共查询到20条相似文献,搜索用时 93 毫秒
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高甲友 《理化检验(化学分册)》2003,39(2):96-98
在H2SO4-NH4OAc(pH3.5)溶液中,巯基乙酸有一灵敏的还原波。当使用单扫描极谱法时,其二阶导数峰电位位于-0.320V(vs.SCE)。用直流极谱法,单极描极谱法和循环伏安法研究了该体系的极谱行为和电极反应机理。结果表明,当使用单扫描极谱法时,该体系属于有吸附性的准可逆过程,测得电极反应电子转移数n=1,H^ ,反应数n′=1。用单扫描极谱法可测定巯基乙酸,测定的线性范围为0.04-2.0mg.L^-1,该方法用于冷烫液中巯基乙酸的测定,结果满意。 相似文献
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极谱(伏安)吸附平行催化波法研究及应用近况 总被引:4,自引:0,他引:4
综述了极谱(伏安)吸附平行催化波的研究及应用,从无机 变价离子测定体系、无机非变价离子测定体系及有机去极剂测定体系3个方面介绍了该法的应用近况。 相似文献
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微量硅的测定一般采用硅钼黄或硅钼蓝比色法,这类方法的灵敏度较低,干扰较多;催化动力学测定微量硅操作繁琐,影响因素多、重现性和精密度较差,实际应用不多;文献[3]曾报道过硅钼杂多酸-碱性染料三元配合物光度法测定微量硅的方法。作者发现,在盐酸介质中,硅锑钼蓝三元杂多酸与罗丹明B形成的四元配合物有一灵敏的极谱波峰,从而建立了示波极谱法测定微量硅的新方法。试验表明,在HCl(0.1mol· 相似文献
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通过测定产物间接测定扁桃甙,如用酶修饰电极测定产物氢氰酸和葡萄糖,其检测限均在10~(-5) mol/L。本文首次采用卷积伏安法研究了扁桃甙的水解以及产物苯甲醛的极谱行为,提高了扁桃甙的检测限。 1 仪器与试剂 XJP-821型新极谱仪(长春应用化学研究所、江苏电分析仪器厂),三电极体系,LZ3-100 相似文献
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单扫描示波极谱法测定人发中磷 总被引:2,自引:0,他引:2
用极谱法直接测人发中磷的方法至今未见报道。本文在文献[1]工作基础上,对其测定条件进行了探讨和改进,并应用于人发中磷的直接测定,获满意结果。磷和钼在酸性条件及抗坏血酸的催化作用下,迅速形成具有电活性的二元磷钼杂多酸,此杂多酸在氨性缓冲溶液介质中(pH 9.5~10.4)产生灵敏的吸附还原波,磷与该波在0.03~15μg/10ml范围内呈线性关系。本法操作简便、快速灵敏。 相似文献
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食品中铅的测定方法多数沿用经典的双硫腙比色法,其他如A.A.S法等由于仪器昂贵不易推广。本文在文献的基础上,以磷酸—氢溴酸—辛可宁为体系以吸附催化极谱法对汾洒等白洒中痕量铅进行了测定,同时与溶出伏安法进行了对照,结果一致。方法的检测限为1×10~(-9)g/ml,标准偏差为0.002,变异系数为2.7%,回收率为91—102%。在示波极谱仪的—0.52%V(VS.S.C.E)范围内得到导数极谱波,其峰高与铅含量在0.01~0.5μg/ml范围内有良好的线性关系。能满足白洒及其他饮料中痕量铅的测定。本法有实用意义。 相似文献
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Abstract— In dimethylsulfoxide the emission spectrum of luminol chemiluminescence is red-shifted by 300 cm-1 from the photoexcited fluorescence of the product 3-aminophthalate dianion, while in aqueous solvent the two spectra are identical. The spectral properties of the product dianion have been measured in aqueous solvent and in a number of aprotic solvents, both at room temperature and at 77°K. The ground states and the excited states from which emissions are observed are characterized. Two alternatives are presented to explain the aprotic emission spectra. 相似文献
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WielA. G. BrulsJoop A. J. Faber†Jan C. van der Leun 《Photochemistry and photobiology》1982,36(5):531-535
The minimal erythema dose (MED) is often used as a quantity by which the influence of certain treatments of the skin can be measured. Differential measurements are performed by assessing the difference of the MED on the skin treated in some way and the untreated skin.
As the MED-measuring scale is discrete, the question is sometimes raised whether it is possible to measure differences smaller than one scale unit. In the present paper it is shown that this is indeed possible; in principle the discreteness of the scale does not impose any restriction on the smallest value of the difference that can be measured. The discreteness of the scale introduces an extra random variation into the measurement. This variation is estimated theoretically. It is automatically included in the usual error analysis.
The discreteness variance is small when compared to other variance components, which are computed from an analysis of variance of actual experiments. Reducing the discreteness variance, by reducing the dose decrement of the MED-measuring scale, therefore, does not enhance the overall accuracy considerably. Finally, it is found that the assessments of the MED by the various observers do not differ significantly from each other, and that multiple assessments do increase the accuracy, especially for small effects. 相似文献
As the MED-measuring scale is discrete, the question is sometimes raised whether it is possible to measure differences smaller than one scale unit. In the present paper it is shown that this is indeed possible; in principle the discreteness of the scale does not impose any restriction on the smallest value of the difference that can be measured. The discreteness of the scale introduces an extra random variation into the measurement. This variation is estimated theoretically. It is automatically included in the usual error analysis.
The discreteness variance is small when compared to other variance components, which are computed from an analysis of variance of actual experiments. Reducing the discreteness variance, by reducing the dose decrement of the MED-measuring scale, therefore, does not enhance the overall accuracy considerably. Finally, it is found that the assessments of the MED by the various observers do not differ significantly from each other, and that multiple assessments do increase the accuracy, especially for small effects. 相似文献
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对苯二胺衍生物的光催化氧化 总被引:1,自引:0,他引:1
以TiO2作为催化剂,利用波长>330nm的光辐照研究了N-取代的对苯-二胺衍生物的光催化氧化。研究表明,氧分子与光生电子 反应生成羟基自由基,羟基自由基氧化PPDs,生成醌二亚胺,后者在羟基的进攻下脱氨生成苯醌,苯醌继续光解无机化。PPDs光催化氧化近似遵循一级反应动力学,醇类和硫酸根离子可抑制PPDs的光催化氧化。催化剂表面荷影响电子转移速率,从而控制光催化氧化的反应速率。 相似文献
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Abstract— The complexity of the room-temperature emission spectrum of Chlorella was investigated by a matrix analysis method. This approach revealed the presence of two independently fluorescent components in the short-wave region of the spectrum. These components, maximal at about 687 and 695 nm, appeared to correspond to the fluorescence of the bulk pigments of PS II and PS I respectively. The analysis was insensitive to the individual species within the photosystems. As such, other minor fluorescent species, usually observed at low temperatures, which presumably correspond to fluorescence from the trapping centres, did not appreciably complicate the analysis. The absorption spectra of the two photosystems were calculated from the fluorescence data. The results were similar to those that have been obtained by other workers from oxygen evolution and DCMU poisoning data but differed from those obtained by computer analysis of the absorption spectrum. Addition of reduced DCPIP was observed to reverse the increase in fluorescence yield and changes in the spectral distribution of emission taking place on poisoning the algae. The correlation between this and the catalysis of photophos-phorylation in aged or poisoned chloroplasts was noted. This correlation was tentatively interpreted as evidence for a direct interaction between the donor system and the photochemical apparatus associated with PS II, rather than with a member of the electron transport chain as is normally assumed. 相似文献
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纳米SiO2锚固光敏基团引发MMA光接枝聚合研究 总被引:1,自引:0,他引:1
对纳米SiO2进行了锚固光引发剂的表面修饰,进而引发甲基丙烯酸甲脂(MMA)光接枝聚合制备有机/无机复合粒子.纳米SiO2粒子首先用氯化亚砜进行表面氯化,再与光引发剂2-羟基-4-(2-羟基乙氧基)-2-甲基苯丙酮(Irgacure2959)反应从而锚固上光引发剂.通过紫外光引发MMA在经过修饰过的纳米SiO2表面上进行表面光接枝聚合.采用IR、TGA和TEM等方法表征了接枝前后纳米粒子的变化,证明了表面接枝物的存在,并研究了不同反应条件对单体转化率、接枝率和接枝效率的影响.研究结果表明,搅拌对接枝过程的影响比较显著.TGA结果显示未搅拌聚合时接枝率只能达到比较小的程度,而在搅拌条件下180min内MMA的接枝率可达到110%. 相似文献
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研究了6′-硝基-1,3,3-三甲基吲(口乃木)苯骈螺吡喃,Ⅰ,和6′-硝基-1-苯基-3,3-二甲基吲(口乃木)苯骈螺吡喃,Ⅱ,的光化学,Ⅰ的直接光解和敏化光解均得到份菁结构的光解产物Ⅲ,量子产率分别是0.42和0.32.Ⅱ直接光解时生成相应的有色光解产物Ⅳ,量子产率是0.40,氮杂蒽酮为敏化剂的敏化光解量子产率是0.58,无疑地,单线态和三线态均参予螺吡喃的发色反应,用这些结果和折算关系式得到,在Ⅰ的直接光解中,Ⅲ主要来自单线态,而在Ⅱ的直接光解中,Ⅳ主要来自三线态.从Ⅰ或Ⅱ的敏化联乙酰燐光实验中求得三线态参数.它们是:φISCⅠ=0.11,φISCⅡ=0.48;3KdtⅠ=3×104秒-1,3KdtⅡ=9×104秒-1,类似地,3KrⅠ=0.12×104秒-1,3KrⅡ=2.52×104秒-1,这样,3φrⅠ值较小是由于3φISCⅠ值较小,而三线态寿命随结构变动不大.最后,取苯乙烯为模型,用它的电子能量与乙烯双键扭曲角度关系图推断出,来自单线态的双离子具有螺环构型,而来自三线态者具有平面状构型. 相似文献