Hi Ken,
Curious because the 31P pw90 is normal. I would expect the pw90 to reflect the efficiency. I am curious that if you tune probe to 31P does the 1H pw90 change significantly? If so it might indicate shenanigans.
With this probe 31P is unique because an internal switch brings in parallel inductance to allow the low band coil to resonate up higher.
best,
Ron
Mobile 919-889-7260
> On Jan 7, 2020, at 14:41, Kenneth Knott <kknott_at_vt.edu> wrote:
>
> Thanks everyone for the responses. Here's some further information.
>
> I am using Veripulse to do the calibrations and sensitivity checks. I use it often and it is very reliable so I'm going to rule out any issues regardings experimental settings.
>
> The sample is the reference sample I have always used. Triphenylphosphate in CDCL3 and it the same we have used for eons. It worked perfectly on our other system so I can rule that out.
>
> The system has an AutoXDB probe. If there are filters then I believe they are in the console. Nothing that I hook up manually. I think these systems may have digital filters.
>
> Thanks again for your help and thoughts. I suppose a bad preamp might be the current front runner?
>
>
>
>> On Mon, Jan 6, 2020 at 1:10 PM Kenneth Knott <kknott_at_vt.edu> wrote:
>> I just performed our annual maintenance and calibrations on our MR400 from the NMR manufacturer formerly named Agilent/Varian...
>>
>> P31 pulse calibrations are right were they always are. Tuning and matching is fine. However, sensitivity is about 1/4 the normal level. I can't quite understand why this would happen to P31 alone. All other X band nuclei (C13, N15) are passing.
>>
>> Any thoughts?
>>
>> --
>> Ken Sharp-Knott
>> Department of Chemistry
>> Analytical Services
>> Virginia Tech
>>
>> (540)267-6502 (Cell)
>> (540)231-0885 (Office)
>
>
> --
> Ken Sharp-Knott
> Department of Chemistry
> Analytical Services
> Virginia Tech
>
> (540)267-6502 (Cell)
> (540)231-0885 (Office)
Received on Wed Jan 08 2020 - 13:56:31 MST