Titania-coated silica spheres were prepared by a layer-by-layer self-assembly technique for use as a high-performance liquid chromatography packing. This packing has a high surface area of 202.1 m(2)/g, a large pore volume of 0.36 cm(3)/g, and a pore diameter of 7.0 nm. Furthermore, the packing particles exhibit narrow pore size distribution and good pore structure. The chromatographic behavior of the packing was studied under both normal and reversed-phase conditions. Low column pressures were observed. Aromatic isomeric compounds were well separated on the TiO(2)/SiO(2) column under normal phase conditions; pyridine and aniline derivatives were separated on the octadecyl-bonded TiO(2)/SiO(2) (ODT) column, respectively, under reversed-phase conditions, and highly symmetrical peaks were obtained for 15 basic compounds. The chemical stability of the stationary phase was tested with sodium phosphate solution (10 mmol/L, pH = 10) at 25 degrees C and potassium phosphate solution (50 mmol/L, pH = 10) at 50 degrees C.

A high-performance liquid chromatographic (HPLC) method has been developed for separation and quantitative analysis of flavonoid aglycones in Rhododendron anthopogonosides Maxim. Flavonoids in their bound forms were hydrolyzed with acid before HPLC analysis. Analytical samples were pretreated by solid-phase extraction on C-18 reversed-phase cartridges. Optimum separation on a 4.6 mm x 250 mm i.d. C-18 column was achieved by use of a 52:48 (v/v) mixture of methanol and an aqueous solution of 10 mm citric acid and 1 mm sodium dodecyl sulfate as mobile phase. The flow rate was 1.0 mL min(-1) and the detection wavelength 360 nm. Five flavonoids, myricetin, quercetin, luteolin, kaempferol, and ishorhamnetin, were separated with high resolution without use of gradient elution. The method was successfully used for efficient quality-control analysis by quantifying flavonoids in R. anthopogonosides. Repeatability tests showed that intra-day and inter-day RSD was <10%. LOD of the five flavonoids were <0.85 mu g mL(-1). Recovery ranged from 90.2 to 112.5%, with RSD <11.1%.

Reaction of Ru3(CO)12 with the thio-Schiff base ligand acetylferrocenyl-thiosemicarbazone provides a one-step synthesis of the chiral cluster [Ru3(CO)9{1,2-μ-FcC(CH3) = NNC(S)NHCH3}] as a racemic mixture. One molecule of thiosemicarbazone was consumed in the cluster formation process, in which the ligand was deprotonated and acted as a bidentate N, S donor as well as bridging. The title cluster has been characterised by NMR, IR, HPLC and an X-ray structure determination.

A novel cellulose tris(N-3,5-dimethylphenylcarbamate) (CDMPC) chiral stationary phase (CSP) was prepared by coating CDMPC on TiO2/SiO2, which was prepared by coating titania nanoparticles on silica through a self-assemble technique. At first, 2-hydroxyl-phenyl acetonitrile and α-phenylethanol were separated on this new CSP to evaluate the chiral separation ability. Then, two pesticides, matalaxyl and diclofop-methyl were separated. The influence of the mobile phase composition on the enantioselectivity was discussed, and the repeatability and stability of the CSP were studied too.

Chromatographic performance of octadecyl-bonded TiO2/SiO2 stationary phase was evaluated with Engelhardt and Tanaka test mixtures. In the two test protocol, some parameters influencing the retention, such as methylene selectivity (CH2), steric selectivity (O/T), hydrogen bonding capacity (C/P), and ion exchange capacity (B/P) were obtained. By separating several same compounds with different mobile phases, different results were obtained and they were compared with that in the reference, in which octadecyl-bonded titania packing was prepared and a similar test was carried out. All of the results suggest that the octadecyl-bonded TiO2/SiO2 stationary phase not only has good methylene selectivity and steric selectivity, but also shows a large potential in the separation of basic compounds.

Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) coated TiO2/SiO2 has been prepared by coating CDMPC on TiO2/SiO2 which consists of micrometer-sized silica spheres as core and nanometer-sized titania particles as surface coating. Eight basic indole ring derivative enantiomers were separated on this CDMPC coated CSP and symmetrical peaks were obtained using hexane as the mobile phase and various alcohols as modifiers. The influence of the mobile phase composition and structural variation of the solutes on the enantioseparation was investigated and discussed.

Two enatiomers of indole ring derivatives have been chiral separated on amylase-tris(3,5-dimethylphenylcarbamate) chiral stationary phase(CSP),using hexane as the mobile phase with various alcohols as modifiers.The influence of the mobile phase composition on the enantioselectivity was discussed.By comparing the results from amylase-tris(3,5-dimethylphenylcarbamate) chiral stationary phase and cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase,the separation abilities are different on the two stationaries.

ZrO2/SiO2 particles, which were prepared by a layer-by-layer self-assemble technique and consist of micrometer-sized silica spheres as cores and nanometer-sized zirconia particles as surface coatings, have a higher surface area and pore volume than other zirconia supports have. Further more it is more stable than silica is. In this paper we made a reversed-phase support by bonding octadecyltrichlorosilane on ZrO2/SiO2 particles, it had a comparable high carbon amount of 9.62% and good chemical stability being stable up to pH 11. The chromatographic behavior showed that the support acted as a true reversed chromatographic stationary phase and had a hydrophobic selectivity. Basic and aromatic compounds are well separated and the peaks are symmetrical.

The uniform titania nanoparticle multilayers/micrometer-sized silica particle(TiO2/SiO2) have been fabfabricated by consecutively assembling of surfactant C12H25SO4Na(SDS) and titanium dioxide nanoparticles onto SiO2 micro beads and subsequently removing the surfactant by calcinations. The specific surface area, total pore volume, and average pore diameter of TiO2/SiO2 are 202.1 m(2)/g, 0.3628 cm(3)/g and 7.0 nm, respectively. This titania supports was used to separate basic molecules, acidic molecules and non-basic isomeric aromatic mixtures under normal-phase conditions and compared with that of zirconia supports. It is shown that this enables the purification of basic fine chemicals and aromatic substances. The material exhibits good permeability, low back pressure, so it is an ideal packing for high performance liquid chromatographic applications.

ZrO2/SiO2 particles, which were prepared by a layer-by-layer self-assemble technique and consist of micrometer-sized silica spheres as cores and nanometer-sized zirconia particles as surface coatings, have a higher surface area and pore volume than other zirconia supports have. Further more it is more stable than silica is. In this paper we made a reversed-phase support by bonding octadecyltrichlorosilane on ZrO2/SiO2 particles, it had a comparable high carbon amount of 9.62% and good chemical stability being stable up to pH 11. The chromatographic behavior showed that the support acted as a true reversed chromatographic stationary phase and had a hydrophobic selectivity. Basic and aromatic compounds are well separated and the peaks are symmetrical.

In this paper, we prepared a reversed-phase support by bonding octadecyltrichlorosilane onto TiO2/SiO2 particles, which were prepared by a layer-by-layer self-assembly technique and consists of micrometer-sized silica spheres as core and nanometer-sized titania particles as surface coating. The chromatographic behavior of the support was studied in detail. The support acted as a true reversed chromatographic stationary phase and had a hydrophobic selectivity. Further more, it had a comparable high carbon content of 11.51% and showed good stability in the basic solution of pH 10.

Two types of novel reversed-phase packing materials were made by adding TiO2/SiO2 (or ZrO2/SiO2) and octadecyltrichlorosilane into toluene with stirring and refluxing for 36 h. TiO2/SiO2 and ZrO2/SiO2 particles were prepared by a layer-by-layer self-assemble technique and consist of micrometer-sized silica spheres as cores and nanometer-sized zirconia or titania as surface coating. The carbon loading of C-18-bonded TiO2/SiO2 was 11. 51% and that of C-18-bonded ZrO2/SiO2 was 9. 62%. The hydrophobic selectivity and sensitivity were studied respectively and compared in details; the results showed that the packing supports both acted as true reversed chromatographic stationary phase with similar hydrophobic selectivity. The chromatographic behaviors of the two types of novel reversed-phase packing material were evaluated with nine aromatic compounds. The chromatographic studies showed that either of the packing materials would be a good choice to separate aromatic compounds, however, the selectivity of C-18-bonded TiO2/SiO2 was a little better than that of C-18-bonded ZrO2/SiO2.