Substoichiometric determination of manganese in a synergistic extraction system and its application to the analysis of biological materials

The substoichiometric isotope dilution analysis for manganese(II) in a synergistic extraction system of a chelating agent and a neutral ligand is described. The substoichiometric extarction is based on a substoichiometric amount of 2-thenoyltrifluoroacetone and an excess of 1,10-phenanthroline. The recommended condition and the reproducibility of the present system were examined. The present method was applied for NBS-SRM tomato leaves and NIES-SRM chlorella, and very good results with high accuracy and precision were demonstrated.     

Partial purification, and some properties and reactivities of cetraxate benzyl ester hydrochloride-hydrolyzing enzyme

Debenzylating enzyme from Aspergillus niger enzyme (commercial crude cellulase) catalyzes the hydrolysis of cetraxate benzyl ester hydrochloride (2), a precursor of the antiulcer agent (1). The enzyme was highly purified by three kinds of chromatographies (hydrophobic, ion exchange, gel filtration) with a recovery of 36%. The content of the debenzylating enzyme was about 0.1% in the crude cellulase, but the enzyme showed no cellulase activity. The purified enzyme was inactivated by Hg2+, and diisopropyl phosphorofluoridate (DFP). It was a monomer with a molecular weight of about 35,000, and its isoelectric point was estimated to be 5.3. It showed a debenzylating activity for the phenylpropionic acid benzyl ester moiety of various benzyl ester derivatives, and the benzyl ester of phenylalanine or that of tyrosine was also well hydrolyzed.     

Synergistic extraction of americium(III) with 2-thenoyltrifluoroacetone and crown ethers

Extracton, of Am³⁺ in benzene with 2-thenoyltrifluoroacetone (HTTA) and crown ethers (CEs) such as 15-crown-5, 18-crown-6, dicyclohexano-18-crown-6, dibenzo-18-crown-6, dicyclohexano-24-crown-8, and dibenzo-24-crown-8 was investigated. Synergistic effect by CE was observed regardless of the kind of CE examined. The extracted species was found to be Am(TTA)₃(CE), and adduct formation constants between Am(TTA)₃ and CE in the organic phase were determined. The sequence of constant could not be explained only by basicity of CE and the steric effect of CE should be taken into account to elucidate the adduct complex formation.     

Separation of99mTc from parent99Mo by solid-phase column extraction as a simple option for a new99mTc generator concept

Evidence is obtained to show that the liquidliquid extraction separation of^99mTc from⁹⁹Mo with methyl ethyl ketone, methyl propyl ketone and methyl isobutyl ketone can be transformed into a solid-phase column extraction procedure. The aqueous alkaline⁹⁹molybdate solution is immobilized on a column of a granular large-pore diatomaceous earch support, which is the neluted with the abovementioned extractants. Rapid and clean separation of^99mTc can be with all three solvents. The^99mTc can be back-extracted from the organic phase on a column filled with distilled water /or saline/ loaded granular diatomaceous earth /Extrelut^®/. The possibility of using the abovementioned procedure as a basis for a new^99mTc/⁹⁹Mo generator concept is envisaged.     

Substoichiometric isotope dilution analysis of iron in biological materials by the 8-quinolinol-extraction

A highly precise and accurate method for the determination of minor amounts of iron by substoichiometric isotope dilution analysis is described. The constant amount of Fe(III) is substoichiometrically extracted with 2·10⁻⁴M oxine in chloroform from the aqueous phase of pH 9.2–10.0 containing 6·10⁻³M tartrate. The interfering ions such as Mn(II), Co(II), Ni(II), Cu(II), and Zn(II), can be removed by the preliminary extraction of Fe(III) from 7.5M hydrochloric acid solutions into isopropyl ether. The present method has been applied to the determination of iron in biological standard reference materials, i.e., the NBS Spinach (SRM-1570) and the NIES Pepperbush (SRM No. 1), and the results obtained are 548±9 ppm (NBS certified value: 550±20 ppm) and 193±4 ppm, respectively.     

Liquid-liquid extraction behavior of arsenic(III), arsenic(V), methylarsonate and dimethylarsinate in various systems

The liquid-liquid extraction of inorganic arsenite and arsenate and of methylarsonate and dimethylarsinate is investigated by using the corresponding arsenic species labeled with arsenic-74. The extraction systems tested are halides (chloride, bromide and iodide), diethylammonium diethyldithiocarbamate, didodecyltin dichloride, and pyrogallol/tetraphenylarsonium chloride. All the arsenic species were quantitatively extracted in the iodide system; from the log D values obtained in extraction and back-extraction, they are probably extracted as the corresponding tervalent species because of reduction with iodide. Appropriate conditions for selective extraction of As(III), As(V) and methylarsonate are described.     

Selective substoichiometry for inorganic arsenic(V) by ion-pair extraction with pyrogallol/tetraphenyl-arsnium chloride and its application in the analysis of seaweed

Arsenic(V) is substioichiometrically extracted from 0.4–3 M sulfuric acid solutions into 1,2-dichloroethane with 1.0 × 10^?5 M teraphenylarsnium chloride in the presence of 2.0 × 10^?1 M pyrogallol. Reproducibility of the substoichiometric extractions with a constant amount of tetraphenylarsonium chloride is high (0.5% RSD). This substiochiometric extraction is very selective for arsenic(V) from arsenic(III), monomethylarsonic acid, and dimethylarsinic acid. The extraction combined with the isotope dilution principle was applied to the determination of arsenic(V) in an acid-digestd solution of a seaweed sample (Laminaria religiosa Miyabe) and to the determination of total arsenic in this sample.     

Substoichiometric isotope-dilution analysis for strontium by liquid-liquid extraction with a macrocyclic crown ether or cryptand

Strontium(II) is substoichiometrically extracted into 1,2-dichloroethane with 1.0 × 10^?4 M cryptand-2.2.2 or 18-crown-6 in the presence of 1.0 ×10.2 M picrate at pH 8–10 or 7–9, respectively. A constant substoichiometric amount of strontium(II) is extracted (relative standard deviation, 0.5%). The method combined with isotope dilution is applied to determine strontium(II) in a seaweed sample (Laminaria religiosa Miyabe); the values obtained were 546 ± 9 μg g^?1 with cryptand-2.2.2 and 546 ± 7 μg g^?1 with 18-crown-6.     

Aqueous-phase behavior of natural glycolipid biosurfactant mannosylerythritol lipid A: sponge, cubic, and lamellar phases

The aqueous-phase behavior of mannosylerythritol lipid A (MEL-A), which is a glycolipid biosurfactant produced from vegetable oils by yeast strains of the genus Pseudozyma, was investigated using polarized optical microscopy, small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). MEL-A was found to self-assemble into a variety of distinctive lyotropic liquid crystals including sponge (L3), bicontinuous cubic (V2), and lamella (Lalpha) phases. On the basis of SAXS measurements, we determined the structure of the liquid crystals. The estimated lattice constant for Lalpha was 3.58 nm. DSC measurement revealed that the phase transition enthalpies from the liquid crystal to the fluid isotropic phase were in the range of 0.22-0.44 kJ/mol. Although the present MEL-A phase diagram closely resembled that obtained from relatively hydrophobic poly(oxyethylene) or fluorinated surfactants, the MEL-A L3 region was spread considerably over a wide temperature range (20-65 degrees C) compared to L3 of those surfactants: this is probably due to the unique structure which is molecularly engineered by microorganisms. In this paper, we clarify the aqueous phase diagram of the natural glycolipid biosurfactant MEL-A, and we suggest that the obtained lyotropic crystals are potentially useful as novel nanostructured biomaterials.