Reference frequencies on the Avance 600

Frequencies for Avance 500 at 300K
Measured10/15/01 by aph.

Spin	Frequency (MHz)	Approximate Chemical Shift.
¹H of DSS (0.0 ppm reference)	500.1300000 (at 300K)**	0.00 ppm by definition
¹H of H₂O	500.1323524*	4.704 ppm (at 300 K)
¹H in center of amide HN	500.1341011	8.20 ppm
¹⁵N (0.0 ppm reference) (IDRR)^	50.677318 (at 300K)**	0.00 ppm by definition
¹⁵N of ¹⁵N-urea	50.6817049	78.4 ppm
¹⁵N in center of amide ¹⁵NH	50.6837118	118.0 ppm
¹³C (0.0 ppm reference (IDRR)^	125.7574534 (at 300K)**	0.00 ppm by definition
2^[13]C of acetate	125.7607357	26.1 ppm
Center of Ca + Cb ¹³C	125.7632382	46.0 ppm
Ca ¹³C	125.7644958	56.0 ppm
carbonyl ¹³C	125.7797125	177.0 ppm

*This frequency is essentially termperature independent: Other frequences unless noted will be slightly temperature dependent and should be correced as appropriate.

**This frequency and associated chemical shift is highly temperature dependent.

^Calculated using the IUPAC-recommended indirect referencing ratios relative to the DSS 1H standard. The ratios are 0.101329118 for ¹⁵N and 0.25144953 for ¹³C.

For setting the carrier frequencies to be used in a determination:

The frequency table above doesn't drift much in normal operation. Look for it to be updated every year or so, or after the magnet is deenergized and reenergized.
Expect the
Carrier frequencies are set in the RF channels as if the experiment was being done at 300K.
Carrier frequencies are usually specified in pulse program comments in ppm. To find the actual frequency to set in the channel for x ppm, look up the 0.00 ref frequency above for that isotope. Then derive the frequency to set (y) as

x = (y-ref)/ref

The most commonly specified carrier settings are already tabulated above.

For determining center point offsets in ppm to use in processing the data.

These should be corrected for the actual temperature of the determination.

In normal operation, the frequencies do not drift much
Carrier frequencies during an experiment are generally set as if the experiment were at 300K, regardless of the actualy temperature. I.e., a direction to set ¹⁵N carrier at 118 ppm always means to set it at 60.8127522. [(60.8127522 - 60.8055771)/60.8055771 = 0.000118].