Page 467 - Tandem Techniques

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NMR spectrometer. The liquid chromatograph consisted of a syringe pump, a pressure gauge and an
injector with a loop volume of 10 µ

Figure 11.8
The LC/NMR Tandem System
The column was also located in the bore of the magnet, and was connected to the rf coil by means of a
short length of Teflon tubing. The pump and mobile phase supply were separated from the column and
magnet by a 3 m length of Teflon tubing. The chromatographic conditions were developed employing a
separate UV detector. The microbore column was 15 cm long, 1 mm I.D., and packed with a 5 µm C18
reversed phase packing. The mobile phase was prepared by mixing appropriate amounts of 2% TFA in
D20 (pD = 2.4), and deuterated acetonitrile, 74:26 v/v. The mobile phase flow rates that were employed
ranged from 10 to 50 µl/min. The samples were dissolved in 25% deuterated acetonitrile in deuterated
water and 0.25 N D was added to render soluble. The measuring conditions were as follows.

a. Ley-Arg, 1.4 µg (28 nm) (512 scans).

b. An oxytocin fragment 6-9, Tyr-Pro-Leu—Gly-NH2, 0.78 µg (15.6 nM), (512 scans).

c. Deca-peptide, Gly-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly, 1.2 µg (23 nM), (256 scans).

d. A hexa-deca-peptide, Val-Phe-Gly-Thr-Gly-Thr-Lys-Val-Thr-Val-Leu-Glu-Gin-Pro-Lys-Ala, 0.8 mg
(16nM), (256 scans).