巴洛沙星-Tb^3＋-ATP荧光体系的建立及其分析应用

在二元配合物巴洛沙星-Tb^3＋中加入ATP,Tb^3＋在其特征波长545nm处的荧光强度增强,据此建立了新的巴洛沙星Tb^3＋-ATP荧光体系。在最优化实验条件下,增强的荧光强度与ATP的浓度呈良好的线性关系,线性范围为2．0×10^-6-3．0×10^-5mol／L,检出限为8．0×10^-7mol／L。详细的机理研究表明,ATP能与巴洛沙星-Tb^3＋形成大的三元络合物荧光体系。新建立的荧光体系成功地应用于ATP注射液中ATP的定量检测。对不同批次ATP注射液进行加标回收试验,回收率为101％-106％,测定结果的相对标准偏差为1．1％-1．9％（n=5）。     

Corona Discharge Ionization Source for a Planar High-Field Asymmetric Waveform Ion Mobility Spectrometer

A corona discharge (CD) ionization source was prepared for a planar high-field asymmetric waveform ion mobility spectrometer (FAIMS). The effects of discharge current and discharge distance on ionization efficiency were investigated; and the electric field dependence of the ion injection in the reaction region was studied. The results showed that the discharge current of CD source had good linearity with the intensity of reactant ion peak (RIP), and the RIP intensity increased to a stable level at the discharge distance of >5 mm. An injection electrode was introduced to improve the ionization efficiency. A square-wave voltage applied to the electrode was found to provide optimal performance of ion injection and utilization. The operating parameters of the CD-FAIMS were optimized to achieve trace level detection of dimethyl methylphosphonate (DMMP) sample. The detection limit for DMMP was 0.5 µg/m^3.     

Enhanced Stability of Electrochemical Detection with Surfactant Containing Mobile Phases in Liquid Chromatography and Flow Injection Analysis

Abstract

The use of surfactant containing mobile phases to prevent or reduce the effects of adsorptive fouling of glassy carbon electrodes is reported. Both cationie and antonic surfactants are studied at concentrations above and below the critical micelle concentration. For the oxidative reactions studied here, anionic surfactants have little effect on the fouling problem, likely because of electrostatic attraction of the generated cattonic intermediate to surfactant adsorbed on the electrode surface. Cationic surfactants, however, have the desired effect. Two cationic surfactants, cetyltrimethylammonium chloride and n-decylamine were studied with solutes p-nitrophenol, phenylenediamine and chlorpromazine. With these surfactants present in the mobile phase there was generally no loss of electrochemical response after up to 55 sequential injections. Adsorption of the electroactive specie prior to the electron-transfer process is shown to be a significant cause of poor chromatographic efficiency for some solutes.     

Determination of Vitamin D3 and 25-Hydroxyvitamin D3 Using Liquid Chromatography with Amperometric Detection

Abstract

The electrochemical behaviour of vitamin D₃ and 25-hydroxyvitamin D₃ (25-OH D₃) in a high performance liquid chromatography system using amperometric detection is described. Separation is carried out using a C18 reversed-phase column and the optimum mobile phase was a 0.1 M LiClO₄ solution in methanol-water (97:3, v/v) at a flow rate of 1.25 ml/min. 25-OH D₃ and vitamin D₃ were eluted with good resolution at retention times of 3 and 6 minutes respectively, and determined by amperometric detection with a glassy carbon electrode at + 1.050 V (vs Ag/AgCl). Calibration graphs for both substances showed good linearity when amounts of vitamin D₃ between 18 and 312 ng and 27 and 412 ng of 25-OH D₃ were injected. Detection limits of 8 ng (vitamin D₃) and 25 ng (25-OH D₃); relative standard deviations of 3.2% (vitamin D₃) and 5.8% (25-OH D₃) were obtained.     

Chemical Detection Of Selected Hallucinogens In Water

Abstract

A specific and non-destructive test for basic esters of benzilic and α-glycolic acids in water is described. The compounds are collected on a glass fiber filter as water insoluble complexes with sodium tetraphenylboron. The filter is dried and sprayed with a 2-diphenylacetyl-l, 3-indandione-l-imine derivative. A positive test is the visual observation of fluorescence.     

LCEC Detector with Graphite-Teflon Electode

Abstract

A compression molded graphite-Teflon electrode is evaluated as a detector for the electrochemical detection of phenolic compounds, separated by reverse-phase high-performance liquid chromatography. Detection limits for these phenolic compounds range from 0.5–1 ng. Repetitive injections yield peak heights with RSDs less than 1%. Passivation of electrode surface by phenols is discussed. In addition, construction of a flow cell to be used in conjunction with graphite-Teflon electrode is also described.     

Derivatization of Drugs and Bioorganics for Improved Detection by Gas Chromatography and Photoionization Detection (GC-PID)

Abstract

Pentafluorophenyldimethylsilylchloride (flophemesyl chloride, FICI) has recently been used for derivatizations of alcohols, leading to significant improvements in detectability by gas chromatography (GC)-photoionization detection (PID) and electron capture detection (ECD). This off-line reaction has now been applied to a number of related alcohol derivatives, naturally occurring bioorganics such as cholesterol, androsterone, and similar sterols and steroids. Standard GC-ECD-PID analytical parameters have been determined, such as detection limits, calibration plots, ECD and PID relative response factors (RRF), ECD/PID relative response factor ratios, etc. for underivatized and derivatized substrates. Packed and capillary column GC conditions have been used with a 10.2 eV PID lamp. Application of the optimized derivatization-GC-ECD-PID method is reported for bioorganics in biological media. The overall results demonstrate the immediate applicability of such an approach for a number of alcohol derivatives, especially those having biological properties.     

Atomic Absorption Spectrometry with Thin-Wall Tungsten Tube Atomizer in the Presence of Ammonium Thiocyanate

Abstract

A sensitive atomic absorption spectrometry with a thin-wall tungsten tube atomizer is described. By addition of thiocyanate, sensitivities and detection limits were improved over that of a conventional atomizer for several elements.     

New DNA Technology and the DNA Biosensor

Abstract

Recently there has been an increasing demand to produce systems for the detection of specific DNA sequences that are amenable to non-specialised laboratories. This demand has led to many innovative and novel approaches to DNA analysis which may collectively be termed ′new DNA technology′. Here, we review these advances in relation to their applicability for the production of a DNA biosensor. The present state of the art is described and future possibilities are considered.     

Detection of DNA Hybridization via Fluorescence Intensity Variations of ZnSe-DNA Quantum Dot Biosensors

ZnSe quantum dots (QDs) that were capped with 11-mercaptoundecanoic acid (MUA) and conjugated to amino-modified ssDNA molecules exhibited variations in fluorescence emission intensity upon hybridization with complementary ssDNA in solution, a phenomenon that can be exploited for rapid detection of free ssDNA sequences. Conjugation of MUA-capped ZnSe QDs to amino-modified ssDNA molecules resulted in increased fluorescence emission intensity and stability at room temperature. Increasing the length of the ssDNA, that was conjugated to the QDs, resulted in increased fluorescence emission intensity up to a length of about 50 nucleotide bases, beyond which the peak emission intensity reached a plateau. Hybridization of QD-ssDNA conjugates with complementary ssDNA, either in free form or bound to QDs from the same population, resulted in additional fluorescence emission intensity amplification. A small red shift was observed when three-dimensional QD-dsDNA-QD structures were formed. The QD-ssDNA sensors with single ssDNA molecule per QD were developed and used for rapid quantitative detection of fully or partially complementary free ssDNA sequences in aqueous solution. Partial hybridization of the QD-ssDNA sensors with short ssDNA targets resulted in smaller QD emission intensity amplification, when compared to full hybridization. A QD-ssDNA sensor containing a sequence corresponding to the hemoglobin beta gene was used to detect and discriminate between free ssDNA targets consisting of a complementary ssDNA sequence and targets containing a single-base mutation that can cause sickle-cell anemia. Such QD-based biosensors can form the basis for rapid separation-free assays that can be used to detect target biomolecules in solution.