1. Purpose

Good ¹³C sensitivity is one of the most important points concerning the performance of any routine NMR service instrument in its everyday use. Therefore, standardized tests have been developed which, to yield meaningful results, must be very critically and honestly performed. For ¹³C two different tests are in common use. The sensitivity test with ethyl benzene shown here tests the spectrometer performance on both the ¹³C observe and the ¹H decoupler channels. In comparison, the ASTM procedure (Exp. 3.9) checks only the ¹³C performance on the observe channel.

2. Literature

T. D. W. Claridge, High-Resolution NMR Techniques in Organic Chemistry, Pergamon, Oxford, 1999, 107–108.
C. Anklin, D. v. Ow, H. Ruegger, Standard Test Procedures for Supercon Systems, Spectrospin AG, Fällanden, 1988.

3. Pulse Scheme and Phase Cycle

Single-pulse carbon-13 NMR sequence with proton composite-pulse decoupling and phase cycle

4. Acquisition

Time requirement: 10 min

Sample: 10% ethyl benzene in CDCl₃, degassed and sealed.

The magnet is shimmed as well as possible (see Ch. 1, Section 1.4). For a meaningful sensitivity test, the ¹³C line-shape test (Exp. 3.8) should be satisfactory. The CPD