二安替比林甲烷分光光度法测定高铬铁矿中微量钛

铬铁矿中含铬量(wCr)在30%～40%之间,杂质测定只涉及铁、磷、二氧化硅、三氧化二铝、氧化钙、氧化镁,现行铬铁矿的检测标准未涉及钛的测定方法,但在生产上要求控制钛的含量。据报道二安替比林甲烷(DAPM)光度法测定微量钛具有灵敏度     

光度法快速测定水泥中的钛

研究了显色剂二安替比林甲烷分光光度法测定钛Ti(IV)的方法.在酸性介质中,二安替比林甲烷与钛发生灵敏显色反应,生成黄色络合物,最大吸收波长为390 nm,摩尔吸光系数为2.9×104 L/(mol·cm),钛含量c在0～35 μg/(25 mL)范围内与吸光度A符合比耳定律,线性回归方程为A=0.03243+0.02388c,溶液中大量共存离子均不干扰测定.该方法不需要萃取、分离步骤,可直接测定水泥中微量钛的含量.     

金属材料分析方法的选择和施行——第四讲 金属材料中钛的测定（续）

⑤方法的精密度　提供了由8家试验室协作对方法的精密度进行试验的结果。见表10。表10　DAPM光度法测定钛的精密度试验结果(n=8)Tab.10　ResulfofprecisiontestoftheDAPMphotometricmethodCRM的名称及编号证书值wTi(%)测定值wTi(%)重复性限R1(%)再现性限R2(%)低合金钢NBS19g0.0270.0280.00130.0043低合金钢NBS170a0.2810.2820.0090.0228铸铁NBS122d0.0070.0060.00190.0037高炉生铁NBS1144a0.3200.3300.01180.0168高合金钢NBS3440.0760.0790.00220.0065特种钢NBS11560.2100.2000.00540.0143[注1]　该方法系测定总钛量。试…     

三元络合物钛-变色酸-二安替比林甲烷的组成及在矿石分析中的应用

自从Ганаго等提出用钛(Ⅳ)-变色酸(CTA)-二安替比林甲烷(DAPM)三元络合物测定合金中钛以来,其应用获得了明显地进展。作者也将此法用于岩石及钒钛磁铁矿中钛量的测定,效果良好。方法简便、准确,适应范围广。关于此三元络合物的组成,Ганаго等测定为Ti(Ⅳ):CTA:DAPM=1:2:2,我国分析工作者的实验结果也为1:2:2。作者却得到了不同的结果,本文拟着重讨论一下这个问题。     

利用钛—硫氰酸盐—二安替比林甲烷三元络合物微量钛的萃取分光光度测定

目前,测定铬铁矿中微量钛的常用比色法有过氧化氢法、变色酸法、钛铁试剂法及二安替比林甲烷法。这些方法用于测定微量钛,灵敏度尚嫌偏低。为了提高灵敏度,有关文献中提出了用三元铬合物进行分光光度测定。这些方法有钛—DAPM—二氯化锡三元铬合物法、钛—硫氰酸盐—二苯胍法、钛—硫氰酸盐     

二安替比林甲烷光度法测定硅铁中微量钛

二安替比林甲烷光度法测定钛已被广泛应用于钢铁中钛的测定，本文使用二安替比林甲烷光度法测定硅铁中钛，试验了分析条件的影响，试验结果，钛在10-200μg／50mL范围内遵守比耳定律。     

新显色剂二溴羟基苯基荧光酮的氧化显色反应及双波长分光光度法测定废水中的铬

本文利用光度法和电位滴定法探讨了铬(Ⅵ)与二溴羟基苯基荧光酮(DBHPF)的显色反应,发现在酸性介质中为DBHPF的氧化显色反应。DBHPF曾成功地应用于钛钼钨锡等元素的测定。本文利用Cr(Ⅵ)与DBHPF的氧化显色反应,进一步研究了双波长分光光度法测定Cr(Ⅵ)的条件。应用拟定的新方法测定了电镀废水中的铬(Ⅵ)和总铬量,结果满意。     

Ti(Ⅳ)-CTA-DAM三元配合物及其铝合金中微量钛的测定

光度法测定铝合金中钛的方法很多.但用本文提出方法,目前尚未见文献报道.根据文献,本文研究了Ti(Ⅳ)-CTA-DAM三元配合物及其铝合金中微量钛的测定.在酸性介质中,Ti(Ⅳ)与变色酸(CTA)、二安替比林甲烷(DAM)生成一种很稳定的紫红色配合物,其反应式可表示如下:     

金属材料分析方法的选择和施行第四讲 金属材料中钛的测定（续）

2.6.2　二安替比啉甲烷作为显色剂用于钛的测定二安替比啉甲烷(以下简写作DAPM)属离子缔合物形成显色剂,系白色粉状固体,相对分子质量为406.5(含结晶水),熔点为155～157℃,150℃以上试剂分解。试剂微溶于水,但溶于稀酸或氯仿、乙醇等有机溶剂中。在酸性介质中DAPM通过其分子中的羰基-C=O与一个或两个氢离子实现质子化:一般认为,DAPM质子化的阳离子与某些金属络阴离子形成离子缔合型络合物:[Mm+Xn](n-m)-+(n-m)RH+RH+(n-m)·[Mm+Xn](n-m)-式中　Mm+———价态为m+的金属阳离子X———阴离子,如卤素离子或硫氰酸盐等n———金属阳离…     

固相萃取光度法测定饮用水中挥发酚的研究

研究了用Waters Sep-Park-C18小柱固相萃取光度法测定饮用水中挥发酚的方法。水样中经水汽蒸馏分离后的挥发酚，用4－氨基安替比林显色，显色产物可用C18固相萃小柱萃取、乙醇洗脱后用分光光度法测定。方法污染小，操作简便，便于批量样品处理，用于饮用水中挥发酚的测定，结果令人满意。     

Generation and detection of levuglandins and isolevuglandins in vitro and in vivo

Levuglandins (LGs) and isolevuglandins (isoLGs), formed by rearrangement of endoperoxide intermediates generated through the cyclooxygenase and free radical induced oxidation of polyunsaturated fatty acids (PUFAs), are extraordinarily reactive, forming covalent adducts incorporating protein lysyl ε-amino groups. Because they accumulate, these adducts provide a dosimeter of oxidative injury. This review provides an updated and comprehensive overview of the generation of LG/isoLG in vitro and in vivo and the detection methods for the adducts of LG/isoLG and biological molecules in vivo.     

Enthalpies of solution of purine and adenine in water and in dimethylsulfoxide

Journal of Solution Chemistry - Enthalpies of solution of purine and adenine in water and in demethylsulfoxide were measured calorimetrically in the temperature range 25–40°C. ΔH s...     

Coassembly of Nanorods and Nanospheres in Suspensions and in Stratified Films

The entropically driven coassembly of nanorods (cellulose nanocrystals, CNCs) and nanospheres (dye‐labeled spherical latex nanoparticles, NPs) was studied in aqueous suspensions and in solid films. In mixed CNC‐latex suspensions, phase separation into an isotropic latex‐NP‐rich and a chiral nematic CNC‐rich phase took place; the latter contained a significant amount of latex NPs. Drying the mixed suspension resulted in CNC‐latex films with planar disordered layers of latex NPs, which alternated with chiral nematic CNC‐rich regions. In addition, fluorescent latex NPs were embedded in the chiral nematic domains. The stratified morphology of the films, together with a random distribution of latex NPs in the anisotropic phase, led to the films having close‐to‐uniform fluorescence, birefringence, and circular dichroism properties.     

Determination of diazepam and nordazepam in milk and plasma in the presence of oxazepam and temazepam

For studies on the excretion of drugs into milk a sensitive high-performance liquid chromatographic assay was developed to quantitate diazepam and nordazepam in the milk and plasma of humans and rabbits in the presence of their major metabolites, oxazepam and temazepam. Flurazepam was used as an internal standard. The assay involves extractions with diethyl ether and an additional acid clean-up step. Chromatographic separation was achieved by a LiChrospher 60 RP-select B (5 microns) column and KH2PO4- acetonitrile (69:31, v/v) adjusted to pH 2.80 as a mobile phase. The same extraction and chromatographic conditions were suited to both types of samples, milk and plasma. The limits of determination using ultraviolet detection at 241 nm was for diazepam 20 ng/ml and for nordazepam 15 ng/ml. The absolute recoveries of diazepam, nordazepam and flurazepam in human milk were 84, 86 and 92% and in human plasma 97, 89 and 94%, respectively. The within- and between-day accuracy and precision for diazepam and nordazepam in milk and plasma at all concentrations tested (20-1500 ng/ml) were better than 8%. The high fat content which occurs in rabbit milk presented no limitation for the extraction of lipophilic diazepam: the method was successfully used to monitor milk and plasma concentrations of diazepam and nordazepam in lactating New Zealand White rabbits during 26-h infusions of diazepam (1.4 mg/h).     

Comparison and correlation of in vitro, in vivo and in silico evaluations of alpha, beta and gamma cyclodextrin complexes of curcumin

In the present study investigated the effect of curcumin (CUR) alpha (α), beta (β) and gamma (γ) cyclodextrin (CD) complexes on its solubility and bioavailability. CUR the active principle of turmeric is a natural antioxidant agent with potent anti-inflammatory activity along with chemotherapeutic and chemopreventive properties. Poor solubility and poor oral bioavailability are the main reasons which preclude CUR use in therapy. Extent of complexation was β-CD complex (82 %) > γ-CD (71 %) > α-CD (65 %). Pulverization method resulted in significant enhancement of CUR (0.002 mg/ml) solubility with CUR α-CD complex (0.364 mg/ml) > CUR β-CD complex (0.186 mg/ml) > CUR γ-CD complex (0.068 mg/ml). Gibbs-free energy and in silico molecular docking studies favour formation of α-CD complex > β-CD complex > γ-CD complex. With reference to CUR, relative bioavailability of CUR α-CD, CUR β-CD and CUR γ-CD complexes were 460, 365 and 99 % respectively. CUR–CD complexes exhibited increased bioavailability with an increase in t_½, tmax, Cmax, AUC, Ka, and MRT; and a decrease in Ke, clearance and Vd values. AUC increase was CUR α-CD complex > CUR β-CD complex > CUR γ-CD complex. Significant difference (p < 0.05) was observed between CUR α-CD complex and CUR γ-CD complex by one-way ANOVA and Dunnett’s post hoc test for multiple comparison analysis. Correlation observed between in vitro, in vivo and in silico methods indicates potential of in silico and in vitro methods in CD selection.     

Structure of dimethoxyamine in the crystalline and gaseous phases and in solution

Conclusions It has been established by the methods of x-ray diffraction analysis and electron diffraction analysis and measurements of the dipole moments and the birefringence that in the crystalline and gaseous phases, as well as in solution, N,N-dimethoxyamine has a gauche-gauche conformation, which is stipulated by a stabilizing nO-N-O* orbital interaction. The geometric parameters of the molecule have been determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2235–2242, October, 1986.     

Homo- and hetero-complexes of exchangeable apolipoproteins in solution and in lipid-bound form

The self-association state of human plasma apolipoprotein E (apoE) in solution and in complexes with dimyristoylphosphatidylcholine (DMPC) varying in stoichiometry was studied in sub-micromolar concentration range by gel filtration, fluorescence anisotropy, fluorescence quenching and energy transfer measurements with apolipoprotein labeled with lysine-specific fluorescent dyes. Together, these results confirm the equilibrium scheme for various apoE structures in solution: oligomer (in aged preparations) <==> 'closed' tetramer <==> 'open' tetramer ('molten globule' state) <==> native or partially denatured monomer <==> fully denatured monomer. Within DMPC:apoE discoidal complex (125:1) the apolipoprotein association state seems to be intermediate between that in solution and in larger vesicular complex (1000:1); for both complexes, the degree of exposure of fluorescein chromophores into water phase decreased. Hetero-associates of apoA-I and apoC-III-1 in solution and in the complexes with DMPC appear to behave similarly to apoE. When extrapolated to native HDL particles, 'molten globule' state seems to be a structure responsible for the interaction of exchangeable apolipoproteins with phospholipid. For a first time, the location of various apolipoprotein molecules on disc periphery was confirmed. The lysine residue(s) seems to locate closely to reacting residue(s) within apolipoprotein molecules in associates, however, with different package constraints for discoidal versus vesicular complexes with phospholipid.     

Fluorimetric quantification of clodronate and alendronate in aqueous samples and in serum

The bisphosphonates clodronate and alendronate are drugs in the therapy of osteoporosis or Paget's disease. They are highly hydrophilic and therefore of low oral bioavailability. Determination methods for bisphosphonates are often laborious and expensive equipment is needed. The presented quantification method based on kinetic measurement of the fluorescence decrease of an Al³⁺-morin complex can be used to determine the bisphosphonate content in aqueous and plasma samples. The intra- and inter-assay accuracies were found to be within 98.8% and 102.3% of the target samples for clodronate and within 97.2% and 105.0% of the target samples for alendronate. The LOQ was defined as 15.6 ng/ml for clodronate and 62.5 ng/ml for alendronate. In serum samples, intra- and inter-assay accuracy was found to be within 99.0% and 101.6% of the target samples for clodronate and within 97.8% and 102.6% of the target samples for alendronate. In serum samples, the LOQ was defined as 1.55 mg/ml for clodronate and 0.39 mg/ml for alendronate. Though less sensitive in serum, the presented method could support research on the development of drug delivery systems in vitro and in vivo for the investigated and other structurally related bisphosphonates.