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== Er, what? ==
== Er, what? ==
Yes. There are many, many types of spectroscopy. This ones involves magnets and radio frequencies, and can (potentially) tell you things about a liquid which is placed into a thin/tall glass tube. The principle under which it operates is the same as an MRI scanner; however, rather than making pictures, it makes squiggly lines. It is not a [https://www.youtube.com/watch?v=9Gq3UEAiWio Gas Chromatograph], nor a Mass Spec, as a few have called it...
Yes. There are many, many types of spectroscopy. This ones involves magnets and radio frequencies, and can (potentially) tell you things about a liquid which is placed into a thin/tall glass tube. The principle under which it operates is the same as an MRI scanner; however, rather than making pictures, it makes squiggly lines. It is not a [https://www.youtube.com/watch?v=9Gq3UEAiWio Gas Chromatograph], nor a Mass Spec, as a few have called it...
Unlike some other techniques which allow for elements to be looked at (ICP-MS, ICP-OES, XRF, etc.), this one is concerned with compounds and specifically with Hydrogen.
== But Why? ==
== But Why? ==
= Theory =
= Theory =
== Terminology ==
* NMR - Nuclear magnetic resonance
* TMS - Tetramethylsilane - A colorless liquid commonly used as a reference standard.
* Proton NMR - What they really mean is a Hydrogen Atom.
* Probe - The detector of an NMR. Most commonly, this is Hydrogen-1, but probes for other elements exist. The probe is ultimately just a coil, but it is tuned to the element of interest.
* First generation instruments would use a constant RF frequency but ramp the magnetic field up slowly, and this is in fact what this unit did in its original form.
* Second generation instruments would keep the magnetic field constant but pulse the RF, covering the entire set of radio frequencies. Advances in computing and signal processing enabled Fourier transforms, and this is precisely what the retrofit to this instrument allows it to do.
= Operation =
= Operation =
NMR uses thin glass tubes for samples. A sample needs to be liquid. Special solvents are often used to prepare a sample, but, direct analysis is possible. No harm in trying and seeing what happens.
NMR uses thin glass tubes for samples. A sample needs to be liquid. Special solvents are often used to prepare a sample, but, direct analysis is possible. No harm in trying and seeing what happens.
= Terminology =
== Hardware ==
* NMR - Nuclear magnetic resonance
* NMR Tube: A thin and long glass tube that holds your sample.
* TMS - Tetramethylsilane - A colorless liquid commonly used as a reference standard.
* Sample spinner: A white piece of plastic that goes around the NMR tube. This serves two purposes:
* Proton NMR - What they really mean is a Hydrogen Atom.
** It keeps the sample centered in the sample tube
** It allows the sample to the spun while inside the tube. (This is done with compressed air that is supplied to the NMR). Spinning allows for better spectra to be taken.
Sample gauge: There is a small hole on top of the unit toward the front. This is merely to set the height of the sample spinner.
= Operation =
== Operation / Background ==
* Unless performing more elaborate techniques, NMR spectra are generally a squiggly line.
* Unless performing more elaborate techniques, NMR spectra are generally a squiggly line.
** Y-Axis is intensity. Simple enough.
** Y-Axis is intensity. Simple enough.
** X-Axis has quirks:
** X-Axis has quirks:
*** It technically represents the amount the frequency of whatever is being analyzed is higher than the signal from TMS (which is used for calibration and is considered 0).
*** It technically represents the amount the frequency of whatever is being analyzed is shifted from the signal from TMS (which is used for calibration and whose peak is considered 0).
*** Also, 0 starts from the right side. Higher frequencies are to the left 0 on the X-Axis (Historical Quirks)
*** Also, 0 starts from the right side. Higher frequencies are to the left 0 on the X-Axis (Historical Quirks)
*** Finally,
*** Technically, we are measuring how many Hertz higher something is than where the signal for TMS is.
*** In practice, we never use Hz because the amount of shift would depend on the strength of the NMR we have. Since it would be nice to sensibly compare data across different instruments, the amount of Hertz shift is divided by the frequency of the instrument. We call this value PPM.
** Technically, we are measuring how many Hertz higher something
** PPM ultimately represents "chemical shift" and
= Software =
= Software =
* NUTS: Used to process/look at spectra. There are alternatives to NUTS.
* NUTS: Used to process/look at spectra. There are alternatives to NUTS.
== PNMR ==
== PNMR ==
