The analytical measurement principle Qualion NMR NMR Technology The analytical measurement principle

What is ¹H NMR? * Magnetic Resonance Imaging Hydrogen Nuclear Magnetic Resonance Provides picture of the hydrocarbon structure, from which we determine physical and chemical information Non invasive like MRI*, therefore all samples can be returned back to the process. Heavy opaque or dark materials easily analyzed Technology developed since 1950’s MRI * Magnetic Resonance Imaging

What is ¹H NMR Analysis? NMR = Nuclear Magnetic Resonance “Nuclear” - NMR looks at the nuclei of molecules (protons-neutrons) More specifically at their “nuclear spin” Some nuclei have a “magnetic moment” due to that spin (behave like a small magnet) Most important, nuclei are 1H ,13C,19F and 31P ¹H-NMR is looking at ¹H-protons in molecules, excellent for hydrocarbon analysis

The Electromagnetic Spectrum SPECTROSCOPY ANALYTICAL TECHNOLOGIES X-ray UV VIS IR Microwave ESR NMR NMR spectroscopy uses radio-waves to interact with samples

¹H Proton – Magnetic Moment (M) Hydrogen Atom (Proton) M + Proton is spinning Magnetic moment (M) generated

Nuclear Spins and Magnetic Fields In a strong magnetic field (Bo), magnetic moments M align along Bo With no magnetic field, magnetic moments M are randomly oriented S M M M N

Alignment and precessing of M Magnetic Moments Align and Precess at a Frequency wo Bo N S S Wo wo is proportional to the Bo size e.g. Bo = 1.35 Tesla wo = 57 MHz

Bulk Magnetic Moment – M0 Precessing spins can be described as a bulk magnetic moment Mo* Bo N S Mo *Mo = Summation of individual magnetic moments of all protons in the sample

Re-align to a second magnetic axis RF pulse is turned on for 4-20 microseconds and generates a second magnetic field B1 RF @ 57 MHz Bo N S Mo B1 Magnetic field B1 causes Mo to move and re-align to the second magnetic axis

Re-align to original magnetic axis The protons relax and re-align to their original equilibrium position along Bo Axis FID RF @ 57 MHz When RF Pulse ends Bo N S Mo B1 “Relaxation” of Mo generates an RF current that is picked by the irradiation coil : A decay signal is generated, called Free Induction Decay signal (FID)

Measurement in a NMR Process analyser Top View Magnet Flow Pipe Probe

NMR permanent magnet technology Multiple matched magnet segments. physically brought together to form condensed magnetic field of 1.35 Tesla N S Mechanical shims obtain rough Bo homogeneity N S Electrical shim gradients N S Current passed through wire gradients creates shaped magnetic fields that are used to “straighten” field lines

Fast Fourier Transform- FFT Time domain signal Frequency domain signal Free Induction Decay(FID) NMR Spectrum F.F.T.

Chemical Shift in NMR spectra How does the NMR resolve the different protons in the spectra ? Each proton in a different chemical environment (bond) “senses” a different magnetic field BX due to the shielding created by surrounding electrons More electrons = more shielding

Protons in different chemical environment External applied field Bo Actual field at protons electron

Difference in “sensed” magnetic field Due to a difference in the “sensed” magnetic field, protons A and B precess at a different frequency WA and WB Bo BA N BB S S WB WA wA and wB are proportional to the size of BA and BB The precessing frequency becomes the fingerprint of the chemical environment of the different protons

Fast Fourier transform From FID to results Time domain signal Frequency domain signal Fast Fourier transform NMR Spectrum Free Induction Decay(FID) Chemometric calibration models Results

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