IR NMR MS Spectroscopy
Chemistry
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Spectroscopy is the study of quantized interaction
of energy (typically electromagnetic energy) with matter.
The derivation of structural information from spectroscopic data
is an important part of chemistry. A common way to simplify
this process is to combine information from major spectroscopic and
spectrometric techniques as
NMR 1,IR2 and MS 3.
1) NMR - Nuclear Magnetic Resonance Spectroscopy
2) IR - Infrared Spectroscopy
3) MS - Mass Spectrometry
Butanone MS, IR, 1H-NMR and 13C-NMR
sample spectra
Fig.1 MS-spectra containing a CH3C=O
fragment(43 m/e)
Fig.2 IR-spectra with a strong C=O
absorbation (1705 cm-1)
Fig.3 1H-NMR spectra indicating a
methyl-methylene coupling
Fig.4 13C-NMR spectra. Off resonance
decoupled (upper) and proton decoupled with a 13C line in
an typical area (209ppm) for C=O.
Mass Spectrometry
Show isotope formula : Show C[12]2H[1]6 (isotope formula)
instead of C2H6 .
Text field (upper): Fragment masses separated by spaces
+/-me- : Accuracy for the search/iteration
in electron masses (1840 me- = 1 mn).
Iterate -> : A method in which finds solutions to MS problems
by the use of selected isotopes.
CHEMIX will try to match input masses by combining masses of all the
selected isotopes and their index values (iterative limits). If
to many isotope combinations matches the input data, a dotted line
(...) will be seen. This problem can be avoided by a reduction of the
(+/-me-) value.
By not selecting Iterate, CHEMIX will perform a
search in the MS-data file.
IR and NMR Spectroscopy (H[1] and C[13])
Text fields : IR wave numbers (cm-1) or
NMR ppm values.
Interpretation of parameters and results
(1/1), (1/2), (2/3).... (hits/potential hits)
(1/1) = 1 hit of potential 1 hit (Hit% = 100)
(1/2) = 1 hit of potential 2 hits (Hit% = 50)
(2/2) = 2 hits of potential 2 hits (Hit% = 100)
(5/8) = 5 hits of potential 8 hits (Hit% = 5/8*100 = 62.5)
LPHV (Lowest Potential Hit Value) represent the lowest
accepted denominator in a fraction (1/LPHV). The result of
increasing LPHV from 1 -> 2 (at least two
resonance/absorption areas must be present in data file), is that even
a 100 hit% as (1/1) will be ignored as a valid hit.
Save
Save experiment : MS(+/-me- + selected
isotopes + spectral data) + IR/NMR spectral data.
The default settings for Spectroscopy can be changed and saved
by the use of Settings -> Save settings
CHEMIX
School - Spectroscopy assignment
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