This note describes how to generate compound retention times that are permanent and universal through Retention Time Locking using the Agilent 7890A GCs, Agilent 5975 series MSD and Agilent 7000 series triple quadrupole MS systems
The document describes a method using the Pressure Controlled Tee (PCT) configuration to achieve rapid backflushing of gas chromatography columns without venting the mass spectrometer system. This approach prevents sample matrix carryover and extends column life while maintaining analytical robustness.
Furthermore, the note details how Retention Time Locking (RTL) can be applied to this setup. By locking retention times to a specific compound (chlorpyrifos-methyl), analysts can ensure that scheduled events in MS acquisition modes like SIM or MRM remain valid even after column maintenance or replacement. The text provides experimental data showing that retention times are reproduced within 1 second of expected values, simplifying method development and database usage for pesticide analysis.
| Locking Compound Retention Time Target | 13.443 min |
|---|---|
| Column Configuration (Experimental) | Two 15-m DB-5ms columns |
| Column Flow Difference Setting | 0.04 mL/min |
| Retention Time Accuracy | better than an average of 1-sec |
It provides a simple approach to rapid backflushing and GC servicing on all MS systems without venting the mass spectrometer.
It makes compound retention times permanent and universal, so complex MS acquisition methods do not need to be changed when columns are trimmed or replaced.
By replacing the removed section of the column with an equal length of capillary column using the Ultimate Union connector included in the G1472A kit.