Quantification of volatile PAHs present at trace levels in air flow by aqueous trapping—SPE and HPLC analysis with fluorimetric detection

In the context of a European project, a new approach of sampling of volatile polycyclic aromatic hydrocarbons (PAHs) from air was developed. In fact, the aim of this project was to test the efficiency of an air cleansing prototype reactor, which was operating by non-thermal plasmolysis. With an eye to model the atmosphere ejected by the prototype, we needed to vaporise the volatile PAHs in an air stream at concentrations as low as those recommended by European Directives (96/62/CE) for PAHs in ambient air (i.e. 1 ng m⁻³). Our strategy was based on the analysis of PAHs trapped in an aqueous medium, in order to avoid important losses of volatile compounds observed during the delicate desorption-concentration step when classical solid supports are used. Then a study was carried out to determine: the design of the collecting part, the flow-rate of the air sampling, the nature and concentration of chemical additives used to enhance PAH solubility in water. The very highly diluted aqueous media obtained after the bubbling step were concentrated by solid-phase extraction (SPE) on hydrophobic cartridges and analysed on-line by reversed-phase HPLC with UV and fluorimetric detections. Lastly, the sampling technique was directly applied to the outlet of the air cleansing prototype and the analysis after 3-6 h of non-thermal plasmolysis showed that the target volatile PAHs were not present in an air stream initially polluted by volatile organic compounds.     

A simple and simultaneous determination of acyclovir and ganciclovir in human plasma by high-performance liquid chromatography

A simple high-performance liquid chromatographic method was developed for the simultaneous determination of the therapeutic levels of acyclovir and ganciclovir in human plasma. After precipitation of plasma proteins with 6% perchloric acid, acyclovir and ganciclovir were simultaneously determined by reversed-phase chromatography with spectophotometric detection at 254 nm. The peak heights for acyclovir and ganciclovir were linearly related to their concentrations ranging from 0.063 to 2.080 micro g/mL. The recovery was 100.48-102.84% for acyclovir and 99.26-103.07% for ganciclovir. The intra- and inter-day relative standard deviation values were in the range 0.186-8.703% for acyclovir and 0.137-6.424% for ganciclovir. The detection limits for both compounds were 0.01 micro g/mL determined as the signal-to-noise ratio of 3. The present method is applicable to therapeutic monitoring during antiviral medication.     

玻璃基片上纳米碳管电极的集成

利用微波等离子体化学气相沉积法在玻璃孔穴中定位生长纳米碳管电极, 分析了负偏压对纳米碳管电极生长的影响. 该电极对铜离子的电化学检测性能分析结果表明, 所制备的纳米碳管电极具有良好的电化学检测性能, 位于－0.0100 V附近的铜离子的还原峰峰形良好, 其电流在铜离子浓度为0.01~0.30 mmol•L^-1时, 与Cu²⁺浓度呈良好的线性关系, 相关系数为0.9975, 且具有较好的长期稳定性和重现性.     

Separation and Determination of Clenbuterol,Cimaterol and Salbutamol by Capillary Electrophoresis with Amperometric Detection

Capillary electrophoresis with amperometric detection was applied to determine some β₂‐agonists, such as clenbuterol, cimaterol and salbutamol in this paper. The working electrode used was a 0.3 mm diameter carbon disk electrode. In this work, the pH 6.0–6.4 borax‐potassium dihydrogen phosphate was used as running buffer (150 mmol/L), 10 kV as the separation voltage and 1.05 V (vs. Ag/AgCl, 3 mol/L KCl) as the detection potential. Under the optimum conditions, the analytes were baseline separated within 16 min. Linear range for cimaterol, clenbuterol and salbutamol was 1.0–2000, 2.0–2000 and 1.0–2000 ng/mL, respectively. The detection limits (define as 3σ/k) were 0.5, 1.0 and 0.4 ng/mL for cimaterol, clenbuterol and salbutamol, respectively. The developed method has been applied to determine these three analytes in feed and urine by standard addition. The mean recoveries for these three analytes ranged from 89.0% to 102.0%.     

Hydrodynamic Radius Characterization of a Vinyl-Type Polynorbornene by Size-Exclusion Chromatography with a Static and Dynamic Laser Light Scattering Detector

Both absolute molecular weight and molecular sizes (radius of gyration and hydrodynamic radius) of a vinyl-type polynorbornene eluting from size-exclusion chromatography columns were determined by combined with a static and dynamic laser light scattering detector. The hydrodynamic radius of polymer fraction eluting from size-exclusion chromatography columns was obtained from dynamic laser light scattering measurements at only a single angle of 90° by introducing a correction factor. According to the scaling relationship between molecular sizes and molecular weight and the ratio between radius of gyration and hydrodynamic radius, the vinyl-type polynorbornene took a random coil conformation in 1,2,4-trichlorobenzene at 150 °C.     

Determination of vanadium, molybdenum and tungsten in complex matrix samples by chelation ion chromatography and on-line detection with inductively coupled plasma mass spectrometry

In this work, two kinds of chelating resin, bis(2-aminoethylthio)methylated resin (BAETM) and γ-aminobutyrohydroxamate resin (γ-ABHX) were synthesized. Of these, the former has a hydrophobic skeleton, and the latter a hydrophilic skeleton. The functionalities of each were 0.91 and 2.21 mmol g⁻¹, respectively. The chelating behavior of these resins towards vanadium, molybdenum and tungsten as a function of pH was studied. To perform trace metals analysis in complex matrices, a hyphenated method-chelation ion chromatography (CIC) coupled on-line detection with inductively coupled plasma mass spectrometry (ICP-MS) was developed. With a BAETM resin column (5×0.4 cm i.d.) as the separator, a sample volume of 20 μl, nitric acid (pH 1.5) as the eluent and a flow rate of 1 ml min⁻¹, the detection limits for the determination of vanadium, molybdenum and tungsten were lower than 0.05 ng ml⁻¹and the linear ranges were up to 100 ng ml⁻¹ for each element. By increasing the injected sample volume to 250 μl, the resin concentrator improved the detection limit to 0.01 ng ml⁻¹. For the determination of these elements (5 ng ml⁻¹ for each) spiked in artificial sea water samples, γ-ABHX resin column (3×0.6 cm i.d.) demonstrated well resolved peak separation between the analytes and the matrix elements—calcium and magnesium, by using sodium nitrate (10 ml, 10⁻⁴ M) as the eliminator.     

Derivatization of carboxylic acids with 9-bromomethylacridine using micellar phase-transfer catalysis

Summary Micellar phase-transfer catalysis (MPTC) offers the opportunity to derivatize carboxylic acids directly in an aqueous matrix without prior extraction of the acids into a suitable aprotic solvent. The currently developed MPTC system consists of a non-ionic surfactant, Arkopal N-130, an ion-pair agent, tetrakis-(decyl)-ammonium bromide, and a novel fluorescence reagent, 9-bromomethylacridine. The MPTC system can be applied to the derivatization of many types of carboxylic acids. The reaction rate is affected by the lipophilicity of the acid and by the presence of other functional groups. For lipophilic carboxylic acids the reaction is complete within 5 min at 60°C and pH 7.0.     

生物质裂解产物的制备及HPLC检测其成分的虚拟仿真实验开发

In order to improve university laboratory teaching and practical education under the background of information technology, as well as overcome the difficulty for practical training, develop a virtual simulation experiment platform for rapid pyrolysis of natal materials and high-performance liquid chromatographic (HPLC) detection of its components. The experiment integrates the actual operation process of the plant to produce cleaved products by rapid pyrolysis of biomass with HPLC detection. The virtual experiment is divided into biomass sample pretreatment, rapid biomass pyrolysis, bio-oil extraction, and HPLC determination of complex components, making the biomass cleavage workshop "real" through simulation. This virtual simulation experiment fully integrates the utilization of biomass resources and basic chemistry courses (such as organic chemistry, instrumental analysis, chemical engineering principles, etc.), which are widely involved in agricultural and forestry majors with advantageous characteristics value.     

磁性纳米标记检测技术在生物医学即时检测领域的研究进展

基于磁性纳米材料的磁标记检测技术具有灵敏度高、线性范围广、信号检测便捷等优点。由于生物样品自身磁背景信号极低,相比于光学标记检测技术,磁标记检测技术在蛋白质、核酸、细胞、病原体及生物组织检测中均表现出更高的灵敏度,在生物医学即时检测领域展现了良好的应用前景。该文围绕磁性纳米粒在即时检测领域的最新研究进展,重点介绍了其在蛋白质、核酸以及几类病原体检测方面的应用,并对基于磁性纳米粒的即时检测技术发展方向及应用前景进行了展望。     

Chromatographic Analysis of Trans Resveratrol in Italian Wines: Comparisons between FL, UV and MS Detection

Resveratrol (3,5,4′-trihydroxystilbene) is a phytoalexin that belongs to the group of stilbenes, known to occur in grapes and consequently in grape products. Its presence in wine is an important qualitative parameter because of the several beneficial effects on human health. The aim of this work is the development of a high-performance liquid chromatographic (HPLC) method for the determination of trans resveratrol in wines, and comparisons between the results obtained by different detection techniques: UV-vis spectroscopy, fluorescence spectroscopy and mass spectrometry. Resveratrol is analysed on a C-18 column using gradient elution. The method permits direct injection of sample, revealing to be time-saving, overcoming the need of sample pre-treatment steps. Detection limits were 154.8 ng mL⁻¹ by HPLC-UV, 118.0 ng mL⁻¹ by HPLC-FL and 48.0 ng mL⁻¹ by HPLC-MS. Trans resveratrol has been then quantified in a group of 52 wines derived from different Italian regions, cultivars and winemaking technologies by HPLC-UV.