Vergleich einiger Methoden zur Bestimmung des Phosphors in Phosphatiden

Comparison of a Few Methods for the Determination of Phosphorus in Phosphatides The gravimetric uniform method of the DGF (identical with the gravimetric uniform method of the IUPAC), uniform methods for the colorimetric determination according to DGF und IUPAC and a titrimetrical analytical method were compared by multiple determinations of phosphorus content of a soybean- and rapeseed oil lecithin and statistical evaluation of the results. The weight analytical factor as prescribed in the gravimetric methods appears to be too low and has therefore been left open for discussion.     

Generalization of the possibility of eliminating the filtration step in the determination of acid-soluble chloride content in cement and concrete by potentiometric titration

In this work, it is demonstrated that it is possible to eliminate the filtration step in the determination of the acid-soluble chloride content of cement and concrete by potentiometric titration, irrespective of the method used for detecting the end-point of the titration. Extensive analytical results are presented corresponding to several types of cement and to a broad range of chloride concentrations in concrete. Some requirements to avoid errors in such analytical determinations are discussed.     

Residual Stress State of Brazed Ceramic/Metal Compounds, Determined by Analytical Methods and X-ray Residual Stress Measurements

The residual stress state of brazed ceramic/metal compounds is described by means of X-ray residual stress determinations and analytical calculations using a model of three elastic infinite plates. It is shown that the residual stress state of the soldered compound depends on the materials combination and on the geometrical conditions. The combination of X-ray residual stress measurements and analytical calculations allows decisions on whether the assumption of a linear elastic model, based on elementary bending theory, is valid for the particular compounds.     

Determination of rates of thermal decomposition of polymerization initiators with a differential scanning calorimeter

A commercial differential scanning calorimeter has been used to determine thermal and kinetic data of some typical polymerization initiators. Since the rate of heat change due to decomposition is directly related to the rate of decomposition at a given temperature, suitable analysis of the differential thermal curve can yield the Arrhenius parameters of a reaction from a single run. In order to test the method, the well-established first-order decomposition of azobisisobutyronitrile was determined in di-n-butyl phthalate as solvent. Reproducible results were obtained which accorded with published data by orthodox determinations. The rates of thermal decomposition in solution of benzoyl peroxide and diisopropyl peroxydicarbonate were also determined. The method provides a rapid means for the direct determination of fast rates not possible with orthodox analytical determinations.     

Redistribution of Aluminum Ions During Processing of Sialon Ceramics

Precise determinations of the variation in Al concentration in β-sialon grains of the garnet and cordierite sialon systems were made by means of quantitative energy-dispersive X-ray analysis in an analytical electron microscope. Different signs of the concentration gradients in the grain indicate differences in secondary crystallization mechanisms, while Al distributions with respect to grain size indicate a changing glass-silicon nitride compatability during crystallization. The technique was also applied to the glassy grain-boundary phase allowing the determination of the glass-forming region of the cor-dierite-sialon system. A detailed evaluation of errors in analytical transmission electron microscopy (AEM) is described.     

Aerobic Oxidation of Glucose with Gold Catalyst: Hydrogen Peroxide as Intermediate and Reagent

Careful analytical determinations show that the gold‐catalysed aerobic oxidation of glucose occurs through a two‐electrons mechanism leading to gluconate and hydrogen peroxide. This latter decomposes before reaching the critical concentration for competing with O₂ in glucose oxidation. A mechanism of glucose oxidation on gold nanoparticles is presented.     

煤及其燃烧产物中无机组分分析方法比较

从三个方面对煤及其燃烧产物中无机组分的分析方法进行了比较和评价：1)比较和评价了煤及其燃烧产物中矿物分析方法，其中主要讨论了XRD法和CCSEM法；2)比较和评价了煤及其燃烧产物中元素含量的分析方法，主要包括X-射线和v-射线技术；原子吸收或发射技术(AAS／AES)和质谱法(MS)；3)比较和评价了煤及其燃烧产物中微量元素的赋存形态分析方法，主要包括直接分析方法和间接分析方法．     

抗体及其在免疫传感器中的应用

免疫传感器是一种以抗体－抗原反应为基础的生物传感器。基于这类反应的高度亲合性及专一性,免疫传感器具有极高的选择性和灵敏度。本文主要介绍抗体的结构、生产技术以及光学、电化学、声表面波和半导体换能器在免疫传感器中的最新应用     

Automatic flow system for simultaneous determination of iron and chromium in steel alloys employing photometers based on LEDs as radiation source

A multicommutated flow system for simultaneous determination of iron and chromium in steel alloys by photometry is described. The flow network consisted of an automatic injector and four solenoid valves assembled to form two independent analytical pathways, each one comprising reaction coils and a flow cell. The light source (LED) and detector (photodiode) were attached to the flow cells to form a compact unit. The flow system was microcomputer controlled by Quick BASIC 4.5 software, which carried out all steps of the analytical procedure. The feasibility of the system was proved by the determination of iron and chromium in steel alloys and its accuracy was accessed by comparing results with those obtained by plasma atomic emission spectrometry (ICP-AES). No significant difference at the 95% confidence level was observed. Other profitable features such as low reagent consumption (0.33 mg 1,10-phenantroline and 0.03 mg 1,5-diphenylcarbazide per determination); relative standard deviations (n = 5) of 0.4% for iron and 1.2% for chromium; and an analytical throughput of 160 determinations per h were also achieved.     

Fast gas chromatography: Applications in milk fat analysis

In our society saving time is important because time is money. For this reason the development of instrumentation able to perform analytical determinations with a high speed is an on‐going matter, particularly regarding routine control analyses. In the last few years the possibility of performing gas chromatographic analysis in a very short time has been increasing. In this paper a general overview of fast chromatography and our experience of its application to the analysis of milk fat triacylglycerols is reported.     

On the determination of belite in clinker by X-ray method

The results of β-C₂S analysis in clinker can be essentially distorted due to the overlap of potassium sulfate lines on analytical line 120. In case of significant quantities of K₂SO₄ in clinker β-C₂S determinations are suggested to be performed either on a sample washed by water or on the coarse fraction of clinker powder obtained by its separation on the sieve.     

微波消解ICP-AES法测定润滑油中的铁,镍,铜,锌,硼,磷

通过微波消解处理润滑油,ICP法测定润滑油中铁,镍,铜,锌,硼等元素,通过正交实验进行微波消解条件优化,并进行了精密度实验,标准样品的回收率为98%以上,相对标准偏差小于1%。     

A comparison by warburg respirometry and die-away studies of the degradability of select nonionic surface-active agents

The relative biodegradability of several classes of nonionic surfactants have been determined by Shake Flask, Die-Away and Warburg Respirometer tests. Analytical techniques used to follow the degradation processes involved the measurement of loss of surfactant properties (surface tension or foamability), colorimetric determinations and oxygen uptake studies. Nonionic products prepared from naturally occurring or synthesized straight chain hydrophobes were shown to exhibit based upon branched chain materials. A good correlation of data by the various analytical techniques was obtained on the straight chain based products.     

Characterization and identification of lipids by their critical solution temperatures

The mutual solubility of two liquids which are not miscible in all proportions is essentially a function of the temp. Rising temp usually increases the solubility, possibly reaching a point, i.e., the upper critical solution temp (CST), at which the two components become miscible in all proportions. The CST is characteristic for the two liquids involved. A microtechnique developed by Fischer simplifies rapid and accurate determinations of the upper critical solution temp. This technique is described and its application to the characterization and identification of pure lipids and lipid mixtures is demonstrated. The significance of this simple laboratory procedure and its relation to complementary analytical methods is discussed.     

Application of ESI and MALDI‐TOF MS for triacylglycerols analysis in edible oils

Triacylglycerols (TAG) are the most important group of compounds present in vegetable oils. These biomolecules, determining the physical, chemical and nutritional properties of the oils, are considered to be good fingerprints for quality and authenticity control. Therefore, TAGs characterization is a very important task in edible oil field, which has been undertaken by different analytical methods. The analysis of vegetable oils is still dominated by classic determinations, which are however laborious and time‐consuming and cannot be used routinely. More recently, advances in MS instrumentations coupled with online separation techniques and data processing have contributed to great expansion of MS in oil study, allowing the development of innovative analytical approaches that exhibit higher sensitivity, accuracy and rapidity in vegetable oils investigations. In the present contribution, a review of the most relevant applications of novel mass spectrometric techniques, such as ESI and MALDI, both alone and hyphenated with HPLC, used for analysis of the complex TAGs mixture of edible oils is illustrated.     

Biodegradation of nonionic ethoxylates

The biodegradation of alcohol ethoxylates (AE) and alkylphenol ethoxylates (APE) is reviewed. Biodegradation test methods, ranging from laboratory tests to full-scale waste treatment plant studies are described for these surfactants. A comparison is made between primary and ultimate biodegradability criteria and the limitations of the various analytical methods used in these determinations are discussed. The most recently published data suggest sewage bacteria degrade AE by a mechanism which is different from that by which APE degrades. The use of radiolabeled surfactants to elicit more detailed information about the biodegradation mechanisms of AE is described. The role of biodegradation on the impact of surfactants released to the environment is assessed, and future environmental concerns for nonionics are considered.     

Estimation of nitric oxide emissions from an internal combustion engine

The analysis of nitric oxide, the principal nitrogen oxide in raw exhaust gas, is described by two different techniques. Concordance of analytical determinations using the Saltzman colorimetric solution method with the gas phase chemiluminescence method is demonstrated. By dilution of exhaust gas from an internal combustion engine with nitrogen it is shown that gas samples can be stored for periods of at least 30 min without significant change in sample composition with respect to nitric oxide. This procedure enables reliable estimations of nitric oxide in exhaust gas contained in a sealed transportable vessel to be performed at sites remote from the sample point, without introducing errors due to loss of nitric oxide by chemical reaction in the time between sampling and analysis.     

The quantitative analysis of the light stability of insoluble singlet oxygen sensitizers

Evaluation of insoluble sensitizing materials for further technological development must include tests of their energy transfer efficiency as well as of their light stability. A procedure for the determination of the light stability of insoluble sensitizer particles including the preparation of surfaces to be irradiated and analysed is given. A close link to the widely adopted analytical methods used in industrial dyestuff, pigment and polymer laboratories (Xenotest irradiation, Cielab analysis) assures its easy implementation. The procedure may also be used for sensitizing materials already irradiated in suspensions. Standardized irradiations of blue wool patterns facilitate those determinations for procedures involving the irradiation of photoactive surfaces.     

Characterisation of porous and barrier layers of anodic oxides on different aluminium alloys

Electrochemical impedance spectroscopy (EIS) provides a powerful tool for obtaining detailed information on the electrochemical properties of both porous and barrier layers on different aluminium alloys. The impedance value at a given frequency can serve to calculate the electrochemical parameters of the oxide layers represented by each component of the equivalent circuit (EC) which reproduces the behaviour of the studied systems. It is thus possible, with these parameters, to analyse the effects of any factor on the sealing and ageing processes of anodic aluminium oxide layers. Electrochemical results are completed with a detailed analytical study of the oxide layers by XPS, with gravimetric determinations of the changes experienced in the anodising and sealing processes, and with microstructural characterisation of the anodic films by scanning electron microscopy (SEM).