苦丁茶中总黄酮的三波长-光谱法定量分析

采用三波长 分光光度法测定苦丁茶中有效化学成分黄酮的含量 ,有效地消除了吸收峰不对称给定量分析能造成的影响 ,并校正了基于干扰组分 (饮料中添加剂等 )的吸收光谱具有可能是散射造成的背景线性吸收产生的基线倾斜。回归方程为 :ΔA =- 3.70 2× 1 0 -3 +3.70 2 3C ,相关系数r =0 .9994 ,黄酮的浓度在6 0 0～ 1 6 0 0mg/L范围内 ,分别在波长为λ1 =4 70nm ,λ2 =4 2 0nm ,λ3 =370nm处测吸光度时 ,则ΔA与浓度C之间呈良好的线性关系 ,可按标准曲线法进行定量分析。方法的回收率为 98%～ 1 1 2 % ,相对标准偏差小于1 1 4 %。方法的准确度与精密度均令人满意 ,而且操作简便易行     

双波长分光光度法同时测定矿石中钛和铁

本文试验了直接使钛和铁与二氨替比林甲烷同时显色,利用等吸收点法,在本文的试验条件下,于λ_1=388nm及λ_2=513nm处测定两个波长的吸光度,并以A_(388nm)-A_(513nm)求出两个吸光度差值(△A),即为钛的结果。铁的测定可以用两个方法:一个是在波长560nm处直接测定     

硫氰酸盐双波长分光光度法测定高铅矿石中钼量

在常规的硫氰酸盐光度法测定钼的硫酸介质中,加入80g·L-1乙二胺四乙酸二钠盐(EDTA-2Na)溶液7mL,使48mg·L-1以下共存的铅(Ⅱ)无法生成硫酸铅,不干扰钼的测定,应用此条件测定了含铅量较高的矿石中钼的含量。样品(0.100 0~0.500 0g)于高铝坩埚中,用过氧化钠3g融熔,熔块用水浸出,定容至100mL,分取部分试液,加入EDTA-2Na溶液7mL后按常规条件显色,用双波长方法以460nm(λ1)为测定波长,650nm(λ2)为参比波长测量吸光度(A),计算ΔA(Aλ1-Aλ2)。钼的质量浓度在6.0mg·L-1以内与相应的ΔA之间呈线性关系,方法的检出限(3s/k)为8.1×10-3 mg·L-1。应用此方法测定了2个CRM(GBW 07238,GBW 07285)中的钼量,测定值与认定值相符,测定值的相对标准偏差(n=9)依次为2.8%,1.2%。     

曙红Y瑞利散射、二级散射及倍频散射法测定痕量铝

试验表明:在pH 5.0的乙酸盐缓冲介质中,铝(Ⅲ)与曙红Y反应体系的瑞利散射(RRS)、二级散射(SOS)和倍频散射(FDS)均有增敏现象。分别选择λex=λem=598nm(RRS),λex=330nm、λem=660nm(SOS)和λex=604nm、λem=302nm(FDS)作为3种散射强度的测定波长。试验时,选择曙红Y溶液的浓度为5.0×10-5 mol·L-1;在室温反应3min。结果表明:上述3种散射光谱法所测得的ΔIRRS,ΔISOS和ΔIFDS均与铝(Ⅲ)的质量浓度在一定范围内呈线性关系,其检出限(3s)依次为7.5,4.0,8.0μg·L-1。二级散射法的线性范围较宽(0.012~1.5mg·L-1),且检出限最低。用此法分析了人发和茶叶样品,所得结果与原子吸收光谱法的结果相符。用标准加入法进行回收试验,回收率在96.3%~105%之间,测定值的相对标准偏差(n=7)均小于5%。     

双波长分光光度法同时测定贵金属冶金物料中铱,铑的研究

本文利用铱、铑与溴化亚锡和2-巯基苯并噻唑的显色反应,建立了同时测定铱、铑的双波长分光光度法。铱的测定用等吸收波长法(λ_2=415nm,λ_1=523nm);铑的测定用倍率系数法(λ_2~′=476nm,λ_1~′=460nm,K=2.20)。铱、铑的含量在工作曲线浓度(100μg/10ml)范围内以1:8或8:1共存互不干扰。方法简便快速,结果准确。用于实际物料分析,结果满意。     

催化荧光光度法测定痕量铜(Ⅱ)

基于在氨水-氯化铵缓冲介质中,铜(Ⅱ)催化过氧化氢氧化靛蓝胭脂红,导致反应体系的荧光增强,提出了荧光光度法测定痕量铜(Ⅱ)的一种灵敏的方法。在320 nm(eλx)及391 nm(eλm)波长处,反应体系的ΔF(F-F0)与铜(Ⅱ)的质量浓度在0.2～100μg.L-1范围内呈线性关系。方法的检出限(3σ)为0.05μg.L-1。该方法用于大米、面粉和茶叶中铜的测定,测得方法的回收率在96.2%～104.9%之间,测定值的相对标准偏差(n=5)在0.72%～1.5%之间。     

流动注射-分光光度法测定钴钼催化剂浸渍液中高浓度钼离子

在0.75mol·L-1硫酸溶液中,抗坏血酸可将Mo6+还原为Mo5+,而硫氰酸铵能与生成的Mo5+显色,在波长465nm处有最大吸收峰,据此提出了一种流动注射-分光光度法测定钴钼催化剂浸渍液中超高浓度钼离子含量的方法。钼的质量浓度在3.3～93.3g·L-1范围内与其ΔA呈线性关系,方法的检出限(3s/k)为0.35g·L-1。方法用于钴钼催化剂浸渍液中钼离子含量的测定,测得方法的回收率在95.0%～101%之间,测定值的相对标准偏差(n=11)小于1%。     

1,2-萘醌-4-磺酸钠为显色剂吸光度差值法测定盐酸普鲁卡因

1,2-萘醌-4-磺酸钠与盐酸普鲁卡因在pH 4.70的条件下反应,产物在300和483 nm处有两个吸收峰,可用两波长下吸光度差值测定盐酸普鲁卡因,本文对吸光度差值与分析物浓度之间的关系作了理论推导。吸光度差值(ΔA)与盐酸普鲁卡因质量浓度在2.0~36.0 mg/L范围内具有良好线性关系,线性回归方程为:ρ=37.092 0ΔA-0.332 3,线性相关系数为0.999 1,相对标准偏差为1.49%,回收率为97%~105%。试验了pH值、放置时间及干扰离子对测定的影响。此法简便、快速、准确,可用于注射液中盐酸普鲁卡因含量的测定,与药典方法对照,结果满意。     

金银花中绿原酸的微波预处理提取及检测

采用微波预处理法对金银花中绿原酸的提取进行优化,用三波长法测定了绿原酸的含量.设计正交试验,以绿原酸的含量为指标,考察乙醇用量、乙醇浓度和微波处理时间对金银花中绿原酸提取工艺的影响.三波长法检测波长为λ1=280 nm,λ2=325 nm,λ3=380 nm,其回归方程为ΔA=0.0426C 0.0017,相关系数为R=0.998.结果表明在气化剂用量20 mL,乙醇浓度为70(,微波辐射70 s时绿原酸得率最高.与常用的提取和测定方法相比,此方法对设备要求不高,具有更高的准确性与精密度.     

Schiff碱Cu(II)配合物的结构、光谱及电化学性质

为了探讨配合物结构对性质的影响,合成了两个Schiff碱的铜配合物{[Cu(II) (L1)]ClO_4(1)和[Cu(II)(L2)-(H_2O)_2](BF_4)_2(2)},并用红外、质谱和元素分 析对它们进行了表征,用X射线衍射方法测定了它们的昌体结构。实验结果表明： 配合物1和2均属三斜晶系,P1空间群。1的晶胞参数为a = 1.1147(6)nm, b = 1. 1481(7)nm, c = 0.770(3)nm; α = 98.81(4) °,β=106.94(4)°γ= 66.49(4)° ;V=0.8715(8)nm~3,Z=2,R=0.044.2的晶胞参数为a=1.0819(4)nm, b = 1.4095(6) nm, c = 1.0192(4)nm; α=96.54(4)°,β=106.18(3)°,γ=80.51(3)°;V=1. 4681(5)nm~3, Z=2, R = 0.068.此外,配合物1的Cu-O(1)键长[0.1880(5)nm]和可 见吸收波长(λ_(max)=557nm)比2[0.1982(6)nm,λ_(max)=605nm]短。配合物2在- 0。80～-1.20V范围内出现两个氧化和两个还原过程。     

催化荧光光度法测定痕量过氧化氢

在pH 7.0的磷酸氢二钠-磷酸二氢钾缓冲溶液中,四羧基铁酞菁(FeTCPc)能催化过氧化氢氧化L-酪氨酸,形成荧光二聚体,据此提出了荧光光度法测定水中过氧化氢的方法。在激发波长(λex)320nm与发射波长(λem)410nm处,反应体系的ΔF(F-F0)与过氧化氢的浓度在7.6×10-7～2.7×10-5 mol.L-1之间呈线性关系,方法的检出限(3s/k)为5.2×10-8 mol.L-1。以此方法对两种水样进行分析,测得回收率在96.5%～96.9%之间,测定值的相对标准偏差(n=5)在1.0%～2.8%之间。     

抑制荧光光谱法测定模拟废水中痕量汞

基于在pH 8.00磷酸氢二钠-柠檬酸缓冲介质中,血红蛋白对过氧化氢氧化对甲酚反应具有强的催化作用,汞(Ⅱ)对上述指示反应具有灵敏的抑制作用,从而提出了抑制荧光光谱法测定模拟废水中汞含量的方法。优化的试验条件如下:①血红蛋白的浓度为2.00×10-7 mol·L-1;②对甲酚的浓度为1.60×10-3 mol·L-1;③过氧化氢的浓度为1.11×10-3 mol·L-1;④反应时间为80min。在激发波长318nm、发射波长405nm处,反应体系的ΔF(即F0与F值之差)与汞(Ⅱ)的浓度在2.00×10-8～1.00×10-5 mol·L-1范围内呈线性关系。方法用于模拟废水的分析,测得加标回收率在94.0%～105%之间,相对标准偏差(n=8)在2.5%～3.3%之间。     

Coumarin phosphorescence observed with N^N Pt(II) bisacetylide complex and its applications for luminescent oxygen sensing and triplet-triplet-annihilation based upconversion

A dbbpy platinum(II) bis(coumarin acetylide) complex (Pt-1, dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) was prepared. Pt-1 shows intense absorption in the visible region (λ(abs) = 412 nm, ε = 3.23 × 10(4) M(-1) cm(-1)) compared to the model complex dbbpy Pt(II) bis(phenylacetylide) (Pt-2, λ(abs) = 424 nm, ε = 8.8 × 10(3) M(-1) cm(-1)). Room temperature phosphorescence was observed for Pt-1 ((3)IL, τ(P) = 2.52 μs, λ(em) = 624 nm, Φ(P) = 2.6%) and the emissive triplet excited state was assigned as mainly intraligand triplet excited state ((3)IL), proved by 77 K steady state emission, nanosecond time-resolved transient absorption spectroscopy and DFT calculations. Complex Pt-1 was used for phosphorescent oxygen sensing and the sensitivity (Stern-Volmer quenching constant K(SV) = 0.012 Torr(-1)) is 12-fold of the model complex Pt-2 (K(SV) = 0.001 Torr(-1)). Pt-1 was also used as triplet sensitizer for triplet-triplet-annihilation based upconversion, upconversion quantum yield Φ(UC) up to 14.1% was observed, vs. 8.9% for the model complex Pt-2.     

可溶性镍酞菁的光谱特性研究

利用UV-Vis吸收光谱、荧光光谱及半经验ZINDO/S方法,研究了4种可溶性镍酞菁(FPcNi、MePcNi、iBPcNi、iPPcNi)的电子吸收光谱和荧光光谱.研究结果表明:随着取代基的供电子能力增加,酞菁的最大吸收波长(λ_max)和发射波长(λ_em)发生红移,摩尔消光系数变小;随着溶液浓度增大,酞菁聚集体浓度增大,λ_max发生蓝移,但浓度对λ_em影响较小,同时荧光相对强度随浓度增大,出现最大值;随着溶剂配合能力的增加,λ_max、λ_em都发生红移.     

UV absorption cross sections between 230 and 350 nm and pressure dependence of the photolysis quantum yield at 308 nm of CF3CH2CHO

Ultraviolet (UV) absorption cross sections of CF(3)CH(2)CHO were determined between 230 and 350 nm by gas-phase UV spectroscopy. The forbidden n → π* transition was characterized as a function of temperature (269-323 K). In addition, the photochemical degradation of CF(3)CH(2)CHO was investigated at 308 nm. The possible photolysis channels are: CF(3)CH(2) + HCO , CF(3)CH(3) + CO , and CF(3)CH(2)CO + H . Photolysis quantum yields of CF(3)CH(2)CHO at 308 nm, Φ(λ=308nm), were measured as a function of pressure (25-760 Torr of synthetic air). The pressure dependence of Φ(λ=308nm) can be expressed as the following Stern-Volmer equation: 1/Φ(λ=308nm) = (4.65 ± 0.56) + (1.51 ± 0.04) × 10(-18) [M] ([M] in molecule cm(-3)). Using the absorption cross sections and the photolysis quantum yields reported here, the photolysis rate coefficient of this fluorinated aldehyde throughout the troposphere was estimated. This calculation shows that tropospheric photolysis of CF(3)CH(2)CHO is competitive with the removal initiated by OH radicals at low altitudes, but it can be the major degradation route at higher altitudes. Photodegradation products (CO, HC(O)OH, CF(3)CHO, CF(3)CH(2)OH, and F(2)CO) were identified and also quantified by Fourier transform infrared spectroscopy. CF(3)CH(2)C(O)OH was identified as an end-product as a result of the chemistry involving CF(3)CH(2)CO radicals formed in the OH + CF(3)CH(2)CHO reaction. In the presence of an OH-scavenger (cyclohexane), CF(3)CH(2)C(O)OH was not detected, indicating that channel (R1c) is negligible. Based on a proposed mechanism, our results provide strong evidences of the significant participation of the radical-forming channel (R1a).     

Cl2O photochemistry: ultraviolet/vis absorption spectrum temperature dependence and O(3P) quantum yield at 193 and 248 nm

The photochemistry of Cl(2)O (dichlorine monoxide) was studied using measurements of its UV/vis absorption spectrum temperature dependence and the O((3)P) atom quantum yield, Φ(Cl(2)O)(O)(λ), in its photolysis at 193 and 248 nm. The Cl(2)O UV/vis absorption spectrum was measured over the temperature range 201-296 K between 200 and 500 nm using diode array spectroscopy. Cl(2)O absorption cross sections, σ(Cl(2)O)(λ,T), at temperatures <296 K were determined relative to its well established room temperature values. A wavelength and temperature dependent parameterization of the Cl(2)O spectrum using the sum of six Gaussian functions, which empirically represent transitions from the ground (1)A(1) electronic state to excited states, is presented. The Gaussian functions are found to correlate well with published theoretically calculated vertical excitation energies. O((3)P) quantum yields in the photolysis of Cl(2)O at 193 and 248 nm were measured using pulsed laser photolysis combined with atomic resonance fluorescence detection of O((3)P) atoms. O((3)P) quantum yields were measured to be 0.85 ± 0.15 for 193 nm photolysis at 296 K and 0.20 ± 0.03 at 248 nm, which was also found to be independent of temperature (220-352 K) and pressure (17 and 28 Torr, N(2)). The quoted uncertainties are at the 2σ (95% confidence) level and include estimated systematic errors. ClO radical temporal profiles obtained following the photolysis of Cl(2)O at 248 nm, as reported previously in Feierabend et al. [J. Phys. Chem. A 114, 12052, (2010)], were interpreted to establish a <5% upper-limit for the O + Cl(2) photodissociation channel, which indicates that O((3)P) is primarily formed in the three-body, O + 2Cl, photodissociation channel at 248 nm. The analysis also indirectly provided a Cl atom quantum yield of 1.2 ± 0.1 at 248 nm. The results from this work are compared with previous studies where possible.     

双波长叠加分光光度法测定水中微量氰化物

在弱酸性介质中和氯胺T存在条件下,CN-可与异烟酸-硫代巴比妥酸形成一蓝色染料,该染料具有两个吸收峰,分别位于642 nm和525 nm处,且其在两波长处的吸光度之和△A(△A=Aλ1+Aλ2)与氰化物含量在一定的范围内呈良好的线性关系,据此建立了测定水样中微量氰化物的异烟酸-硫代巴比妥酸双波长叠加分光光度法.该法氰化...     

新型镉配合物[Cd(IPDB)_2Cl_2]的合成及其晶体结构

以2-(4-二甲氨基苯基)咪唑[4,5-f]1,10-邻菲啰啉(IPDB)为配体,Cd Cl_2·2.5H_2O为镉源,用水热法合成了一个新型的镉配合物[Cd(IPDB)_2Cl_2,(1)],其结构和性能经FL,FT-IR,元素分析,X-射线单晶衍射和TG表征。1属斜方晶系,空间群Pbcn,晶胞参数a=14.933(12),b=8.349(7),c=31.93(3),α=γ=90°,β=90(4)°,V=3 981(6)~3,Dc=1.438 g·cm~(-3),Z=4,R_1=0.048 0,ωR_2=0.109 8。每个Cd分别与2个双齿螯合的IPDB中的一个N和2个Cl配位,形成畸变的八面体几何构型。在490 nm波长激发下,1的最大荧光发射峰位于569 nm。1的初始分解温度为495℃,失重为72.24%。     

Methoxy-substituted isoTQEN family for enhanced fluorescence response toward zinc ion

Previously, we have reported that 1- and 3-isoTQENs (N,N,N',N'-tetrakis(1- or 3-isoquinolylmethyl)ethylenediamines) exhibit a specific fluorescence enhancement toward zinc ion. In this study, three methoxy-substituted derivatives of 1-isoTQEN were synthesized and their fluorescent response toward zinc ion was studied. The substitution pattern of the methoxy group significantly changes the solubility of compounds in aqueous DMF, λ(max) in the absorption spectra, excitation/emission wavelengths and fluorescence intensity of zinc complexes. In the presence of zinc ion, 7-MeO-1-isoTQEN exhibits higher fluorescence intensity and longer excitation/emission wavelengths (λ(ex) = 342 nm, λ(em) = 526 nm) than 6-MeO-1-isoTQEN (λ(ex) = 303 nm, λ(em) = 469 nm) and 5,6,7-triMeO-1-isoTQEN (λ(ex) = 340 nm, λ(em) = 504 nm). The fluorescence intensity of a zinc complex of 7-MeO-1-isoTQEN (? = 0.122) is four times higher than the parent 1-isoTQEN (? = 0.034) under the same conditions. The crystal structure of 7-MeO-1-isoTQEN-Zn complex reveals that all six nitrogen atoms participate to the metal coordination with ideal octahedral geometry, affording significantly high metal binding affinity comparable with TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine). 7-MeO-1-isoTQEN detects zinc ion concentration change in cells by fluorescence microscopic analysis.     

Coordination of nickel and copper dithiolate to 2,2′‐bipyridine‐based π‐conjugated polymers

π‐Conjugated polymers (Poly1–Poly3) containing a 2,2′‐bipyridine (bpy) unit were subjected to coordination to nickel and copper dithiolate for the purpose of manipulating the photophysical properties. The absorption maximum peak of Poly1 [maximum wavelength (λ_max) = 446 nm] redshifted by 36 nm upon the coordination of bpy to NiCl₂, which produced Poly1–NiCl₂. A further bathochromic shift was observed in the spectrum of Poly1–mntNi [mntNi = (maleonitrile dithiolate)nickel; λ_max = 499 nm] bearing the dithiolate ligand, which stemmed from the extension of the conjugated system over the nickel dithiolate moiety through the bpy unit. An increase in the [Ni]/[bpy] ratio in Poly1–mntNi rendered the original maximum peak at 446 nm smaller and the lower energy charge‐transfer peak at 499 nm larger; the isosbestic points remained at 380 and 475 nm. The green fluorescence (λ_max = 504 nm) emitted from Poly1 markedly diminished upon the coordination of nickel dithiolate because of the effective energy transfer. The absorption maximum peak of Poly1–mntNi in chloroform at 499 nm blueshifted to 471 nm when the volume ratio of the chloroform/N,N‐dimethylformamide solvent reached 10:90. The coordination of nickel dithiolate to Poly2 and Poly3 also brought about redshifts of the absorption maximum peaks of as much as 55 and 61 nm, respectively. The absorption maximum peak of Poly1–(phenyldithiolate)nickel(pdtNi) (λ_max = 474 nm) redshifted by 28 nm in comparison with that of Poly1, whereas the magnitude of the shift of Poly1–bis(thiophenoxide)nickel(btpNi) bearing two thiophenoxide ligands was 20 nm. Poly1–mntCu with a tetrahedral copper center was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2631–2639, 2004