A new cryoscopic micro-method for the determination of molecular weights

A method is described for molecular weight determination based on a temperature-heat content curve About 2 mg of substance is required The method is applicable even when solute and solvent form mixed crystals. A wide variety of solvents may be used. The method may yield good results in the polymer field.The accuracy obtained is better than 1%. The new method appears to be more reliable and accurate than known cryobcopic methods     

Bayesian calibration

Two methods of analyzing calibration data are compared: the familiar least-squares method and an empirical Bayes method. The least-squares method uses the information obtained from the current calibration run but ignores all information obtained from previous runs. The empirical Bayes method uses the current information plus summarized information from past calibration runs, e.g., estimates of the means and variances of the parameters. Both methods are applied to simulated and real data. The empirical Bayes method is defined for any number of calibration standards, while the definition of the least-squares method requires modification when the number of standards is less than the number of parameters. The absolute error in predicting unknown analyte concentrations is used as a measure of goodness of calibration. When only one or two standards are used, the Bayes method results in better calibration than the least-squares method; e.g., with one standard, the average error with the Bayes method is at least 30% less than that with the least-squares method. The Bayes method is most useful when (i) run-to-run variation in calibration parameters is small (yet large enough to warrant regular calibration), (ii) residual error is significant, and (iii) it is desirable to use few calibration standards.     

湿法磷酸中硫酸根含量的测定

据工业磷酸和食品级磷酸中的硫酸根含量可用目视比浊法的原理对湿法磷酸中的硫酸根含量进行了吸光光度比浊法的测定研究与分析。可得到目视比浊法不能得到的连续数据。与重量法相比无显著差异,反应后测定的不同地测定结果的影响不显著,ＲＳＤ小于２％,回收率大于９４％,可作湿法磷酸及其制品中硫酸根含量的一种快速,准确,简便的仪器分析方法。     

Über die Eigenschaften eines neuen Chromogens für die Blutzuckerbestimmung nach der GOD/POD-Methode

A method is described which uses the ammonium salt of 2,2′-azino-di-[3-ethyl-benzothiazoline-(6)-sulphonic acid] as a redox indicator for the photometric determination of glucose with glucose oxidase and peroxidase. The sensitivity of this method is more than four times better than the method using o-dianisidine. The test solution including all reagents necessary for the determination of glucose is highly stable.     

Summary of ISO/TC 201 Standard: XXX. ISO 18516: 2006—Surface chemical analysis—Auger electron spectroscopy and X‐ray photoelectron spectroscopy—Determination of lateral resolution

This International Standard describes three methods for measuring the lateral resolution achievable in Auger electron spectrometers and X‐ray photoelectron spectrometers under defined settings. The straight‐edge method is suitable for instruments where the lateral resolution is expected to be larger than 1 µm. The grid method is suitable if the lateral resolution is expected to be less than 1 µm but more than 20 nm. The gold‐island method is suitable for instruments where the lateral resolution is expected to be less than 50 nm. The standard contains three informative annexes that provide illustrative examples of measurements of lateral resolution. Copyright © 2008 John Wiley & Sons, Ltd.     

粘土中游离氧化铁的分离及其测定

研究了盐酸羟胺-草酸-草酸铵体系提取粘土中游离氧化铁及其测量,试验表明,用此体系提取拈土中的游离氧化铁,其测量结果与DCB法一致,而提取及测量所需的时间却较前者短。相对标准偏差RSD≤2．0％。     

Cutoff radius effect of the isotropic periodic sum and Wolf method in liquid-vapor interfaces of water

As a more economical but similarly accurate computation method than the Ewald sum, the isotropic periodic sum (IPS) method for nonpolar molecules (IPSn) and polar molecules (IPSp), along with the Wolf method are of interest, but the cutoff radius dependence is an important issue. To evaluate the cutoff radius effect of the three methods, a water-vapor interfacial system has been studied by molecular dynamics. The Wolf method can produce adequate results for surface tension compared to that of the Ewald sum (within 2.9%) at a long enough cutoff radius, r(c). However, the estimation of the electrostatic potential profile and dipole orientational function is poor. The Wolf method cannot estimate electrostatic configuration at r(c) ≤ L(z)∕2 (L(z) is the longest lattice of the system). We have found that the convergence of the surface tension and the electrostatic configuration of the IPSn method is faster than that of the IPSp method. Moreover, the IPSn method is most accurate among the three methods for the same cutoff radius. Furthermore, the behavior of the surface tension against the cutoff radius shows a greater difference for the IPSn and IPSp method. The surface tension of the IPSp method fluctuates and presents a similar result to that of the Ewald sum, but the surface tension for the IPSn method greatly deviates near r(c) = L(z)∕3. The cause of this deviation is the difference between the interfacial configuration of the water surface and the cutoff treatment of the IPS method. The deviation becomes insignificant far from r(c) = L(z)∕3. In spite of this shortcoming, the IPSn method gives the most accurate result in estimating the surface tension at r(c) = L(z)∕2. From all the results in this work, the IPSn and IPSp method have been found to be more accurate than the Wolf method. In conclusion, the surface tension and structure of water-vapor interface can be calculated by the IPSn method when r(c) is greater than or equal to the longest lattice of the system. The IPSp method and the Wolf method require a longer cutoff radius than the longest lattice of the system to estimate interfacial properties.     

Analysis of wax esters in edible oils by automated on-line coupling liquid chromatography-gas chromatography using the through oven transfer adsorption desorption (TOTAD) interface

An automated method for the direct analysis of wax esters in edible oils is presented. The proposed method uses the TOTAD (through oven transfer adsorption desorption) interface for the on-line coupling of normal phase liquid chromatography and gas chromatography. In this fully automated system, the oil with C32 wax ester as internal standard and diluted with heptane is injected directly with no sample pre-treatment step other than filtration. The proposed method allows analysis of different wax esters, and is simpler and faster than the European Union Official Method, which is tedious and time-consuming. The obtained results closely match the certified values obtained from the median of the analytical results of the inter-labs certification study. Relative standard deviations of the concentrations are less than 5%. The method is appropriate for routine analysis as it is totally automated.     

工业废水中微量铜（Ⅱ）和氰化物的流动注射光度分析

采用ＦＩＡ技术，以光度比色法为基础，建立了工业废水中微量Ｃｕ＾２＋和ＣＮ＾－的顺序自动分析方法和装置。其对二种离子的测定频率为６０样／ｈ，相对标准偏差＜１．０％，工作曲线的ｒ值≥０．９９９，各项分析技术指标均优于手工法操作。     

ICP—AES法测定百合中的微量元素

用ICP-AES法对兰州百合和湖南百合、药用百合中的Fe、Mn、Cu、Zn等18种元素进行了分析研究。结果表明,百合中含有丰富的人体必需微量元素;湖南食用百合比兰州百合的微量元素含量高,Fe含量高于兰州百合的5倍之多,Zn含量几乎是兰州百合的10倍之多。加标回收率为83%~106%,该法具有操作简便、快速和准确度高等优点。说明湖南百合具有较高的保健价值,为进一步开发百合提供了科学依据。     

Rapid method for the determination of alachlor, atrazine and metolachlor in groundwater by solid-phase extraction

A solid-phase extraction method is described for the separation of alachlor, atrazine and metolachlor from groundwater using solid-phase disposable columns. The method is rapid, reproducible and uses considerably fewer reagents than classical liquid-liquid methods. The average recoveries were greater than 90% for all three compounds.     

石墨炉原子吸收光谱法测定中药口服液中的铬铅镉

利用石墨炉原子吸收光谱法测定,采用常温消解和密闭微波消解等方式处理口服液样品,并进行比较。结果表明,采用HNO3 HClO4 H2O2作为消解试剂用常温消解方式进行消解后,可不加基体改进剂直接进行测定,在此基础上研究了石墨炉原子吸收测定的最佳条件。应用这种方法测定了双黄连、清开灵、生脉饮和抗病毒口服液中痕量镉、铬和铅,RSD小于5．0％,回收率在83．4％～113％。     

Improved method for measurement of rhodanese activity using methanethiosulfonate as sulfur donor substrate and its application to human serum.

We have developed a sensitive method for the measurement of rhodanese activity in human serum which is based on the colorimetric method for the determination of thiocyanate produced from methanethiosulfonate and cyanide as substrates. Thiocyanate gives a red complex with ferric ion in an acidic condition. The present method is about 70-fold more sensitive than the conventional method using cyanide and thiosulfate as substrates and correlates well (r = 0.997) with the conventional method in bovine liver rhodanese. Within-run precision of the method is 0.91% for 420 units/l serum and the calibration curve is linear up to 1850 units/l. The normal value for human serum, determined by the present method on 31 healthy persons, was 20.9 +/- 20.0 units/l (mean +/- 2S.D.). Rhodanese activity was clearly elevated in some serum samples which were observed at abnormal values in some biochemical diagnostic tests and showed significant positive correlations with guanase activity (r = 0.728, p less than 0.01) and glutamic-oxalacetic transaminase activity (r = 0.625, p less than 0.01).     

气相色谱在细胞色素P-450单充氧酶模拟体系中的应用 Ⅰ.金属卟啉催化下环己烷单充氧反应中产物的定量分析及在动力学研究方面的应用

本文研究了金属卟啉-氧化剂-烷烃仿酶体系中的气相色谱定量测定方法,获得了该体系的最佳色谱条件和产物的相对重量校正因子。该方法的相对误差小于0.2％,相对标准偏差小于0.6％。对四种类型的金属卟啉催化的环己烷充氧化反应对动力学研究结果表明:反应物的生成量与反应时间呈良好的直线关系,其相关系数大于0.99。     

Determination of drug protein-binding by high-performance liquid chromatography using a chemically bonded bovine albumin stationary phase

A liquid chromatographic method for the determination of the degree of protein-binding of drugs has been established, using a stationary phase to which bovine serum albumin has been bonded chemically. In a structurally heterogeneous group of compounds, results of the method correlate well with protein-binding data obtained by equilibrium dialysis (r = 0.89, n = 23, p less than 0.001). Within a series of analogous piperazines a good correlation is found (r = 0.981, n = 11, p less than 0.001). The chromatographic method allows automation of the measurement of protein-binding of large series of compounds with protein-binding ranging between 10 and 99%. The method is not expensive and is less time consuming than equilibrium dialysis. Only 1 mg of technical-grade material is required to determine the protein-binding, and radioactive labelling of the material is not necessary.     

沉积物中铝含量的流动注射分光光度法测定

本文根据自行设计的一套流动注射（ＦＩＡ）双光束分光光度计装置，研究了河底沉积物中微量铝测定的适宜条件，设备简单，操作容易。灵敏度较普通光度法提高近１倍，进样速率为８０－９０次／ｈ，相对标准偏差小于０．９％。     

药用丁基胶塞灰分的热重分析条件优化

针对药用丁基胶塞的灰分指标,考察了热重分析法的反应温度和恒温时间对测试结果的影响,优化了热重分析法测定胶塞灰分的检测方法. 方法测得的胶塞灰分值相对标准偏差为0.01%,且测试耗时少于1 h. 在缩短检测时间的同时,检测结果的准确性和重现性均优于用方法YBB00262005和方法ASTM D6370-99检测所获得的结果.     

用气相色谱法测定碳酸二甲酯的纯度及其杂质

提出用HP -Wax强极性毛细管柱分离,热导检测器检测,以环戊醇作内标定量,同时测定碳酸二甲酯纯度及其杂质。探讨了方法的内标校正因子、各组分的线性相关性及微量水的分离和定量等,结果令人满意。其相对标准偏差<4.6% ,绝对误差<0.04%。     

Discrete microsample injection into a gaseous carrier

Discrete injection (DI) of mul- volume liquid samples into a continuous flow of air as carrier is demonstrated. Atomic-absorption (AA) detection is used. Calibration graphs for zinc, obtained by using the DI-AA-air carrier method have a slope 1.8 times that of graphs obtained by the flow-injection analysis (FIA)-AA-air carrier method. The DI-AA-air carrier signals are higher and sharper than the FIA-AA-water carrier signals, and even exceed the AA steady-state signals for the same zinc solutions, owing to improved nebulization/atomization. The air-carrier method is more rapid than the liquid-carrier method. Measurement rates of 600/hr are possible. The signals show precision comparable to that attainable with water as carrier. The method is particularly useful for flame or plasma detectors and is potentially useful with different gases or vapours as carriers, and for gas-liquid reactions in FIA.     

ICP-AES测定钼铁中杂质元素

研究了用ICP-AES测定钼铁中硅、磷和铜的方法,建立了最佳工作条件,采用基体匹配方法,应用软件中谱线干扰校正程序消除了干扰,检出限小于0．005％,回收率在93％-108%之间,RSD小于1．0％。方法简便、快速、准确。