Abliz Zeper

Study on fragmentation behavior of taxoids by tandem mass spectrometry

We have studied the fragmentation behavior of positive and negative ions of taxol and 6/8/6 type taxoids, the influence of different substituents on fragmentation, and the correlativity between fragmentation patterns and structure by MS/MS technique with different ionization methods such as FAB-MS, ESI-MS, etc. We have also investigated in detail the fragmentation of various molecular-related ions, such as [M+H]+, [M+Na]+ and [M-H]− ions, and the formation pathways of characteristic fragment ions. It has been found that there exists some competing reaction between the loss of C-13 side chain and decomposition by loss of acetic acid. In addition, by comparing CID spectra obtained with low- and high-energy collision, it is seen that CID-MS/MS with low-energy collision is more suitable for the study of the structural analysis of small molecules and drug metabolites. The experimental results demonstrate that MS/MS spectra can reflect more effectively the slight difference of structure between the related compounds and their structural characteristic features than MS spectra, and can also provide a beneficial analysis basis for these kinds of compounds.

Advances in mass spectrometry imaging and its application

The developments and applications of mass spectrometry imaging (MSI) have become a frontier field in mass spectrometry and molecular imaging, and it deserved much attention over the last few years. In this review, we summarize the main techniques, methods and applications of MSI, and discuss its future and trends. Moreover, some recent contributions on the development of MSI from China are also introduced.

Plasma Preparation Method for Metabolomic Analysis Based on Rapid Resolution Liquid Chromatography-Mass Spectrometry

Abstract This study was undertaken to compare different methods for plasma preparation in metabolomic analysis. Plasma proteins were either precipitated with four different organic solvents or subjected to solid-phase extraction (SPE) on C 18 -boned phase, with consideration to the number of extracted standard compounds. The eluent was analyzed by RRLC-MS. The results indicated that acetonitrile could be used to effectively precipitate plasma proteins with the best extracting effect. Then, the optimal conditions for acetonitrile preparation were further investigated. A 3-fold volume of cold acetonitrile coupled with slow precipitation was employed. The results, according to the reproducibility, precision and freeze thawing stability of the sample, showed that the method is satisfactory and could be applied in metabolomic analysis of plasma preparation. Furthermore, the reproducibility of the method using principal component analysis (PCA) was sufficient to ensure data quality in metabolomic applications by carefully monitoring the quality control samples randomly inserted among the real sample queue, and the method would be applied in metabolomic studies.

Development of Method for Serum Preparation and Lipidomics Analysis Based on Rapid Resolution Liquid Chromatography-Mass Spectrometry

A rapid resolution liquid chromatography-mass spectrometric(RRLC-MS) method was developed and validated for the determination of endogenous lipid metabolites in human serum.The samples were pretreated by lipid extraction with methylene chloride-methanol(2 ∶ 1,V/V) mixture solvent and introduced to RRLC-MS under intensive optimization of chromatography conditions and mass spectrometry parameters.The chromatographic separation was performed on an ACQUITY UPLC CSH C18 column(100 mm×2.1 mm,1.7 μm) with mobile phase containing 10 mmol/L ammonium formate(0.1% formic acid)(A) and acetonitrile-isopropyl alcohol(1 ∶ 1,V/V) mixture solution(B) in a linear gradient elution.The MS detection was carried out by the integrated ionization approach using electrospray ionization(ESI) in both positive and negative ion modes and atmosphere pressure chemical ionization(APCI) in positive ion mode.Typical lipid molecules such as free fatty acids(FFAs),phospholipids(PLs),sphingophosphalipids(SPs),glycerolipids(GLs),cholesterol(Chol.) and cholesterol esters(CEs) had been detected with high sensitivity,good precision and reliable stability.Furthermore,the principal component analysis(PCA) results of the quality control(QC) samples among the real sample queue indicated the data reliability of the method in lipidomics applications.