基于糖和苯硼酸动态共价键的高效蛋白质表面修饰方法

糖和蛋白质的相互作用参与了很多重要的生命过程.研究糖和蛋白质的相互作用有多种手段,石英晶体微天平(QCM)是其中重要的一种.研究中常需要将蛋白质通过共价键连接在天平芯片的表面.但是,用于检测糖分子的蛋白质多为植物凝集素,它们的分子量大,表面可修饰位点少,通过共价键修饰在芯片表面的效率偏低.本文提出一种基于糖和苯硼酸之间动态共价键的新修饰方法,能够大幅度提高蛋白质在芯片表面的修饰效率.     

应用基团键贡献法计算烷烃和环烷烃的折光指数

根据分子中基团的特性和连接性,发展了一种直接根据分子结构信息计算烷烃和环烷烃折光指数的新方法－基团键贡献法,该方法既考虑分子中基团的特性,又考虑基团之间的连接性(化学键),同时具有基团贡献法和化学键贡献法的特点。应用基团键贡献法对950种烷烃和环烷烃折光指数的计算结果表明,计算值与实验值的一致性令人满意,平均误差0.11%,进一步对聚乙烯、聚丙烯和聚1-丁烯等聚合物的折光指数进行预测,也取得了令人满意的结果。     

Determination of Sr in soil by tungsten coil atomic emission spectrometry

Strontium was determined in soil by tungsten coil atomic emission spectrometry (WCAES). Since aluminum enhances strontium emission and is a common component of soil, it was first necessary to develop a method to remove aluminum from digested soil solutions. This was accomplished by buffering solutions to a pH of 5.5 with ammonium bicarbonate. Each buffered solution was filtered through a 0.45 μm syringe filter. Twenty-five μL of the filtrate were injected into a WCAES instrument and analyzed. The method effectively removed aluminum from digested samples. The next goal was to develop a fast soil digestion method that could be used in field analyses. A potential application for a fast method is the detection of radioisotopes after the detonation of a radioactive dispersion device ("dirty bomb"). Such devices could potentially contain strontium-90, and a field method would be necessary to quickly determine the concentration of strontium. Two different soil digestion methods were tested. The first (method A) was a typical method using aqua regia, hydrogen peroxide, and heat. The second (method B) was a faster method that involved shaking soil with concentrated acid for 30 s. Strontium "spike" recoveries showed that method B was not as effective at recovering strontium from soil. The % strontium recoveries (method B) were 87% compared to 93% for method A. A NIST SRM "San Joaquin Soil" was analyzed using both soil digestion methods. Strontium recoveries were 76% and 59% for methods A and B respectively, suggesting that digestion conditions needed to be more thorough.     

Quantitative and selective analysis of lactose by capillary electrophoresis

Summary A CE method has been validated for the analysis of batches of lactose used as a pharmaceutical raw material. This method was shown to be selective for lactose and was found to be quantitative. The separation was achieved due to on-capillary chelation of the lactose with borate ion. The resulting complex was detected at 195nm. An internal standard is employed to improve injection precision and detector linearity. A system peak occurred in the separation and was systematically investigated to show that it was not sample related. The method was validated and successfully submitted to regulatory authorities and is now in routine use in a number of our quality control laboratories.     

Validation study of the VitaKit A test kit for the determination of vitamin A in fluid milk (2% fat) for routine quality control. Performance Tested Method 061001

A validation study of VitaKit A for quantitation of total vitamin A in 2% fluid milk was carried out according to the guidelines provided by AOAC INTERNATIONAL. The VitaKit A was compared, in terms of repeatability and accuracy, with the U.S. Food and Drug Administration-Interstate Milk Shippers HPLC reference method for determination of total vitamin A in fluid milk with 2% fat. The data obtained by the VitaKit A method are in excellent agreement with the data obtained by the HPLC reference method. Further, a low LOD (0.33 international unit/mL) was obtained for the VitaKit A method; the presence of interferents, like cholesterol and vitamin D3, in the milk had minor influence on the quantitation of total vitamin A by the VitaKit A method. The VitaKit A test kit was found to be stable for 1 year from the date of manufacture when stored at 2-8 degrees C. The method requires 2 h processing time, compared to 1-2 days for the HPLC reference method. The results of this validation study clearly demonstrate that the VitaKit A method is reliable, rapid, and accurate for the quantitation of total vitamin A in fluid milk containing 2% milk fat. An independent study by Q Laboratories Inc., Cincinnati, OH, under the validation guidelines of AOAC INTERNATIONAL, confirmed these findings.     

Rapid and simple method for the determination of alpha 1-acid glycoprotein in serum by column liquid chromatography.

A rapid and simple method for the determination of alpha 1-acid glycoprotein (AAG) in serum was developed by using an anion-exchange column for clean-up of serum and a hydroxyapatite column for high-performance liquid chromatography (HPLC). A good correlation was observed between this HPLC method and the conventional radial immunodiffusion method. The method may also be used to determine the AAG concentration in the serum of experimental animals.     

Single laboratory validation of a method for the determination of hydroxymethylfurfural in honey by using solid-phase extraction cleanup and liquid chromatography

A method is described for the determination of hydroxymethylfurfural (HMF) in honey. The method, which is based on solid-phase extraction cleanup followed by liquid chromatography (LC) with UV absorbance detection, was tested on a variety of different honey types: liquid, set, blended, filtered, crystalline, and comb honey. A sample of honey fortified with a known amount of HMF acted as an in-house reference material. LC with diode-array detection showed that the HMF peak did not contain any peaks of coeluting interfering species. Stability studies showed that honey samples should not be repeatedly frozen and thawed because the temperature changes caused a gradual increase in the HMF concentration. It was also shown that aqueous HMF standard solutions should be kept in the dark at 4 degrees C to avoid degradation of the HMF. The method was internally validated, and the measurement uncertainty was estimated to be +/-9.0 at 40 mg/kg, the legal limit. A comparison of the relative standard uncertainty with the Horwitz relative standard deviation showed that the method was suitable for its purpose and should be validated by a collaborative trial.     

基于迭代小波变换的光谱信号本底扣除方法研究

本底会对光谱分析结果产生很大的干扰作用,为获取特征峰的有效信息,必须首先去除本底。该文提出了一种基于小波变换的本底扣除算法,通过对光谱及后续光谱迭代进行小波变换,利用逼近系数估计本底,直到本底收敛。提出了判断多次估计的本底最大误差是否足够小的收敛准则。利用该算法去除本底后,即可进行特征峰信息的提取。分别利用仿真光谱和实验能量色散X射线荧光光谱对算法进行了验证,并与传统小波变换和多项式拟合法进行了对比。结果表明,该算法能够更准确扣除光谱本底,对其他光谱的本底扣除也具有借鉴意义。     

A silicon sensor for measurement of liquid flow and thickness of fouling biofilms

A silicon sensor for the measurement of the flow velocity and thickness of a flouling biofilm was designed and fabricated. Using micro-machining in silicon, small and thermally-insulated sensor areas could be constructed. A physical model was worked out showing that with a double-chip method, both flow velocity and biofilm thickness can be measured. Experiments showed that this method gave a smaller accuracy in thickness measurements compared to a single-chip method at constant flow velocity. The accuracy in thickness measurement was ±0.5 for the single-chip method at ±3.5 μm for the double-chip method. The accuracy in flow velocity measurement decreased at increased film thickness, from about ±10% of the measured value at zero film thickness to about ±30% of the measured value at 20μm film thickness. A pilot experiment studying biofilm development in sea water over a period of 48 days is also presented.     

液相色谱-串联质谱法测定人血浆中阿扑吗啡

盐酸阿扑吗啡(apomorphinehydrochloride)为吗啡的衍生物,系中枢多巴胺D2受体激动剂,其舌下片制剂是目前用于治疗男性勃起机能障碍的新药。为了研究该制剂中阿扑吗啡的药代动力学特性,我们建立了阿扑吗啡血药浓度测定的液相色谱-串联质谱法。测定了28名健康志愿者口服阿扑吗啡舌下片后阿扑吗啡的血药浓度。已有文献报道采用HPIC-UV、HPLC-荧光、HPLC-电化学和GC等方法测定血浆中阿扑吗啡浓度,在灵敏度方面均低于我们所建立的方法。     

Efficient synthetic method of Psammaplin A

A new concise and efficient synthetic method of Psammaplin A was developed. Psammaplin A was obtained with 50% overall yield in nine steps from p-hydroxybenzaldehyde and ethyl acetoacetate via Knoevenagel condensation and direct nitrosation as key steps. This method might be very efficient to construct a quite diverse library of Psammaplin A type analogs.     

Sequential injection technique employed for stoichiometric studies, optimization and quantitative determination of some fluoroquinolone antibiotics complexed with iron(III) in sulfuric acid media

A sequential injection spectrophotometric method for stoichiometric studies, optimization and quantitative determination of ciprofloxacin and norfloxacin was developed. The work is based on the complexation reaction of ciprofloxacin and norfloxacin with iron(III) in sulfuric acid media and a spectrophotometric measurement of absorbances of the corresponding complexes at 447 and 430 nm respectively. The stoichiometries and formation constants were determined. A 1:2 iron(III) to drug mole ratio was found to give the most predominant complexes for both drugs with 5.00 x 10(-3) M H(2)SO(4) and at 0.20 M ionic strength utilizing Job's method and the molar ratio method. A numerical method was utilized for the calculation of the formation constants, the logarithms of which were found to be 7.756 +/- 0.121 and 7.839 +/- 0.056, for ciprofloxacin and norfloxacin respectively. A factorial design together with the all-model-search method was utilized for the optimization of the concentration and aspiration volume of iron(III) as these were the variables which most affected peak absorbance. Working dynamic ranges of 50-500 ppm and 50-400 ppm were obtained for ciprofloxacin and norfloxacin respectively. The method was found to be suitable for the determination of these compounds in pharmaceutical preparations.     

Study on the comparator method using substoichiometry I. Principle

A new comparator method using substoichiometry was developed. In this method, the content of the element can be determined by the measurement of both radioactivities of an isolated part of the element in question and of the comparator. The method was applied to the determination of lanthanum in NBS botanical standard reference materials, and availability of the method was shown.     

Determination of bisphenol A in thermal printing papers treated by alkaline aqueous solution using the combination of single‐drop microextraction and HPLC

A method for the quantitative determination of bisphenol A in thermal printing paper was developed and validated. Bisphenol A was extracted from the paper samples using 2% NaOH solution, then the extracted analyte was enriched using single‐drop microextraction followed by HPLC analysis. Several parameters relating to the single‐drop microextraction efficiency including extraction solvent, extraction temperature and time, stirring rate, and pH of donor phase were studied and optimized. Spiked recovery of bisphenol A at 20 and 5 mg/g was found to be 95.8 and 108%, and the method detection limit and method quantification limit was 0.03 and 0.01 mg/g, respectively. Under the optimized conditions, the proposed method was applied to the determination of bisphenol A in seven types of thermal printing paper samples, and the concentration of bisphenol A was found in the range of 0.53–20.9 mg/g. The considerably minimum usage of organic solvents (5 μL 1‐octanol) and high enrichment factor (189–197) in the sample preparation are the two highlighted advantages in comparison with previously published works.     

Use of solid-phase microextraction for the detection of acetic acid by ion-trap gas chromatography-mass spectrometry and application to indoor levels in museums

A simple and efficient method using solid-phase microextraction (SPME) and gas chromatography-ion trap mass spectrometry (GC-ITMS) was developed for the analysis of acetic acid in air. The choice of the SPME fibre revealed to be critical as well as the sampling and desorption time. A dilution vessel was used for calibration. The precision of the method was found to be 4.7% relative standard deviation (RSD) and the detection limit 5.7 microg m(-3). The SPME-GC-MS technique was applied to the analysis of acetic acid in museum atmospheres.     

Optimization of high-performance liquid chromatographic parameters for the determination of capsaicinoid compounds using the simplex method.

A high-performance liquid chromatographic method was developed for the analysis of capsaicinoid compounds, the pungent principles of capsicum fruits. A sequential simplex method was applied to optimize the chromatographic response function used to assess the quality of separation by varying the chromatographic parameters. The separation was achieved in 11 min using a C-8 column of 15-cm length and 4.6 mm diameter using a UV detector. A flow rate of 1.15 ml min(-1) at a column temperature of 43.5 degrees C using 63.7% methanol in water gave the most efficient separation. The method was found to be suitable for the determination of the major capsaicinoid compounds in the capsicum samples.     

Extraction of maleic hydrazide residues from potato crisps and their determination using high-performance liquid chromatography with UV and atmospheric pressure chemical ionisation mass spectrometric detection

A method was required for the determination of maleic hydrazide residues in potato crisps. A published method for the extraction of the analyte from onions and potatoes was evaluated and found to be inappropriate due to the inability of the extracting solvent to penetrate the oily matrix. A method was developed to overcome this problem; the resulting recovery data (mean=92.9%. R.S.D.=8.3%, N=16) confirmed its efficiency, and was used to analyse 48 retail potato crisp samples. To confirm possible residues identified by screening with HPLC-UV, and HPLC-atmospheric pressure chemical ionization MS method was developed. There was good agreement between the data obtained from the detection techniques (R²=0.978, slope=1.11).     

随机共振与仪器分析中弱信号的检测

样品分析过程中，往往得到背景噪声很强的信号，尤其在微量和痕量水平；当信号的信噪比很小时，通常的方法不能满足检测要求，该文基于随机共振理论提出了一种新的弱信号的检测方法并对相关参数进行了讲座主；方法是通过噪声的协调作用，获得系统的“共振”，从而实现弱信号的检测，应用于模拟和实验信号的处理结果证明了方法的可行性。     

Determination of cyanuric acid using exact matching isotope dilution mass spectrometry

A high‐accuracy double isotope dilution mass spectrometric method using an exact matching approach with GC coupled to a mass spectrometer for the analysis of cyanuric acid in fortified milk powder was developed. Various parameters for sample clean‐up such as the type of SPE cartridge, GC column and type of derivatizing agent used were investigated. The method was found to be linear in the concentration range of 0.03 to 2 mg/kg of cyanuric acid in milk powder. LOD and LOQ were found to be 0.9 and 3 μg/kg, respectively. Recoveries in the range of 95.7 to 102.2% were obtained for the in‐house fortified milk powder samples, with RSD of measurements in the range of 0.2 to 3.0%. A metrological approach was undertaken to examine all possible biases that contributed to the combined measurement uncertainty of the method. This high‐accuracy method can serve as a reference method for techniques commonly applied in routine testing laboratories.     

A modified simplex method for multifactor optimization of selectivity in gas chromatography

A computer-assisted advanced simplex method is presented for the simultaneous optimization of multifactor ( stationary phase loading, carrier gas flow rate and column temperature ) for separation of ten compounds in gas chromatography. A three factors factorial design was used. The method was based on a special polynomial established from fifteen preliminary runs, using resolution as the selection criterion, with connection to a general simplex method. Excellent agreement is found between the predicted data and the experimental results, and most of experiments required in the general simplex method can be omitted.