Use of the molybdenum-thiocyanate-rhodamine 6G ternary complex for spectrophotometric molybdenum determination without extraction

A modified thiocyanate method without extraction by using rhodamine 6G as a secondary ligand was developed. Molybdenum in 1.0×10⁻² M HCl, after the addition of ascorbic acid, was heated for 10 min in a 90 °C water bath for reduction. Suitable amounts of glycerine, Triton X-100, rhodamine 6G solutions and 2+1 (v/v) 9 M H₂SO₄+3 M KHSO₄ were added in this order. This solution was allowed to cool to room temperature and the absorbance at 570 nm was measured against a reagent blank 45 min after the addition of thiocyanate solution and the second aliquot of Triton X-100 solution. The complex was stable for at least 4 h, the order of reagent addition was important, and thiocyanate should be in large excess. Beer’s law was obeyed over the range 0.9×10⁻⁶ to 1.1×10⁻⁵ M Mo with the molar absorptivity being 1.1×10⁵ l mol⁻¹ cm⁻¹. The R.S.D. for the determination of 0.7 mg Mo l⁻¹ was 1.83% (n=8). Possible interferences of various cations and anions on molybdenum determination were studied. The proposed method was applied to the determination of molybdenum in a dental alloy, Wiron 99.     

Simultaneous kinetic spectrophotometric determination of cyanide and thiocyanate using the partial least squares (PLS) regression

The partial least squares (PLS-1) calibration model based on spectrophotometric measurement, for the simultaneous determination of CN⁻ and SCN⁻ ions is described. The method is based on the difference in the rate of the reaction between CN⁻ and SCN⁻ ions with chloramine-T in a pH 4.0 buffer solution and at 30 °C. The produced cyanogen chloride (CNCl) reacts with pyridine and the product condenses with barbituric acid and forms a final colored product. The absorption kinetic profiles of the solutions were monitored by measuring absorbance at 578 nm in the time range 20-180 s after initiation of the reaction with 2 s intervals. The experimental calibration matrix for partial least squares (PLS-1) calibration was designed with 31 samples. The cross-validation method was used for selecting the number of factors. The results showed that simultaneous determination could be performed in the range 10.0-900.0 and 50.0-1200.0 ng mL⁻¹ for CN⁻ and SCN⁻ ions, respectively. The proposed method was successfully applied to the simultaneous determination of cyanide and thiocyanate in water samples.     

Highly Thiocyanate‐Selective PVC Membrane Electrode Based on Lipophilic Ferrocene Derivative

A novel anion‐selective PVC membrane electrode based on bis‐[(3‐ferrocenyl)‐(2‐crotonic acid)] copper(II) complex [Cu(II)‐BFCA] as neutral carrier is described, which demonstrates excellent potentiometric response characteristics toward thiocyanate ion and anti‐Hofmeister selectivity sequence in following order: SCN^?>I^?>ClO >Sal^?>Br^?>NO >Cl^?≈NO >SO >SO . The electrode shows a near‐Nernstian response for thiocyanate ion in a wide range of 9.0×10^?7–1.0×10^?1 M with a detection limit 6.8×10^?7 M and a slope of ?59.1 mV/decade in pH 5.0 of phosphate buffer solution at 20 °C. The influences of lipophilic cationic and anionic additives on the response properties of the electrode were investigated. High sensitivity and wide linear dynamic range were observed for the electrode in the presence of hexadecyltrimethylammoniumborate (HTAB) as a lipophilic cationic additive. The electrode was successfully applied to the determination of thiocyanate ion in waste water and human saliva.     

一种新的ⅥA族化学反应振荡器：Na_2S_2O_8－KSCN－CuSO_4体系

一种新的ⅥＡ族化学反应振荡器：Ｎａ_２Ｓ_２Ｏ_８－ＫＳＣＮ－ＣｕＳＯ_４体系林娟娟，高庆宇，宋浩，黄振炎，赵学庄（南开大学化学系，天津，３０００７１）关键词化学振荡，非线性化学反应，过硫酸盐，硫氰酸盐自经典的均相ＢＺ化学振荡反应体系的发现及提出耗散结构...     

Facile Conversion of Epoxides to Thiiranes with Ammonium Thiocyanate Catalyzed with Oxalic Acid

Epoxids are efficiently converted to the corresponding thiiranes by ammonium thiocyanate (NH 4 SCN) in the presence of catalytic amounts of oxalic acid with excellent isolated yields under mild and nonaqueous reaction conditions. This conversion performed under both conventional heating and microwave conditions. Distinct rate enhancement is observed under microwave irradiation.     

Optimizing the Electrocatalytic Activity of Surface Confined Co Macrocyclics for the Electrooxidation of Thiocyanate at pH 4

We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH 4 exhibit linear amperometric response for thiocyanate concentration in the range 10^?7 and 10^?3 M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation.     

离子色谱法测定液体乳制品中硫氰酸盐

提出了离子色谱法测定液体乳中硫氰酸盐的方法。鲜奶或酸奶样品经乙腈提取和C18固相萃取柱净化后,再经Ion Pac AG11-HG保护柱及Dionex ICS-3000分离柱分离,由70 mmol.L-1氢氧化钾溶液洗脱,利用电导检测器检测。硫氰酸盐的质量浓度在0.20～10.0 mg.L-1范围内呈线性,方法的检出限(3S/N)为0.08 mg.L-1。方法用于鲜奶和酸奶样品分析,回收率在92.5%～104.5%之间,相对标准偏差(n=6)小于4.5%。     

A novel thiocyanate-selective electrode based on a zinc–phthalocyanine complex

A novel thiocyanate (SCN⁻)-selective PVC membrane electrode based on a zinc-phthalocyanine (ZnPc) complex as neutral carrier is described. The membrane electrode containing ZnPc with 5.1% (w/w) ionophore, 29.2% (w/w) PVC, and 65.7% (w/w) 2-nitrophenyl octyl ether (o-NPOE) as plasticizer displayed an anti-Hofmeister selectivity sequence , and exhibited near-Nernstian potential response to thiocyanate ranging from about 1.0×10⁻¹ to 1.0×10⁻⁶ mol L⁻¹ with a detection limit of 7.5×10⁻⁷ mol L⁻¹ and a slope of 58.1±0.5 mV per decade in pH 3.0 phosphate buffer solution at 25 °C. This preferential response is believed to be associated with the unique coordination between the central metal of the carrier and thiocyanate.      

Syntheses and crystal structures of two cadmium coordination polymers [Cd(2-mBIM)(NCS)(SCN)] n and [Cd2(2-mBIM)2(NO3)2(C4H4O4)(H2O)5] n based on bis(2-methylimidazol-1-yl)methane

Two cadmium(II) coordination polymers, [Cd(2-mBIM)(NCS)(SCN)] _n (1) and [Cd₂(2-mBIM)₂(NO₃)₂(C₄H₄O₄)(H₂O)₅] _n (2) (2-mBIM = bis(2-methylimidazo-1-yl)methane, C₄H₄O₄= succinate), have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in the triclinic space group P 1 with a = 9.0770(5) Å, b = 9.4043(4) Å, c = 19.8720(9) Å, α = 101.551(1)°, β = 93.498(1)°, γ = 108.484(1)°, V = 1562.02(13) ų, and Z = 2. Each Cd(II) is octahedrally coordinated and connected with two adjacent Cd(II)'s by double end-to-end thiocyanate bridges, resulting in the formation of 1-D zigzag chains, linked to each other via bridging 2-mBIM giving a 2-D supramolecular framework. Complex 2 crystallizes in the monoclinic space group P2(1)/n with a = 12.6543(6) Å, b = 7.7128(4) Å, c = 17.3089(9) Å, β = 109.3980(10)°, V = 1593.45(14) ų, and Z = 2. Cd(II) is coordinated with oxygen and nitrogens from two independent 2-mBIM, in a cis-configuration to form a 1-D helical structure. A 3-D supramolecular network comprised of succinate anion bridged 1-D helical chains, and weak hydrogen bonds between dimer waters gave 2-D layers.