Application of a 'Lock Mass' on an LTQ Orbitrap to Maintain Accurate Mass Assignments throughout Large Biomarker Discovery Studies

摘要

Bis(2-Ethylhexy)Phthalate ion (C24H38O4)H+ with an exact mass of 391.28428 is independent of the gradient composition and is a better choice for 'lock mass" ion than commonly used polycyclodimethylsiloxane (PCM ) ions. Frequency of "Lock Mass" ion detection improves with the increase of "lock mass" ion abundance. 30percent Increase of "lock mass" ion abundance adds only a few ms to the scan and does not limit the trap capacity. Lock mass" 391.28428, injected in FT with 30percent abundance allow low mass assignment errors for large scale biomarker discovery experiments (over 30 days).