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液相層析質譜分析 LC-MS Method development and Analyte Identification. 授課教師:賴滄海教授 03-12-2008. Ionization. ESI Sonic Spray I APCI APPI APLI. Ion Separation. Mass range Scan speed Mass resolution Mass accuracy. Mass Accuracy.
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液相層析質譜分析LC-MS Method development and Analyte Identification 授課教師:賴滄海教授 03-12-2008
Ionization • ESI • Sonic Spray I • APCI • APPI • APLI
Ion Separation • Mass range • Scan speed • Mass resolution • Mass accuracy
Mass Accuracy An unknown compound appears at m/z 180.094. in the positive ion mode. The mass accuracy of the spectrometer is 2-5 ppm.
Mass Analyzer • Quadrupole • Ion trap • Linear ion Trap • Time of flight
Steps in the quantification of drugs • Sampling • Sample preparation • Separation • Detection • Data analysis
General Considerations • What to measure ( drug/metabolites) • Select matrix (blood,serum,plasma,tissue) • Sample limitations (volume,sample size) • Linear range • Lower limit of quantification • Internal standard
Problems with Deuterated Is [13C,D3] rofecoxib exchange with Hydrogen atoms on water molecular [J Chromatogr B 2002;767:117-129]
Positive identification with GC-MS(SIM) • 3 ions • Retention time the same as standards • Ion ratio correct • S/N > 3 • Sample processed to remove interferences
Aspects to be considered when setting up LC-MS procedures • Influence of the mobile phase • Influence of sodium and potassium on the formation of adducts • Influence of the curtain gas flow • Reproducibility of mass spectra • Influence of ion suppression • GC-MS data to verify LC-MS results
Mass spectrometry • Ionization • Matrix effect • Full scan • MRM
Figure 2.5 The influence of collision energy on the fragmentation of tacrolimus at (a)10, (b)20,(c)30,(d)40 and (e)50eV.
Sample preparation • Sample dilution and protein precipitation • Liquid-liquid extraction • Solid phase extraction • Two dimensional chromatography (column switching)