Adduct Search
Description
Definition of an adduct ion
An ion formed by interaction of two species, usually an ion and a molecule, and often within the ion source, to form
an ion containing all the constituent atoms of one species as well as an additional atom or atoms.
This method identifies common adducts (selected by the user) in a single peak list. The adducts are identified by
two conditions:
- the retention time of the original ion and the adduct ion should be same, and
- the mass difference between the original ion and the adduct must be equal to one of the adducts selected by the
user
MZmine has a built-in list of common adducts and their masses. The user can add custom adducts either individually
or by loading them from a file. Once custom adducts have been added or loaded they will become part of the
application configuration and don't have to be added/loaded again.
The following figure shows a spectrum with a phosphate adduct ion.
The following figure shows a peak list after identifying two "Deuterium" adducts.
Method parameters
- RT tolerance
- Maximum permissible difference in retention time to set a relationship between peaks
- Adducts
- List of adducts, each refers a specific m/z difference between related peaks
- m/z tolerance
- Tolerance value of the m/z difference between peaks
- Max adduct peak height
- Maximum height of the recognized adduct peak, relative to the main peak
Adduct choices
The figure below shows the Adduct Search parameters dialog. Beside the list of adducts are four buttons that function
as follows:
- All
- Selects all of the check-boxes in the list of adducts.
- Clear
- Clears the check-boxes in the list of adducts.
- Add...
- Allows the user to specify an individual custom adduct. A dialog is displayed in which the user can enter the
name and mass difference of the new adduct.
- Import...
- Loads custom adducts from a comma-separated values (CSV) file. The file should be formatted with one adduct
defined per line, with each line having the adduct's name and mass difference values separated by a comma.
- Export...
- Saves the adducts to a comma-separated values (CSV) file.
- Reset
- Restores the list of adducts to the original default set.