State of Platinum Group Metals and Gold in Mineral Acid Solutions and the Catalytic Activity of These Metals in the Oxidation of N-Methyldiphenylamine-4-Sulfonic Acid

The state of rhodium, iridium, platinum, and gold in HCl, HClO₄, H₂SO₄, and HNO₃ solutions was studied by capillary electrophoresis. The electrophoresis was performed in an acidic phosphate buffer solution using an unmodified fused-silica capillary. It was found that the catalytic activity of the metals in the reaction of N-methyldiphenylamine-4-sulfonic acid oxidation with periodates in weakly acidic solutions depends on the analyte speciation. It was found that rhodium and iridium cations formed upon the treatment of a sample with concentrated perchloric acid catalyze the above reaction; this is favorable for the selective determination of these cations in the presence of platinum and gold.     

Etude du pouvoir oxydant de quelques periodates de tetraalkylammonium en milieu non aqueux

The reactivity of some tetraalkylammonium periodates in periodate oxidation has been studied by electrochemistry in non-aqueous media. Conductimetric and spectrometric investigations suggest the existence of different forms of periodate, depending on the concentration and on the properties of the solvents. A study of the relation between structure and reactivity is introduced.     

Decarboxylation with Carbon Monoxide: The Direct Conversion of Carboxylic Acids into Potent Acid Triflate Electrophiles

We report a new strategy for the conversion of carboxylic acids into potent acid triflate electrophiles. The reaction involves oxidative carbonylation of carboxylic acids with I₂ in the presence of AgOTf, and is postulated to proceed via acyl hypoiodites that react with CO to form acid triflates. Coupling this chemistry with subsequent trapping with arenes offers a mild, room temperature approach to generate ketones directly from broadly available carboxylic acids without the use of corrosive and reactive Lewis or Bronsted acid additives, and instead from compounds that are readily available, stable, and functional group compatible.     

Cation-cation interactions between uranyl cations in a polar open-framework uranyl periodate

Novel open-framework alkali metal uranyl periodates, having the formula A[(UO2)3(HIO6)(OH)(O)(H2O)].1.5H2O (A = Li, Na, K, Rb, Cs), have been prepared through mild hydrothermal synthesis. These isostructural compounds contain distorted UO7 pentagonal bipyramids that are linked through a uranyl (UO22+) to uranyl cation-cation interaction. This interaction arises from a single axial uranyl oxygen coordinating at an equatorial site of an adjacent uranyl unit. These uranium oxide polyhedra are further bound by IO6 distorted octahedra creating an open-framework structure whose channels contain the alkali metal cations.     

Highly sensitive and selective amperometric sensors for nanomolar detection of iodate and periodate based on glassy carbon electrode modified with iridium oxide nanoparticles

Iridium oxide nanoparticles are grown on a glassy carbon electrode by electrodepositing method. The electrochemical behavior and electrocatalytic activity of modified electrode towards reduction of iodate and periodate are studied. The reductions of both ions occur at the unusual positive peak potential of 0.7 V vs. reference electrode. The modified electrode is employed successfully for iodate and periodates detection using cyclic voltammetry, hydrodynamic amperometry and flow injection analysis (FIA). In the performed experiments, flow injection amperometric determination of iodate and periodate yielded calibration curves with the following characteristics: linear dynamic range up to 100 and 80 μM, sensitivity of 140.9 and 150.6 nA μM⁻¹ and detection limits of 5 and 36 nM, respectively. The repeatability of the modified electrode for 21 injections of 1.5 μM of iodate solution is 1.5%. The interference effects of NO₂⁻, NO₃⁻, ClO₃⁻, BrO₃⁻, ClO₄⁻, SO₄²⁻, Cu²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Cd²⁺, Ca²⁺, Na⁺, K⁺, NH₄⁺ and K⁺, CH₃COO⁻ and glucose were negligible at the concentration ratio of more than 1000. The obtained attractive analytical performance together with high selectivity and simplicity of the proposed method provide an effective and e novel modified electrode to develop an iodate and periodate sensor. Sensitivity, selectivity, the liner concentration range and the detection limit of the developed sensor are all much better than all known similar sensors in the literature for iodate and periodate determination.     

The determination of nitrate by infrared spectroscopy

Summary Nitrate may be determined by precipitation with nitron acetate and determination of the absorbance at 7.3 in a potassium bromide disc. The results are reproducible at milligram levels with a standard deviation of around ±5%. The presence of twice the amount of nitrite, perchlorate, bromate, chlorate, chromate, periodate or iodide has no significant effect on the determination.

---

Zusammenfassung Nach Fällung mit Nitronacetat läßt sich Nitrat durch Messung der Absorption bei 7,3 in Kaliumbromid bestimmen. Die Resultate sind im Milligramm-Maßstab mit einer Standardabweichung von etwa ±5% reproduzierbar. Die gleichzeitige Anwesenheit der doppelten Menge Nitrit, Perchlorat, Bromat, Chlorat, Chromat, Perjodat oder Jodid hat keinen merklichen Einfluß auf die Bestimmung.

---

Résumé On peut doser les nitrates par précipitation par l'acétate de nitron et mesure de l'absorption à 7,3 sur pastille en bromure de potassium. Les résultats sont reproductibles à l'échelle du milligramme avec une déviation standard de ±5% environ. La présence d'une quantité double de nitrites, perchlorates, bromates, chlorates, chromates, periodates ou iodures ne produit pas d'effet important sur le dosage.

     

(n, 2n) reactions in iodate and periodate systems

The chemical consequences of (n,2n) reactions on crystalline sodium iodates and sodium periodates, containing¹²⁷I or¹²⁷I+¹²⁹I, were investigated measuring the initial yields and the post irradiation thermal annealing yields at 90°C for three separated fractions: I+I^o, IO ₃ ^– and IO ₄ ^– . The results show different effects for each system and neither isotope effect nor qualitative differences on thermal annealing were observed. The influence of the nuclear reaction type, of the hot-atom's nature and of the structural and chemical environment are discussed.     

Investigation of the thermal decomposition of some periodates by means of emanation thermal analysis (ETA) and DTA

Thermal decomposition of Be₃(IO₅)₂ · 12H₂O, Mg₂I₂O₉ · 11H₂O, Ca₂I₂O₉ · 9H₂O and Ba₂I₂O₉ · 9H₂O in the temperature interval of 20 to 600° was studied by means of emanation thermal analysis (ETA) and differential thermal analysis (DTA). The magnetic properties of decomposition intermediates of periodates studied are discussed.     

Na2EDTA滴定法测定铜冶炼烟尘中铋含量

研究了测定铜冶炼烟尘中铋含量的Na_2EDTA络合滴定方法。对测定体系中的各干扰元素进行了研究,探讨了测定方法的各项测定条件。方法的相对标准偏差为0.40%～0.67%,样品加标回收率在99.9%～100%,方法精密度高,准确度好。适用于铜冶炼烟尘中铋含量为5.00%～16.00%的测定。     

溴酸钾滴定法测定铜冶炼烟尘中的砷含量

研究了测定铜冶炼烟尘中砷含量的溴酸钾滴定方法。对测定体系中的各共存元素进行研究,探讨了测定方法的各项测定条件,方法的相对标准偏差RSD为0.13%～0.61%,样品加标回收率在99.5%～100%,方法精密度高,准确度好,适用于铜冶炼烟尘中砷含量为1.00%～50.00%的测定。     

双指示物质动力学分析法研究Ⅰ.锰(Ⅱ)-乙二胺四乙酸二钠-铬(Ⅵ)催化体系

本文报道了双指示物质测定痕量锰的新催化光度法, 探讨了该方法的理论基础,确定了催化体系的适宜反应条件.本办法灵敏度比单指示物质法高6.4倍,用于测定谷物样品中锰.     

分光光度法同时测定多元素的研究(Ⅱ)——以CPA-矩阵法计算混合体系中微量锆和铪

本文将m-NPF+CTMAB体系用于锆、铪混合物中微量锆、铪的同时测定。确定了同时测定锆,铪的最佳实验条件。通过使用CPA-矩阵法计算解决了混合体系中锆、铪分量的测定;对光度分析中应用CPA-矩阵法的关键——选择适宜的测定波长问题作了进一步讨论,提出了“相关波长”和“相关组份”的概念。     

催化电位滴定法测定铬鞣剂中铬(Ⅲ)

报道了以氨三乙酸存在下锰(Ⅱ)催化KIO4氧化结晶紫的反应指示终点,结晶紫电极作指示电极用催化电位滴定法测定铬鞣剂中Cr(Ⅲ)的方法。该法终点灵敏、准确度高、重现性好,结果满意,用标准加入法测得的平均回收率为100.03%,RSD为0.24%。     

荧光素与牛血清蛋白作用的光谱研究与分析应用

研究了在生理条件下,荧光素与牛血清白蛋白相互作用形成复合物,最大吸收峰的波长480nm,比荧光素红移9nm。该法简便、快速,线性范围宽,干扰少,灵敏度较高,用于牛血蛋白样品测定的结果准确。     

Simultaneous determination of antazoline and naphazoline by the net analyte signal standard addition method and spectrophotometric technique

A novel net analyte signal standard addition method (NASSAM) was used for simultaneous determination of the drugs anthazoline and naphazoline. The NASSAM can be applied for determination of analytes in the presence of known interferents. The proposed method is used to eliminate the calibration and prediction steps of multivariate calibration methods; the determination is carried out in a single step for each analyte. The accuracy of the predictions against the H-point standard addition method is independent of the shape of the analyte and interferent spectra. The net analyte signal concept was also used to calculate multivariate analytical figures of merit, such as LOD, selectivity, and sensitivity. The method was successfully applied to the simultaneous determination of anthazoline and naphazoline in a commercial eye drop sample.     

Chemical effects of (n, γ) reactions in periodate systems

Szilard-Chalmers effect in crystalline periodates NaIO₄, Na₃H₂IO₆ and Na₄I₂O₉·3H₂O containing¹²⁷I and¹²⁷I+¹²⁹I was investigated. The initial yields and thermal annealing behaviour of the¹²⁸I and¹³⁰I induced activities were found to be different for each type of periodate; both isotopes kept their own behaviour in systems having at the same time¹²⁸I+¹³⁰I and an isotope effect was evident. The de-excitation of the hot atoms through Auger processes and subsequent relaxation steps in a particular chemical and structural environment seems to explain the results better than nuclear recoil.     

Selective kinetic spectrophotometric determination of copper at nanograms per milliliter level

A sensitive and selective kinetic method is proposed for the determination of nanogram amounts of copper. The method is based on the catalytic effect of copper on the reduction of Ponceau S by sodium sulfide in an alkaline media. The rate of the reaction is monitored spectrophotometrically at 560 nm. The method allows determination of copper concentrations in the range 2-400 ng ml(-1) with a relative standard deviation of approximately 2%. The proposed method, which is highly selective to copper, has been applied satisfactory to its determination in real samples.     

Kinetic spectrophotometric determination of rutin by its inhibitory effect on the oxidation of amaranth by potassium periodate

A novel kinetic spectrophotometric method is described for the determination of rutin. The method is based on the inhibitory effect of rutin on the oxidation reaction of amaranth by potassium periodate in acidic media at 100 degrees C. The linear range for the determination of rutin is 0.02 - 0.50 microg/ml, and the detection limit is 0.014 microg/ml. The method has been successfully applied to the determination of rutin in medicine of rutin tablet and traditional Chinese medicine.     

动力学荧光光度法测定己烯雌酚

基于酸性介质中己烯雌酚对羟自由基与吖啶橙氧化还原反应的阻抑作用,建立了测定己烯雌酚的动力学荧光分析新方法。方法线性范围为0.1~50 ng/mL,检出限为0.03 ng/mL。