基体辅助激光解吸电离飞行时间质谱法测定钙调素的分子量

近几年来，由于各种“软”电离技术的发展和应用「‘，’‘，为利用质谱分析生物大分子提供了一条十分有效的途径［‘j，其中基体辅助激光解吸电离飞行时间质谱法（MALDI－TOF－MS）是最有前途的技术之一D‘．钙调素（CaM）是动植物中普遍存在的多功能的胞内钙受体蛋白，参与调控许多生理反应［”．最近几年也在细胞外区域发现了钙调素及其功能［”．钙调素分子量的准确、快速测定是钙调素性质、结构和功能研究的首要问题．目前CaM分子量的测定大多采用SDS－PAGE、凝胶过滤和沉淀平衡等方法，例如对牛脑CaM分子量的SDS－PAGE测…     

Determination and differentiation of nitrilotriacetic acid and ethylenediaminetetra-acetic acid

Ethylenediaminetetra-acetic acid (EDTA) and nitrilotri-acetic acid (NTA) can be differentiated and determined by titration with metal ions to visual metallochromic dye end-points. EDTA can be determined without interference from NTA, either by titrating with copper(II) at pH 5 using PAN indicator, or by titrating with iron(III) at pH 6 and 70 degrees using Tiron indicator. The total chelating power (EDTA + NTA) can be determined either by titrating with lead(II) at pH 4.4 using dithizone indicator, or by titrating with iron(III) at pH 3.5 using Tiron indicator ; NTA is determined by difference. The lowest concentration at which NTA can be determined in EDTA by titration to the iron(III)-Tiron end-point is about 1 wt.%. The apparent stability constants of the iron(III)-Tiron complexes under the conditions of the titration at pH 3.5 and pH 6 have been determined using the method of continuous variations.     

Determination of uranium,zirconium, magnesium and iron in bismuth alloys

Uranium in bismuth alloys is determined by a procedure where E.D.T.A. is added to complex bismuth and other metals and uranium oxinate is extracted by chloroform and determined spectrophotometrically. Zirconium is determined spectrophotometrically using alizarin S as reagent under carefully controlled conditions of acidity and time of colour formation. Magnesium is determined indirectly by measuring the absorption of oxine spectrophotometrically after precipitating the magnesium oxinate complex and redissolving. Bismuth is first separated by extraction of its iodide complex with methyl isobutyl ketone, and other interfering metals by extraction of their oxinate complexes at pH 6.5. Iron is determined as its thiocyanate complex after extraction with methyl isobutyl ketone, bismuth thiocyanate remaining in the aqueous phase.     

Experimental determination of molecular polarizability anisotropy of nematogens by depolarized Rayleigh light scattering

The anisotropy of molecular polarizability Δα of several nematogens has been determined by depolarized Rayleigh light scattering. The experimentally determined values were found to be noticeably smaller than those obtained by MOPAC calculation. Δα values determined from order parameter S and refractive indices show reasonably good agreement with those determined in the present experiment. This result warns us that Δα calculated by MOPAC, particularly at a finite wavelength, may be larger than the true value.     

Determination of the purity of methyl nitrite

The purity of methyl nitrite prepared by the esterification of methanol with aqueous nitrous acid was determined by absorbing gaseous samples in solutions of acidic potassium permanganate and hydriodic acid. Nitrate formed in the oxidation reaction was determined by steam distillation, and iodomethane formed in hydriodic acid was determined by gas-liquid chromatography. The method was used to evaluate purification procedures.     

New method for determining total dietary fiber by liquid chromatography

The molecular weight limit of water-soluble dietary fiber (SDF) determined by the Prosky method was studied by liquid chromatography (LC). It was confirmed that only SDF with an average degree of polymerization of 12 or higher can be determined by the Prosky method. Total dietary fiber (TDF) was determined by 2 additional methods using LC. In the first method, the total quantity of insoluble dietary fiber (IDF) and high molecular weight SDF (HMSDF) was determined according to the modified Prosky method (MES-TRIS buffer-based). The quantitatively collected final filtrate was analyzed by LC for the quantity of low molecular weight SDF (LMSDF), and the 2 quantities were totaled to obtain TDF. TDF values thus determined for rice, polished or unpolished, soybean flour, and pressed barley were higher than those determined by the Prosky method by approximately 6, 3.5, and 3.5%, respectively. In the second method, direct determination by LC analysis was done on samples after enzymatic treatment according to the Prosky method. Results showed that the determination of LMSDF, in particular, was highly accurate and more effective. In both of these methods, the quantity of LMSDF was determined from its chromatographic peak area ratio to glucose as an internal standard, which was produced by hydrolysis.     

光度法快速测定不锈钢中的铬、镍、钼、钛、锰

试样用等体积硝酸和盐酸混合酸溶解,用高氯酸将Cr(Ⅲ)氧化为Cr(Ⅵ),用定量Fe(Ⅱ)将Cr(Ⅵ)定量还原为Cr(Ⅲ),用铬酸"剩余光度法"测定铬,丁二酮肟光度法测定镍,硫氰酸盐光度法测定钼,变色酸(1,8-二羟基萘-3,6-二磺酸)光度法测定钛,高锰酸光度法测定锰。测定结果与标准值基本一致,铬、镍、钼、钛、锰测定结果的相对标准偏差分别为0.2%、0.3%、1.5%、2.0%、2.0%。     

Thermodynamics of the extraction of scandium(III) by the liquid cation exchangers dinonylnaphthalenesulfonic acid and bis(2-ethylhexyl) phosphoric acid

The thermodynamic functions for the extraction of Sc³⁺ by liquid cation exchangers HD and HDEHP are determined radiometrically by the temperature coefficient method. The role of diluent dielectric constant on the extraction of Sc³⁺ by HD is also studied. The thermodynamic parameters determined indicated that the free energy variation for the extraction of Sc³⁺ by HD is mainly determined by the entropic terms arising from the hydration—dehydration process of the exchanged ions. In the case of HDEHP as extractant, the free energy variations are determined mainly by the entalpic terms of the system.     

Dosage complexométrique de bromures et d'iodures en présence l'un de l'autre

Bromides and iodides are determined simultaneously by precipitation as silver halide In another aliquot, silver halides are oxidized, bromine being liberated, the iodate formed is then reduced to iodide which precipitates. The silver precipitates are treated with ammoniacal tetracyano nickelate and displaced nickel is determined complexometrically Bromide is determined by difference     

Performance of ion chromatography in the determination of anions and cations in various natural waters with elevated mineralization

The performance of ion chromatography in the determination of anions and cations in natural mineral waters of different composition and different total mineralization was evaluated. Up to 12 ions of the 20 usually included in extended chemical analysis of natural waters were successfully determined by ion chromatography alone. At least 98.60% and up to 99.96% of total cation composition of mineral waters was determined by ion chromatography. Hydrogen carbonate predominated in anion composition of mineral waters and was determined titrimetrically. The percentage of anions determined by ion chromatography in the remaining anion composition of mineral waters was between 98.90% and 99.96%. The agreement between total concentrations of anions and cations in individual mineral waters determined predominantly by ion chromatography is very good and the performance of ion chromatography for the basic and for the extended chemical analysis of highly mineralized water samples is very high. Method development was assisted by previously developed algorithms and appropriate experimental conditions are also discussed.     

Spectrophotometric determination of formaldehyde,furfural, and vanillin in bisulfite solutions

Formaldehyde, furfural, and vanillin are determined in solutions containing bisulfite. The interference of bisulfite is eliminated by oxidation with iodine before furfural and vanillin are determined spectrophotometrically in ultraviolet light. Formaldehyde is determined with chromotropic acid by a slightly modified procedure; bisulfite is not destroyed previously.     

Simultaneous determination of oxygen and cadmium in cadmium and cadmium compounds

Cadmium and its compounds were analysed for oxygen and cadmium by a modification of the Schütze-Unterzaucher method. Oxygen in some compounds such as cadmium oxide, nitrate and sulphate could not be determined by the usual method. The method of adding carbon was employed for the determination of total oxygen. Total oxygen could be determined by the addition of 5 mg of carbon to a sample boat and heating at 950 degrees . The determination was also carried out by addition of naphthalene (2 mg). It was found that the cadmium powder and cadmium flake used contained ca. 1 and 0.15% oxygen, respectively. Oxygen and cadmium in cadmium and its compounds were simultaneously determined by the addition of 2 mg of naphthalene. Cadmium was determined colorimetrically by use of glyoxal-bis-(2-hydroxyanil). Oxygen and cadmium in the samples could be determined simultaneously with an average error of -0.02 and -0.22%, respectively.     

电感耦合等离子体发射光谱法测定石灰中二氧化硅和磷含量的研究

以ICP-AES法测定石灰中二氧化硅和磷含量,确定了检测方法,通过试验对仪器进行优化,确定分析谱线、称样量等,采用标准溶液绘制校准曲线,通过标准样品验证,回收率在101-113%,相对标准偏差为0.004-0.0055%（n=5）。     

Quantitative determination of amorphous nicardipine hydrochloride in long acting formula (NIC-LA) using light anhydrous silicic acid

We investigated a method to quantitatively determine amorphous nicardipine hydrochloride (NIC) in the NIC-long acting formula (LA) model formulas prepared using NIC, light anhydrous silicic acid (LASA) and carboxymethylethylcellulose (CMEC). Consequently, since the quantity of total NIC in the formula can be determined by means of HPLC and crystal NIC can be determined by the differential scanning calorimetry (DSC) method because the heat of fusion (85.08 J/g) of NIC is constant and unaffected by excipients, we developed the HPLC-DSC method by which the quantity of amorphous NIC is calculated as the difference between the quantity of total NIC determined by HPLC and the quantity of crystal NIC determined by DSC. This practical HPLC-DSC method was confirmed to have good accuracy and reproducibility.     

Preconcentration and x-ray spectrometric determination of arsenic(III/V) and chromium(III/VI) in water

The speciation of chromium and arsenic in their two common oxidation states is determined by the use of selective preconcentration and energy-dispersive x-ray spectrometry. Chromium(VI) and arsenic(III) are recovered by precipitation with dibenzyldithiocarbamate and filtration. Chromium(III) and arsenic(V) are determined in the filtrate by coprecipitation with hydrated iron(III) oxide. The chromium and arsenic content of each precipitate is determined by use of x-ray spectrometry.     

The semi-micro determination of fluorine,chlorine, and nitrogen in organic compounds: The use of cation exchange resins

The organic compounds are fused in a nickel bomb with sodium in the usual way. If no oxygen is present, the nitrogen is determined as cyanide by Deniges' method. After destruction of cyanide with formaldehyde the total chloride and fluoride is determined by passing the solution through a cation exchange column and determining total acidity in the eluate. The chloride in the same or a separate eluate is then determined by treatment with mercuric oxycyanide or by titration with silver nitrate.     

分光光度法快速测定低合金钢中的铌

用盐酸—过氧化氢溶解试样，在2．9mol／L盐酸溶液介质中，铌与氯磺酚—S形成稳定的蓝紫色络合物，其最大吸收波长约为650nm，用分光光度法可以测定低合金钢中的铌。用该法对含铌标准样品进行测定，测得值与标准值基本一致，测定结果的相对标准偏差为2．1％～6．7％。     

Water-Based Oil Spill Dispersants Based on Rosin Formaldehyde Resins

Water-soluble surfactants based on rosin acids were synthesized from condensed rosin acid-formaldehyde. This was completed by esterification of series of rosin acid formaldehyde resins with poly(ethylene glycol) having different molecular weights to produce series of rosin esters. The structure of the produced resins was determined by infrared and ¹HNMR analysis. The molecular weight of the produced surfactants was determined by gel permeation chromatography (GPC) technique. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration (CMC), and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration (Γmax), the area per molecule at interface (A_min), and the effectiveness of surface tension reduction (πCMC) were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption process were calculated and are discussed. The dispersion efficiency of the prepared surfactants as petroleum oil spill dispersants was determined and correlated with the surface activity, concentrations of the prepared surfactants and type of petroleum crude oil.     

A scheme for the analysis of monazite and monazite concentrates

A scheme using ion-exchange methods is described for the analysis of monazites and monazite concentrates. The sample is opened up with concentrated sulphuric acid, and the resultant solution is applied to a column of Zeocarb 225 resin. After phosphate has been washed out, lead, aluminium, titanium, iron, uranium, calcium and magnesium are eluted with N hydrochloric acid and determined by specific, mainly spectrophotometric, methods. Rare earth elements are eluted with 3 N hydrochloric acid. Cerium is separated from the other rare earths by solvent extraction of its nitrate with methyl iso-butyl ketone; both groups are determined gravimetrically. Thorium is eluted from the ion-exchange resin with 3.6 N sulphuric acid and determined spectrophotometrically with thorin.The sulphuric acid-insoluble minerals are brought into solution by a double fusion method, and the determinations are carried out by a combination of ion-exchange and photometric procedures. Silica, phosphorus pentoxide, tin and chromium are determined by photometric methods, using separate portions of the sample.Lanthanum, yttrium and ytterbium are determined in a 1 M perchloric acid solution of the mixed rare earth oxides (less cerium) using flame photometry. Samarium, praseodymium and neodymium are determined by spectrophotometry.     

Determination of lattice and grain boundary diffusion coefficients in protective alumina scales on high temperature alloys using SEM,TEM and SIMS

Grain and grain boundary diffusion coefficients in alumina scales on FeCrAl-based ODS alloys have been determined. The boundary diffusion-coefficients have been derived by combining gravimetrically determined growth rate data with SEM and TEM analyses of the oxide scale microstructure. The diffusion coefficients determined have been used as input parameters for a computer model describing the oxygen isotope exchange between grain and grain boundary in the alumina scale which forms during a two-stage oxidation using (18)O-tracers. This comparison of the calculated tracer profiles with profiles determined experimentally by SIMS allows the estimation of the lattice diffusion coefficient of oxygen in the alumina scale.