Question

The 1H NMR signal for a compound appears at 2000 Hz when recorded on a 200-MHz NMR spectrometer. What is the chemical shift for this proton?

What would be the chemical shift in a)ppm and b) Hz, if the spectum were recorded on a 500-MHz instrument?

Answer 1

Solution :-

chemical shift = sample value / reference value

                    = 2000 Hz / (200 MHz * 1*10^6 Hz)

                    = 1.0*10^-5

1.0*10^-5 * 1 ppm / 1*10^-6 = 10 ppm

so at the 200 MHz NMR spectrometer the chemical shift value is 10 ppm and in Hz it is 2000 Hz

now lets calculate the shemical shift value when 500 MHz spectrometer is used

chemical shift = 2000 Hz / (500 MHz * 1*10^6 Hz/1 MHz) = 4.0*10^-6 = 4.0 ppm