Search for Species Data by Molecular Weight
Note: This search is by molecular weight based on single (most-abundant) isotope atomic masses. These weights may vary significantly from molecular weights based on average atomic masses. The molecular weights reported elsewhere in this site are based on average atomic masses.
Please follow the steps below to conduct your search (Help):
Molecular Weight Search Help
Search options (step 1) (Back to search)
You may search for species based on molecular weight values in two ways:
- Specify a single value; the system will search for values within 0.5 units of this value.
- Specify a range. The limits of the range should be separated by a comma.
Rules for formula restriction (step 2) (Back to search)
A chemical formula may be entered to restrict the search to species which match the formula. The manner in which the formula is interpreted is controlled by two checkboxes below the formula entry box:
- Allow elements not specified in formula
- When checked, this option indicates that species containing elements not specified in the formula will also be matched. For example, a search for C2 will match all of the species which contain exactly two carbon atoms and any number of other atoms.
- Allow more atoms of elements in formula than specified
- This option indicates that species containg more atoms than specified of a given element will be matched. For example, a search for HC with only this option checked will match only hydrocarbons.
Rules for data types (step 4) (Back to search)
- If one or more of the data types are checked, the search will be restricted to species which contain at least one of the data types specified.
- If none of the data types are checked, there will be no restrictions on the search.