Figure 4. J-coupling splitting enhancement HSQC spectroscopy.

¹H, ¹³C HSQC spectra showing the C(6) of glucose are shown ( A, B and C). The spectrum with no J-coupling splitting enhancement is shown in blue ( A), with an enhancement of two in green ( B) and with an enhancement of four in red ( C). The ¹³C trace of the HSQC spectra ( D), taken from the ¹H frequency as depicted by the dashed line, clearly shows the increase in observed splitting. The J-coupling splitting enhancement is achieved using an additional spin echo subsequent to the ¹³C evolution period. The delays to achieve the scaling of the splittings are multiples of dw such the use of a delay of 3*dw will result in a J-coupling splitting enhancement of 4 (one from the t ₁ evolution and three from the J-coupling splitting enhancement spin echo). The observed splitting can be simulated ( E) giving the following incorporation percentages. From the no J-coupling splitting enhancement spectrum 6.8% / 41.2% / 52 % for [6- ¹³C] / [5,6- ¹³C] / [U- ¹³C], from the two-fold J-coupling splitting enhancement 6.3% / 41.4% / 52.3 % for [6- ¹³C] / [5,6- ¹³C] / [U- ¹³C] and from the four-fold J-coupling splitting enhancement 5.9% / 41.6% / 52.5 % for [6- ¹³C] / [5,6- ¹³C] / [U- ¹³C].