甲基绿-高碘酸钾系统催化动力学光度法测定痕量铱(Ⅳ)

基于以H3PO4为反应介质,用HAc-NaAc(1+8)(pH5.7)作缓冲溶液,在沸水浴中加热条件下,痕量铱(Ⅳ)能灵敏地催化高碘酸钾氧化甲基绿的褪色反应,建立了一种测定痕量铱(Ⅳ)的新催化光度法。研究了反应的最佳条件。催化反应吸光度A与非催化反应吸光度A0的差值ΔA与铱(Ⅳ)的质量浓度ρ在0～2.0μg/25mL范围内呈良好的线性关系。检出限为2.97×10-10g/mL。对1μg/25mL铱(Ⅳ)测定的相对标准偏差为1.7%(n=11)。测定了动力学参数。该催化反应对铱(Ⅳ)为一级反应,总反应为准一级反应。反应的表观速率常数为4.613×10-4/s,表观活化能为40.56kJ/mol。该方法用于分子筛样品和活性炭中痕量铱(Ⅳ)的测定,回收率97.9%～104.4%。     

甲基红-高碘酸钾催化光度法测定铱

在稀硫酸介质中 ,铱可催化高碘酸钾氧化甲基红褪色 ,据此建立了一个测定铱的催化光度新方法。铱的浓度在 0～ 2 .0μg/ 2 5 m L范围内与催化反应速率呈线性关系 ,检出限为 6.44× 1 0 - 4μg/ m L。对 0 .1 μg Ir( )及 1 .0 μg Ir( )独立测定 1 0次的相对标准偏差分别为 1 .98%和 1 .82 %。本法对冶金产品和岩矿中铱测定的相对标准偏差为 0 .64%～ 2 .30 %,标准加入回收率为 98.8%～ 1 0 3.8%。     

铱催化高碘酸钾氧化钍试剂动力学光度法测定痕量铱

在磷酸和热水浴中,铱(Ⅳ)对高碘酸钾氧化钍试剂的反应具有催化作用,依此建立了测定铱的新催化光度法。铱的浓度在0.20μg/10mL～2.0μg/10mL范围内与催化反应速率有良好的线性关系,检出限为6.24×10-3μg/mL。对0.50μg/10mLIr(Ⅳ)测定的相对标准偏差为2.0%(n=10)。该催化反应对铱(Ⅳ)和钍试剂分别为一级反应,其表观活化能为81.66kJ/mol。实验了40多种共存离子的影响,大多数的常见离子不干扰。用该方法测定岩矿和冶金产品中铱的含量,相对标准偏差为1.0%～1.1%,加标回收率为95%～100%。     

二甲基黄催化动力学光度法测定痕量铱

基于在H3PO4介质中,Ir(Ⅳ)对KIO4氧化二甲基黄的反应具有催化作用,建立了测定痕量铱的新催化光度法.测定铱的线性范围为(3.2～8.8)×10-2 μg/mL,检出限为7.54×10-7 g/L.对0.04 μg/mL Ir(Ⅳ)测定的相对标准偏差为1.5%(n=11).该催化反应对Ir(Ⅳ)和二甲基黄均为一级反应,其表观活化能为103.8 kJ/mol.试验了40多种共存离子的影响,大多数的常见离子不干扰测定.用该方法测定了岩矿和冶金产品中铱的含量,相对标准偏差为0.93%～2.5%,加标回收率为98.2%～102%.     

催化褪色反应动力学法测定痕量铜

作者发现铜(Ⅱ)对过氧化氢在硫酸介质中氧化甲基橙的褪色反应有催化作用,找到了影响催化褪色反应的最佳条件,建立了测定痕量铜(Ⅱ)的新方法。灵敏度为9.22×10~(-11)g/ml,测定范围0～2.0μgCu~(2+)/50ml。用于测定几种实物样品中的痕量铜,得到满意的结果。相对标准偏差0.2％～2.3％。     

高碘酸钾氧化中性红褪色催化动力学光度法测定痕量硒(Ⅳ)

基于3.2×10-4mol/LH2SO4介质中,痕量硒(Ⅳ)催化KIO4氧化中性红的褪色反应,建立了测定痕量硒(Ⅳ)的动力学光度法。在固定加热时间段(6min)后,于530nm处测定中性红的吸光度降低值监控反应速率。方法检出限为0.36μg/L,校准曲线的质量浓度线性范围为0～8.0μg/L。实验了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响。研究了反应的最佳条件,并测定了一些动力学参数,催化反应的表观活化能为81.60kJ/mol。11次重复测定0.1μg/25mL和0.2μg/25mLSe(Ⅳ)的相对标准偏差分别为2.1%和1.9%。方法用于食品和人发样品中痕量硒(Ⅳ)的测定,相对标准偏差为0.33%～3.8%,加标回收率为96.0%～103.0%。     

新体系催化光度法测定痕量铁

研究了在硫酸介质,氯代十四烷基吡啶增溶增敏下,有活化剂存在,痕量铁催化抗坏血酸还原几种三氮烯类试剂的褪色反应,测定了反应级数及表观活化能.探讨了反应机理,建立了高选择性测定痕量铁的方法,线性范围0～12μg/25ml,相对标准偏差为3.2%(n=8).用于人发、水样及食品中痕量铁的测定.     

双波长双指示剂催化动力学光度法测定食品中的痕量铜

在pH=9.65的NH3-NH4Cl缓冲溶液中,利用Cu2+对H2O2氧化中性红和溴甲酚紫褪色反应具有较强的催化作用,通过测量460nm和590nm波长下催化体系和非催化体系的吸光度,建立了双指示剂、双波长催化动力学光度法测定痕量Cu2+的新方法。方法的线性范围为0.0060～0.072μg/mL,检出限为8.0×10-12g/mL。对Cu2+进行11次平行测定的相对标准偏差为2.9%。方法用于面粉和大米中痕量铜的测定,结果令人满意。     

铅试金-石墨炉原子吸收光谱法测定矿石中痕量铱的研究

以钯做灰吹保护剂，用铅试金分离富集硅酸盐矿石中的痕量铱，将钯-铱合金用王水溶解，建立了石墨炉原子吸收光谱测定矿石中痕量铱的分析方法。研究了铅试金熔剂配比、保护剂的类型及用量、灰吹温度对铱分离富集性能等因素对本方法的影响。实验结果表明：熔剂配比m(硼砂)∶m(纯碱)∶m(黄丹粉)∶m(淀粉)=5∶2∶10∶1,10 mg钯作为保护剂，灰吹温度900℃时，基于3 g称样量可完全富集矿石中20μg铱。方法的相对标准偏差(RSD,n=11)为3.70%～8.12%,线性范围为0.25～20.0μg/L,加标回收率为97.06%～99.13%,10倍于铱的其他共存贵金属对测定无干扰。该方法可用于含铱矿石的分析，用标准样品进行了方法验证，可满足矿石样品中铱的痕量分析。     

丁基罗丹明B-过硫酸钾催化动力学光度法测定痕量银

报道了以银催化过硫酸钾氧化丁基罗丹明B褪色的动力学光度法测定痕量银的方法。该法的线性范围为0.8~48μg/L,检出限为3.6×10-10g/mL。对浓度为24μg/LAg(Ⅰ)测定的相对标准偏差为2.1%(n=11),表观活化能为87.55kJ/mol。本法应用于磺胺嘧啶银乳膏中银的测定,相对标准偏差为2.3%~2.7%,回收率为97.4%~98.3%。     

MECHANISM OF PHOTOREDUCTION OF THIAZINE DYES BY EDTA STUDIED BY FLASH-PHOTOLYSIS-I

Abstract— The photoreduction of thiazine dyes by ethylene diamine tetraacetic acid (EDTA) was investigated by Rash photolysis. This reaction was found to occur according to a three-step mechanism. the first being the formation of the dye triplet state followed, in weakly acid solutions, by protonation. During the second step, the triplet state of the dye disappears through two competing processes: spontaneous deactivation and reaction with EDTA, which leads to the semireduced dye. The third step leads to the leucodye. It is shown that the overall quantum yield of photoreduction is governed by the second step and can be calculated from the ratio of the rate constants of the two elementary processes involved in this step. This ratio was measured over a wide pH range.     

溴酸钾氧化吖啶黄催化褪色光度法测定痕量亚硝酸根的研究

研究了在 0.10 mol·L-1的盐酸介质中,亚硝酸根催化溴酸钾氧化伯胺基结构碱性染料吖啶黄褪色反应的适宜条件与影响因素,建立了催化动力学褪色光度法测定痕量亚硝酸盐的新方法。亚硝酸根浓度在0.25~20.00μg/25 mL范围内符合比耳定律,其λmax=455nm,Sandell灵敏度为36.20 ng·cm-2,RSD为1.15%~5.97%,回收率为 97.5%~105.0%。方法用于环境样品、生物材料、食品等实际样品中亚硝酸根的测定,试剂简单,方法快速,选择性好,结果满意。     

SITES OF PHOTOSENSITIZATION BY DERIVATIVES OF HEMATOPORPHYRIN

Leukemia L1210 cells were incubated in vitro with the tumor-localizing product HPD (hem-atoporphyrin derivative) for 0.5. 4 and 18 h. Effects of subsequent irradiation on viability, membrane transport and integrity, DNA synthesis and intracellular ATP concentration were assessed. Intracellular porphyrin pools were analyzed by HPLC. A 30 min incubation led to concentration of a readily-exchangeable pool of monomeric HPD components at plasma membrane loci; irradiation resulted in photodamage to membrane transport and a loss in capacity for dye exclusion. In contrast, increasing the incubation time led to a corresponding increase in the size of a non-exchangeable intracellular pool of other HPD components. Subsequent irradiation led to depletion of intracellular ATP and loss of capacity for biosynthesis of DNA, but little plasma membrane damage.     

ANALYSIS OF THIOCYANATES BY NMR

Abstract

An unexpected nmr spectrum of β-phenyl ethyl thiocyanate in CDCl₃ solution has led to its analysis in a series of solvents of increasing polarity. Changes in polarity produce increments of ^δAB, transforming the signal from a singlet for 4 methylenic protons to a clear A₂B₂ pattern. Signals appear to split following increasing values of dielectric constants and dipole moments. Rotational isomerism is assumed to be the reason for it since the reaction field parameter depends directly on the dipole moments of rotamers, thus changes in their population affect the reaction field and ultimately the chemical shifts.     

DETERMINANTS OF PHOTOSENSITIZATION BY PURPURINS

The human colon adenocarcinoma cell line, WiDr, was exposed to Photofrin II, hematoporphyrin derivative (HPD), hematoporphyrin (HP) or tetrasodium-meso-tetra(4-sulfonatophyenyl)porphine (TPPS4) followed by irradiation with light. Clonogenicity was determined and the resultant survival curves compared and shown to be qualitatively similar in shape. However, for equal amounts of drug in the medium, there were large differences in photosensitizing efficiency with Photofrin II approximately 5, 25 and 50 fold more effective than HPD, HP and TTPS4, respectively. For the same power used, all drugs were less efficient photosensitizers under red light (600-1100 nm) than under white light (300-110 nm). For all drugs this could be explained in terms of changes in light absorption over the two wavelength ranges. Differences in clonogenic cell survival could not be explained in terms of differences in singlet oxygen production (from published values). A reduction in drug uptake into the cells was sufficient to explain the differences between Photofrin II, HPD and HP, while TPPS4 was 5-fold less effective compared to other drugs than would be expected from drug uptake measurements. Two methods for measuring drug uptake were compared and shown to give different results for Photofrin II. Measurements of drug fluorescence in 0.1 N NaOH yielded 5-fold lower values than when measurements were in 1 N HCl following heat treatment to monomerise aggregated drug. Clearly the reliability of the method used in determining drug uptake must be carefully ascertained.     

硫酸根的分光光度法测定

本文就硫酸根的间接及直接光度测定的基本原理，试剂，方法和应用等作了较为系统的评述。列出重要文献６７篇。     

超快速液相色谱法测定甲基苯丙胺

建立了用超快速液相色谱(UFLC)仪测定甲基苯丙胺含量的方法。采用XR-ODS柱,流动相为0.05%磷酸-甲醇(85∶15),流速为0.4 mL/min,检测波长为215 nm。该法在1~5000μg/mL浓度范围内线性关系良好,r2=0.9998,日内与日间保留时间和峰面积的相对标准偏差均小于6%,样品的加标回收率为92.4%~116.7%,检出限为0.68μg/mL。该方法适用于甲基苯丙胺的定性定量分析。     

PHOTOREDUCTION OF THIONINE BY WATER

Abstract —The photoreduction of thionine by water has been studied, using a technique applied in earlier work on photoreduction of methylene blue. It is found for thionine as for methylene blue, that a long-lived excited intermediate is formed, and that two such intermediates react to produce a single reduced molecule, thus providing adequate energy for the reaction. The mechanism proposed for methylene blue photoreduction is shown to be applicable to thionine photoreduction as well, indicating the unimportance of the amine methyl groups. Although in previous work it was suggested that H₂O was the reducing agent, none of them, however, could determine the H₂O₂ formed. The formation of H₂O₂ is confirmed in this work, and the kinetics of its formation are shown to be in accordance with the mechanism.     

PHENYLATION OF PYRIDINE BY PHOTOLYSIS OF DIPHENYL SULFONE

Abstract

The photolysis of diphenyl sulfone in neat pyridine or pyridine diluted with the organic solvent, with a high-pressure mercury arc lamp, was studied. The presence of acetone in the reaction system remarkably promoted photochemical conversion of the sulfone. The isomer distribution ratios (β > α > γ) of phenylpyridines produced during the reaction were clearly different from those (α > β > γ) so far reported for a free-radical phenylation of pyridine. Benzenesulfinic acid produced in the reaction was separated from the product mixture and identified as its S-benzylthiuronium derivative.     

膨润土吸附氨基酸研究

本文用钠、钙两种类型膨润上对四种不同性质氨基酸进行了静态吸附试验，并对膨润土吸附氨基酸有关因素进行了研究。试验证明：钙膨润土吸附氨基酸能力较强，酸处理膨润土吸附性最好，等电；点时吸附量最大。在浓度为500mg·L－1pH＝7溶液中，酸处理膨润土吸附赖氨酸可达200mmol·100g－1。