Dear Sangita,

In case you´re working with peptides these will preferentially ionise as doubly and triply charged ions and this way you´ll be able to monitor compounds with Mw>1200 (using your own example you may scan the transition 650.6>350.5).

Hope this helps,

Ana

You are right for multiply charged ions it is possible. However there is single charge compound with m/z >1200 using QTRAP4000 and it is a published manuscript. I am just wondering how can those high m/z ions can be quantified using the instrument.

Thank you for your response.

Four double, triple or more charge ion. Your Molecular wt is divided by no of charge ion. If your molecular wt is 2000 and double ion charge then m/z = 2000/2 = 1000. So 1000 can be monitor using QTRAP4000 for 

Hi Hiten,

Thank you for your comment. I understand the concept of using transition and how it is different for single and multiple charge compound. But I have seen a published paper that is using QTRAP4000 for single charge compound quantification to quantify compound using >1200 m/z value. Is that the mistake? I just want to confirm that I am not missing anything about MRM scan quantification.

As per below site,

http://www.speciation.net/Database/Instruments/Applied-Biosystems/4000-QTRAP-LCMSMS-System-;i2778

QTRAP m/z range is given below.

Mass Range

m/z of 5 to 2800 in Q1/Q3 RF/DC mode, m/z of 50 to 2800 in linear ion trap mode

I hope it help you.

HI Sangita.

Hiten is correct about mass range in 4000 QTRAP. You could explore your Alayst Software and change mass range for better analysis. I think this configurations are in Tune guide in Analyst software.

I hope this help you.