Homework Help: NMR Signal Question Help Needed!

1. Oct 13, 2009

johnq2k7

Suppose you acquire the 31P NMR signal from a region of muscle of a healthy subject using a 3 Tesla magnet. Assume that the signal has contributions from ATP,PCR, Pi, and from an unknown phosphorous containing biochemical. Assume that all decay shapes are exponential.

Note: H1- 42.575 MHz/T for y/2pi , 31P- 17.235 MHz/T for y/2pi, and 13C- 10.705 for y/2pi

31P- nucleus (chemical shifts), ATP-alpha= -7.52 ppm
ATP-beta= -16.26 ppm
ATP-gamma= -2.48 ppm
PCr= 0 ppm
Pi= 5.02 ppm

a.) Determine the ratio S_PCr@0/ S_ATP@0, where S_PCr@0 is the contribution to the intial signal amplitude from PCr, and S_ATP@0 is the contribution to the initial signal amplitude from ATP.

b.) If the peak in the spectrum from the unknown biochemical is centered at a frequency 100 Hz to the left of the Pi peak (where PCr is on the right of the Pi peak), determine the value of the chemical shift for the peak from the unknown chemical, with PCR as the reference peak.

c.) If the full width at half maximum (FWHM) of the peak from the unknown chemical is 10 Hz and its height s half that of the PCr peak, determine the concentration of the unknown chemical assuming that there is only one phosphorous nucleus per molecule.

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution