Modification of the Varian XL-100 NMR spectrometer for submilligram natural abundance 13C analyses

Abstract
Quadrature detection modifications and a microcell arrangement are described for the Varian XL‐100 NMR spectrometer which routinely improve sensitivity in 13C Fourier transform sample‐limited studies by a factor of 4–5. The power requirement of the rf pulse amplifier is relaxed by a factor of 4. Previously attainable resolution is not affected.