Rongji Dai

Synergistic effect of resorcarene and cyclodextrin mixed stationary phase in gas chromatography

SummaryA new resorcarene derivatives, ethylhexylresorcarene, was synthesized and used as stationary phase in opentubular (capillary) columns. It was combined with heptakis(2,6-di-O-pentyl-3-O-trifluoroacetyl)-β-CD and coated on fused-silica capillary tubes. By studying the chromatographic properties of the mixed stationary phase and its selectivity for different isomers, as well as comparing with the resorcarene and the CD used as individual stationary phases, a synergistic effect was observed on the mixed stationary phase.

Consequence of diluting modified β-cyclodextrins in a side-chain crown ether polysiloxane and in a side-chain liquid-crystalline polysiloxane-containing crown ether as stationary phases in capillary gas chromatography

SummaryThis paper investigates the possibility of using a sidechain crown ether polysiloxane (PDB-14-C4) and a side-chain liquid-crystalline polysiloxane-containing crown ether (PSC-3) as matrices for peralkylated β-CD employed as stationary phases. Three columns, coated with PSC-3 + permethylated β-CD, PDB-14-C4 + permethylated β-CD and PDB-14-C4 + perethylated β-CD were characterized by gas chromatography. The column efficiencies, phase transitions, and selectivities were measured and compared.

Synergistic effects in mixed gas chromatographic stationary phases containing hepatkis(2.3.6-tri-O-pentyl)-β-cyclodextrin and AgNO3 or TINO3 in the separation of xylene isomers

SummaryThe gas chromatographic separation of xylene isomers using special mixed stationary phases consisting of heptakis(2.3.6-tri-O-pentyl)-β-CD-AgNO3, heptakis (2.3.6-tri-O-pentyl)-β-CD-TINO3 or bentone-34-AgNO3 is investigated. The first two have positive synergistic effects for the separation of m, and p-xylene isomers, but negative synergistic effects for the m, and oisomers. The separation effects depend on temperature, mixing ratio and how mixing is accomplished.

Investigation into the separation of achiral and chiral molecules on fused-silica capillary columns coated with three peralkylated cyclodextrins

SummaryThree peralkylated β-cyclodextrins (CD), perethylated β-CD, perbutylated β-CD and peroctylated β-CD have been coated on to untreated fused-silica capillary tubing and used to separate some achiral and chiral compounds. The separation mechanism is discussed in the paper.

The investigation of pyrolysis mechanism of heptakis[3-O-methyl-2,6-di-O-(methoxybenzyl)]-β-cyclodextrin by Py-GC and Py-GC/MS

Abstract The thermal stability and pyrolysis mechanism of heptakis[3-O-methyl-2,6- di -O-(methoxybenzyl)]-β-cyclodextrin (MMBCD) were investigated by pyrolysis gas chromatography (Py-GC) and Py-GC/MS. MMBCD was stable up to 300 °C. Several optical and positional isomers were baseline separated using MMBCD as the stationary phase.

Pyrolysis-gas chromatography investigation of peralkylated β-cyclodextrins used as a capillary GC stationary phase

Six peralkylated β-cyclodextrins used as a GC stationary phase for the separation of positional and optical isomers were characterized by Py-GC. The Py-GC results showed that long-chain alkylated cyclodextrins are more thermally stable than those with short chains. Their degree of alkylation was also studied by thermally assisted hydrolysis and methylation in Py-GC. The capillary columns coated with these β-cyclodextrin derivatives showed excellent separation of some optical isomers.

Investigation on five novel substituted β-cyclodextrins used as GC stationary phases

SummaryFive β-cyclodextrin derivatives, heptakis[2,6-di-O-pentyl-3-O-(4-nitrobenzyl)-β-CD (CD-I), heptakis [2,6-di-O-pentyl-3-O-(5-hexenyl)]-β-CD (CD-II), heptakis-(2, 6-di-O-cinnamyl-3-O-methyl)-β-CD (CD-III), heptakis-(2, 6-di-O-cinnamyl-3-O-acetyl)-β-CD (CD-IV) and heptakis(2, 6-di-O-cinnamyl-3-O-trifluoroacetyl)-β-CD (CD-V), were synthesized and coated on fused-silica capillary coluns. Their chromatographic characteristics were tested and compared with heptakis (2,3,6-tri-O-pentyl)-β-CD (CD-VI) and heptakis (2,6-di-O-pentyl-3-O-trifluoroacetyl)-β-CD (CD-VII). It was found that the size, polarity, and aromatic property of the substituted group at the 3-position of heptakis (2,6-di-O-pentyl)-β-cyclodextrins greatly influenced their chromatographic properties and separation ability. The introduction of aromatic group or a group containing a double-bond may bring π-π interactions between the host and guest molecules, and therefore increased the separation ability of the β-CDs for substituted benzene isomers. Introduction of cinnamyl groups in to the 2,6-3-position of β-CD has a significant effect on the chromatographic properties of the stationary phases(CD-III-CD-V).

The Py-GC and Py-GC/MS investigation of liquid crystalline polysiloxanes containing benzyl ether and biphenyl mesogen

Abstract The thermal stability and pyrolysis pathway of liquid crystalline polysiloxanes containing benzyl ether and biphenyl mesogen were investigated by pyrolysis gas chromatography (Py-GC) and Py-GC/MS. The polysiloxanes were stable up to 250 °C.