激光诱导纳秒时间分辨荧光法原位测定吸附于红树叶片表面的菲

实现吸附于植物叶片表面多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)的现场原位测定,是该研究领域的发展方向之一。本实验利用激光诱导纳秒时间分辨荧光(Laser-induced nanosecond time-resolved fluorescence,LITRF)系统,建立了原位测定吸附于秋茄(Kandelia obovata,Ko)、木榄(Bruguiera gymnorhiza,Bg)和桐花树(Aegiceras corniculatum,Ac)3种红树叶片表面菲(Phenanthrene,Phe)的新方法。本方法测定吸附于Ko、Bg和Ac叶片表面Phe的线性范围分别为2~1400 ng/spot,1~1000 ng/spot和4~2000 ng/spot,检测限分别为0.20,0.14和0.42 ng/spot,加标回收率为89.6%~108.1%,78.2%~92.4%和93.2%~112.9%,且方法的相对标准偏差小于6.0%(n=9)。将方法用于实验室暴露样品的原位测定,并与光纤荧光法对比,其灵敏度、线性范围改善显著,更有利于实现植物叶片上PAHs的现场原位测定。     

一种简便的原位测定红树叶片表面菲的荧光分析方法

采用自行设计的多用途荧光比色皿,建立了一种秋茄(Kandelia obovata,Ko),桐花树(Aegiceras comiculatum,Ac)和白骨壤(Avicennia marina,Am)叶片表面菲(Phenanthrene,Phen)简便的原位测定方法,本方法测定Ko,Ac和Am表面Phen的线性范围分别为6.5 ～ 1200 ng/spot,18.5～600 ng/spot和3.2～700 ng/spot,检出限分别为0.6,0.7和1.3 ng/spot,加标回收率分别为92.4％～101.0％、94.8％～108.2％和93.8％～103.6％,相对标准偏差小于6.5％.本方法的检出限和相对标准偏差均优于固体表面光纤荧光法(Solid surface optical fiber fluorimetry,SSF),线性范围与SSF法处于同一数量级.本方法与SSF法测得的红树叶片表面Phen的浓度并无显著差异(p＞0.05),但本方法极大地简化了操作,提高了重现性.     

石英晶体微天平实时监测低密度脂蛋白在胆固醇修饰葡聚糖上的吸附及其动力学研究

利用石英晶体微天平实时监测低密度脂蛋白(LDL)在胆固醇修饰葡聚糖(CMD)上的吸附,并对其吸附动力学进行研究.结果表明,CMD与LDL之间的相互作用符合Langmuir吸附方程,当LDL浓度(ng/μL)为9.9,12.38和14.14时,其吸附平衡常数[K/(mol·L-1·s-1)]分别为0.0477,0.0536和0.0628,表面吸附量(ng/cm2)分别为107.6,139.6和167.9.最大吸附量达到284.8ng/cm2,吸附率为72.91%.     

镍钛合金纤维基体上氧化锌纳米片的电沉积及其对环境水样中紫外线吸收剂的高效固相微萃取

以镍钛合金(NiTi)丝为固相微萃取(SPME)纤维基体,采用水热法原位生长网状交联钛/镍复合氧化物纳米片(TiO_2/NiOCNSs),随后通过电化学沉积,将氧化锌纳米片(ZnONSs)可控组装在NiTi-TiO_2/NiOCNSs纤维上。与HPLC联用,考察所组装NiTi-TiO_2/NiOCNSs@ZnONSs纤维对水样中痕量紫外线吸收剂的吸附性能,优化实验条件,建立了SPME-HPLC测定方法。在0.05~200μg/L范围内具有良好线性关系(相关系数0.999),检出限为0.009~0.065μg/L;该法的单根纤维日内测量相对标准偏差(RSDs)为4.6%~5.5%,日间测量RSDs为5.4%~6.8%,该法的5根不同批次所组装纤维RSDs为6.7%~7.9%。实际水样分析结果表明,加标回收率为86.8%~105.9%。所组装NiTi基纤维具有良好制备重现性和很长的使用寿命,一根纤维可完成整个分析过程和批量样品的测量。所建立方法适用于不同类型环境水样中痕量紫外线吸收剂的富集分离和灵敏测定。     

原位组装TiO2纳米管阵列固相微萃取-高效液相色谱联用测定环境水样中痕量紫外线吸收剂

用阳极氧化法在钛丝表面原位组装了TiO2纳米管阵列(TNTs)作为固相微萃取(SPME)纤维头,TNTs的孔径在100~150 nm之间,壁厚为20~30 nm。与高效液相色谱(HPLC)联用,考察了TNTs-SPME纤维头对水样中痕量紫外线吸收剂的吸附效率,优化了实验条件。所建立TNTs-SPME-HPLC法测定紫外线吸收剂的线性范围为0.2~400μg/L,检出限为0.05~0.37μg/L(S/N=3);对于加标50μg/L的水样平行进行5次测量,同一微萃取头在单日内和隔日间的相对标准偏差(RSD)分别为6.8%~9.2%和10%~13%,重复制作微萃取头的RSD为9.7%~14%。方法用于环境水样分析结果表明,实际水样加标回收率为85.9%~113.2%。所制作微萃取纤维头适用于测定环境水样中的痕量紫外线吸收剂。     

球形立方相纳米二氧化铈-ICP-MS法同时测定痕量铅和镉

采用室温固相法合成球形立方相纳米CeO2,建立了纳米CeO2富集分离,ICP-M S同时测定痕量Pb(Ⅱ)和Cd(Ⅱ)的方法。在pH 7.0,10 mg CeO2,吸附15min后,纳米CeO2对Pb(Ⅱ),Cd(Ⅱ)的吸附率均可达100%;以2mL 0.05 mol/L HCl溶液为洗脱剂、洗脱20 min后,对Pb(Ⅱ)和Cd(Ⅱ)的洗脱率可分别达到98%和95%以上;纳米CeO2对Pb(Ⅱ),Cd(Ⅱ)的最大静态吸附容量分别为496.9μg/g和243.1μg/g,富集倍数均可达250倍,共存离子影响小。优化ICP-MS仪器工作条件,选择205Bi和115In为在线内标进行Pb(Ⅱ)和Cd(Ⅱ)的测定,检出限分别为1.7 pg/mL和9.2 pg/mL,RSD分别为4.8%和0.94%。方法应用于实际水样,回收率分别为Pb(Ⅱ)93.6%~106.4%,Cd(Ⅱ)96.2%~108.9%。     

溶解态菲及其中间代谢产物1-羟基-2-萘甲酸的同时测定

运用导数-同步荧光光谱建立了快速同时测定溶解态菲(Phenanthrene,Phe)及其中间代谢产物1-羟基-2-萘甲酸(1-Hydroxy-2-naphthoic acid,1H2NA)的分析方法。所建方法同时测定Phe与1H2NA的线性范围分别为4.0~1.0×103μg/L和4.0~1.2×103μg/L,检出限分别为0.08μg/L和0.07μg/L,加标回收率分别为96.5%~105.3%和99.2%~106.5%,相对标准偏差均小于1.0%。该方法可应用于实验室条件下溶解态Phe微生物降解过程中Phe和1H2NA的测定,具备原位研究Phe降解过程中间代谢产物1H2NA的应用潜力。     

稀土Pr6O11上CO和表面羟基反应的原位FT-IR研究

利用FT-IR原位考察了稀土氧化镨上CO和表面羟基的反应。在473K以下,未检测到CO和氧化镨表面反应的吸附物种;在CO气氛中,升温到473K,观察到甲酸根吸附物种的红外特征峰1578,1371和1367cm~(-1)。用同位素D_2部分还原的氧化镨吸附CO以及甲酸吸附证实了CO与氧化镨表面的羟基反应可生成表面甲酸根吸附物种。讨论了CO在氧化镨表面的反应机理及甲酸根的氧化过程。     

高效液相色谱法测定小鼠肝组织中两种甲氧基补骨脂素

建立小鼠肝组织中8-甲氧基补骨脂素(8-MOP)与5-甲氧基补骨脂素(5-MOP)的高效液相色谱测定方法。采用正交试验设计对样品的前处理方法进行优化,Waters Symmetry C_(18)柱(250 mm×4.6 mm,5μm)分离,流动相为甲醇-水(55:45,V/V),流速为1.0 m L/min,荧光检测器激发与发射波长分别为334 nm与484 nm。小鼠肝组织中8-MOP与5-MOP在0.10~25μg/m L范围内线性良好,r值分别为0.9998与0.9994;8-MOP与5-MOP的定量限分别为4.0 ng/g和1.0 ng/g;8-MOP与5-MOP的加标回收率分别为101.1%~102.0%与94.2%~103.2%;提取回收率分别为96.6%~98.6%与92.6%~98.4%;基质效应分别为95.6%~98.2%与91.4%~99.6%;日内精密度分别为2.7%~3.3%与5.2%~5.5%;日间精密度分别为1.4%~2.4%与0.3%~1.6%。给药后小鼠肝组织中8-MOP含量为23.1~48.7 ng/g。方法适用于小鼠肝组织中8-MOP与5-MOP的同时测定。     

大气样品中氯代和溴代二噁英/呋喃同位素稀释分析方法的建立及应用

本研究结合已有的多氯代二噁英/呋喃(PCDD/Fs)分析方法,建立了多溴代二噁英/呋喃(PBDD/Fs)和PCDD/Fs的同位素稀释高分辨气相色谱-质谱联用(HRGC-HRMS)分析方法。样品抽提液经酸性硅胶床、多段硅胶柱、Florisil柱净化后,分别对其中8种2,3,7,8-PBDD/Fs和17种2,3,7,8-PCDD/Fs进行测定。PBDD/Fs仪器分析条件:EI 模式,选择性离子监测,分辨率10000以上,电子发射能50 eV,灯丝电流0.75 mA;DB-5 MS柱(60 m×0.25 mm i.d.,0.25μm);进样口、离子源及传输线温度分别为250℃、250℃和305℃;载气,He(1.0 mL/min)。结果表明:平行标准样品分析相对标准偏差(RSD)≤10.3%;PBDD/Fs和PCDD/Fs回收率在73%~112%之间;标准参考样品测定平均值与标准值基本符合,平行样RSD≤12.0%。方法检出限:TBDF,0.25 pg/μL;TBDD,0.3 pg/μL;PeBDFs,0.5 pg/μL;PeBDDs,1.0 pg/μL;HxBDD/Fs,1.5 pg/μL;TCDD/Fs,0.5 pg/μL;PeCDD/Fs和HxCDD/Fs,2.5 pg/μL;HpCDD/Fs以及OCDD/Fs,5 pg/μL。测定某地区大气样品颗粒相中PBDD/Fs和PCDD/Fs浓度分别在1.01~2.43 pg/m3和6.19~10.8 pg/m3之间;气相中的浓度为0.036~0.801 pg/m3和1.37~12.1 pg/m3。     

光纤荧光法对吸附于红树叶片表面上荧蒽的测定

利用光纤荧光法实现了吸附于白骨壤(Am)、海漆(Ea)、秋茄(Kc)、桐花树(Ac)和老鼠簕(Ai)叶片表面上荧蒽(Fla)的定量测定.所建方法测定吸附于Am、Ea、Kc、Ac和Ai叶片表面上Fla的线性范围分别为2.5 ～500、2.0 ～600、4.5 ～1 100、15 ～600、3.5 ～450 ng/spot,相应的检出限分别为0.91、0.63、1.12、3.52、1.40 ng/spot,方法的相对标准偏差小于7.8%(n=15),加标回收率分别为97% ～108%、78% ～95%、77% ～90%、84% ～108%和78% ～102%.利用所建方法考察了5种红树叶片正反面吸附不同量Fla的信号强度随时间的变化情况.结果表明:在200 min内,叶片正反面上Fla的信号均发生不同程度的衰减,且反面的信号衰减率大于正面;5种红树叶片正反面对Fla的吸附特性均不同;吸附于叶片正面的Fla多残留在叶片表面,而吸附于叶片反面的Fla易向叶片内部迁移.     

Determination of honokiol and magnolol by micro HPLC with electrochemical detection and its application to the distribution analysis in branches and leaves of Magnolia obovata

A simple and sensitive method has been developed for determining honokiol and magnolol in fresh Magnolia obovata (M. obovata) by micro high-performance liquid chromatography with electrochemical detection (microHPLC-ECD). Chromatography was performed using a Capcell Pak C-18 UG 120 microbore octadecylsilica (ODS) column, methanol-water-phosphoric acid (65 : 35 : 0.5, v/v/v), as a mobile phase and applied potential at +0.8 V vs. Ag/AgCl. Peak heights were found linearly related to the amounts of honokiol and magnolol injected from 0.67 pg to 2.0 ng (r>0.999). The detection limits (S/N=3) were 0.13 pg, respectively. Honokiol and magnolol of 0.27 ng were detected with relative standard deviation (RSD) of 0.73 and 1.17% (n=5), respectively. Honokiol and magnolol in Magnolia Bark of the Japanese Pharmacopoeia were extracted with 70% methanol, diluted with a mobile phase, and injected into the microHPLC-ECD for determination. Recoveries of honokiol and magnolol in Magnolia Bark exceeded 98.7% with RSD, less than 0.93% (n=5). Determination of the distributions of honokiol and magnolol in bark, phloem, wood, leaf blades, and petioles of fresh M. obovata were made using weight samples of 40-238 mg. This method is useful to determine honokiol and magnolol in M. obovata, which is a candidate for crude magnolia bark for traditional Japanese herbal medicines.     

A novel analytical approach for investigation of anthracene adsorption onto mangrove leaves

A solid surface fluorimetry approach was established for direct determination of anthracene (An) adsorbed onto fresh mangrove leaves. The experimental results showed that the linear dynamic ranges for determination of An adsorbed onto Avicennia marina (Am), Bruguiera gymnorrhiza (Bg), Kandelia candel (Kc) and Rhizophors stylosa (Rs) leaves varied from 0.92 to 8.71, 0.089 to 0.70, 0.063 to 5.61 and 0.11 to 1.82 microgg(-1), with detection limits of 5.77, 1.79, 4.29 and 1.42 ngg(-1), respectively, and with a relative standard deviation less than 10% (n=5). The experimental recovery results for adsorbed An on Am, Bg, Kc and Rs leaves were among 79.2-85.9, 75.1-102.3, 70.2-93.8 and 73.1-110.8%, respectively. Using the established method, we investigated the effects of exposure time of An and the different quantity of leaf-wax among the four species of mangrove on the amount of An adsorbed. Under the same experimental conditions, the adsorption of An on the upper and lower sides of the same mangrove leaf, and at different regions on the upper side of the same mangrove leaf were also studied. The results demonstrated that the leaves of different mangrove species contained different quantities of leaf-wax, and with the same exposure conditions to An, the quantity of leaf-wax among the four species showed a significant positive correlation with the amount of An adsorbed onto the leaves.     

Fluorescence spectra and chemical species of fluorescein molecules adsorbed on a calcinated porous Vycor glass

Properties of fluorescence and the excitation spectra of fluorescein molecules adsorbed onto a calcinated (773 K) porous Vycor glass have been investigated as a function of the amount of adsorbed dye (the surface coverage, θ = 0.00051 and 0.0098). The fluorescence and fluorescence-excitation spectra of fluorescein adsorbed onto Vycor glass showed the spectrum only due to cation species at θ = 0.00051. On the other hand, the spectra observed at θ = 0.0098 suggested the presence of cation, anion, and dianion species on the surface of Vycor glass. These results indicated the existence of at least two different types of adsorption sites involving the Brønsted acid site on the surfaces of Vycor glass.     

Deposition precipitation for the preparation of carbon nanofiber supported nickel catalysts

Deposition precipitation of nickel hydroxide onto modified carbon nanofibers has been studied and compared to deposition onto silica. The carbon nanofiber support materials consisted of graphite-like material of the fishbone-type with a diameter of 20-50 nm and a specific surface area of 150 m2/g. Modification involved surface oxidation (CNF-O) optionally followed by partial reduction (CNF-OR) or thermal treatment (CNF-OT). Titration of the support materials showed the presence of 0.17 and 0.03 mmol/g carboxylic acid groups for CNF-O and CNF-OR, respectively. For the CNF-OT only basic groups were present. The deposition precipitation of 20 wt % nickel onto these supports has been studied by time dependent pH and nickel loading studies. With silica, nickel ion adsorption did not occur prior to nucleation of the nickel hydroxide phase at pH = 5.6. With CNF-O, nickel ion adsorption took place right from the start of the deposition process at pH = 3.5, and at pH = 5.6 already 4 wt % nickel was adsorbed. Nucleation of nickel hydroxide onto adsorbed nickel ion clusters proceeded subsequently. Characterization of the dried Ni/CNF-O samples with TEM and XRD showed well dispersed and thin (5 nm) platelets of nickel hydroxide adhering to the carbon nanofibers. After reduction at 773 K in hydrogen the Ni/CNF-O contained metallic nickel particles of 8 nm homogeneously distributed over the fibers. With CNF-OR and CNF-OT, precipitation of large platelets (> 500 nm) separate from the support took place. Clearly, the presence of carboxylic acid groups is essential to successfully deposit nickel hydroxide onto modified carbon nanofibers.     

Simultaneous determination of acetylsalicylic acid and salicylic acid in human plasma by isocratic high‐pressure liquid chromatography with post‐column hydrolysis and fluorescence detection

A selective, sensitive and rapid high‐performance liquid chromatography method with post‐column hydrolysis and fluorescence detection was developed for the simultaneous quantification of acetylsalicylic acid and its metabolite salicylic acid in human plasma. Following the addition of 2‐hydroxy‐3‐methoxybenzoic acid as internal standard and simple protein precipitation with acetonitrile, the analytes were separated on a ProntoSIL 120 C₁₈ ace‐EPS column (150 × 2 mm, 3 µm) protected by a C₈ guard column (5 µm). The mobile phase, 10 mm formic acid in water (pH 2.9) and acetonitrile (70:30, v/v), was used at a flow rate of 0.35 mL/min. After on‐line post‐column hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) by addition of alkaline solution, the analytes were measured at 290 nm (λ_ex) and 400 nm (λ_em). The method was linear in the concentration ranges between 0.05 and 20 ng/μL for both ASA and SA with a lower limit of quantification of 25 pg/μL for SA and 50 pg/μL for ASA. The limit of detection was 15 pg/μL for SA and 32.5 pg/μL for ASA. The analysis of ASA and SA can be carried out within 8 min; therefore this method is suitable for measuring plasma concentrations of salicylates in clinical routine. Copyright © 2012 John Wiley & Sons, Ltd.     

Adsorption behavior of methylene blue and its congeners on a stainless steel surface

Methylene blue and its congeners as model dyes were adsorbed onto stainless steel particles at different ionic strengths, pH values, and ethanol contents, and the adsorption mechanism was investigated. A Fourier transform infrared spectroscopy (FTIR) analysis of the dyes adsorbed on the stainless steel plate was carried out to determine the orientations of the adsorbed dyes on stainless steel surface. The adsorption isotherms for all the dyes tested were approximated by a Langmuir equation (Q=Kq(m)C/(1+KC)) in most cases except under strongly basic conditions. From the ionic strength and ethanol content dependencies of the K value in the Langmuir equations, both the electrostatic and hydrophobic interactions were indicated to contribute to the adsorption of the dyes at neutral pH. By comparing the K and q(m) values for the methylene blue congeners and with the aid of the FTIR analyses, it was found that the kind of substituent groups at most positions of the polyheterocycles of methylene blue strongly affects the adsorption behavior, particularly the area occupied by an adsorbed dye molecule, the affinity for the stainless steel surface, and the orientation of the adsorbed dye molecule on the stainless steel surface.     

Determination of benzo[a]pyrene tetrols by column-switching capillary liquid chromatography with fluorescence and micro-electrospray ionization mass spectrometric detection

The present work displays capillary liquid chromatographic column switching methodology tailored for determination of benzo[a]pyrene tetrol isomers in biological matrices using on-line fluorescence and micro-electrospray ionization mass spectrometric detection. A well-established off-line crude solid phase extraction procedure was used in order to make the method compatible with several biological matrices. The solid phase extraction eluates were evaporated to dryness, redissolved in 1.0 ml methanol:water (10:90, v/v), loaded onto a 0.32 mm I.D. x 40 mm 5 microm Kromasil C(18) pre-column for analyte enrichment and back-flushed elution onto a 0.30 mm I.D. x 150 mm 3.5 microm Kromasil C(18) analytical column. The samples were loaded with a flow rate of 50 microl min(-1) and the tetrols were separated at a flow rate of 4 microl min(-1) with an acetonitrile:10 mM ammonium acetate gradient from 10 to 90%. A sample loading flow rate up to 50 microl min(-1) was allowed. The fluorescence excitation and emission were set to 342 and 385 nm, respectively, while mass spectrometric detection of the benzo[a]pyrene tetrols was obtained by monitoring their [M - H](-) molecular ions at m/z 319. The method was validated over the concentration range 0.1-50 ng ml(-1) benzo[a]pyrene tetrols in a cell culture medium with 100 microl injection volume, fluorescence detection and the first eluting tetrol isomer as model compound, resulting in a correlation coefficient of 0.993. The within-assay (n= 6) and between-assay (n= 6) precisions were determined to 2.6-8.6% and 3.8-9.6%, respectively, and the recoveries were determined to 97.9-102.4% within the investigated concentration range. The mass limit of detection (by fluorescence) was 3 pg for all the tetrol isomers, corresponding to a concentration limit of detection of 30 pg ml(-1) cell culture medium. The corresponding mass spectrometric mass limits of detection were 4-10 pg, corresponding to concentration limits of detection of 40-100 pg ml(-1) cell culture medium.     

Different Interactions between Isomeric Tetrakis-(N-Hexadecylpyridiniumyl) Porphyrins and CdS Nanoparticles

Using porphyrin amphiphiles TC(16)PyP(2), TC(16)PyP(3), and TC(16)PyP(4) as photosensitizers, the interaction between amphiphilic porphyrins and colloidal CdS nanoparticles was studied by observing their absorption spectra, fluorescence spectra, and fluorescence lifetimes. The experimental results reveal that upon addition of CdS nanoparticles to a TC(16)PyP(3) or TC(16)PyP(4) solution, TC(16)PyP(3) or TC(16)PyP(4) is adsorbed onto the surface of the colloidal nanoparticles due to electrostatic action. The absorption spectra display the characteristic absorption of metalloporphyrin. Moreover, this adsorption also leads to red-shifted fluorescence spectra and the quenching of fluorescence emission. These changes are related to the formation of complexes. Nearly 90% of the fluorescence emission of 5x10(-6) mol/L TC(16)PyP(4) can be quenched with 6.8x10(-4) mol/L CdS colloid nanoparticles. Only 60% of the fluorescence emission of 5x10(-6) mol/L TC(16)PyP(3) can be quenched with 6.8x10(-4) mol/L CdS nanoparticles. The fluorescence quenching is attributable mainly to static quenching. According to the fluorescence quenching curves, the apparent association constants of TC(16)PyP(4) and TC(16)PyP(3) with colloidal CdS nanoparticles are 1.42x10(3) (mol/L)(-1) and 6.76x10(2) (mol/L)(-1), respectively. However, TC(16)PyP(2) does not adsorb onto the surface of colloid nanoparticles due to its larger steric hindrance; its absorption and fluorescence spectra are unchanged. Copyright 2000 Academic Press.     

基于纳米金固定半抗原的电化学免疫传感器灵敏检测克伦特罗

研制了一种基于纳米金固定半抗原的间接竞争电化学免疫传感器,可灵敏检测克伦特罗.在金电极表面组装1,6-己二硫醇单分子膜,通过Au-S共价作用连接纳米金颗粒,通过吸附作用固定克伦特罗牛血清白蛋白偶联物.样品中的待测组分与固定化的克伦特罗偶联物竞争结合单克隆抗体,碱性磷酸酯酶标记的二抗选择性地与电极表面捕获的一抗反应,进而催化底物1-萘酚磷酸酯水解生成1-萘酚,在电极表面氧化产生电信号.在优化的实验条件下,克伦特罗浓度在0.1～1000 μg/L范围内与电流强度线性相关,线性方程为I(A)-8.79× 10-7-2.66× 10-7logC (μg/L),相关系数0.9960,检出限达20 ng/L.同时测定了猪肉及猪肝样品中克伦特罗含量,相对标准偏差平均值为7.0％,加标回收率在89.1％～105.6％之间,与传统的间接竞争酶联免疫吸附法对照,结果无显著性差异.