So how can you tell if something is wrong with your mass spectrometry and liquid chromatography systems? We talk a lot about lab safety in general, but in this post we’re focusing on troubleshooting—because it’s critical to catch performance issues before they reach the level of a lab safety concern. Additionally, you don’t want to waste precious time and samples performing tests when your MS/LC systems aren’t working properly. For these reasons, it’s key to regularly evaluate your equipment and know what to do when something appears “off.”
Begin with the Lab Safety Basics
A good way to begin any inspection is with a visual overview of the entire system. You want to make sure everything looks normal. Does anything look out of place? Are there any leaks, or misaligned connections between the MS and the LC?
Of course, making these types of evaluations is a lot easier to do if you can get up close and personal with your machines, which is why we created our adjustable HPLC-UHPLC cart. It can easily be raised or lowered, allowing you to bring all parts of your system to eye level.
Break Down the Liquid Chromatography / Mass Spectrometry System
Next, you want to “break down the system” into its component parts—specifically mass spectrometry and liquid chromatography. For the LC, you want to watch the standard mixture separation, checking pressure traces and flow measurement, and running an injection check. You can isolate problems to one of a half-dozen areas:
With mass spectrometry, the critical issue is infusion. You want to watch the voltages, detector signal and vacuum gauges. (Since we trust you are using our dedicated MS lab bench, with its vacuum pump enclosure that provides 75% noise reduction, you probably won’t notice any noise changes in the vacuum pumps.) Here, you can isolate the problem to:
- Ionization or source
- Mass analyzer
CIV is short for “compare with installation values.” The engineers who install your instruments are some of your best lab safety allies because they know more about your equipment than anyone else. In addition to keeping track of installation values, make friends with your installers, ask them questions, and see if they will give you a copy of their own troubleshooting manual or other documents that aren’t normally given out to customers.
Specific things to pay attention to at the time of installation (and to record for future reference) include:
- Vacuum settings (for all regions, when possible)
- Voltage readbacks (copy screen shots of acceptable values)
- Mixes as tuned for use (including sensitivity, resolution, stability, mass calibration, S/N)
- Listing of best practices for auto-tune or calibration
- Chromatographic performance (pressure range, peak width, RT stability)
- Clear descriptions of error log messages
- PM schedule recommendations for your specific use patterns
- Recommendations for finding spare parts
- Restrictions on solvent usage, pH values, etc.
Employ System Suitability Protocols
One helpful way to prevent lab safety problems and ascertain test parameters for mass spectrometry and liquid chromatography applications is to develop a system suitability protocol. This will help you monitor any changes that occur in your hardware or software. Analysis of a known sample provides data which can easily be compared with prior readings using a logbook that tracks prior performance, problems, and solutions.
Specific metrics for LC performance include retention time, peak shape, and chromatographic resolution; for mass spectrometers, you want to check sensitivity/response, mass accuracy, and precision. Always use the same method for LC and MS, and monitor metrics variability over a number of injections. Poor system suitability data should be kept to assist in troubleshooting future performance issues.
Enhance Your Lab’s Efficiency
We believe that optimal performance depends upon keeping instruments well calibrated and constantly monitored. We also believe that dedicated lab furniture will help you extend the life of your instruments and keep them performing at their best. For more information on our lab benches, contact us today.