MeltDBWiki/RoundingMZ: Difference between revisions
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== Round m/z values of mass spectra to | == Round m/z values of mass spectra to integral values == | ||
* Several | * Several mass spectral databases contain mass spectra in nominal m/z notation whereas MS instruments are able to obtain higher resolution. | ||
* KEGG compounds database contains more than 10000 compounds with annotated masses | * High resolution mass spectra can be compared to nominal m/z spectra by rounding the measured m/z values to integral values. | ||
* The KEGG compounds database contains more than 10000 compounds with annotated masses and most of the masses are below 1000 Dalton. | |||
* C, H, N, O, P, S are the main atoms of biological compounds. | |||
[[Image:MeltDBWiki$$RoundingMZ$histweight.png]] | [[Image:MeltDBWiki$$RoundingMZ$histweight.png]] | ||
* The possible | * The possible fractional values of the compound masses are dependent on the integral compound mass. | ||
[[Image:MeltDBWiki$$RoundingMZ$scatter.png]] | [[Image:MeltDBWiki$$RoundingMZ$scatter.png]] | ||
* To round m/z to | * Mass spectrometric devices may drift, meassured m/z values can therefore vary. | ||
* To round m/z to integral values as robust as possible, 0.75 instead of 0.5 may be used. | |||
* In the fractional interval 0.725 to 0.775 only 15 compounds are listed in the KEGG compounds database. | |||
[[Image:MeltDBWiki$$RoundingMZ$histmz.png]] | [[Image:MeltDBWiki$$RoundingMZ$histmz.png]] | ||
Revision as of 18:54, 10 April 2008
Round m/z values of mass spectra to integral values
- Several mass spectral databases contain mass spectra in nominal m/z notation whereas MS instruments are able to obtain higher resolution.
- High resolution mass spectra can be compared to nominal m/z spectra by rounding the measured m/z values to integral values.
- The KEGG compounds database contains more than 10000 compounds with annotated masses and most of the masses are below 1000 Dalton.
- C, H, N, O, P, S are the main atoms of biological compounds.
- The possible fractional values of the compound masses are dependent on the integral compound mass.
- Mass spectrometric devices may drift, meassured m/z values can therefore vary.
- To round m/z to integral values as robust as possible, 0.75 instead of 0.5 may be used.
- In the fractional interval 0.725 to 0.775 only 15 compounds are listed in the KEGG compounds database.
