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.     

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.     

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 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.     

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.     

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.     

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.     

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.     

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.     

In vitro pH-dependent drug release from N4-(4-carboxybutyryl)-1-beta-D-arabinofuranosylcytosine and its conjugate with poly-L-lysine or decylenediamine-dextran T70

N4-(4-Carboxybutyryl)-1-beta-D-arabinofuranosylcytosine (glu-ara-C), the conjugate of glu-ara-C and poly-L-lysine (PLL), (PLL-glu-ara-C), and the conjugate of glu-ara-C and decylenediamine-dextran T70 (T70-C10), (T70-C10-glu-ara-C), were prepared. Drug regeneration from glu-ara-C and the conjugates was investigated in buffered solutions of pH 4,5,7,7.4 and 8. The character of the drug release from the conjugates was different from that from glu-ara-C. Namely, the release of 1-beta-D-arabinofuranosylcytosine (ara-C) from glu-ara-C was accelerated under both weakly acidic and weakly basic conditions, while it was accelerated only under weakly basic conditions from the conjugates. Overall, the drug release profiles from the conjugates showed similar patterns. However, under neutral and weakly basic conditions, ara-C was regenerated more rapidly from PLL-glu-ara-C than from T70-C10-glu-ara-C. During the incubation of glu-ara-C and the conjugates under weakly acidic conditions, 1-beta-D-arabinofuranosyluracil (ara-U) was detected and its amount increased with time to similar extents.     

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.     

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.     

DNA Extraction from Formalin-fixed and Paraffin-embedded Tissues by Triton X-100 for Effective Amplification of EGFR Gene by Polymerase Chain Reaction

For first-line non-small-cell lung cancer(NSCLC) therapy, detecting mutation status of the epidermal growth factor receptor(EGFR) geneconstitutes a prudent test to identify patients who are most likely to benefit from EGFR-tyrosine kinase inhibitor(TKI) therapy. Now, the material for detecting EGFR gene mutation status mainly comes from formalin-fixed and paraffin-embedded(FFPE) tissues. DNA extraction from FFPE and the amplification of EGFR gene by polymerase chain reaction(PCR) are two key steps for detecting EGFR gene mutation. We showed a simple method of DNA extraction from FFPE tissues for the effective amplification of EGFR gene. Extracting DNA from the FFPE tissues of NSCLC patients with 1% Triton X-100(pH=10.0) was performed by heating at 95℃ for 30 min. Meanwhile, a commercial kit was used to extract DNA from the same FFPE tissues of NSCLC patients for comparison. DNA extracted products were used as template for amplifying the exons 18, 19, 20 and 21 of EGFR by PCR for different amplified fragments. Results show that DNA fragment size extracted from FFPE tissues with 1% Triton X was about 250-500 base pairs(bp). However,DNA fragment size extracted from FFPE tissues via commercial kit was about from several hundreds to several thousands bp. The DNA yield extracted from FFPE tissues with 1% Triton X was larger than that via commercial kit. For about 500 bp fragment, four exons of EGFR could not be amplified more efficiently from extracted DNA with 1% Triton X than with commercial kit. However, for about 200 bp fragment. This simple and non-laborious protocol could successfully be used to extract DNA from FFPE tissue for the amplification of EGFR gene by PCR, further screening of EGFR gene mutation and facilitating the molecular analysis of a large number of FFPE tissues from NSCLC patients.     

Use of chemometric and geostatistical methods to evaluate pesticide pollution in the irrigation and drainage channels of the Ebro river delta during the rice-growing season

Data sets obtained from quantitative analysis of seventeen pesticides in water samples from a network of irrigation and drainage channels in the Ebro river delta (Catalonia, NE Spain) have been analysed by chemometric and geostatistical methods. Samples were taken at fourteen locations during the main rice-growing season, from May to August 2005. Principal-component analysis enabled investigation of the spatial and temporal distribution of the main pollution patterns caused by application of pesticides in the region under study. A first pesticide-contamination pattern from the Ebro river was differentiated from a second more specific pattern from the water-drainage channels of the delta, collected from the rice fields. The seasonal peak in this more specific rice pesticide source was observed in July. Coupling the results from chemometric data analysis with use of geostatistical methods was shown to be a useful procedure for discovery of the most significant spatial and monthly variations of the main pesticide-contamination patterns, taking into account the particular geographical structure of the area under study.     

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.     

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.     

Comparison of calculated and experimental flow velocities upstream from the sampling cone of an inductively coupled plasma mass spectrometer

Experimentally-determined flow velocities in the 6 mm upstream from the sampling cone of an inductively coupled plasma mass spectrometer were compared with velocities determined from a computer simulation of the flow and those calculated from a modified hemispherical sink model. The measured values and those from the simulation agreed within experimental error, but differed from the values calculated from the modified hemispherical sink model by as much as 30%. An empirical alternative to the modified hemispherical sink model is presented that allows for accurate calculation of flow properties upstream from the sampling cone under a range of plasma conditions.     

THE COORDINATION ADSORPTION OF AMINES ON CARBOXYL RESIN IN Cu~(2+) FORM FROM NON-AQUEOUS MEDIUM AND DESORPTION WITH ANHYDROUS ELUANT

The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu~(2+) form from water,ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are higher than thatfrom water, and nearly zero from ethanol. The separation factors for the adsorption of these three amines from mixed solutionwere also examined. The results of continuous column operations show that the breakthrough capacity of aniline from n-hexane reaches 90 mg/g dry resin in Cu~(2+) form, and the amines adsorbed can be stripped with anhydrous ethanol effectively.Adsorption onto carboxyl resin in Cu~(2+) form from non-aqueous medium and desorption with anhydrous eluant can overcomethe run-off of Cu~(2+) from the resin, and would show potential advantages in the separation of some water-insoluble naturalproducts.     

Extractability of dioxins from soil: I. Extractability of dioxins from airborne particulates and humic acid fraction in soil

The extractability of dioxins (polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls) from airborne particulates (APs) and humic acid (HA) in soil was evaluated. APs collected from ambient atmosphere and dioxins-associated precipitated HA fraction (PHA) were extracted by pressurized liquid extraction with either toluene or acetone. Native dioxins were equivalently extracted from APs with both solvents, whereas only acetone could satisfactorily recover the ¹³C-labelled compounds from metal-free PHA. The recovery rates of dioxins by toluene extraction from metal-free PHA varied with the organic carbon content of the PHA. However, even with acetone, the recovery of dioxins from metal-bound HA was poor (11–40%). These results suggest that PHA prevented the solvents from accessing sequestered dioxins. This characteristic of solid HA may influence the extractability of dioxins from humus-rich soil.