University of Wisconsin–Madison

S/N of NMRFAM Spectrometers

Spectrometer (Field) / Probe

(1H sens.) 0.1%Ethyl Benzene (EB)

(1H sens.) 10%Ethyl Benzene (EB)

Sucrose (2 mM in H2O:D2O 9:1)

(13C) ASTM (60% C6D6and 40% p-Dioxane)

 (19F) Trifluorotoluene 0.05% in CDCl3

Kerry (500)/CP TXO

1391

1691

Kerry (500)/RT TXO

373

228

Devon (500)/CP TCI

4387

882

918

Dexter (600)/CP QCI

5309

913

1100

*mass equiv.

318

55

67

Kurgan (600)/ 1.7 mm

973

303

67

*mass equiv.

16000

5050

1100

Vosges (600)/CP TXO

7175

1286

1394

7682

*mass equiv.

430

77

85

                       
Vosges (600)/RT TXI

1527

374

Telemark (750)/CP TXI

6091

758

1060

Telemark (750)/RT TXI

1866

483

 Fleckvieh   10276  1735  1505  1861

CP  – cryoprobe

RT – room temperature probe

*mass equiv.  – this is the effective S/N for the equivalent mass of material compared across the 600 MHz spectrometers.  Thus, if a sample is quantity limited, not solubility limited, cramming it all into the 1.7 mm tube to run on Kurgan will give the best S/N.

Comments:

  • Telemark vs. Vosges in S/N:

Vosges’ cryoprobe has about 15% greater S/N than Telemark’s cryoprobe for EB but a whopping 70% for sucrose.  This is due to a mix of console improvements (probably minor) and cryoprobe improvements.  For scaling, assuming the ratios hold true, a new cryoprobe for Telemark should be about 20% better S/N for EB and 40% better S/N for sucrose than the probe on Vosges, or 85% better S/N for EB and 55% better for sucrose than the current probe.

  • Dexter vs. Vosges in S/N:

Dexter’s cryoprobe is tuneable to 31P in addition to the normal 1H, 13C, and 15N nuclei.   Thus, the two cryoprobes are not directly comparable, although presumably a new probe would have a modest boost to S/N, probably in the 10% range.