甲氧苄啶的同步增敏荧光光谱分析法研究

用同步荧光光谱法研究了在溴化十六烷基三甲铵(CTMAB)和β_环糊精(β_CD)存在时甲氧苄啶的荧光光谱性质,发现CTMAB和β_CD分别对甲氧苄啶有荧光增敏作用,在7.926×10-8~2.378×10-6mol.L-1浓度范围内荧光强度与甲氧苄啶的浓度存在良好的线性关系,样品回收率为99%~100%,建立了在溶液中高选择性和高灵敏度测定甲氧苄啶含量的新方法。     

左炔诺孕酮的荧光光谱分析法

用荧光光谱法研究了硫酸介质中左炔诺孕酮与 β_环糊精主客体包络反应的条件及机理 ,以及溴化十六烷基三甲铵的增敏作用 ,提出了在水溶液中测定左炔诺孕酮的荧光光谱分析法;该法灵敏度高 ,检出限低(3.20×10 -8mol/L) ,荧光强度与左炔诺孕酮浓度在6.40×10 -8～3.20×10 -6mol/L范围内呈良好线性关系 ,方法的相对标准偏差为0.9 %(n=5)。     

头孢哌酮钠的直接和间接示波测定

在pH4.2HAc -NaAc缓冲溶液中 ,头孢哌酮钠在示波图阴极支 -1.48V(vsSCE)处产生一个灵敏切口 ;而在0.2mol/LNaOH底液中 ,头孢哌酮钠与 β_环糊精(β_CD)形成包结物使 β_CD在示波图上产生的切口变浅。根据这些示波特性 ,建立了测定头孢哌酮钠注射剂中头孢哌酮钠含量的直接和间接二次微分简易示波伏安法。实验结果表明 :直接测定头孢哌酮钠的线性范围为1.2×10 -5～2.2×10 -4mol/L ,检出限为6.0×10 -6mol/L ,对3.000×10 -5mol/L进行5次测定的RSD为2.1 % ;而间接测定的线性范围为2.0×10 -6～9.0×10 -5mol/L ,检出限8.0×10 -7mol/L ,对2.500×10 -6mol/L进行5次测定的RSD为2.7 %。与直接法相比较 ,间接测定头孢哌酮钠的检出限更低而线性范围更宽     

曲安奈德的荧光光谱法研究

提出了测定曲安奈德 (TA)的简单、灵敏的荧光光谱新方法。实验条件包括浓硫酸、加热温度及时间、溶剂、β CD的用量及CTMAB的影响 ,建立了两种荧光光谱法测定TA的新体系 :(1)CTMAB体系 ,线性范围为 0～ 4 .6× 10 -6mol/L ,检出限为 3.5 9× 10 -8mol/L ;(2 ) β CD与乙醇体系 ,线性范围为 0～ 2 .3× 10 -6mol/L ,检出限为 1.9× 10 -8mol/L。用于实际药物试样分析 ,获得满意结果。     

吲哚美辛的荧光光谱分析

系统研究了荧光光谱法测定吲哚美辛的条件,包括酸度、溶剂、β-环糊精的用量及β-环糊精与溴化十六烷基三甲基铵(CTMAB)协同作用的影响,发现在pH10.8的缓冲溶液中,CTMAB和β-CD能增敏荧光,从而建立了测定吲哚美辛的高灵敏的荧光光谱分析方法,体系的线性范围为0～2.79×10-6mol／L,检出限为5.73×10-9mol／L;应用本法对市售吲哚美辛片剂进行测定,结果令人满意。     

手性药物心得安对映体的毛细管电泳/电化学分离检测研究

报道了采用毛细管电泳 -方波安培检测法对手性药物对映体———外消旋心得安进行了分离检测研究。以5mmol/LNaOH -8mmol/L柠檬酸 -10mmol/Lβ_CD(pH4.5)为电泳介质 ,未涂层熔融石英毛细管(75μm×45cm)为分离通道 ,分离电压 +12.5kV ,实现了心得安对映体的基线分离。方法的线性范围为2.0×10 -6～1.0×10 -4mol/L ,检出限为5.0×10 -7mol/L。     

胶束增敏荧光光度法测定土霉素的研究

提出了表面活性剂增敏的酸性降解荧光法测定土霉素的新方法。土霉素与浓H2SO4反应,生成强荧光降解物一脱水土霉素,在pH10.0的NH3 NH4Cl缓冲溶液中,CTMAB的存在对脱水土霉素的荧光有较强的增敏和增稳作用,土霉素含量在1.21×10-8mol/L～4.83×10-6mol/L范围内与荧光强度成正比,方法的检出限为6 66×10-9mol/L。应用本法测定片剂中的土霉素,平均回收率为99.6%(n=5)。     

β-环糊精存在下阳离子表面活性剂的毛细管电泳电导法测定

基于H3 BO3 与 β CD配合成大阴离子 ,与不同的阳离子表面活性剂作用不同 ,建立了快速分离检测阳离子表面活性剂的毛细管电泳电导法。研究了H3 BO3 与 β CD的浓度 ,缓冲液的酸度和浓度对分离的影响。在优化的实验条件下 ,溴化四丁基铵 (TBAB)、溴化十二烷基三甲基铵 (DTAB)、溴化十六烷基三甲基铵(CTMAB)阳离子表面活性剂 10min内完全分离 ,峰形良好。线性范围分别为TBAB 10 -3 ～ 10 -5mol/L ,DTAB1.0× 10 -3 ～ 5 .0× 10 -6mol/L ,CTMAB 1.0× 10 -3 ～ 5 .0× 10 -6mol/L。检测限分别为TBAB 7.5× 10 -6mol/L ,DTAB 1.7× 10 -6mol/L ,CTMAB 1.0× 10 -6mol/L。方法用于合成水样分析 ,结果令人满意     

槲皮素-Al~(3+)-十六烷基三甲基溴化铵体系荧光光度法测定总黄酮

用荧光法探索了十六烷基三甲基溴化铵(CTMAB)、十二烷基硫酸钠(SDS)、β-环糊精(β-CD)、聚氧乙烯月桂醚(Brij-35)4种有序介质,及反应时间、pH等条件对槲皮素-Al 3+体系荧光强度的影响。结果表明:四种有序介质中,CTMAB在酸性介质(pH=6.10)下对槲皮素-Al 3+体系荧光增敏效果最好,在λex/λem=450/539nm处有强荧光峰。据此,建立了一种用CTMAB增敏荧光光度法测定总黄酮含量的新方法,其线性范围为4.0×10-8~1.0×10-5 mol/L,检出限为1.24×10-8 mol/L,相对标准偏差(RSD)为2.26%。方法已用于银杏叶片中黄酮含量的测定。     

铁(Ⅲ)-氧氟沙星-SDS三元体系的荧光特性及应用

在表面活性剂十二烷基硫酸钠(SDS)存在下,铁(Ⅲ)能与氧氟沙星形成络合物而猝灭氧氟沙星分子的内源性荧光,使其荧光强度显著降低,据此,提出了铁(Ⅲ) 氧氟沙星SDS体系测定铁(Ⅲ)的荧光分析新方法。铁(Ⅲ)浓度在2.0×10-8~2.0×10-6mol/L范围内与荧光猝灭值△F成正比,方法的检出限为1.0×10-8 mol/L。该法简单,灵敏度高,选择性好,可直接用于水样和食品中微量铁(Ⅲ)的测定,结果满意。     

On-line fermentation gas analysis: Error analysis and application of mass spectrometry

On-line fermentation gas analysis is of general interest because it permits the determination of metabolic rates in almost any biological process using living organisms. The consumption and production of gases (O₂, CO₂, CH₄, etc.) and volatile compounds may be determined without causing any risk of infection. Elemental balancing permits the determination of other metabolic rates if the stoichiometry is known. This was studied with the production of poly-β-hydroxybutyrate (PHB) by Alcaligenes latus. Estimations were based on the measurement of gas partial pressure and flow-rates, pH and alkali consumption rate. Experiments with a small quadrupole mass spectrometer showed unacceptable error propagation. Therefore, dynamic error propagation for all rates was studied using simulation. It was found that, for example, a 1% relative offset-calibration error for oxygen can result in an error in PHB estimation of > 50%. It is suggested that this culture is used in combination with elemental balancing for thorough tests of the accuracy of on-line gas analysis equipment. An on-line process gas analyser based on a quadrupole mass spectrometer (Balzers PGM 407) gave the following precision values (abs. vol.?%) during cultivation of Bacillus subtilis: nitrogen (m/z 14), 0.024; oxygen (m/z 32), 0.020; argon (m/z 40), 0.0011; and carbon dioxide (m/z 44), 0.0034. These values, combined with automatic recalibration, would be sufficient for reasonable estimation of PHB, biomass and substrates.     

Impact of alkali treatment on physico-chemical,thermal, structural and tensile properties of Carica papaya bark fibers

This study aims to examine the effect of sodium hydroxide (NaOH) treatment on the physico-chemical properties, structure, thermal, tensile and surface topography of Carica papaya fibers (CPFs). The surface of raw CPFs was modified by soaking with 5% NaOH solution for 15, 30, 45, 60, 75 and 90?min. The results of thermo-gravimetric analysis revealed that the optimum treatment time for alkali treatment was 60?min. It was found that the alkali treatment improved the properties of the CPFs. The results of TGA, FT-IR, XRD and AFM suggest that the treated CPF is a suitable alternative as reinforcement in polymer composites.     

Chemometric and trend analysis of water quality of the South Chennai lakes: an integrated environmental study

In order to bring out the nature of the factors influencing lake water composition, multivariate statistical analysis and trend analysis were performed based on the hydrochemical data of the study area, namely, South Chennai. Change in land use pattern and settlements along the banks of the lakes alters the quality and quantity of the surface water. In the present study, the R‐mode factor analysis and cluster analysis were applied to the geochemical parameters of the water to identify the factors affecting the chemical composition of the lake water. Dendograms of both the seasons give three major clusters, reflecting the groups of unpolluted to moderately polluted, polluted, and heavily polluted stations. The movement of stations from one cluster to another clearly brings out the seasonal variation in the chemical composition of the lake water. The complex hydrochemical data of the surface water were interpreted by condensing them into three major factors. Factor score analysis was used successfully to delineate the stations under study and the role of the contributing factors, and the nature of factors responsible for the variation in chemical composition of the water has been clearly brought out. Results of trend analysis using ArcGIS clearly indicate that the trend in water quality is deteriorating at a faster rate in the eastern part of the study area. It is understood that although natural shifts probably can account for some of the variation, it is most likely that human activities play a major role in affecting the water quality on a regional scale. Copyright © 2014 John Wiley & Sons, Ltd.     

Time-series analysis in analytical process control

Analysis of time series tries to extract tendencies from measured values dependent on time. For this purpose the cusum technique has proved to be a very sensitive tool for the evaluation of both current and completed time series. Even very weak tendencies can be detected at a high level of noise. Time-series analysis further tries to predict values to come from hitherto performed measurements. As a very flexible model exponential smoothing could be successfully used. Even for processes with a high extent of non-stationarity this model allowed a good prediction owing to the dynamics of the process. Three types of time-series analysis, i.e., evaluation of current measurements, retrospective evaluation and prediction of data (also known as “in vivo”, “post mortem” and “in futurum” time-series analysis) are demonstrated for problems stemming from analytical process control.     

新材料的发展与分析化学

文章介绍了新材料的重要性及发展方向,分析化学在新材料研制中起着耳目的作用,另一方面新材料也为分析化学的进展提供了课题与条件。微量分析、微区分析、表面分析是此领域中的重点。在未来的发展中,分析化学在材料的发展中的地位不会改变,并期待着分析灵敏度与空间分辩率的进一步提高。     

Determination of rank by augmentation (DRAUG)

Determining the rank of a chemical matrix is the first step in many multivariate, chemometric studies. Rank is defined as the minimum number of linearly independent factors after deletion of factors that contribute to random, nonlinear, uncorrelated errors. Adding a matrix of rank 1 to a data matrix not only increases the rank by one unit but also perturbs the primary factor axes, having little effect on the secondary axes associated with the random errors in the measurements. The primary rank of a data matrix can be determined by comparing the residual variances obtained from principal component analysis (PCA) of the original data matrix to those obtained from an augmented matrix. The ratio of the residual variances between adjacent factor levels represents a Fisher ratio that can be used to distinguish the primary factors (chemical as well as instrumental factors) from the secondary factors (experimental errors). The results gleaned from model studies as well as those from experimental studies are used to illustrate the efficacy of the proposed methodology. The method is independent of the nature of the error distribution. Limitations and precautions are discussed. An algorithm, written in MATLAB format, is included. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of Mercury in Geological Materials by Continuous-Flow,Cold-Vapor,Atomic Absorption Spectrophotometry

Abstract

To determine mercury in geological materials, samples are digested with nitric acid and sodium dichromate in a closed teflon vessel. After bringing to a constant weight, the digest is mixed with air and a sodium chloride-hydroxylamine hydrochloride-sulfuric acid solution and then Hg(II) is reduced to Hg with stannous chloride in a continuous flow manifold. The mercury vapor is then separated and measured using cold vapor atomic absorption spectrophotometry (CV-AAS). For a 100 mg sample the limit of detection is 20 parts per billion (ppb) Hg in sample. To obtain a 1% absorption signal, the described method requires 0.21 ppb Hg solution (equal to 16 ppb in sample). Precision is acceptable at less than 1.2% RSD for a 10 ppb Hg aqueous standard. Accuracy is demonstrated by the results of the analysis of standard reference materials. Several elements do interfere but the effect is minimal because either the digestion procedure does not dissolve them (e.g., Au or Pt) or the; are normally of low abundance (e.g., Se or Te).     

A Tin(II) Chloride Based Reduction Method for Multiple-Metal Trace Analysis of Natural Waters

Based on tin(II) chloride reduction in basic medium, a method of general use is proposed for the estimation of the whole gamut of multiple trace metals in natural waters by the atomic absorption method. The quantitative aspects of the method related to variables such as pH of the medium, amount of reductant and operational conditions are studied as a function of absorption sensitivity. The proposed method utilizes only a 50.0 ml portion of the water sample and yields above 90 per cent recoveries for various metals from a single aliquot of the sample. The reported data pertain to the estimation of silver, chromium, copper, iron, lead, mercury, manganese, magnesium, nickel and strontium, reported as averaged over replicate measurements at +-2S confidence level. The precision in individual cases is found to be better than +1.8%.