Hi all,
recentlz I had to measure tiny amounts of substances. Dissolved in
benzene-d6 (99.8%) the proton signals of the substance were
lower than the carbon 13 satellites of the solvent signal.
Unfortunatelz I had no Shigemi tube for this measurements
(as far as i know for benzene there are no shigemi tubes
available). I trief to minimize the amount of solvent and got
reasonable spectra using about 350 microliter of benzene.
The prize for this was a maxed out z6 shim. Nevertheless all
looked fine and i started a HSQC. Result: comparative strong
temperature oscillations (about +/- 0.3K). Tuning of the
temperature controller was not successful. Looking for the problem
is switched off the heater and removed the air input to the
probe. The temperature raised immediately up to 310 ... 315K.
The reason: the probe became heated by the z6 shim and this gave
the strange observations.
BTW: Maybe a microprobe is useful under such circumstances. I have one
for 600 MHz but I am reallz by no means impressed concerning the
sensitivity of the microprobe. What's your experience using
microprobes?
Best regards
Rainer
Received on Fri Mar 23 2001 - 10:15:46 MST