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5 Tips for Calibrating a QTOF Mass Spectrometer

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Do you have questions about your mass spec? How about a workflow? Our community members are involved in active discussions and receive expert answers from customers like you, SCIEX scientists, and support specialists every week. One recent topic concerned the automatic calibration on TripleTOF® systems as answered by Dr. Christie Hunter whose focus is developing and testing innovative MS workflows for omics research through working collaboratively with the instrument, chemistry, and software research groups.

Currently, Dr. Hunter is working on the application of MS-based tools for the quantitative analysis of proteins and using MRM and SWATH® based strategies.

Following are her tips for calibrating a TripleTOF system:

1. Stable Environment – For highest overall mass accuracy performance keep the covers on your instrument and allow for sufficient warm up before performing mass calibration. It is important that your instrument is in a thermally stable room with good environmental controls. Avoid placing your system directly under the HVAC vent or near large windows with exposure to direct sunlight. Mass spectrometers use many different high voltage power supplies which take time to “warm up,” so always warm up your instrument before tuning and calibrating.

2. Regular Calibration to Maintain Accuracy – For higher flow applications using the DuoSpray™ source, typically we use the Calibration Delivery System (CDS). In this situation, calibration is automatically and periodically updated using infusion during the batch.

When using our NanoSpray® Source, or ion sources at any flow rate, LC Auto Calibration can be performed. A calibration sample is injected by LC-MS regularly during the batch. Peaks are detected and once the final peak elutes, the new mass calibration is computed and applied.

Learn more about the new peptide standard for running LC calibration on TripleTOF and information on peptides masses >

3. Avoid Operating Under Saturation Conditions – Ensure you are loading the correct amount of sample onto your LC column to avoid saturation of the chromatography and the mass spectrometer. Learn how to check for MS saturation >

4. Understanding Dynamic Background Calibration (DBC) – With DBC, the background ions present in the MS data are constantly monitored by the Analyst® software. These ions are determined dynamically for every run, and every sample, and constantly updated. This means a separate calibrant does not need to be added during the LC-MS run to maintain a stable calibration. Learn More >

5. Understanding Inter-Sample Calibration – Using inter-sample calibration, Analyst Software assesses the first 30 cycles of MS data of the previous file to determine background ions. This information is then compared to the first 30 cycles of the next file. Calibration is adjusted to account for any drift between runs. Read more >

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