芯片纳流动注射-等离子体质谱测定血浆中的铂

本研究基于微芯片设计了一个纳流动注射系统。将样品装载到芯片的采样通道,通过八通阀的阀位切换实现纳升试样带注射到等离子体质谱。注射体积取决于采样通道的尺寸,5～25 mm长的采样通道引入试样体积为40～200 nL。此纳流动注射系统具有试样消耗低、进样精度高(优于3.0%)、进样死体积极低(接近零)和加工简便等优点。芯片纳流动注射系统的进样量和载流流速分别为200 nL和20!L/min,可获得峰高最强、峰宽较窄的瞬时信号峰。最佳条件下纳流动注射系统的绝对检出限为2.54 fg,比常规进样系统改善了3244倍,样品通量48 h"1。10次测定20!g/L Pt标准溶液和血浆样品S1的精密度分别为1.5%和2.7%。采用纳流动注射系统和常规进样系统测定的6个血浆中Pt含量一致,加标回收率为94.3%～103.0%,表明前者具有很好的准确性。     

通过柱切换技术与高效液相色谱联用的限进性柱对盐酸贝那普利的在线富集性能

以自制的限进性填料柱为预处理富集柱,Luna C₁₈柱为分析柱,通过柱切换技术将限进性填料柱与高效液相色谱联用(RAM-HPLC),研究了盐酸贝那普利的在线富集效果。考察了进样体积与峰面积、系统总压力的关系,以及常规进样与大体积进样的差别。当进样体积在100 μL以内时,峰面积随进样体积的增加而增加;当进样体积大于80 μL时,系统总压力变化明显。考虑对整个系统的保护,选择80 μL作为最大进样体积。同一浓度的样品进样20 μL与进样80 μL所得峰面积之间的线性关系良好。RAM柱对盐酸贝那普利具有良好的富集作用,能够有效提高HPLC的灵敏度,而且具有简单、经济的特点。     

快速测量挥发性有机物的膜进样-飞行时间质谱仪的设计和应用

研制了一种膜进样-微型飞行时间质谱仪, 该仪器使用双层50 μm硅橡胶膜作为大气压下直接进样的接口. 实验结果表明, 随着样品流速的提高, 膜富集效率信号强度呈线性提高. 双膜中间具有真空差分系统, 富集得到的样品被迅速抽走, 进样系统中样品无记忆效应. 样品在膜中的响应时间为100 s, 而打开差分系统后仅需10 s信号即下降为平稳状态. 与毛细管直接进样相比, 双层膜的富集作用显著, 在相同的实验条件下使用膜进样技术测定10×10-6 (体积分数)苯、甲苯和对二甲苯的信号强度分别提高了280, 370和600倍. 膜进样系统与真空紫外光软电离方式联用, 对于苯的检出限已经达到了25×10-9 (体积分数), 线性范围为3个数量级. 由于采用了软电离方法, 无碎片离子产生, 所以能够根据分子量进行快速定性分析. 将该仪器应用于香烟主烟气中可挥发性有机物的在线分析, 得到50多种可挥发性的有机物. 实验结果表明, 膜进样-飞行时间质谱将在在线分析(特别是环境监测)方面具有广泛的应用空间.     

流动注射-毛细管电泳分流式电动进样歧视效应特征的研究

以碱性药物盐酸伪麻黄碱和酸性药物布洛芬为对象研究了分流式电动进样(一种用于流动注射-毛细管电泳(FI-CE)联用系统的新进样方法)歧视效应的特性。结果发现:在样品介质与运行缓冲液一致的条件下,FI-CE分流式电动进样产生的歧视效应与电动进样相似,但获得的校正曲线的线性明显优于电动进样,而与没有歧视效应的压力进样所获得的线性相似。利用这些特征提高了同时测定复方布洛芬片中少量组分盐酸伪麻黄碱和主要组分布洛芬的分析性能。在24次/h的采样频率下,盐酸伪麻黄碱的检测限为0.7 mg/L,比采用压力进样的毛细管电泳法所得的检测限低30%。连续进样11次分析含有13.1 mg/L盐酸伪麻黄碱和81.4 mg/L布洛芬的试样溶液,峰面积的相对标准偏差分别为2.8%(盐酸伪麻黄碱)和1.2%(布洛芬),明显优于采用压力进样的毛细管电泳法。用该法测定了两批复方布洛芬片中两种组分的含量,所得结果与高效液相色谱法的测定结果一致。     

流动注射同位素稀释电感耦合等离子体质谱测定钐

提出了一种利用流动注射同位素稀释电感耦合等离子体质谱测定地质样品中钐的方法。在采样体积为300μL的条件下，该法灵敏度较连续雾化进样提高了近4倍，分析速度为60样／min，检出限为0．42μg/L。     

场放大进样-胶束扫集法测定升麻中3种有机酸

利用两种在线富集技术,对阿魏酸、异阿魏酸、咖啡酸同时测定的方法进行了研究.在胶束扫集的基础上,联用场放大进样,使富集倍数提高了约100倍;检出限降至4 μg/L,线性范围向下延伸到10 μg/L.胶束扫集电动色谱缓冲体系为90 mmol/L SDS 20 mmol/L Na2PO4(pH=2.20) 10%甲醇,分离电压20 kV.进样电压10 kV,进样时间21 s,进水时间210 s(H=20.0 cm),测量波长214 nm.讨论了SDS浓度、进样长度、进样电压等对分离效果的影响.在优化条件下,3种有机酸在14 min内出峰,峰面积RSD≤3.8%.方法检出限(μg/L)、线性范围(μg/L)、相关系数分别为:阿魏酸4.0、10～400、0.9982;异阿魏酸4.0、10～400、0.9970;咖啡酸5.0、10～400、0.9980.回收率为83.9%～114.3%.     

顶空进样–气相色谱法测定环境水质中甲醇和丙酮

建立顶空进样–气相色谱法测定环境水体中甲醇和丙酮的方法。通过实验优化了顶空及色谱条件,顶空进样条件：在80 ℃下加热30 min,取样针温度为100 ℃,传输线温度为110 ℃;色谱条件：采用聚乙二醇毛细管柱,进样分流比为5∶1,进样口温度为220 ℃;检测器温度为280 ℃。甲醇、丙酮的质量浓度分别在0.0～45.0、0.0～4.5 mg/L范围内与色谱峰面积线性关系良好,相关系数均大于0.999。当取样量为10 mL时,甲醇、丙酮的方法检出限分别为0.18、0.017 mg/L。样品加标回收率分别为87.3%～100.9%、84.6%～108%,测定结果的相对标准偏差分别为0.93%～3.95%、1.01%～4.32%(n=6)。该方法无需复杂的样品处理步骤,安全、环保、快捷。     

流动注射-电感耦合等离子体质谱法的基体效应

研究了流动注射小体积进样,电感耦合等离子体质谱法的在体效应,并与连续进样作了比较,流动注射小体积（１００μＬ）进样时,电离电位较高的Ａｓ和Ａｕ基体对分析元素的信号表现为增强效应,分析元素的质量数越大,所受增强效应越小。了电位较低的Ｃｕ、Ｉｎ、Ｌｉ、Ｎａ和Ｐｂ基体对分析元素的信号则表为抑制效应,基体元素的质量数越大,对分析元素的抑制效应也越大;质量数较大的分析元素,所受的抑制效应较;对质量数相近的分析元素,电离电位较高者受的抑制较大,与连续进样相比,流动注射小体积进样时,基体元素对分析元素的抑制效应较弱,而增强效应较强。     

微流动注射-等离子体质谱直接测定白酒中铅和镉

研制了多采样体积的微流控芯片, 结合普通的八通阀实现了等离子体质谱(ICP-MS)亚微升级样品的进样. 研究了白酒基体[52%(体积分数)乙醇]引入量对ICP的稳定性和裂解后所产生碳干扰的情况, 考察了进样体积与灵敏度的关系, 并优化了载流流速. 实验结果表明, 当进样量低于0.8 μL时, ICP-MS能长时间正常运行, 未出现积碳现象; 进一步将进样量降到0.3 μL以下, 可消除白酒基体中的碳所引入的质谱干扰. 在此基础上建立了用微流动注射ICP-MS直接测定白酒中Pb和Cd的方法, 每小时可分析45个样品, Pb和Cd的检出限分别为12和42 ng/L. 以水标准溶液直接测定了6个白酒样品中的Cd和Pb含量, 结果与微波消解-常规进样系统ICP-MS的分析结果一致.     

大体积进样技术在气相色谱-质谱法测定 二英类化合物中的应用

利用大体积进样技术(large volume injection,LVI),结合气相色谱-质谱方法对二英的测定效果进行了研究。同时与传统分流/不分流进样技术进行了对比。对进样体积为1,5,10,25,50和100 μL的色谱图进行了分析。研究表明使用大体积进样方式,在不影响色谱分离度的同时,大幅度提高了分析灵敏度。通过对土壤样品的检测,证明该方法可以用于环境样品的实际测定。     

Influence of heated spray chamber desolvation on the detectability in inductively coupled plasma atomic emission spectrometry

 A comparison study has been made of the performance of a heated spray chamber desolvation system for sample introduction into inductively coupled plasma. The heated spray chamber system Mistral replaces the normal spray chamber of an ICP-spectrometer and improves the efficiency of both aerosol generation and transport to the plasma [1]. 27 elements in 6 sample solutions with different mineralization were measured with and without the heated spray chamber system. The higher the mineralization of the sample solution, the less was the increase of the intensity of the spectral lines of the elements determined. An increase of the intensity by the same factor for most of the elements was observed in different sample solutions like drinking water (factor 6), fresh water (factor 5), sea water (factor 1.5) and acid solutions resulting from the digestions of soil (factor 3–4) and rock (factor 2) samples. A few elements in drinking and fresh water were only detectable by using Mistral. A clear improvement of the detection limits was found, but compared to the increase of the intensity not for all elements by the same factor. The detection limits for water samples are in the lower μg/L- and the higher ng/L-level by using Mistral. So the Mistral is an alternative to the ultrasonic nebulizer. Received: 28 November 1995/Revised: 15 February 1996/Accepted: 21 February 1996     

Elimination of suction effect in interfacing microchip electrophoresis with inductively coupled plasma mass spectrometry using porous monolithic plugs

A suction-free interfacing method was developed for microchip electrophoresis hyphenated with inductively coupled plasma mass spectrometry (MCE-ICP-MS). The hyphenated system was composed of a microchip, a demountable capillary microflow nebulizer (d-CMN) combined with a heated single pass spray chamber, a negative pressure sampling device, a high voltage power supply, a syringe pump and an ICP-MS. To eliminate the nebulizer suction generated by the pneumatic nebulizer and to ensure that the makeup solution flowed into the nebulizer, two porous polymer plugs were fabricated in the microchip. As a result, reasonably true electropherograms were obtained when compared to the CE separation performed in the traditional MCE-ICP-MS mode without porous polymer plugs. Electrophoretic separation of I(-) and IO(3)(-) was achieved within 25 s in a microchip with an effective separation length of only 15 mm at an electric field of 857 V cm(-1) using 10 mmol L(-1) borate (pH 9.2) as the running buffer. A resolution of 1.3 was obtained and the absolute detection limits for I(-) and IO(3)(-) were 0.12 and 0.13 fg, respectively. The precisions (RSD, n = 10) of the migration time and peak height for I(-) and IO(3)(-) were in the range of 1.1-1.6% and 2.5-2.8%, respectively. Two table salt samples were analyzed by an external calibration method. The iodate contents were in accordance with their labeled values. The recoveries of I(-) and IO(3)(-) in the table salt samples were in the range of 92-105%.     

Platinum determination by inductively coupled plasma–sector field mass spectrometry (ICP–SFMS) in different matrices relevant to human biomonitoring

The analytical challenges of Pt determination by ICP-SFMS posed by different human tissues and fluids have been critically assessed. Investigated samples were (1) urine, (2) serum of cancer patients sampled during chemotherapy with carboplatin, (3) microdialysates (20 micro L sample volume) collected from tumor and non-tumor tissue, and, finally-for the first time-(4) human lung tissue to study background concentrations of inhaled platinum. Sample preparation involved microwave digestion and open vessel treatment or simple dilution (microdialysates). Depending on the sample preparation and introduction systems used (microconcentric nebulization, ultrasonic nebulization with and without membrane desolvation) excellent procedural detection limits (3s criterion) of 0.35 pg g(-1) for urine, 420 pg g(-1) for serum, 400 pg g(-1) for lung tissue and 13 pg g(-1) for microdialysates could be obtained. Ultratrace concentrations of 1-40 pg g(-1), and 1000-3000 pg g(-1) were measured in urine and human lung tissue, respectively, as typical for samples in environmental studies. Quantification was carried out by IDMS and standard addition in the case of urine samples. Internal standardization could not correct for non-spectral interferences in external calibration. In the serum and microdialysates of patients during chemotherapy with carboplatin, elevated Pt levels ranging between 0.01 and 10 micro g g(-1) were determined by external calibration ((195)Pt isotope). For all investigated samples spectral interferences could be excluded by following different strategies. High-resolution control measurements ((194)Pt, (195)Pt) were performed in the case of elevated Pt levels, i.e. for microdialysates and serum samples. An Hf/Pt ratio of 0.4 was determined in human lung samples. An HfO formation ratio of 0.2% was assessed for standard solutions at the present experimental conditions, revealing that the contribution of (179)Hf(16)O, (178)Hf(17)O, (177)Hf(18)O to the (195)Pt isotope signal used for quantification was not significant.     

PTV vapor overflow — principles of a solvent evaporation technique for introducing large volumes in capillary GC

The concept of a GC solvent evaporation technique is outlined that involves a modified Programmed Temperature Vaporizing (PTV) injector. The vapor overflow technique is intended for introducing samples in large volumes of solvent by syringe injection of strongly diluted samples or by coupled LC-GC. The liquid is introduced into a packed vaporizing chamber kept above the solvent boiling point at a pressure which is near or below ambient. The carrier gas is essentially switched off. Evaporation and discharge of the solvent vapors occurs by expansion of the vapors, driven by the solvent vapor pressure. For transferring the sapmple into the column, the carrier gas is switched on again and the vaporizing chamber heated. Compared to PTV solvent split injection, vapor overflow offers the following advantages: It automatically optimizes operational parameters, therefore facilitating its application. Losses of volatile materials are minimized by a minimal flow rate through the injector. Vapor overflow is a promising technique for transferring watercontaining eluents in coupled LC-GC since no wettability is required and leaching of pre-column surfaces is avoided.     

A fast passive and planar liquid sample micromixer

A novel microdevice for passively mixing liquid samples based on surface tension and a geometrical mixing chamber is presented. Due to the laminar flow regime on the microscale, mixing becomes difficult if not impossible. We present a micromixer where a constantly changing time dependent flow pattern inside a two sample liquid plug is created as the plug simply passes through the planar mixer chamber. The device requires no actuation during mixing and is fabricated using a single etch process. The effective mixing of two coloured liquid samples is demonstrated.     

Design and performance of a novel electrospray interface

In this work a new electrospray system has been developed which employs heat as a means of desolvation and requires no counterflow of heated gas. This article describes the operation and performance of this device, with particular emphasis on the differences between it and those described earlier. Results are presented that illustrate the dependence of signal intensity on ion source and spray chamber temperatures and on the composition and flow rate of mobile phase into the electrospray. Results on proteins electrosprayed from aqueous solutions are presented including a bacterial protease which has a tight tertiary structure. The ability to obtain fragmentation data by collisionally induced dissociation in the interface is also discussed.     

Automated sample preparation and analysis using a sequential-injection-capillary electrophoresis (SI-CE) interface

A fully automated sequential-injection-capillary electrophoresis (SI-CE) system was developed using commercially available components as the syringe pump, the selection and injection valves and the high voltage power supply. The interface connecting the SI with the CE unit consisted of two T-pieces, where the capillary was inserted in one T-piece and a Pt electrode in the other (grounded) T-piece. By pressurising the whole system using a syringe pump, hydrodynamic injection was feasible. For characterisation, the system was applied to a mixture of adenosine and adenosine monophosphate at different concentrations. The calibration curve obtained gave a detection limit of 0.5 microg g(-1) (correlation coefficient of 0.997). The reproducibility of the injection was also assessed, resulting in a RSD value (5 injections) of 5.4%. The total time of analysis, from injection, conditioning and separation to cleaning the capillary again was 15 minutes. In another application, employing the full power of the automated SIA-CE system, myoglobin was mixed directly using the flow system with different concentrations of sodium dodecyl sulfate (SDS), a known denaturing agent. The different conformations obtained in this way were analysed with the CE system and a distinct shift in migration time and decreasing of the native peak of myoglobin (Mb) could be observed. The protein samples prepared were also analysed with off-line infrared spectroscopy (IR), confirming these results.     

Sorption of platinum on immobilized microorganisms for its on-line preconcentration and chemiluminescent determination in water samples

Fungi of the type Aspergillus sp. were immobilized on a cellulosic resin and used as a biosorbent for the on-line preconcentration and separation of Pt(IV) ions prior to their chemiluminescent determination via flow injection analysis. Biosorption and elution conditions were optimized, and the results compared to biosorbents based on the use of Chlorella vulgaris algae and Saccharomyces cerevisiae yeast in terms of preconcentration and selective retention of Pt(IV). The immobilized fungi presented here have a high potential for use in platinum biosorption. The procedure exhibits the currently lowest limit of detection (0.02 ng mL^?1 of Pt) and very high selectivity. The procedure was applied to the determination of Pt(IV) in river water, road run-off, and wastewater samples.

Pt NPs catalyzed chemiluminescence method for Hg2+ detection based on a flow injection system

Establishing a simple and accurate method for Hg²⁺ detection is of great importance for the environment and human health. In this work, platinum nanoparticles (Pt NPs) with different capped agents and morphologies were synthesized. It was found that Pt NPs exhibited peroxidase‐like activity that can catalyze the chemiluminescence (CL) of the luminol system without H₂O₂. The most intensive CL signals were obtained by using PVP‐capped Pt NPs as catalysis. Based on the fact that Hg²⁺ could further enhance the CL intensity in the Pt NPs‐luminol CL system, a Pt NPs‐catalyzed CL method based on a flow injection system is developed for the sensitive analysis of Hg²⁺. When the concentration of Hg²⁺ in the system increases, the CL intensity would together increase, thereby achieving sensitive Hg²⁺ detection. The limit of detection (LOD) was calculated to be 8.6 nM. This developed method provides a simple and rapid approach for the sensitive detection of Hg²⁺ and shows great promise for applications in other complex systems.     

Three-dimensional atom probe study of the segregation behaviour of Ni91Pt9 alloy after sputtering

To investigate local ordering and segregation phenomenon in a Ni91Pt9-alloy after sputtering and annealing a 3D optical atom probe (OAP) has been used. The specimen tips have been prepared from polycrystalline samples. To sputter the samples a separate preparation chamber with a scannable Ar-sputter-gun is connected to the OAP vessel. When necessary, the sample can be electrically heated to induce segregation and cure the altered layer. After a heat treatment of a Ni91 at. %Pt 9 at.% specimen at 1100 K the surface of a (111)-oriented specimen is enriched in platinum by a factor of two in relation to the bulk. The phenomenon of short-range ordering has been investigated on the surface and in the subsurface volume. A 3D reconstruction of this annealed NiPt specimen shows regions with high concentration of platinum that gives an indication at short-range ordering. Uniform sputtering of the tip without a heat treatment induces a decisive depletion of Pt on the surface and the following subatomic layers. The atom-probe results of specimens in thermal equilibrium are in close agreement to further surface sensitive results obtained from Ion Scattering Spectroscopy (ISS) and Auger Electron Spectroscopy (AES).