Fig. 5: Combined spectrum of Fig 1 to 3 with isotope ratio information and 50 and 100% levels.

5. Check for strong adduct ions
 
During Chemical Ionization adduct ions can be formed. The generation of these ions depends on instrument settings, scan modes and used ionization gas or solvent and are therefore not very specific. In some case however these ions can dominate the spectrum of a compound. 
An example is a compound, that only gives an [M + adduct]⁺ peak instead of an [M+H]⁺ peak. In such a case the adduct ion must be chosen as parent or precursor ion.
Another example is the Source CID spectrum of benzothiazole. Compared to the daughter spectrum of m/z 136 [M+H]⁺ fragmented in a collision cell, every mass found in the CID spectrum is also present in the Source CID spectrum. But additional adduct ions are available for each fragment ion. This is a specific behavior of this compound.
In such cases the dominant adduct ions can be entered at a 90% ratio. This is done at 90% to inform the user of the library, that adduct ions are present in the spectrum.
Minor adduct ions are discarded. 

6. Add additional information
 
This is an important part of each entry. 
Similar to the EI spectrum library the molecular weight, CAS REG number and formula have to be entered. 
Specific for the CI mode is that the ions can have a positive or a negative charge. So enter pos. or neg. To inform the user positive entries are colored green and negative red in the spreadsheet file.

Because not all compounds produce always the same spectrum under all circumstances, give information about the origin of the entry: 
Ionization:
Atmospheric Pressure chemical Ionization (APCI), Electrospray (ESI), GC-ammonia (GC-CI) or
Thermospray (TSP)
Fragmentation: 
Source CID (Source), Quadrupole collision cell (Q3), Ion trap collision cell (Ion Trap).
In case of adducts in the entry:
Type of adducts [M+NH4]+; [M+acetate]- or solvents (ACN, formic acid) used