Development and validation of HPLC methods for the analysis of phenethylamine and indoloquinazoline alkaloids in Evodia species

The aim of this study was to evaluate the chromatographic performance of a PEG stationary phase, in comparison with those of C18 columns, for the HPLC analysis of phenethylamine ((+/-)-synephrine) and indoloquinazoline (rutaecarpine and evodiamine) alkaloids in methanolic extracts of fruits of Evodia rutaecarpa (Juss.) Benth. and E. rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang (i.e., E. officinalis Dode) (Rutaceae family). The method was validated and showed good linearity, precision, accuracy, sensitivity, and specificity. The highest content of both phenethylamine and indoloquinazoline alkaloids was found in methanolic fruit extracts of E. rutaecarpa, and it was closely related to the degree of maturity. E. officinalis fruits displayed low amounts of both types of alkaloids. Furthermore, an enantioselective HPLC method for the enantioseparation of (+/-)-synephrine from Evodia fruits was applied, by using a protein-based chiral stationary phase with cellobiohydrolase (CBH) as the chiral selector (Chiral-CBH). Isolation of synephrine from Evodia aqueous fruit extracts was carried out by strong cation-exchange SPE. The results of the application of the method to the analysis of Evodia samples showed that (-)-synephrine was the main component while (+)-synephrine was present in low concentration.     

Electrophoretic analysis of proteins and enantiomers using capillaries modified by a successive multiple ionic-polymer layer (SMIL) coating technique

The applicability of three-layer coatings consisting of three different polymers (A⁺-B⁻-C⁺ coating) prepared by a successive multiple ionic-polymer layer (SMIL) coating technique to the immobilization of polypeptides and/or proteins onto the inner surface of the capillaries was investigated to provide a high-performance separation medium for proteins and enantiomers in capillary electrophoresis (CE). To obtain a stable protein-coated capillary, high molecular mass poly(ethyleneimine) (PEI) was employed as the first layer in the A⁺-B⁻-C⁺ coating, and then a cationic protein was immobilized as the third layer. Comparisons of analytical performances between the A⁺-B⁻-C⁺ coating and the conventional SMIL-coated (A⁺-B⁻-A⁺ coating) capillary were conducted. The CE separation of cationic proteins was successfully achieved with the prepared capillaries. In addition, the polypeptide- and protein-coated capillaries were applied to the chiral separation of a binaphthyl compound. It should be noted that the chiral separation efficiency was strongly dependent on the second anionic polymer layer of the coating. Effects of the interaction between oppositely charged ionic polymer layers on the separation efficiency are discussed.     

Control of the optical properties of quantum dots by surface coating with calix[n]arene carboxylic acids

A new method for the control of the optical properties of quantum dots (QDs) has been developed using calix[n]arene carboxylic acids (1-3) as surface coating agents for QDs. The calixarene coating of CdSe/ZnS QDs was easily performed in tetrahydrofuran at room temperature. Deprotonation of the carboxyl groups of the calixarene derivatives surrounding the QDs resulted in highly fluorescent water-soluble QDs. The emission peak of the calixarene-coated QDs shifted to longer wavelengths depending on the oligomer size of the calix[n]arene derivative used for the surface coating. Although the red shift of the emission peak decreases with the increase in the particle size of QDs, this surface coating method is useful for the preparation of multi-colored water-soluble QDs from a single-colored hydrophobic QD.     

Preparation of sodium oleate/layered double hydroxide composites with acid-resistant properties

MgAlCO3 type layered double hydroxides (LDHs) with Mg/Al ratios ranging from 2 to 5 were synthesized by coprecipitation. Composites with sodium oleate/LDH were prepared by ion exchange and reconstruction of the LDH in sodium oleate solution. The amount of sodium oleate in the composites prepared by this reconstruction method was higher than that in samples prepared by the ion-exchange method. The basal spacings of the LDHs increased to 3.9 and 1.8 nm after synthesis of the composites, these spacings being in good agreement with models based on the assumption that the oleate ions are intercalated as bilayer and/or micelle structures, and as monolayers in the LDH interlayers, respectively. The number of sorbed oleate ions was higher than calculated from the anion-exchange capacities of the LDHs in most of the samples, increasing as the Mg/Al ratios of the LDHs were increased from 2 to 5. These results suggest that the oleate ions are present not only in the interlayers but also on the surfaces of the LDH particles. The acid-resistant properties of the composites were found to be much higher than for the pure LDHs. It is thus confirmed that the surfaces of the LDH particles in the composites are mostly covered with sorbed oleate ions and that the composites are good candidates as drug delivery materials.     

Removal of arsenious ion by calcined aluminum oxyhydroxide (boehmite)

Aluminum oxyhydroxide (boehmite, BE) shows adsorption ability of arsenious ion. In this study, we calcined BE in the temperature range 200-1150 degrees C, and examined the amount of arsenious ion adsorbed and adsorption mechanism. As a result, the adsorption amount of arsenious ion by BE calcined at 400 degrees C showed the highest value as compared with those by BE calcined at other temperatures. On the other hand, the amounts of arsenious ion adsorbed onto BE showed lower values at 200, 600, and >1000 degrees C than that by BE before calcination. The amount of surface hydroxyl group of calcined BE showed the highest value at the calcination temperature of 400 degrees C. As a result of X-ray analysis, BE showed boehmite structure at less than the calcination temperature of 300 degrees C, while BE was converted to the transitional state of aluminum oxide at more than 400 degrees C. From the result of the amount of arsenious ion adsorbed and FT-IR, it turned out that calcined BE dissociated water molecule when suspended in the water, hydroxyl group was generated on the surface, and the amount of arsenious ion adsorbed was increased because of the ion exchange of these hydroxyl groups with arsenious ions. It was clarified that an adsorbent with high adsorption ability of arsenious ion was obtained by calcination of BE.     

Fast scintillation detectors for high-energy X-ray region

We have developed fast scintillation detectors for nuclear resonant scattering experiments using synchrotron radiation and a nuclear excited level existing in >30?keV. A fast x-ray detector using an organic-inorganic perovskite scintillator of phenethylamine lead bromide (PhE-PbBr₄) had a dominant light emission with a fast decay time of 9.9?ns. An x-ray detector equipped with a 0.9-mm-thick PhE-PbBr₄ crystal (size: ～8 × 7?mm²) was used to detect nuclear resonant scattering in ⁶¹Ni (the first excited level: 67.41?keV; half-life: 5.3?ns). We could successfully record the decaying gamma rays emitted from ⁶¹Ni with a relatively high detection efficiency of 24%. A lead-doped plastic scintillator (NE142, Pb ～5?wt% doped) had been known to have a faster decay time of 1.7?ns. Following a test of a single NE142 detector, a four-channel NE142 detector was fabricated and successfully applied to the synchrotron-radiation based M?ssbauer spectroscopy experiment on ⁶¹Ni.     

Granulation of Nickel–Aluminum–Zirconium Complex Hydroxide Using Colloidal Silica for Adsorption of Chromium(VI) Ions from the Liquid Phase

We combined a nickel–aluminum–zirconium complex hydroxide (NAZ) with colloidal silica as a binder to prepare a granulated agent for adsorbing heavy metals from aqueous media. Three samples with different particle diameters were prepared to evaluate the effects on the properties: small (NAZ-S), medium (NAZ-M), and large (NAZ-L). We confirmed the granulation of the prepared samples at a binder content of 25%. NAZ-S had the largest specific surface area and number of hydroxyl groups, followed by NAZ-M and then NAZ-L. Regarding the adsorption capacity, NAZ-S adsorbed the most chromium(VI) ions followed by NAZ-M and then NAZ-L. The binding energy of Cr(2p) at 575–577 eV was detected after adsorption, and the effects of the temperature, contact time, and pH on the adsorption of chromium(VI) ions were evaluated. We identified the following adsorption mechanism: ion exchange with sulfate ions in the interlayer region of the NAZ samples. Finally, the chromium(VI) ions adsorbed by the NAZ samples were easily desorbed using a desorption solution. The results showed that NAZ offers great potential for the removal of chromium(VI) ions from aqueous solutions.     

Thermoreversible gelation with junctions of variable multiplicity

Effect of junction multiplicity on the phase behavior of physical gels is studied with special attention to the interference phenomena between gelation and phase separation. Three important models of the junction multiplicity are detailed, each representing cross-linking by hydrogen bond, microcrystallization and dipole aggregation. Singularities accompanying the gelation transition are found to be analogous to those of the Bose-Einstein condensation.     

Thermal polymerizations of alkali 4-(1-bromoethyl)benzoates

Thermal reactions of alkali salts of 4-(1-bromoethyl)benzoic acid in bulk were investigated. These reactions were found to produce unexpectedly the graft copolymer, poly(4-vinylbenzoate)-graft-oligo(oxycarbonyl-1,4-phenylenethylidene) ( 1 ). The relative reactivity of the oligocondensation as well as the vinyl polymerization of the salts decreased in the following order: K > Na > Li. The reaction polymerization rate proceeded rapidly during the initial 15 min, and then slowed down.