Chromatography Forum

Hi there,

When I analyse my data I'm getting the message that I miss Ion's, e.g. ions 252 and 127.

I do a full scan and a SIM within one run on a Agilent 5973 MSD.Chromatographic nothing is wrong, the peaks are well seperated. I still can intergrate and quantify them. But I see this weird message.

Does anyone knows what to do?

Thansks in advance.

Regards,

Wouter

get a scan of one of your peaks then in the command line type in tab then hit enter. Put the exact mass of your sim compound in the method ( ie 202.4).

Whoops just read your complete message! 5973 can not do sim/scan! The software leads you to believe it can be done. Even if you have had an outside source reconfigure your 5973 to do so, Agilent will not support it ( want to sell 5975's).

You can do what I do, run 2 methods/sample. One sim and one scan. Kinda a hassle but they won't buy me a 75!

Hi Bigbear

When we bought this MS, it is a second hand, they told us that is was upgraded to 5975, or something close to it. I've done a lot of testing in the meanwhile and this machine can do sim/scan in one run. Gladly because one run takes 50 min. For some of my pesticides I analyze them both sim and scan. And when it's not visible on Scan it still is on SIM, Very nice in fact.

It's not that this is bothering me. But every now and then I notice it and than I'm wondering what is going one. But I will give it a try what you mentioned.

Regards,

Wouter

That's good that you have the upgrade. You will have to know the exact mass for all the compounds you will use durring the run. I got the exact mass for my instrument by running a sim method and acquiring data 0.1 D apart. So for example if my mass was a nominal 282 I set up a group to get all masses from 181.7--182.6. After the run I would take the avg. of the peak and tabulate. The mass with the highest area would be what is entered into the acquisition method. Then set the dwell time so you get 15-20 scans across a low concentration peak. It is quite a bit of work, but I was told not to trust the apparent exact mass data from a scan run.

Good luck

Hi Bigbear,

That is a nice solution when you have little components. I'm running with 170 components, and increasing , so this is not really a solution.

It is not that it is bothering me, but I'm wondering why this happens? What causes my MS to do so?

Anyone suggestions?

Regards

Wouter

Yes I've seen it to. As I said you need the exact mass of the compound in the SIM method and that same mass needs to be entered into the data aalysis method.