lc-ms液質聯(lián)用資料系列(1)-文庫吧資料
2024-12-13 22:04本頁面
【正文】 Q0= 10V RO1 = 11V RO3, moves with RO2 (23V) Lens (IQn) and rod (ROn) voltages are linked Keep ions moving at correct speed through system For best sensitivity, proper mass filtering MS amp。 Neutral Molecules Neutral molecules Weak Acid NH3 Water Toluene Methanol Ethanol Acetonitrile Acetone CH3SH CH3NO2 HCN Phenol Acetic acid Benzoic acid HCl Strong Acid Reagent Ions Strong Base NH2 OH C6H5CH2 CH3O C2H5O CH2CN CH3COCH2 CH3S CH2NO2 CN C6H5O CH3COO C6H5COO Cl Weak Base For RCOOH pounds use NH4ac buffer (pH = ). Try addition of NH3 in case of neutral analytes in negative ion mode. Stay away from triethylamine, it collects in the source! Ionization Suppression Compounds That Cause Sensitivity Suppression – Salts can interfere with ionization and can cluster to plicate spectrum (but also aid in identification) – Strong bases or quaternary amines can interfere with positive mode analytes, . Triethylamine (TEA) – Acids Sulfuric/Sulfonic acids and TFA interfere in negative mode experiments – Phosphate buffer and nonvolatile ion pairing agents (. SDS) can cause severe suppression and plex spectra Dimerization ([2M+H]+) can occur at high concentration, leading to nonlinearity during quantitation – Dimer Signal at m/z = (MW*2)+1 – Can cause nonlinearity at high concentrations Progesterone in Positive Ion ESIMS [M+ Na]+ Intensity,cps Intensity,cps 6e7 Effect of Phosphate Buffer –Q1 MCA (10 scans): from cck q1 ve nano cps 8e7 7e7 CCK dissolved in Phosphate B uffer
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