Capillary Column Inlet System for the Gas Chromatography of Biological Samples

Abstract

A glass injection system consisting of a packed precolumn and gasphase splitter has been developed for the introduction of derivatized biological samples on glass capillary columns. The precolumn provides complete sample evaporation before the splitter zone, traps contaminating nonvolatiles, and prevents decomposition or adsorption of components. In addition, a carrier gas control system is described that permits stable and repeatable adjustment of split ratio and capillary inlet pressure.

The linearity of the splitter has been established using a hydrocarbon mixture covering the range of methylene unit (MU) values in which the steroid derivatives are eluted.     

高温法和烘箱法测定水体中总氮的比较

分别采用烘箱法和高压蒸汽消解法对纯水和电解质溶液中的含氮有机化合物进行了消解,并用镉铜还原法测定了溶液中总氮的含量。实验表明,这两种消解方式无显著性差异,可以采用烘箱法代替压力蒸汽消毒器在电解质溶液中对含氮有机化合物进行消解,且烘箱法操作简单。     

离子排斥色谱法测定生脉注射液中的有机酸

1引言生脉注射液是由红参、麦冬和五味子3种药材经提取后制成的灭菌水溶液,为国家中药保护品种,具有益气养阴,复脉固脱的功效。前期的分析实验表明,生脉注射液中含有有机酸类成分。根据生脉注射液的生产工艺和3种药材的的化学成分研究报道,分析生脉注射液中的有机酸主要来源于五味子。五味子含有柠檬酸、苹果酸、琥珀酸等多种有机酸成分。目前,有机酸的分析方法有气相色谱法[1]、高效液相色谱法[2]、毛细管电泳法[3]及离子色谱法[4]。这些方法专属[5]     

A Study on the Peak Type of Flow Injection Analysis

Abstract

Two equations for justifying whether a FIA peak is a gamma peak or an exponentially modified Gaussian (EMG) peak or neither of them have been presented. From these two equations, the peaks of flow injection extraction and FIA with single-line and two-line manifolds obtained in this paper are gamma peaks.     

Subsecond FFT‐adsorptive Voltammetric Technique as a Novel Method for Subnano Level Monitoring of Piroxicam in its Tablets and Bulk Form at Au Microelectrode in Flowing Solutions

Abstract

In this work a novel method for the determination of piroxicam in flow‐injection systems has been developed. A system using fast Fourier transform continuous cyclic voltammetry (FFTCV), at a gold microelectrode in flowing solution, was used for determining piroxicam in its pharmaceutical formulations. The developed technique is very simple, precise, accurate, time saving, and economical, compared to all of the previously reported methods. The effects of various parameters on the sensitivity of the method were investigated. The best performance was obtained with a pH value of 2, scan rate value of 40 V/s, accumulation potential of (400) mV, and accumulation time of 0.4 s. The proposed method has some advantages over other reported methods, such as, no need for the removal of oxygen from the test solution, a picomolar detection limit, and finally that the method is fast enough for the determination of any such compound, in a wide variety of chromatographic methods. To obtain a sensitive determination, the integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, while performing the measurements. The potential waveform, consisting of the potential steps for cleaning, accumulation, and potential ramp of analyte, was applied on an Au disk microelectrode (with a 12.5 µm in radius) in a continuous way. The method was linear over the concentration range of 1.5–364000 pg/ml (r=0.998) with a limit of detection and quantitation of 0.33 and 1.5 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay piroxicam in tablets.     

Sample Injection for Capillary Electrophoresis on a Micro Fabricated Device/On Chip CE Injection

Abstract

Reproducible injection for capillary electrophoresis on a micro device/Lab on chip is not an easy task. Different injection designs (e.g., T‐type, double T‐type, cross) and different injection modes have been applied (pinched injection, gated injection, optically gated injection, pressure/pneumatic injection, double L injection) with various analytes. Problems and properties of the different modes are described.     

Analytical Separations of Schiff Base Chelates by Reverse Phase Hplc on a 10 Micron C-18 Bonded Silica Subtrate

Abstract

Reverse phase partition chromatography on a 10 micron silica-bonded octadecyl hydrocarbon substrate is applied to the separation of neutral tetradentate chelates of copper (II), nickel (II) and palladium (II) with a range of non-fluorinated and fluorinated beta-ketoamine and salicylaldimine ligands. Variation of retention and resolution with respect to changes in ligand structure and metal chelated is investigated using acetonitrile, methanol and water solvent systems. Detection limits (254 nm) and linearity ranges of response are indicated.     

Determination of Vitamin A in Infant Milk-Based Formulas and Pharmaceutical Formulations Using Flow Injection with Ce(IV)–Na2SO3 Chemiluminescence Detection

A rapid and simple flow injection (FI) method is reported for the determination of vitamin A (retinol) based on its strong enhancing effect on the Ce(IV)–Na₂SO₃ chemiluminescence (CL) reaction in an acidic solution. The effect of key chemical and physical parameters (i.e., reagent concentrations, flow rate, and sample volume) was optimized and potential interferences examined. Under the selected experimental conditions, a linear calibration was obtained between the CL intensity and vitamin A concentration in the range 0.1–8.0 µg mL^?1 (r ²  = 0.9986, n = 8). The limit of detection (3 s x blank) was 0.01 µg mL^?1 retinol (n = 6) and the relative standard deviation (RSD) for 0.25 µg mL^?1 retinol was 2.3% (n = 10) with a sampling rate of 180 h^?1. The method was successfully applied to infant milk-based formulas and pharmaceutical formulations and the results were not significantly different at 95% confidence interval with those obtained by using a spectrophotometric reference method. The possible CL mechanism is also discussed briefly supporting with UV-visible, fluorescence, and CL spectra.     

Determination of Diammonium Glycyrrhizinate and Its Antioxidant Activity Using a Novel Chemiluminescence System

A novel chemiluminescence (CL) system was established for the determination of diammonium glycyrrhizinate (DG) in pharmaceutical preparations and its ability of scavenging hydroxyl radical. It was shown that a strong CL signal was observed when Eosin Y mixed with Fenton reagent. The CL intensity was decreased significantly when DG was added to the reaction system and partially scavenged the hydroxyl radicals in the solution. The extent of decrease in the CL intensity had a good stoichiometrical relationship with DG concentration. Based on this, we developed a new method for the determination of DG using a flow injection chemiluminescence (FI-CL) technique. Under the optimal conditions, the linear range of DG concentration was 6.0 × 10^?8–5.0 × 10^?6 mol/L (R = 0.9982) with a detection limit of 8.0 × 10^?9 mol/L (SN = 3), and the RSD was 3.8% for 2.0 × 10^?7 mol/L DG (n = 11). This method was successfully used in the determination of DG in tablets and the evaluation of hydroxyl radical scavenging capacity of DG. The possible reaction mechanism of the CL system is discussed.