Incorporating lock masses with Q Exactive HF

[mnewmeyer]

We perform routine mass calibrations on our Q Exactive HF system--at least every five days but often more frequently--but do not typically incorporate lock masses in our methods. In an analysis run on a calibration day, we can achieve acceptable mass accuracies so we have not felt the need to incorporate lock masses. However, we don't want to miss out on the opportunity to improve our methods! How, then, do other users incorporate lock masses, if at all, and how does that relate to your calibration schedule (i.e. do you perform external calibration at the beginning of the week and then use lock masses to correct drift over the week)?

[Molly_I2]

Hi @mnewmeyer and welcome to our online community. We will work to get some insight provided for you on this great question and appreciate you sharing it in the forum. @FourierTFormer and @shannon_eliuk - Please help me say hello!

[Nick_Molinaro]

Hi @mnewmeyer  and welcome to our online community. I am an application chemist working both in the field and in the demo lab.  Lock mass correction can be used in a method to help account for any mass drift seen over time since the last calibration, and many customers  utilize it. There are also other customers who do not use a lock mass, and find the orbitrap to meet their accuracy needs, with good success like you. The QE HF is capable of 3 ppm RMS under defined conditions with external calibration and can do better with a lock mass.  I will connect with you directly, and we can discuss some of my personal experiences in more depth once I get a better understanding of the type of work you are using your orbitrap for.

Nick