nmr sample volume

Jane Strouse (strousej@CHEM.UCLA.EDU)
Thu, 05 Nov 1998 12:09:01 -0800

I don't think it makes sense to mandate sample lengths that users have
to have. It is quite useful to tell them a minimum length that will make
shimming easier, but I feel that it is best to tell them the coil lengths
of the probes they will use and they can decide how much shimming they are
up for. As part of a write-up that we have about probes including the
lengths of the coils there is a section on volume vs. length for various
tube sizes. This is what I measured:

C. SAMPLE VOLUMES

Whenever adequate sample is available, always use a relatively long column
of liquid compared to
the length of the coil used for observation. When the quantity of sample
is limited, make sure that
the length of sample is somewhat longer than the observation coil.
Estimates of column lengths as a
function of sample volume are given below for 2.5 mm, 5 mm, and 10 mm
sample tubes. (Sample
lengths are measured from the outside bottom of the tube to the bottom of
the meniscus.)

1. 2.5 mm sample tubes: - 1st 50 ul ~ 11.5 mm; additional 50 ul ~ 13.5 mm
(e.g. 100 ul ~ 25 mm)

2. 5 mm sample tubes: - 50 ul ~ 3.6 mm
(e.g. 450 ul ~ 32.5 mm)

3. 10 mm sample tubes: - 1 ml ~ 16 mm
(e.g. 3 ml ~ 48 mm)

Jane

>Date: Thu, 5 Nov 1998 11:02:57 -0400
>To: ammrl <ammrl@wwitch.unl.edu>
>From: Sandip Sur <sur@chem.rochester.edu>
>Subject: nmr sample volume
>
>Dear AMMRL members:
>
>I have been thinking to standarize sample volume/height and tube quality
>for routine and not-so-experienced nmr users in our department. I am sure
>these and similar nmr management issues were discussed before, but I want
>to receive some feedback from your own experiences.
> It is difficult to judge the quality of each nmr tube by routine
>student users, and I recommend using at least Wilmad 528-pp at 400 MHz or
>even at 300 MHz. The sample height for high resolution nmr in a 5 mm tube
>should be about 5 cm high. I have seen recommendation of 4 cm sample
>height, too. For expensive solvents, smaller sample height is, however,
>desirable.
>
>Thanks in advance for your comments,
>
>Sandip
>
>
>
>
>___________________________________________________________________________
_____
>Sandip K. Sur, Ph.D. Email: sur@chem.chem.rochester.edu
>NMR Facility Tel.: (716) 275 4705 (W)
>Department of Chemistry (716) 275 0912 (W)
>B53B Hutchison Hall, R.C. (716) 586 7794 (H)
>University of Rochester Pager: (716) 275-4231 (ask for me)
>Rochester, NY 14627-0216 Fax: (716) 473 6889
>
>Thursday, November 5, 1998
>
>___________________________________________________________________________
_____
>
>
>
>
>
Dr. Jane Strouse
Dept. of Chemistry and Biochemistry
UCLA
Los Angeles, CA 90095-1569
(310)-825-9841 - voice
(310)-825-0393 - FAX
strousej@chem.ucla.edu