)O(28))(0.065).1.35H(2)O (sample CoCrV). The compounds have been characterized by X-ray diffraction, XAS, vis-UV, FT-IR, and Raman spectroscopies, while the surface textures were assessed by nitrogen adsorption. Reducibility has been studied by temperature-programmed reduction. A similar characterization study has been carried out on samples obtained after calcination of the parent samples in air at increasing temperatures. Results indicate an ordered structure, with Co(II) and Cr(III) ions in octahedral holes of the brucite-like layers and, in CoCrV, decavanadate species with its main C(2) axis parallel to the layers. Thermal decomposition at increasing temperatures takes place, for CoCrC, through intermediate formation of Cr(VI) species, which are again reduced to Cr(III) at higher temperatures; simultaneously, Co(II) is oxidized to Co(III) (even at 673 K), thus leading to formation of Co(II)Co(III)Cr(III)O(4). However, decomposition of CoCrV takes place through partial depolymerization of decavanadate species and formation of Co(II)Cr(2)O(4) and Co(II)(2)V(2)O(7), without intermediate formation of Cr(VI) species.     

Reversed-phase HPLC determination of Co(II), Ni(II) and Fe(III) as their 2-(2-thiazolylazo)-5-dimethylaminophenol chelates

The optimum chromatographic separation conditions for Co(II), Ni(II), and Fe(III) chelates with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM) were investigated. The compositions of chelates were also determined by the HPLC method and thus the possible structure of chelates was given. A precolumn derivatization method was used, followed by separation on an octyl-bonded silica stationary phase with a methanol-tetrahydrofuran-water (40:9:51, v/v/v) mobile phase containing pH 5.8 acetate buffer and 1 x 10(-4)M TAM. The detection limits of Co(II), Ni(II), and Fe(III) at 560 nm are 0.03, 0.02 and 0.1 ng (S N = 2 ), respectively. They can be determined by means of the proposed method without interference from other common metal ions and have been determined in five standard alloys with satisfactory results.     

4-(5-溴-2-噻唑偶氮)间苯二酚反相阳离子对HPLC测定痕量铌、钒、铑、铬

本文报道新试剂4-(5-溴-2-噻唑偶氮)间苯二酚(5-Br-TAR)为柱前衍生试剂,以阳离子表面活性剂作为对离子试剂,用含15 mmol／L的pH 5.8的乙酸-乙酸钠缓冲溶液、0.05 mmol／L溴化钠、10 mmol／L TBA·Br的乙腈-甲醇-水(42 : 13：45,V／V／V)三元体系为流动相,在C8柱上25min内HPLC测定了Nb(V)、V(V)、Rh(Ⅲ)和Cr(Ⅵ)的5-BR-TAR螯合物。当SNR=2时,检出限分别为Nb(V)1.0、V(V)1.6、Rh(Ⅲ)0.9和Cr(Ⅵ)1.9μg／L。该方法用于测定污水中的铬和钒,结果良好。