Liang Xinmiao

Confirmation and identification of the impurities in metolachlor using gas chromatography interfaced with orthogonal acceleration time-of-flight mass spectrometry (GC-oaTOFMS)

The confirmation and identification of the impurities in metolachlor (a herbicde) by using gas chromatography-orthogonal acceleration time of flight mass spectrometry (GC-oaTOFMS) and gas chromatography-quadrupole mass spectrometry (GC-qMS) are described. For the accurate mass measurement can be carried by GC-oaTOFMS, the elemental compositions of molecular and fragment ions in the spectra are suggested. In the experiment the average of mass deviations between the measured and theoretical values was below 2.5mDa. Finally ten impurities were confirmed and identified. They accounted for 94% of the total impurities by weight.

New uniform algorithm to predict reversed phase retention values under different gradient conditions

A new numerical emulation algorithm was established to calculate retention parameters in RP-HPLC with several retention times under different linear or nonlinear binary gradient elution conditions and further predict the retention time under any other binary gradient conditions. A program was written according to this algorithm and nine solutes were used to test the program. The prediction results were excellent. The maximum relative error of predicted retention time was less than 0.45%.

Analysis of the volatile oil from the stem of acanthopanax senticosus(Rupr.et Maxim.)harms with several hyphenated methods of chromatography

Gas chromatography/quadrupole mass spectrometry (GC/qMS), gas chromatography/Fourier transform infrared spectrometry (GC/FTIR) and gas chromatography/orthogonal acceleration time-of-flight mass spectrometry (GC/oaTOFMS) were applied to analyze the volatile oil from the stem of Acanthopanax Senticosus (Rupr. et Maxim.) Harms. Based on the mass spectra search function of GC/qMS with the aid of the discriminability of the geometrical isomer by GC/FTIR and the ability to determine the accurate mass charge ratio (m/z) by GC/oaTOFMS, 68 GC eluants were identified successfully. Compared with the results obtained by GC/qMS only, the analytical results obtained by these hyphenated methods of gas chromatography are more credible.

Separation and Analysis of Volatile Oil from Lonicera japonica thunb

Abstract Offline normal phase liquid chromatography-gas chromatography (NPLC-GC) was applied to separate the volatile oil from Lonicera japonica thunb. The qualitative analysis was carried out on gas chromatography/quadrupole mass spectrometry (GC/qMS) and gas chromatography/orthogonal acceleration time-of-flight mass spectrometry (GC/oaTOFMS). On the basis of the highly efficient separation ability of NPLC-GC and powerful qualitative ability of GC/qMS and GC/oaTOFMS, almost 200 volatile compounds were identified. Compared with the results obtained by GC/qMS only, those by multiple hyphenated techniques are more reliable.

Study on Retention Equation for Protein in Reversed Phase Liquid Chromatography

Study on the retention equation for protein in RPLC can contribute to optimizing gradient conditions for protein separation. In this study, five standard proteins, insulin, cytochrome C, lysozyme, transferrin and myoglobin were selected, and their retention time on three reversed-phase columns (Waters Symmetry 300 C-4, Waters Symmetry 300 C-18, C8HC) under six different linear gradients was obtained. According to nonlinear curve fit (CSASS software), the retention equation for five standard proteins on three columns was established. The regression coefficients of the 15 equations were all above 0: 999, indicating that the equation could accurately describe protein retention behavior on RPLC mode. Based on the equation, retention time for 5 standard proteins under other gradient conditions was predicted, and the relative errors for each protein were below 5%. This retention equation could be used in optimizing gradient conditions for protein separation on RPLC, leading to rapid baseline separation of five mixed standard proteins within 20 min.

A New Oleanane-Type Triterpene Glycoside from Glycyrrhiza uralensis

Abstract In order to investigate the chemical constituents of the roots of Glycyrrhiza uralensis Fisch, the constituents were isolated by using preparative HPLC. The structures of the isolated compounds were identified by spectral evidence. A new oleanane-type triterpenoid saponin (S3) and 11 known compounds were obtained. The new licorice saponin (S3) was identified as 22β-acetoxyl-glycyrrhaldehyde based on MS, UV, IR and NMR spectroscopic data.