Determination of Free L-T4 and Free L-T3 from Blood Using the Immunosensors/Sequential Injection Analysis System

An immunosensors/sequential injection analysis system is proposed for the assay of thyroid hormones free L-T₄ and free L-T₃ in blood samples. The working concentration ranges for free L-T₄ and free L-T₃, are between 2.0 and 720.0 pmol/L and between 2.0 and 340.0 pmol/L, respectively, with detection limits of 1.0 and 1.7 pmol/L, respectively. The selectivity of the immunosensors, as well as the recovery tests done for free L-T₄ and free L-T₃ (99.90 ± 0.01% (n = 10) and 99.94 ± 0.02% (n = 10)), made the immunosensors/sequential injection analysis system suitable for the direct assay of thyroid hormones in blood samples.     

Spectrophotometric determination of magnesium in pharmaceutical preparations by cost-effective sequential injection analysis

A simple and rapid, inexpensive spectrophotometric method was proposed for magnesium assay in pharmaceutical preparations by sequential injection analysis (SIA). The method is based on the reaction between o-cresolphthalein complexone (CPC) and Mg(II) in alkaline media, yielding a pink colored complex with absorption maximum at 570 nm. Since the formation constant between Ca-CPC and Mg-CPC is similar, initially a sample/standard solution was aspirated into the holding coil followed by a mixture of masking-buffer solutions. This was done because masking of calcium should be accomplished before Mg-CPC complexation. Then the reagent was introduced into the reaction coil to produce a colored complex, which is measured spectrophotometrically at 570 nm. In this way the interference of calcium was reduced. Furthermore, all the parameters that affect the reaction were evaluated. The calibration curve is linear over a range of 0-20 mg l⁻¹ of Mg(II) with a detection limit of 0.24 mg l⁻¹. A sample throughput of 80 samples per hour and relative standard deviation <2.0% were achieved. The proposed method was successfully applied for the assay of magnesium in three different compositions of pharmaceutical preparations (tablets). The results were found to be in good agreement with the manual flame atomic absorption spectrophotometry (FAAS) and UV-Vis spectrophotometry methods and with the claimed values by the manufactures. The t-test shows no significant difference at 95% confidence level.     

Fractionation of lead in soils affected by smelter activities using a continuous-flow sequential extraction system

A continuous-flow sequential extraction system was used to study the distribution of Pb, and its association with other elements (Fe, Al and Ca), in soils around a Pb smelter. Soil samples were analysed by a four-step continuous-flow sequential extraction procedure employing a modified Tessier/BCR scheme. Recoveries of Pb using the flow system (88–111%) were higher than those obtained using a conventional batch extraction system. There were also some differences in Pb distribution between fractions as determined using the two extraction systems. The most abundant fraction of Pb was extracted during the dissolution of soil oxides (Fe/Al). Extractograms (plots of concentration of elements vs. extractant volume/time) indicated that anthropogenic Pb was predominantly adsorbed onto Fe oxide surfaces in contaminated soils. In soil profiles, the highest amounts of Pb were found in the topsoil surface layers (0–5?cm) of the contaminated soils with only limited movement into subsurface layers.     

单纯形自动优化的顺序注射分析系统

报道了具有自动优化功能的微机控制的顺序注射光度分析系统的研制。系统主要由注射汞、十位选择阀和带流通池的分光光度检测器构成。操作参数设定、数据采集和处理通过微机完成。采用改进单纯形方法进行系统优化,其算法集成到ＳＩＡ系统控制程序中使优化过程在微机的控制下自动完成。系统研究了ＳＩＡ钼蓝法测磷的操作条件对结果的影响。     

Development of a sequential injection dispersive liquid-liquid microextraction system for electrothermal atomic absorption spectrometry by using a hydrophobic sorbent material: Determination of lead and cadmium in natural waters

A novel on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system coupled to electrothermal atomic absorption spectrometry (ETAAS) was developed for metal preconcentration in micro-scale, eliminating the laborious and time consuming procedure of phase separation with centrifugation. The potentials of the system were demonstrated for trace lead and cadmium determination in water samples. An appropriate disperser solution which contains the extraction solvent (xylene) and the chelating agent (ammonium pyrrolidine dithiocarbamate) in methanol is mixed on-line with the sample solution (aqueous phase), resulting thus, a cloudy solution, which is consisted of fine droplets of xylene, dispersed throughout the aqueous phase. Three procedures are taking place simultaneously: cloudy solution creation, analyte complex formation and extraction from aqueous phase into the fine droplets of xylene. Subsequently the droplets were retained on the hydrophobic surface of PTFE-turnings into the column. A part of 30 μL of the eluent (methyl isobutyl ketone) was injected into furnace graphite for analyte atomization and quantification. The sampling frequency was 10 h⁻¹, and the obtained enrichment factor was 80 for lead and 34 for cadmium. The detection limit was 10 ng L⁻¹ and 2 ng L⁻¹, while the precision expressed as relative standard deviation (RSD) was 3.8% (at 0.5 μg L⁻¹) and 4.1% (at 0.03 μg L⁻¹) for lead and cadmium respectively. The proposed method was evaluated by analyzing certified reference materials and was applied to the analysis of natural waters.     

An increase of utilization efficiency of X-ray beam

The features of absorbed dose field formation in objects irradiated with scanned X-ray beams at double—and four-sided irradiation were investigated both analytically and by Monte Carlo methods. An analytical approach uses an angular/spectrum X-ray characteristics calculated with PENELOPE, JEANT 4 and ModeXR codes. It was shown that the special angular orientation of electron beam incidence on the X-ray converter leads to X-ray dose smoothing on the surface of the irradiated object. At the same time, a double-sided irradiation can provide high X-ray beam efficiency at dose uniformity ration (DUR) <1.5 for sizeable object thickness. At four-sided irradiation, the angular orientation of electron beam incidence on the X-ray converter should be changed so as to focus the electrons to the center of the converter. At this mode X-ray beam efficiency is more than 60%.     

顺序注射化学发光联用技术测定食品中的碘

基于酸性溶液中HCHO存在下,KMnO4可氧化I-产生很强的化学发光的原理,建立了一个简单快速测定微量碘的顺序注射化学发光分析方法。I-在3.0×10-8~8.0×10-6mol/L范围内与发光强度呈良好线性关系。对2.0×10-6mol/L I-11次重复测定的相对标准偏差(RSD)为2.6%,方法的检出限(3σ)1.3×10-8mol/L,测定了4种食品中的碘量,回收率为92.8%~107.7%。分析频率为70 h。     

Gas chromatography–mass spectroscopy optimization by computer simulation,application to the analysis of 93 volatile organic compounds in workplace ambient air

GC–MS optimization method including both advantages from chromatographic separation and mass spectrometric detection was designed for a set of 93 volatile organic compounds. Only a few experiments were necessary to determine the thermodynamic retention parameters for all compounds on a RTX-VMS column. From these data, computer simulation was used in order to predict the retention times of the compounds in temperature programmed gas chromatography. Then, an automatic selection of ions from the NIST database was performed and compared to the optimum conditions (full separation of VOC). This simulation-selection procedure was used to screen a numerous set of GC and MS conditions in order to quickly design a GC–MS method whatever the set of compounds considered.     

Simulation of photon intensity distributions to facilitate the design of beamlines at accelerator-based IR/THz sources

Simulations with the software Synchrotron Radiation Workshop (SRW) for the ANKA infrared (IR) beamlines IR1 and IR2 have shown, that the far-IR and terahertz (THz) edge radiation can interact with the vacuum chamber walls very close to the electron beam. Unfortunately SRW cannot compute wavefronts at large angles of observation and at a close vicinity to the source. As we need to take into account these perturbations for the further propagation of the radiation through the entire beamline optics to the experimental station, we have started to develop our own code.This code can generate the electric and magnetic field vectors by solving Maxwell equations without approximations and without restrictions to the angles of observation or distance to the source. In particular the latter requires that also the magnetic field vectors have to be calculated, to obtain the corresponding photon intensity distribution for situations where the electron beam intersects the observation plane.Moreover it revealed that it is essential to correct for the Coulomb field prior to calculating the photon intensity in cases where the electron beam intersects the observation plane. Therefore our code is not limited to synchrotrons but can also be used for the development of new kinds of IR/THz radiation facilities.     

S=1/2体系的EPR波谱模拟

用一个以Fortran语言编制的S=1/2体系的EPR模拟谱程序.并引入了弛豫项,图谱线型得到了改善,使模拟谱与实验谱更为接近;对超超精细分裂的考虑,使该程序可适合于复杂图谱的模拟;求积分方法的近似处理,缩短了模拟谱的耗时,使复杂图谱的模拟在微机上成为现实.