利用红外光纤传像束测量桥丝感应电流

针对传统的桥丝式电点火头中感应电流测量方法在电磁环境测量时会引入电场或者磁场的干扰,本文基于红外光纤传像束耦合CCD红外探测器,提出一种非接触式远程测量的新方法.通过CCD红外探测器得到桥丝式电点火头辐射的热场灰度图像,根据灰度值与温度、温度与电流的关系标定对应的桥丝微弱的感应电流值.实验结果表明,这种方法可以精确测量...     

星上定标积分球系统的设计

星上定标系统是有效监测遥感器辐射响应性能的重要技术构成,成像光谱仪技术的发展对星上定标系统提出了更高的要求,包括系统小型轻量化及稳定性等技术难题.提出一种较完整的技术方案,以内置卤钨灯为光源,用小型化的积分球为匀光体,采用色温校正技术调节其光谱输出,内置安装标准辐射计监视系统的稳定性.针对积分球系统定标用的光源--卤钨...     

In‐line preconcentration capillary zone electrophoresis for the analysis of haloacetic acids in water

Two in‐line enrichment procedures (large volume sample stacking (LVSS) and field amplified sample injection (FASI)) have been evaluated for the CZE analysis of haloacetic acids (HAAs) in drinking water. For LVSS, separation on normal polarity using 20 mM acetic acid–ammonium acetate (pH 5.5) containing 20% ACN as BGE was required. For FASI, the optimum conditions were 25 s hydrodynamic injection (3.5 kPa) of a water plug followed by 25 s electrokinetic injection (?10 kV) of the sample, and 200 mM formic acid–ammonium formate buffer at pH 3.0 as BGE. For both FASI and LVSS methods, linear calibration curves (r²>0.992), limit of detection on standards prepared in Milli‐Q water (49.1–200 μg/L for LVSS and 4.2–48 μg/L for FASI), and both run‐to‐run and day‐to‐day precisions (RSD values up to 15.8% for concentration) were established. Due to the higher sensitive enhancement (up to 310‐fold) achieved with FASI‐CZE, this method was selected for the analysis of HAAs in drinking water. However, for an optimal FASI application sample salinity was removed by SPE using Oasis WAX cartridges. With SPE‐FASI‐CZE, method detection limits in the range 0.05–0.8 μg/L were obtained, with recoveries, in general, higher than 90% (around 65% for monochloroacetic and monobromoacetic acids). The applicability of the SPE‐FASI‐CZE method was evaluated by analyzing drinking tap water from Barcelona where seven HAAs were found at concentration levels between 3 and 13 μg/L.     

微小型氢火焰离子化检测器及在色谱中的应用

构建了一种微小型氢火焰离子化检测器(μ-FID).与传统FID不同,助燃空气从收集极上部侧面导入,沿收集极与检测器壳体之间的缝隙向下流动,以环状气流沿壁流入燃烧室,流向反转后从中空的收集极内流出.火焰喷口位于燃烧腔的正中心轴线上,该区域助燃气的流动非常稳定,因此噪音电平非常低.采用更高的极化电压以提高离子化效率.对喷口...     

XPS and AFM characterization of the self‐assembled molecular monolayers of a 3‐aminopropyltrimethoxysilane on silicon surface,and effects of substrate pretreatment by UV‐irradiation

The self‐assembled (SA) molecular monolayers of a 3‐aminopropyltrimethoxysilane (3‐APTS) on a silicon (111) surface, and the effects of ultraviolet (UV) pre‐treatment for substrates on the assembling process have been studied using XPS and atomic force microscopy (AFM). The results show that the SA 3‐APTS molecules are bonded to the substrate surface in a nearly vertical orientation, with a thickness of the monolayer of about 0.8–1.5 nm. The SA molecular monolayers show a substantial degree of disorder in molecular packing, which are believed to result from the interactions of amine tails in the silane molecules used with surface functionalities of the substrates, and the oxygen‐containing species from the ambient. UV irradiation for silicon substrates prior to the self‐assembly reaction can enhance the assembly process and hence, significantly increase the coverage of the monolayer assembled for the substrates. Copyright © 2010 John Wiley & Sons, Ltd.     

Simple, stable and sensitive electrogenerated chemiluminescence detector for high-performance liquid chromatography and its application in direct determination of multiple fluoroquinolone residues in milk

A simple, stable and sensitive electrogenerated chemiluminescence (ECL) detector was developed. It was based on tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) immobilized on the surface of a Pt wire with Nepem-105D ion exchange solution. The detector was prepared by inserting a Pt wire with immobilized Ru(bpy)₃²⁺ (working electrode) into a capillary tube, followed by inserting another Pt wire (counter electrode) in this tube and sealing. ECL behavior was investigated using ofloxacin as an analyte. Under optimal conditions, stable ECL intensity was obtained. This detector has been used in HPLC-ECL for the determination of multiple target fluoroquinolone residues in milk. There is no post column reagent addition, which would dilute the analytes, potentially leading to chromatographic band-broadening. The system is very simple with low dead volume, low baseline and background noise, together with high sensitivity and stability. The as-prepared ECL detector, when was used for the determination of ofloxacin, pefloxacin, enrofloxacin and difloxacin in milk, demonstrated adequate sensitivity to allow quantification of trace FQ levels in commercial milk samples. One or more of the target FQ analytes were present at levels above the LOD of the new ECL detector in each and every one of the 22 milk samples analysed.     

A new method for quantitative determination of two uronic acids by CZE with direct UV detection

A new method using capillary zone electrophoresis was developed for the rapid quantification of two common uronic acids, galacturonic acid and glucuronic acid, based on utilization of an alkaline background electrolyte with reversed electroosmotic flow (EOF) within 16 min. The method relies on in‐capillary reaction and direct UV detection at the wavelength 270 nm. The optimum electrolyte solution was prepared of 130 mm sodium hydroxide, 36 mm disodium hydrogen phosphate dihydrate and 0.5 mm cetyltrimethylammonium bromide. EOF was reversed to detect uronic acids and to improve the separation of neutral sugars. The established method was validated and the results showed good linearity, high precision and satisfactory sensitivity. The newly developed method was successfully applied to analyze galacturonic acid and glucuronic acid content in Forsythia suspensa polysaccharides. The method is fast since only sample hydrolysis and dilution are required in the sample preparation. Copyright © 2010 John Wiley & Sons, Ltd.     

Study of the surface ionization detector for gas chromatography

The structure of the surface ionization detector (SID) and the operation parameters of GC-SID were investigated to reduce peak tailing and to enhance sensitivity. The performances of the GC-SID, including its repeatability, linearity, sensitivity, selectivity, and tolerance towards water vapor, were evaluated systematically. Compared with nitrogen-phosphorus detector (NPD), the SID was able to detect fg level triethylamine, and selectively respond to alkylamines, some anilines, and some nitrogen heterocyclic compounds. Among alkylamines, the SID sensitivity to diisobutylamine was rather small. Even so, it was also still 10 times higher than that on NPD. The SID selectivity, defined as the sensitivity ratio between triethylamine and various tested non-nitrogen compounds, was higher than 10(6). It was found that the SID is highly tolerant towards water vapor, allowing direct injection of water sample. Finally, the GC-SID was applied to directly measure trace amines in headspace gases of rotted meat and trace simazine in tap water. The SID sensitivity to simazine was proven to be 5 times higher than that on flame ionization detector (FID). This study suggests that the SID is a promising GC detector.     

反相高效液相色谱法分析三羟乙基胺硬脂酸酯

提出了反相高效液相色谱法测定三羟乙基胺硬脂酸酯中单硬脂酸酯、双硬脂酸酯、三硬脂酸酯的含量。以C18硅胶键合柱(250 mm×4.6 mm,5μm)为分离柱,甲醇与氯仿混合溶液为流动相梯度淋洗,用电雾式检测器检测。三羟乙基胺单、双、三硬脂酸酯的线性范围分别为2.0～50.0,1.0～50.0,1.2～50.0 mg.L-1,方法的检出限(3S/N)分别为1.8,0.5,1.0 mg.L-1。