Cation-exchange separation of metals in dimethyl sulphoxide-aqueous hydrochloric acid media

The behaviour of bismuth, cadmium, copper, lead, silver, tin and zinc on a cation-exchange resin in a solvent system consisting of dimethyl sulphoxide, hydrochloric acid and water was studied. The distribution coefficients of these metal ions between liquid and resin were determined as functions of the concentration of dimethyl sulphoxide and of hydrochloric acid. On the basis of the distribution coefficients found, predictions were made as to the possibilities of separating these metals from mixtures. Such separations were confirmed experimentally for bismuth from lead, bismuth from copper, zinc from lead, lead from cadmium, silver from copper, silver from lead, lead from cadmium from zinc, bismuth from lead from zinc, and bismuth from zinc from copper.     

Chemical data: an essential tool in the regulation of drugs.

How the Bureau of Drugs laboratories and offices obtain chemical data from the scientific literature, from user complaints and product defect reporting systems, from the drug manufacturers, from analyses of drug samples collected from the market, and from analytical research are described. The chemical data thus educed have been used successfully in developing new analytical methods, in establishing better specifications of drug quality, in removing adulterated drugs from the marketplace, in successfully prosecuting purveyors of substandard drugs, and in general assuring that consumers are provided with safe and effective drugs of high quality.     

Experimental characterization of adsorbed macromolecule layers at solid/liquid interfaces

A survey will be given on the experimental methods to characterize the structure of adsorbed polymer layers at solid/liquid interfaces. Characterization parameters accessible by experimental methods are: adsorption isotherm mostly determined from the difference in the solution concentration; fraction of adhered segments, obtained from IR-, NMR- ESR-spectrometry and from microcalorimetry; layer thicknesses of different type from ellipsometry, diffusion, sedimentation, viscosimetry, electrophoresis, force-distance measurements between contacting layers and from segment density profiles obtained by SANS; adsorption enthalpies from microcalorimetry and from displacer-technique. Own experimental data of the adsorption of olystyrene, poly(ethylene oxide)s (PHD), poly(N-vinyl-2-pyrrolidone), poly-(butyl methacrylate)s, poly(vinyl alcohol)s as well as copolymers from ethylene oxide and propylene oxide on interfaces of colloidal silica- and latexparticles and partially on flat chromium-, platinum-and gold surfaces from organic and aqueous solutions and characteristic results from the literature will be compared and discussed in order to get insight into the conformation of the adsorbed macromolecules.     

A Simple Synthesis of Methyl 7-Oxoheptanoate

Methyl 7-Oxoheptanoate has recently been used for the synthesis of 2-(6-methoxycarbonylhexyl)-cyclopent-2-en-l-one, a key intermediate for preparation of the pros tanoids! Several methods have been previously adop 3 ted to prepare the title compound: from cycloheptanone, from 1 -methoxycycloheptenef from suberic acid: from methyl 7-iodoheptanoate6,and from 6-bromohexanoic acid or 7 from E-caprolactone.     

Chemiluminescence from polytetrafluoroethylene

The chemiluminescence emission from commercial samples of polytetrafluoroethylene, PTFE (Halon G-80 and Halon G-10), was studied at temperatures between 25 and 172°C. The emission intensity decreased on extended heating, removal of the surface layer, solvent extraction, or changing from an atmosphere of oxygen to an inert atmosphere. Films of PTFE deposited from the vapor phase showed comparatively little chemiluminescence under these conditions. Ozone-induced chemiluminescence was observed at 37°C from G-10 but not from G-80, or from films deposited from the vapor phase. The chemiluminescence intensity from ozone and G-10 was not reduced by solvent extraction.     

GC-MS analysis of aroma of Medemia argun (mama-n-khanen or mama-n-xanin), an ancient Egyptian fruit palm

The fruits of the edible and medicinal Egyptian palm, Medemia argun, were collected from Aswan in Egypt and the essential oil (EO) from fruits and headspace (HS) of the seeds and fleshy mesocarps were analyzed by GC and GC-MS. Results obtained by GC-MS analysis indicated a high variability in the oil and in the headspace from seeds and mesocarps. Sesquiterpene derivatives were the main group of volatiles in the EO from fruits and in the HS from seeds (45.0 and 64.0%, respectively), while oxygenated hydrocarbon derivatives were the main constituents in the HS obtained from fleshy mesocarps (96.5%). The different chemical composition of the headspace obtained from the seeds and mesocarps of M. argun can be correlated with the different roles that the different constituents play in the prevention of dehydration of the fruits in the desert region from where the plant was collected.     

Extraction of antimony with tertiary amines

The extractability of antimony(III) and (V) with tridodecylamine from various aqueous solutions is reported. Extraction from nitric and hydrofluoric acid solutions is low, but extraction from sulphuric, hydrochloric and hydrobromic solutions is high. Antimony-(III) can be separated from antimony(V) in 7M nitric acid or 0.64M hydrobromic acid. The extraction of antimony from hydrochloric acid solutions in methanol, ethanol, and acetone-water mixtures is greater than from pure aqueous solutions of the same acidity. The elements from which antimony can be separated with tertiary amines are given.     

一种天然纳米纤维捕鸟蛛丝的物理化学结构表征

蜘蛛丝作为功能性结构材料, 其独特的纤维成型方法与优良的结构和性能引起许多人的关注. 从20世纪80年代开始有关蜘蛛丝的研究报道日益增加[1]. 与高温高压下或由溶剂纺丝成型的合成纤维相比, 蜘蛛丝在空气中凝固成型, 丝纤维成型安全、无害, 从腹部若干不同吐丝器产生不同种类的丝具有不同的用途[2]. 蜘蛛拖曳丝(dragline silk)的比强度大于钢丝, 且具有较大的断裂伸长率(9%～30%)[3,4], 抗张强度1.1～1.4 GPa. 在相对湿度50%和应变速率100%/min的条件下, 模量值可达10～50 GPa. 在所有已知纤维品种中, 蜘蛛丝的断裂能是最高的. 此外, 蜘蛛丝在许多方面的综合性能优于最优良的人造纤维. 另外, 蜘蛛丝的细度为已知纤度最小的天然有机纤维, 这种高性能丝具有捕捉昆虫甚至鸟类的功能, 因此蜘蛛丝是具有特异功能的天然纤维材料. 目前, 蜘蛛丝结构和性能的研究主要包括其化学组成[5]、结晶结构[6,7]、结构模型[8,9]以及其NMR表征[10]等, 这些研究揭示了蜘蛛丝的氨基酸组成、分子量及其分布、结晶度、晶胞尺寸、链构象以及结构模型等. 这些研究主要集中在少数几种蜘蛛品种上, 如金色圆网织网蛛(Nephila clavipes)、十字圆蛛(A.diadematus)和大腹圆蛛(A.ventrocosus)等. 目前, 已知的蜘蛛种类大于30 000种[11], 以蜘蛛丝为例的生物大分子材料研究是一个挑战性的课题. 国内蜘蛛丝的研究仅有大腹圆蛛拖曳丝蛋白一级结构的研究报道[12,13]. 本文报道了广西捕鸟蛛丝的红外光谱、形貌结构和原子力显微镜的初步研究结果.     

Determination of ochratoxin A in wine and beer by immunoaffinity column cleanup and liquid chromatographic analysis with fluorometric detection: collaborative study.

The accuracy, repeatability, and reproducibility characteristics of a liquid chromatographic method for the determination of ochratoxin A (OTA) in white wine, red wine, and beer were established in a collaborative study involving 18 laboratories in 10 countries. Blind duplicates of blank, spiked, and naturally contaminated materials at levels ranging from < or =0.01 to 3.00 ng/mL were analyzed. Wine and beer samples were diluted with a solution containing polyethylene glycol and sodium hydrogen carbonate, and the diluted samples were filtered and cleaned up on an immunoaffinity column. OTA was eluted with methanol and quantified by reversed-phase liquid chromatography with fluorometric detection. Average recoveries from white wine, red wine, and beer ranged from 88.2 to 105.4% (at spiking levels ranging from 0.1 to 2.0 ng/mL), from 84.3 to 93.1% (at spiking levels ranging from 0.2 to 3.0 ng/mL), and from 87.0 to 95.0% (at spiking levels ranging from 0.2 to 1.5 ng/mL), respectively. Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 6.6 to 10.8% for white wine, from 6.5 to 10.8% for red wine, and from 4.7 to 16.5% for beer. Relative standard deviations for between-laboratories reproducibility (RSDR) ranged from 13.1 to 15.9% for white wine, from 11.9 to 13.6% for red wine, and from 15.2 to 26.1% for beer. HORRAT values were < or =0.4 for the 3 matrixes.     

Quality evaluation of traditional Chinese drug toad venom from different origins through a simultaneous determination of bufogenins and indole alkaloids by HPLC

A simple and efficient HPLC method has been developed to evaluate the quality of traditional Chinese medicine toad venoms. The major bioactive ingredients, including 10 bufogenins and 4 indole alkaloids in the drug, were separated and quantified on a phenyl-hexyl column with a UV detector. A total of 27 toad venom samples from two species, Bufo bufo gargarizans CANTOR and Bufo melanostictus SCHNEIDER, from the different drug production regions of China, were analyzed. The chromatograms showed significant differences with respect to the samples from different origins. These toad venom samples can be distinctly classified into 4 groups by cluster analysis using the contents of the 14 main constituents, including toad venom samples from B. bufo gargarizans from north China, median China and south China, and samples from B. melanostictus from south China. Toad venom samples from B. bufo gargarizans from median China were considered to be of the highest quality.     

Determination of molecular weight distribution for polypropylene by column fractionation and gel-permeation chromatography

Investigations on the molecular weight distribution of cyrstalline polypropylene were carried out by column fractionation and gel-permeation chromatography for the purpose of comparing the determination methods. Average molecular weight, standard deviation, skewness, and kurtosis were calculated as statistical parameters from the distribution curve of each, and the number-average and weight-average molecular weights were determined by osmometry and light scattering. The molecular weight distribution curves obtained from column fractionation were found to be narrower than those from gel-permeation chromatography, and it was confirmed that the molecular weight distribution curve obtained from GPC was more accurate and reliable than that from column fractionation by the fact that the average molecular weight from GPC agreed fairly well with that from the absolute methods. On the other hand, no clear difference between these determination methods was observed with respect to skewness and kurtosis of the data, while the standard deviation from GPC seemed to be greater than that from column fractionation.     

Calculation of cryoscopic data

The accuracies of determinations of purity and freezing point based upon cryometric freezes suffer from the scatter of data, from the failure of systems ever to recover from the effects of supercooling, and from complex phenomena that elevate temperature during the later parts of runs. Methods are here proposed for decreasing the errors caused by scatter of data and failure to recover from supercooling. These methods utilize the optical projection of calculated curves upon the actual data and involve a new interpretation of the nature of recovery from supercooling.     

Traceability in perspective

Results that reference SI units rarely pose problems in chemical measurement because traceable standards, with uncertainties derived from a chain of calibrations from the SI, are readily available at the analyst??s bench. These uncertainties are nearly always far smaller than that required for fitness for purpose in the analytical result. Moreover, the greater part of the uncertainty in a typical result is not derived from primary measurements traceable to the SI but from recovery problems and matrix effects. Even so, the incidence of wildly inaccurate results stems not from this uncertainty but from ??blunders??, deviations from the correct procedure. Attention to traceability beyond that employed by any competent analyst therefore cannot reduce the uncertainty. Furthermore, there is no rational reason to reduce the uncertainty if the result is already fit for purpose. The current focus on traceability is distracting analysts from the more pressing task of eliminating blunders.     

Determination of fumonisins B1 and B2 in corn and corn flakes by liquid chromatography with immunoaffinity column cleanup: collaborative study.

A liquid chromatographic (LC) method for the determination of fumonisins B1 (FB1) and B2 (FB2) in corn and corn flakes was collaboratively studied by 23 laboratories, which analyzed 5 blind duplicate pairs of each matrix to establish the accuracy, repeatability, and reproducibility characteristics of the method. Fumonisin levels in the corn ranged from <0.05 (blank) to 1.41 microg/g for FB1 and from <0.05 to 0.56 microg/g for FB2, whereas in the corn flakes they ranged from <0.05 to 1.05 microg/g for FB1 and from <0.05 to 0.46 microg/g for FB2. The method involved double extraction with acetonitrile-methanol-water (25 + 25 + 50), cleanup through an immunoaffinity column, and LC determination of the fumonisins after derivatization with o-phthaldialdehyde. Relative standard deviations for the within-laboratory repeatability (RSDr) of the corn analyses ranged from 19 to 24% for FB1 and from 19 to 27% for FB2; for the corn flakes analyses, RSDr ranged from 9 to 21 % for FB1 and from 8 to 22% for FB2. Relative standard deviations for the between-laboratories reproducibility (RSDR) of the corn analyses ranged from 22 to 28% for FB1 and from 22 to 30% for the FB2; for corn flakes analyses, RSDR ranged from 27 to 32% for FB1 and from 26 to 35% for FB2. Mean recoveries of FB1 and FB2 from corn spiked with FB1 at 0.80 microg/g and with FB2 at 0.40 microg/g were 76 and 72%, respectively; for corn flakes spiked at the same levels recoveries were 110 and 97% for FB1 and FB2, respectively. HORRAT ratios for the analyses of corn ranged from 1.44 to 1.53 for FB1 and from 0.96 to 1.48 for FB2, whereas for corn flakes they ranged from 1.60 to 1.82 for FB1 and from 1.39 to 1.68 for FB2.     

宁夏枸杞甜菜碱提取物高效液相色谱指纹图谱研究

建立宁夏枸杞甜菜碱提取物高效液相色谱指纹图谱,为鉴别不同来源的宁夏枸杞提供依据。以10批宁夏不同产地的宁夏枸杞主栽品种"宁杞Ⅰ号"样品建立枸杞甜菜碱提取物指纹图谱共有模式,采用"中药色谱指纹图谱相似度评价系统"软件进行数据处理,对15批不同来源的枸杞样品进行了分析。结果表明:8个特征峰构成了宁夏枸杞甜菜碱提取物的色谱指纹图谱,不同产地、不同品种的枸杞样品甜菜碱提取物指纹图谱存在差异;建立的枸杞甜菜碱提取物高效液相色谱(HPLC)指纹图谱对不同产地、不同品种枸杞的鉴别有参考价值。     

人尿中氟含量的测定及其意义

采用氟离子选择电子法对右江民族医学院28名≥19岁的成年健康学生(其中男生18名,女生10名)早上和晚上尿样分别进行了氟含量测定。结果表明,早上和晚上尿样尿氟含量有一定差异,而早上尿样中的氟含量小于晚上尿样。可认为从早到晚的时段内,人体从食物、水源或其它途径摄入了氟,从而出现了差异;样品氟含量的最大值0.959 mg/L在百色地区正常人尿氟百分位数法(P25～P97.5)正常值范围0.589～2.268 mg/L内,可认为右江民族医学院的人员未出现氟中毒,处于一个氟安全的地区。     

Analysis of mural paintings in Istria

Fragments of wall paintings from Istria, coming from the Basilica of Guran near Vodnjan, from the cemeterial Church of Saint Simeon in Guran and from the Benedictine monastery of Santa Maria Alta near Bale were studied. The analytical instrumental techniques used were Optical Microscopy, Scanning Electron Microscopy equipped with an EDS microanalysis detector, X Ray diffraction, FTIR infrared Spectroscopy and Raman Spectroscopy. Red and yellow pigments used in Guran and Bale have bean derived from red and yellow istrian bauxites, as already demonstrated for works from 11th to 15th century. The blue pigment found in the paintings of the Bale Chapel is a lapislazzuli blue; this fact confirms the literature data referring to the period from 11th to the 16th century. The materials and pigments used at Bale and Guran fit with the Istrian tradition and history of painting going back to the first Carolingian period.     

Investigation of methyl tert-butyl ether levels in river-, ground-, and sewage-waters analyzed using a purge-and-trap interfaced to a gas chromatograph-mass spectrometer

River water collected from 27 sites in 21 rivers, groundwater from 66 sites in 34 cities, and 2 sewage plants in the Niigata Prefecture, Japan (total 301 samples) were analyzed for methyl tert-butyl ether (MTBE) using an improved purge-and-trap-GC-MS method. The amount of MTBE found in water samples from the 27 river sites ranged from 0.003 to 5.3 microg l(-1). MTBE was found in all 27 sites during winter but it was found at only 9 sites and 14 sites, respectively, during the summer. MTBE was found most frequently (in 21 sites) at levels ranging from 0.003 to 0.009 microg l(-1) during February. The highest levels of MTBE were always found in the samples collected from the same site. The amount of MTBE found in sewage water samples ranged from <0.003 to 0.025 microgl(-1). No significant differences were observed between the amounts of MTBE recovered from inflow and outflow waters. Relatively high levels (0.02-0.034 microg l(-1) ) of MTBE were found in January at two sites, which were located on the upper course of the Shinano River. MTBE levels ranged from 0.004 to 0.035 microgl(-l) and from 0.005 to 0.041 microgl(-1) at the mouths of the Shinano River and Agano River, respectively. The levels of MTBE in groundwater collected from 66 sites in 34 cities in Niigata Prefecture ranged from <0.003 to 5.9 microg l(-1).     

Pyrolysis—gas chromatography of normal human cells and amniotic fluid

Human cells derived from tissues and biological fluids have been characterized by pyrochromatography. Normal cells from the brain, kidney, liver and spleen of given individuals have been differentiated by their pyrochromatograms. Pyrochromatograms, are presented for cells from cultured skin fibroblasts which were obtained from cystic fibrotic individuals as well as those taken from disease-free individuals. Characteristic pyrochromatograms were also obtained from amniotic fluid.     

The extraction of iridium and platinum from organic solvents by polyurethane foam

The feasibility of extracting iridium and platinum from organic solvents onto polyurethane foam was studied. Distribution ratios obtained were 1.1 x 10(4) for the extraction of iridium from ethyl acetate, 225 for the extraction of iridium from acetone and 4.8 x 1O(3) for the extraction of platinum from ethyl acetate. Capacities of about 16% w/w were obtained for extraction of iridium from ethyl acetate, and about 2.4% for extraction from acetone.