(1) Capillary Voltage: -3.0 kv.(2) Cone Voltage: -40 v.
(3) Collision Energy: 18 ev.
(4) MRM: m/z 299.5 →m/z 255.2.
Thursday, January 22, 2009
Biosample Assay by LC-MS (2)
(1) Capillary Voltage: -3.0 kv.(2) Cone Voltage: -40 v.
(3) Collision Energy: 18 ev.
(4) MRM: m/z 299.5 →m/z 255.2.
Monday, January 19, 2009
Ionization Suppression Summary
(1) Compounds That Cause Sensitivity Suppression.
-Salts can interfere with ionization and can cluster to complicate spectrum (but also aid in identification).
-Strong bases or quaternary amines can interfere with positive mode analytes, e.g. Triethylamine(TFA).
-Acid -Sulfuric/Sulfonicacids and TFA interfere in negative mode.
-Phosphate buffer and non-volatile ion pairing agents (e.g. SDS) can cause severe suppression and complex spectrum.
(2) Dimerization([2M+H]+) can occur at high concentration, leading to non-linearity during quantitation.
-DimerSignal at m/z = (MW*2) + 1.
-Can cause non-linearity at high concentrations.
-Salts can interfere with ionization and can cluster to complicate spectrum (but also aid in identification).
-Strong bases or quaternary amines can interfere with positive mode analytes, e.g. Triethylamine(TFA).
-Acid -Sulfuric/Sulfonicacids and TFA interfere in negative mode.
-Phosphate buffer and non-volatile ion pairing agents (e.g. SDS) can cause severe suppression and complex spectrum.
(2) Dimerization([2M+H]+) can occur at high concentration, leading to non-linearity during quantitation.
-DimerSignal at m/z = (MW*2) + 1.
-Can cause non-linearity at high concentrations.
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