银（III）配合物-鲁米诺流动注射化学发光新体系测定肾上腺素

儿茶酚胺是一类非常重要的神经递质,在人体的心血管系统、神经系统、内分泌腺、肾脏、平滑肌等组织系统的生理活动中起着广泛的调节作用。肾上腺素为儿茶酚胺的一种,建立灵敏、高效的肾上腺素检测技术具有重要的临床意义。本文将银（Ⅲ）配合物与鲁米诺组成新的流动注射化学发光体系,利用碱性介质中肾上腺素对三价银配合物－鲁米诺化学发光体系有明显的增强效应来测定肾上腺素的含量,并据此建立了高效测定肾上腺素的流动注射化学发光新方法。在优化的条件下,该方法测定肾上腺素的线型范围为1.0×10－9～1.0×10－7 mol L-1,检出限为8.0×10－10 mol L-1,对1.5×10－8 mol L-1肾上腺素11次平行测定,其相对标偏差为2.9％。利用建立的分析方法测定了药物肾上腺素,并对三价银－鲁米诺化学发光新体系测定肾上腺素的反应机理进行了讨论。     

Two new C-glucofuranosyl isoflavones in puerarin injection

Two new C-glucofuranosyl isoflavones of impurities in puerarin injection were isolated.Their structures were determined to be 8-C-α-glucofuranosyl-7,4'-dihydroxyisoflavone and 8-C-β-glucofuranosyl-7,4'-dihydroxy-isoflavone by chemical and spectral analysis.     

Flow/sequential injection sample treatment coupled to capillary electrophoresis. A review

Various flow sample handling approaches coupled to capillary electrophoresis (CE) are reviewed, covering the research in this field in the 12 years since the milestone year of 1997, when practical interfaces to on-line couple flow injection (FI) and capillary electrophoresis were first developed independently by two research groups. Some previous attempts are also presented. Since 1997 a plethora of ingenious coupled systems have been developed. Although several reviews are available on various aspects of the topic, we have opted for a comprehensive overview of all FI-CE systems, as well as related and similar systems. This coupling has thus also led to the development of systems based on hybrids between the classical and microchip approaches. Truly microchip FI-CE systems are also included in this review.The developed systems have been used for various sample treatments, including on-line membrane-assisted sample treatment, column-based preconcentration, on-line derivatization and monitoring, to name just a few. The utility of coupling flow sampling to CE has been demonstrated in various practical applications that are discussed in detail. The current state-of-the-art and foreseeable future developments are also discussed.     

A review on sequential injection methods for water analysis

The development of fast, automatic and less expensive methods of analysis has always been the main aim of flow methodologies. The search for new procedures that still maintain the reliability and accuracy of the reference procedures is an ever growing challenge. New requirements are continually added to analytical methodologies, such as lower consumption of samples and reagents, miniaturisation and portability of the equipment, computer interfaces for full decision systems and so on. Therefore, the development of flow methodologies meeting the extra requirements of water analysis is a challenging work.Sequential injection analysis (SIA) presents a set of characteristics that make it highly suitable for water analysis. With sequential injection analysis, most routine determinations in waters can be performed more quickly with much lower reagent consumption when compared to reference procedures. Additionally, SIA can be a valuable tool for analyte speciation and multiparametric analysis. This paper critically reviews the overall work in this area.     

Sequential injection analysis (SIA) and response surface methodology: A versatile small volume approach for optimization of photo-Fenton processes

Optimization of photo-Fenton degradation of copper phthalocyanine blue was achieved by response surface methodology (RSM) constructed with the aid of a sequential injection analysis (SIA) system coupled to a homemade photo-reactor. Highest degradation percentage was obtained at the following conditions [H₂O₂]/[phthalocyanine] = 7, [H₂O₂]/[FeSO₄] = 10, pH = 2.5, and stopped flow time in the photo reactor = 30 s. The SIA system was designed to prepare a monosegment containing the reagents and sample, to pump it toward the photo-reactor for the specified time and send the products to a flow-through spectrophotometer for monitoring the color reduction of the dye. Changes in parameters such as reagent molar ratios, residence time and pH were made by modifications in the software commanding the SI system, without the need for physical reconfiguration of reagents around the selection valve. The proposed procedure and system fed the statistical program with degradation data for fast construction of response surface plots. After optimization, 97% of the dye was degraded.     

Enhanced resolution comprehensive two-dimensional gas chromatography applied to the analysis of roasted coffee volatiles

The present research is based on the full exploitation of the separation power of a 0.05 mm internal diameter (ID) capillary, as a comprehensive two-dimensional (2D) GC (GC × GC) secondary column, with the objective of attaining very high-resolution second dimension separations. The aim was achieved by using a split-flow system developed in previous research [P.Q. Tranchida, A. Casilli, P. Dugo, G. Dugo, L. Mondello, Anal. Chem. 79 (2007) 2266], and a dual-oven GC × GC instrument. The column combination employed consisted of a polar 30 m × 0.25 mm ID column connected, by means of a T union, to a detector-linked high-resolution 1.1 m × 0.05 mm ID apolar analytical column and to a 0.33 m × 0.05 mm ID retention gap; the latter was connected to a manually operated split valve. As previously demonstrated, the use of a split valve enables the regulation of gas flows through both analytical columns, generating the most appropriate gas linear velocities. Comprehensive 2D GC experiments were carried out on Arabica roasted coffee volatiles (previously extracted by means of solid-phase microextraction) with the split-valve closed (equal to what can be defined as conventional GC × GC) and with the split-valve opened at various degrees. The reasons why it is absolutely not effective to use a 0.05 mm ID column as second dimension in a conventional GC × GC instrument will be discussed and demonstrated. On the contrary, the use of a 0.05 mm ID column as second dimension, under ideal conditions in a split-flow, twin-oven system, will also be illustrated and discussed.     

Analysis of whole congener mixtures of polybromodiphenyl ethers by gas chromatography–mass spectrometry in both environmental and biological samples at femtogram levels

A sensitive and selective method for the determination of the whole congener distribution of polybromodiphenyl ethers in environmental and biological samples in one single instrumental run is described. The method is based on gas chromatography coupled to low-resolution mass spectrometry in negative ion chemical ionization mode. It allows determination of these compounds at concentration levels lower than 10⁻¹⁴ g. A programmed temperature vaporization injector has been used to ensure maximum compound transfer to the chromatographic column while maintaining low thermal degradation levels of the more brominated congeners. Selectivity was increased by modification of the MS source parameters for optimization of the abundance of the high mass fragment ions. Under optimized condition, good repeatability (1.7–9.1%) and reproducibility (4.1–20%), and low detection limits, ranging between 1.5 and 15 pg ml⁻¹, were obtained. These features afforded reliable quantification of these compounds in snow and human samples at the concentrations in which these compounds are found.     

Temporal variability of colloidal material in agricultural storm runoff from managed grassland using flow field-flow fractionation

This paper reports the use of flow field-flow fractionation (FlFFF) to determine the temporal variability of colloidal (<1 μm) particle size distributions in agricultural runoff waters in a small managed catchment in SW England during storm events. Three storm events of varying intensity were captured and the colloidal material in the runoff analysed by FlFFF. The technique had sufficient sensitivity to determine directly the changing colloidal profile over the 0.08–1.0 μm size range in the runoff waters during these storm events. Rainfall, total phosphorus and suspended solids in the bulk runoff samples were also determined throughout one storm and showed significant correlation (P < 0.01) with the amount of colloidal material. Whilst there are some uncertainties in the resolution and absolute calibration of the FlFFF profiles, the technique has considerable potential for the quantification of colloidal material in storm runoff waters.     

Particle size distributions of silver nanoparticles at environmentally relevant conditions

Silver nanoparticles (Ag NPs) are becoming increasingly popular as antimicrobial agents in consumer goods with consequent risk to environmental health from discharges. Environmentally relevant fate and transport investigations are limited but essential to gain understanding towards bioavailability and toxicology. In this study, monodisperse 15 nm citrate-stabilised Ag NPs were synthesised, characterised and then fractionated by flow field-flow fractionation (FlFFF) at environmentally relevant conditions (pH 5 or 8, presence of natural organic macromolecules (NOM) and presence of sodium or calcium). At low ionic strength, Ag NPs particle size increased as pH increased from 5 to 8. However, changing the ionic strength from 10⁻³ to 10⁻² M Na increased instability of the Ag NPs, and loss of peak at pH 5 but in the presence of humic substance (HS), a reduction in NP size was seen, most likely due to a reduction in the diffuse layer. The presence of Ca²⁺ ions, at the higher ionic strengths caused complete loss of the solution Ag NPs with or without HS, most likely due to aggregation. At the lower Ca²⁺ ionic strength the Ag NPs were still unstable, but again, in the presence of HS the NPs were largely dispersed. The presence of HS improved stability of Ag NPs under these conditions by forming a surface coating resulting in both steric and charge stabilisation. This work implies that Ag NPs could have long residence times in aquatic systems in the presence of HS potentially resulting in increased bioavailability.     

Recent developments in electrochemical flow detections—A review: Part I. Flow analysis and capillary electrophoresis

Recent years have provided numerous new examples of applying flow-through electrochemical detectors in chemical analysis. This review, based on about 250 original research papers cited from the current analytical literature, presents their application in flow analysis and capillary electrophoretic methods. Example applications are also given for arrays of electrochemical sensors in flow analysis and electrochemical detection in microfluidic systems. Potentiometric detection with ion-selective electrodes predominates in flow analysis carried out mostly in a flow-injection system, while amperometric and conductivity detections are most commonly employed in capillary electrophoresis.