PRACTICAL CONSIDERATIONS FOR THE USE OF ACQUITY QDA DETECTOR

[Anna.ser]

Hi, i have to develop a new method for the detection of impurities through an UPLC-MS analysis, using a QDA detector (simple quadrupole detector).

The problem is that i've never used this detector, the lab moved from an UV detection to a MS QDA (ESI) one: does anyone used the apparatus acquity qda from WATERS ?

im here for information concerning the pratical considerations while using it .

thank you !

[tkubowicz]

Hello

Check Waters website. There is a lot of aplications and materials.
If you need some help here you need to be more specific and give us details:
-type of analytes
-sample information (matrix)
-qual/quant details
If you've nevere used QDA check first manuals (user guide/operator manual) and learn how to operate it and what parameters you need to be aware of.

Regards

Tomasz Kubowicz

[Anna.ser]

The study concerns the detection of impurities during stability tests , so the analytes will be a small molecules.

The aim is to use the MS detection to identify with more accuracy the peak of compounds already detected by the LC analysis.

All technical or analytical information concerning the apparatus are welcome !!
( even the information if the QDA can be turned off after the use if the next analysis will be after one month /???)

thank you

[tkubowicz]

Hello

You still didn't give us anything...
-compound (name/structure/formula or type)
-sample matrix (tablets, raw materials etc)
-method used for LC (parameters, mobile phase etc)
-sample prep

If you're not sure if you can switch off QDA I strongly recommend to read user/ operator manual. In my opinion it is basic for working with any instrument (especially if you're going to develop/optimize method)

Regards

Tomasz Kubowicz

[DR]

QDa can be used in-line with UV or PDA detectors, they can be shut off and bypassed if not needed, they do have some special considerations for installation (a place to vent, a place to put a vacuum pump, trap and other sundries including a Nitrogen input.

The usual LC/MS caveats and restrictions apply (you don't want to feed the QDa anything that is not volatile - no sulfonic acid or phosphate salts, for example).

[Magpie]

-Depending on your settings, files created by the QDa will be significantly larger than PDA files.

-The standard QDa does not have a divert valve. (I believe they recently offered one as an add-on option). Thus if you have a big slug of junk coming at the beginning or end of your run, you're stuck with dirtying up your instrument. Or a worse scenario is if you are interested in just LC/UV data and forget to manually bypass the QDa and run a mobile phase with an inorganic buffer.

[DR]

^True - the OP was not very specific about reuse...

[Anna.ser]

hello everyone,

than you for your answers , i have more detailed question:

- the calibration of the qda is automatic and done by an intern oil which generates peaks when heated: which kind of oil , can we calibrate by preparing a specific calibrant , how many time do us have to check this function.

- the cleaning of the apparatus if polluted , which solution or specific solvant can we use ( especially that u mentionned the problematic of the absence of the divert valve)

Thank you

[Magpie]

- the calibration of the qda is automatic and done by an intern oil which generates peaks when heated: which kind of oil , can we calibrate by preparing a specific calibrant , how many time do us have to check this function.

You'll likely have to ask Waters Technical support directly for this information. But I doubt there is way to use a different calibrant. In any case, I'm not sure what improvements would be achieved by using a different calibrant. Mass accuracy won't be improved by using a different calibrant since the MS has unit resolution. Is there a reason that you want to use a different calibrant?

- the cleaning of the apparatus if polluted , which solution or specific solvant can we use ( especially that u mentionned the problematic of the absence of the divert valve)

After the individual dirtied up the QDa with the inorganic salt, we called service to open up the instrument and clean it out. (After we gave them a hard time about how introducing inorganic salts into mass specs make for unhappy labmates).