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Abstract: The volatile components between stems and roots and also among five Clematis species from China were studied and analyzed by gas chromatography–mass spectrometry (GC–MS) combined with alternative moving window factor analysis (AMWFA), a new chemometric resolution method. Identification of the compounds was also assisted by comparison of temperature-programmed retention indices (PTRIs) on HP-5MS with authentic samples included in our own laboratory database under construction. A total of 153 different compounds accounting for 86.6–96.5% were identified and significant qualitative and quantitative differences were observed among the samples. The major volatile components in different essential oils from Clematis species were n-hexadecanoic acid and (Z,Z)-9,12-octadecadienoic acid. Our work further demonstrated chemometric resolution techniques upon the two-dimensional data and PTRIs can provide a complementary and convenient method for fast and accurate analysis of complex essential oils. [Copyright &y& Elsevier]

Abstract: It is controversial regarding to the roles of acetaldehyde and ethanol in the central nervous system. In the present study, the effects of acetaldehyde and ethanol on extracellular levels of glutamate, taurine and GABA in the anterior cingulate cortex (ACC) of freely moving rats were investigated by using the microdialysis technique coupled to high performance liquid chromatography (HPLC) with fluorescent detection. The result showed that glutamate levels were significantly decreased after acute administration of acetaldehyde (AcH, 20 and 100mg/kg, i.p.), while taurine levels were significantly increased after the higher dose of acetaldehyde (100mg/kg, i.p.). GABA levels had no changes at any doses of acetaldehyde tested. Interestingly, similar changes of these amino acids were induced by ethanol (EtOH, 3g/kg, i.p.) when sodium azide (NaN3, 10mg/kg, i.p.), a catalase inhibitor that can reduce brain ethanol metabolism, was used simultaneously. These findings suggest that acetaldehyde and ethanol have the similar effects on the extracellular output of glutamate, taurine and GABA in the ACC. [Copyright &y& Elsevier]

Abstract: In order to make programmed-temperature retention index (PTRI) data be shared by other chromatographers and laboratories, conversion of PTRI from one set of experimental conditions to another is investigated in detail in this work. It was found that the differences between the PTRIs at different heating rates are structurally dependent, especially the number of ring in molecules. Thus, with the help of molecule constitutional descriptors, equations of PTRI conversion to certain initial temperature, heating rate, and stationary phase were obtained with high correlation coefficients and low standard deviations. Calculation errors of PTRI conversion between different heating rates and between different initial temperatures were from 1.1 to 2.9 retention index units (i.u.), which is in the same order with experiment errors. It is well known that reproducibility of PTRI on a polar column is not as good as that on an apolar column because of the apolarity of the n-alkane homologues. Thus, topological descriptors were used for PTRI conversion between two columns with different polar stationary phases, giving better results than those obtained by constitutional descriptors. This shows that topological descriptors could provide more molecular structural information than constitutional descriptors. However, as constitutional descriptor has the advantages of clear physical meaning and very simple calculation, it is our first selection when the PTRI calculation accuracy is satisfied. The method developed is simple in calculation, easy to be performed with high accuracy. [Copyright &y& Elsevier]

Abstract: Continuous gradient elution chromatography (CGEC) was employed to purify and separate enzymes and polysaccharides from the sap of Rhus vernicifera Chinese lacquer tree. There are three different molecules with laccase enzyme activity. Two are enzymes of each other (L1, and L2), whereas the third (RL) is an entirely separate entity. Two polysaccharides (GP1 and GP2) were also found. The Rhus laccase (RL), and isoenzymes L1 and L2, have peak molecular masses of 109,100, 120,000, 103,000 respectively; each has four copper atoms per molecule, and the pI values were 8.2, 8.6, and 9.1, respectively. The structure of the laccases was studied by Fourier-transform infrared (FT-IR) and Matrix-assisted laser desorption/ionization time-of flight (MALDI-TOF) mass spectrometry. The typical amide I (1646cm−1) and amide II (1545cm−1) bands were observed. The results from MALDI-TOF were similar to those from CGEC, but the molecular mass from the MALDI-TOF was significantly different from that obtained from sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). [Copyright &y& Elsevier]