I'm kind of new to GCMS. I hear about "retention time locking". What is it, and is it necessary?
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Sunday, May 4, 2025 9:44:40 AM
What is Retetion Time Locking?
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What is it?
Retention time locking provides a way to make a particular set of compounds elute from the GCMS at a desired time. This is usually within +/- a few seconds. When a method for a GC/MS is developed on one instrument and shared across multiple instruments to ensure quality data the peaks must remain in the isolation windows, requires consistent retention times. RT locking can provide analysts and laboratory QC departments assured consistent data quality.
To do retention time locking, first, 5 files are injected at increasing pressure. A plot is created of time versus pressure/flow. The user then can decide what RT he desires for his compound(s) and the system automatically finds the flow associated with this RT and "locks" the method so that future injections will always be within specification.
RTL Calibration Files - Five data files collected at varying pressures (-20%, -10%, nominal, +10%, +20%), a curve is constructed of
RTL Lock File - The data file used to set the lock. In this file, the actual retention time of the lock compound and the pressure used to collect the file are compared against the calibration curve and lock retention time to determine the lock pressure.
Lock Pressure - The pressure determined from a comparison of the RTL lock file acquisition pressure and retention time to the calibration curve and lock retention time.
Retention time locking provides a way to make a particular set of compounds elute from the GCMS at a desired time. This is usually within +/- a few seconds. When a method for a GC/MS is developed on one instrument and shared across multiple instruments to ensure quality data the peaks must remain in the isolation windows, requires consistent retention times. RT locking can provide analysts and laboratory QC departments assured consistent data quality.
To do retention time locking, first, 5 files are injected at increasing pressure. A plot is created of time versus pressure/flow. The user then can decide what RT he desires for his compound(s) and the system automatically finds the flow associated with this RT and "locks" the method so that future injections will always be within specification.
RTL Calibration Files - Five data files collected at varying pressures (-20%, -10%, nominal, +10%, +20%), a curve is constructed of
RTL Lock File - The data file used to set the lock. In this file, the actual retention time of the lock compound and the pressure used to collect the file are compared against the calibration curve and lock retention time to determine the lock pressure.
Lock Pressure - The pressure determined from a comparison of the RTL lock file acquisition pressure and retention time to the calibration curve and lock retention time.
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