Understand how protons respond to magnetic fields. Protons aligning with a magnetic field are in a lower energy state than those "facing" it. The concept is similar to swimming with the current--it takes far less energy than swimming against it. If an external magnetic field has strength B and proton magnetic moment is u, then the difference in energy (E) between spin states is E = uB/I. Variable I is particle spin state. For protons, I = 1/2. Protons have a magnetic moment of 1.41e-26 J/T (Joules/Tesla). A magnetic field strength of 2.35 T would induce an energy difference of 1.41e-26 * 2.35 / (1/2) = 1.41e-26 J/T * 4.7 T = 6.627e-26 Joules.
Account for an induced magnetic field. An external magnetic field (Bext) induces a smaller "counterfield" around a proton (Bcounter). The effective magnetic strength "felt" by a proton (B) is determined by subtracting the counter-field: B = Bext - Bcounter.
Rank nearby atoms by electron affinity. Protons in CH3Cl (chloromethane) register at 3.05 ppm. Since chlorine (Cl) is more electronegative than bromine (Br), it would be expected that CH3Br (bromomethane) would have slightly lower ppm values. Indeed, CH3Br reaches the hydrogen proton peak at 2.682 ppm.
Calculate expected chemical shift (S). S = (v - v0)/v0, where v is the resonant proton frequency in question. Variable v0 is a reference proton frequency. The NMR signal from tetramethylsilane (TMS) defines the v0 reference peak. Protons more shielded by electrons than hydrogen protons in TMS show up with negative ppm. Resonant proton frequencies v and v0 are calculated using quantum mechanics.
Account for split signals. Split signals are separated by coupling constant J. J-value depends on molecular geometry (dihedral angle a) and experimental parameters A, B, and C in the form J = A + Bcos(a) + Ccos(2*a). Lower temperature may reveal signal splitting since lower temperatures correspond to less noise in data gathered by NMR spectroscopy.
Integrate peak areas. Integrated NMR peaks provide relative amounts of each structural "type" of proton. If a molecule contains several equivalent protons, as in CH4, then there will be one peak. If there are two proton types, as in CH3CHO, two peaks will show up. One peak would correspond to the hydrogen in "CHO" and will enclose a certain area. Another peak, corresponding to the three hydrogen protons in "CH3" would enclose an area three times as large as the "CHO" hydrogen peak.