硝酸钾-硫氰酸铵-水体系萃取浮选铜间接测定甲巯咪唑

建立了KNO3-NH4SCN-水体系萃取浮选铜间接测定甲巯咪唑的新方法.研究表明:在SCN-存在下,控制溶液pH 4.0～6.0,Cu(Ⅱ)可被甲巯咪唑分子中的巯基还原生成的Cu(I)与SCN-形成CuSCN白色乳状沉淀,加入KNO3可使该沉淀浮选至水相表面,通过测定溶液中剩余Cu(Ⅱ)的量,从而间接测定甲巯咪唑的含量.CuSCN的浮选率(E%)与甲巯咪唑的质量浓度呈良好的线性关系.当Cu(Ⅱ)加入量为50 μg时,测得线性范围为0.25～3.00 μg/mL(相关系数为0.9996).检出限为0.097 μg/mL.该法可用于片剂、血清、尿样中甲巯咪唑的测定.     

KBrO3-溴酚蓝体系催化光度法测定微量甲醛

在室温及H2SO4介质中, 基于甲醛对KBrO3氧化溴酚蓝有显著的促进作用, 建立了测定微量甲醛的动力学催化光度法. 方法的线性范围为0.70～11.0 μg/mL, 检出限为0.015 μg/mL. 用该方法对某实验室废水中甲醛含量进行了测定, 结果满意.     

催化光度法测定水中的氟

在中性溶液中,游离的F-对H2O2氧化酸性铬兰K褪色反应具有催化作用,基于此建立了测定微量F-的催化光度分析的新方法.结果表明,有色溶液的最大吸收波长为522 nm,测定的线性范围为0.4～11.2 μg/mL,检出限为9.9×10-4 μg/mL.该法用于水中微量F-的测定,结果令人满意.     

催化动力学荧光法测定水中氟

在酸性条件下,游离的F-对高碘酸钾氧化罗丹明B的反应具有催化作用,可使罗丹明B的荧光减弱.基于此,建立了测定微量F的催化动力学荧光光度分析新方法.结果表明:溶液的荧光激发波长和发射波长分别为562 nm、582 nm,测定的线性范围是0.04～2.6 μg/mL,检出限是0.032 μg/mL,并已用于水中微量F-的测定.     

吸附柱分离-离子色谱法测定锑中微量硫

建立了吸附柱分离-离子色谱法测定锑样中微量硫的方法.方法采用王水,氢溴酸,浓HCl等试剂将锑样溶解,并使锑样中的硫转化为SO42-,低温加热蒸干,使锑完全挥发.然后在氧化铝柱上过柱,用氨水洗脱,最后将处理好的样品溶液注入离子色谱系统进行分析测定.优化了离子色谱操作条件,以流速为1.2 mL/min的3.5 mmol/L的Na2CO3与1.0 mmol/L的NaHCO3作为淋洗液,对标准液和样品溶液的测定,线性范围为0.2～100 μg/mL,检出限为0.2 μg/mL,回收率为92.9%～103.1%,该法适合锑样中微量硫的测定.     

催化光度法测定蔬菜中微量碘的研究

在H3PO4介质中,碘对高碘酸钠氧化丁基罗丹明B的反应有显著的催化作用,据此建立了测定微量碘的催化动力学光度法.方法灵敏、简便、选择性好.测定Ⅰ-的检出限为17.7 ng/mL, 线性范围为0.02～2.00 μg/mL,已用于蔬菜中碘的测定.     

动力学光度法测定痕量维生素K3的研究

在氢氧化钠介质中,微量维生素K3,对高碘酸钾氧化苯并红紫4B褪色反应有明显的催化作用,据此建立了测定维生素K3含量的动力学光度分析法.确定了反应动力学参数,方法的线性范围为0.02～1.1 μg/mL.检出限为1.0×10-8 g/mL.方法用于维生素K3片剂中维生素K3含量的测定,结果令人满意.     

微波消解火焰原子吸收光谱法连续测定金银花中铁、锌、铜和锰

采用微波消化技术,以氘灯背景校正方式,在HNO3介质中,直接用火焰原子吸收法在同一体系中连续测定了金银花中微量元素Fe、Zn、Cu、Mn,并优化了最佳实验条件.在选定条件下,检出限为Fe 0.0047 μg/mL,Zn 0.0032μg/mL,Cu 0.0052μg/mL,Mn 0.0028μg/mL,相对标准偏差为1.5%～3.2%,回收率为96.4%～103.4%.适用于金银花中微量Fe、Zn、Cu、Mn的测定.     

CdTe量子点同步荧光法测定人血清白蛋白

以巯基乙酸(HS-CH2COOH)为稳定剂,水相中合成了CdTe量子点.在pH 6.40的0.002 mol/L KH2PO4-Na2HPO4缓冲溶液中,固定波长差为220 nm时一定量蛋白质的加入能明显增强量子点的同步荧光强度,并且荧光峰强度增加值与血清白蛋白浓度间存在良好的线性关系,据此建立了一种高灵敏度的测定微量蛋白质的方法.该方法测定人血清白蛋白的线性范围为0.08～2.80 μg/mL,检出限为0.032 μg/mL,10次重复测定1.80 μg/mL的血清白蛋白相对标准偏差为1.1%,已用于实际样品的测定.     

硫普罗宁的药代动力学及光度法测定

建立了光度法测定硫普罗宁的新方法。研究表明:在SCN-和KNO3存在下,控制溶液pH4.0,Cu(II)被硫普罗宁还原生成的Cu(I)与SCN-反应形成CuSCN沉淀,该沉淀能浮在水相表面。通过测定溶液中剩余Cu(II)的量,可以测定硫普罗宁的含量。吸光度与硫普罗宁浓度之间存在良好线性关系。线性方程:A=4.898-0.3616ρ(μg/mL),线性范围为0.25～12.0μg/mL,相关系数R=0.9993,检出限为0.16μg/mL。该方法可直接用于药物中硫普罗宁含量的测定及其药代动力学行为研究。     

Spectrophotometric determination of micro amounts of thiosulfate by liberation of thiocyanate from mercury(II) thiocyanate

The proposed determination of thiosulfate is based on the liberation of thiocyanate by the reaction of thiosulfate with mercury(II) thiocyanate and spectrophotometric determination of the thiocyanate with iron(III). The reaction of thiosulfate with mercury(II) thiocyanate is elucidated with reference to a system containing phosphate buffer; the phosphate is shown to participate directly in the reaction, and a balanced chemical equation is given. Optimum conditions are described for the stoichiometric formation of 3 mol of thiocyanate from 1 mol of thiosulfate. The method can be applied to the determination of thiosulfate in the range 3 × 10^?6–1.4 × 10^?4 M (1.7–78.5 μg thiosulfate in 5 ml).     

A reaction-rate method for the determination of thiocyanate,based on its inhibitory effect on the iodate-hypophosphite reaction

An automatic spectrophotometric reaction-rate method is described for the determination of thiocyanate in aqueous solutions, based on its inhibitory effect on the iodate-hypophosphite reaction. The time required for the reaction to proceed between two pre-determined levels is measured automatically and related directly to the thiocyanate concentration. The recommended reaction-rate method is fast, simple, sensitive, accurate (to 2%) and precise (1.7%, relative standard deviation). The useful analytical range of concentrations of thiocyanate is 4 × 10^?5 to 5 × 10^?4M. Maximum tolerable amounts of interfering ions are also presented.     

Indirect determination of thiocyanate with ammonium sulfate and ethanol by extraction-flotation of copper

A new method for the indirect determination of thiocyanate with ammonium sulfate and ethanol by extraction-flotation of copper in the presence of ascorbic acid is described. A small amount of Cu(II) is reduced to Cu(I) by ascorbic acid, then Cu(I) is precipitated with SCN-. In the course of phase separation of ethanol from water, the precipitated CuSCN stays in the interface of ethanol and water. A good linear relationship is observed between the flotation yield of Cu(II) and the amount of SCN-. Using 1.0 ml of 1 x 10(-3) M ascorbic acid solution, 50 micrograms of Cu(II), 3.5 g of (NH4)2SO4 and 3.0 ml of ethanol with a total volume of 10 ml, the concentration of thiocyanate could then be determined by determining the flotation yield of Cu(II). The detection limit for thiocyanate is 5 x 10(-5) M. Every parameter was optimized and the reaction mechanism was studied. The method is simple and rapid and it was successfully applied to the determination of thiocyanate in urine and saliva of smokers and non-smokers and in venous blood of patients infused with sodium nitroprusside.     

Determination of trace thiocyanate in body fluids by a kinetic fluorimetric method

A simple and very sensitive kinetic fluorimetric method is reported for the determination of trace amount of thiocyanate. The proposed method is based on the inhibition effect of thiocyanate on oxidation of rhodamine 6G by potassium bromate in sulfuric acid solution. The detection limit for thiocyanate is 1.63 x 10(-6) mmol/l. The linear range of the determination is 4.82 x 10(-6)-4.13 x 10(-5) mmol/l. This method has been used to determine trace thiocyanate in urine and saliva of smokers and non-smokers. The results obtained are satisfactory.     

Separation of trace amounts of palladium (II) with crown ether from hydrochloric acid and potassium thiocyanate media

A new method for the separation of trace amounts of palladium from hydrochloric acid and potassium thiocyanate media has been established based on the formation of an ion-pair complex of palladium thiocyanate anion Pd(SCN)4(2-) and the cationic potassium complex of dicyclohexyl- 18-crown-6 (DC18C6) in chloroform. The effect of various factors (solvent, crown ether, potassium thiocyanate, hydrochloric acid, reagent concentration, shaking time, phase volume ratio, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of palladium has been investigated. The method can be combined with subsequent FAAS determination of palladium. The procedure was applied to determine palladium traces in chloroplatinic acid and rhodium chloride.     

Spectrophotometric determination of chloride in plants

This indirect spectrophotometric determination of chloride in plants is based on displacement of thiocyanate from mercury(II) thiocyanate. Thiocyanate is extracted into nitrobenzene as tris(l,10-phenanthroline)iron(II) thiocyanate for measurement at 516 nm. Accuracy and precision are similar to those of the Volhard method but only about 2–200 mg samples are needed.     

Colorimetric recognition and sensing of thiocyanate with a gold nanoparticle probe and its application to the determination of thiocyanate in human urine samples

A colorimetric method for the determination of thiocyanate (SCN(-)) ion with a cystamine-modified gold nanoparticle (Au NP) probe is presented. In this method, recognition is based on electrostatic attraction and directional hydrogen bonding between thiocyanate and cystamine on the surface of an Au NP. In phosphate buffer solution (PBS, pH 5.2, 10 mM), the cystamine-modified Au NPs readily aggregated upon incubation with N,N-dimethyl-1-naphthylamine (denoted "2N"), and a visible change in the color of the solution from red to blue was observed. When present, thiocyanate interacted with the gold nanoparticle probe more prominently than 2N, thereby protecting the gold nanoparticles and attenuating the degree of aggregation. The solution was observed (by the naked eye) to change in color from blue to purple and then back to red as a function of thiocyanate concentration (<10 μM). Iodide was noted to be a significant interferent; however, the optical absorption spectrum in the presence of iodide was fortunately easily distinguished from that for thiocyanate, thereby making it possible to discriminate iodide from thiocyanate. It was possible to determine thiocyanate in human urine samples using this method. This colorimetric method opens up a new avenue for assaying thiocyanate considering its rapid readout and simple implementation, which makes it convenient to determine thiocyanate in biological samples, especially at levels below 100 μM.     

Determination of trace amounts of thiocyanate by a new kinetic procedure based on an induction period

A new, simple and sensitive kinetic spectrophotometric method with no need for removing of interfering substances is proposed for the determination of thiocyanate ion in biological and water samples. The procedure is based on the inhibiting effect of thiocyanate on the sodium periodate-potassium bromide-meta cresol purple (MCP) system in acidic media. The induction period of the reaction is proportional to the SCN- concentration. The decolorization of meta cresol purple by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. Under optimum conditions, thiocyanate can be determined in the range of 0.02-0.8 microg ml(-1) with a 3sigma detection limit of 5 ng ml(-1). The relative standard deviations for 10 replicate determinations of 0.060, 0.10 and 0.50 microg ml(-1) thiocyanate are 3.7, 2.4 and 1.0%, respectively. This method has been successfully used to the determination of thiocyanate content in smokers and non-smokers saliva and spiked water sample.     

Kinetic spectrophotometric determination of thiocyanate based on its inhibitory effect on the oxidation of methyl red by bromate.

A kinetic spectrophotometric method for measuring thiocyanate is described. The proposed method is based on the inhibitory effect of thiocyanate on the oxidation of Methyl Red by bromate in the presence of nitrite, which was monitored at 520 nm. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. Thiocyanate can be measured in the range of 0.05-1.1 microg ml(-1) with a detection limit of 0.025 microg ml(-1). This method has been used to determine trace thiocyanate in urine and tap water samples.     

Separation of trace amounts of palladium (II) with crown ether from hydrochloric acid and potassium thiocyanate media

A new method for the separation of trace amounts of palladium from hydrochloric acid and potassium thiocyanate media has been established based on the formation of an ion-pair complex of palladium thiocyanate anion Pd(SCN)₄ ^2– and the cationic potassium complex of dicyclohexyl-18-crown-6 (DC18C6) in chloroform. The effect of various factors (solvent, crown ether, potassium thiocyanate, hydrochloric acid, reagent concentration, shaking time, phase volume ratio, composition of the extracted species, foreign ions, etc.) on the extraction and back-extraction of palladium has been investigated. The method can be combined with subsequent FAAS determination of palladium. The procedure was applied to determine palladium traces in chloroplatinic acid and rhodium chloride.