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The following message was posted to: PharmPK
Dear all,
I had an discussion with my friend and how many of you agree for this:
Detail of the Discussion:
API 3000/4000, Manual Tuning coupled with the use of FIP mode (Harvard
apparatus).
During the Q1 scan of the compound at a flow rate of 10ul/ min, How
many of you would like to employ the use of source temperature. My
friend tells me that he uses the source temp in MRM (0.5ml/min) but
not in Q1 scan when the Flow rate is at 10uL/min.
I have a controversial opinion on this and say that source temp has to
be employed for the evaporation of the nebulized droplets during
scanning irrespective of flow.
Opinions are highly appreciated
Santosh Tata
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The following message was posted to: PharmPK
Dear Santosh,
I would employ heating regardless. Better evaporation/spray and keeps
source cleaner.
Best regards,
Stuart Coleman
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I agree with Stuart.
For the tuning process you'll need sufficient ions but not necessarily
optimal source conditions.
Best regards,
Frederik Pruijn
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Dear snthosh
At lower flow rates (10ul/min) IS voltage is enough to make small
droplet , along with this we were applying the nebuliser gas which
will give small mist . for this reason IS voltage and nebuliser gas
can give full fledged ionization of the molecule at lower flower
rates .
there may some other reasons also
Regards
Ravindranath reddy
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The following message was posted to: PharmPK
The heating has to do with flow rates only and not with scan function.
You can get away with no heating at 1-10 uL/min on either model.
At 0.5 mL/min, there is real risk in leaving heaters off on a 3000 or
not letting it heat up before you start flow. The 3000 orifice is
passively heated by the TIS or HN probe and takes time to equilibrate.
There is no thermocouple at the site so our practice is to leave heating
on for at least 1/2 hour before running. We don't turn the heaters off
and that seems to work fine. Since the orifice plate is behind the
curtain plate we assume it takes time to heat all that metal up.
We've found the danger of someone forgetting to turn the heat back on
and cranking up the flow rate is that arcing can occur near the 3000
orifice and the whole interface needs changed out. We haven't seen
downside to leaving heaters on all the time (for example like heaters
burning out or more frequent source cleanings). The 4000 is much more
forgiving with the orthogonal spray and I don't know that arcing is a
danger but we still leave the heat on it also.
If you're in a quan lab, a switching valve and heart cutting in peaks is
your best friend if you don't want to clean your system very often.
Sprays stabilize very quickly. No makeup pump needed.
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Dear Santosh, i will not operate the source temperature with a flow
rate of 10ul/min as the flow conditions will differ when operated
through LC. the source temperature may give a wrong interpretation of
the response. regard sabhi
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