A package for representing molecules or ions formed in mass spectrometers.

1. Chemical: unstructured chemicals, storing name, formula, and other information; Chemical(name::String, formula::String, info::Vector{Pair{Symbol, Any}}).
2. Ion: charged Chemical with specific adduct or molecule loss; Ion(core::AbstractChemical, adduct::AbstractAdduct).
3. IonCluster: multiple Ions with similar m/z; IonCluster(ions::Vector{<: AbstractIon}, abundance::Vector{Float64}).

Currently supported elements:

C, H, O, N, P, S, Li, Na, K, F, Cl, Ag, [13C], [2H] (D), [3H] (T), [17O], [18O], [15N], [33S], [34S], [35S], [6Li], [40K], [41K], [37Cl], [109Ag]

Prefefined adducts:

• LossElectron: [M]+
• Protonation: [M+H]+
• ProtonationNLH2O: [M+H-H2O]+
• ProtonationNL2H2O: [M+H-2H2O]+
• ProtonationNL3H2O: [M+H-3H2O]+
• DiProtonation: [M+2H]2+
• TriProtonation: [M+3H]3+
• AddNH4: [M+NH4]+
• AddHNH4: [M+H+NH4]2+
• Add2NH4: [M+2NH4]2+
• Sodization: [M+Na]+
• SodizationProtonation: [M+Na+H]2+
• DiSodization: [M+2Na]2+
• AddElectron: [M]-
• Deprotonation: [M-H]-
• DeprotonationNLH2O: [M-H-H2O]-
• DiDeprotonation: [M-2H]2-
• TriDeprotonation: [M-3H]3-
• AddOAc: [M+CH3COO]-
• AddHCOO: [M+HCOO]-
• LossCH2O: [M-CH2O]-
• AddO: [M+O]-
• AddC2H2O: [M+C2H2O]-
• LossCH8NO: [M-CH8NO]-
• LossC2H8NO: [M-C2H8NO]-
• AddC3H5NO: [M+C3H5NO]-
• AddC2H5NO: [M+C2H5NO]-
• LossCH3: [M-CH3]-
• DeprotonationLossSerineAddH2O: [M-H-Serine+H2O]-

User can custumize adduct by PosAdduct and NegAdduct.

For example, [2M+H]+, and [M-2H-2H2O]2- can be created by PosAdduct(2, "+H", 1), and NegAdduct(1, "-2H-2H2O", 2) respectively.

• chemicalname: name of a chemical (AbstractChemical).
• chemicalformula: formula of a chemical.
• ischemicalequal: whether two chemicals equal.
• ioncore: core of an ion.
• ionadduct: adduct of an ion.
• kmer: number of "M" of an adduct or ion.
• charge: number of charges of an adduct or ion.
• adductelement: changes of elements of an adduct or ion.
• adductformula: formula of an adduct.
• abundantion: most abundant ion of an IonCluster.
• isionequal: whether two ions equal.
• isionequal: whether two adducts equal.
• rt: retention time.

• mw: molecular weight of a chemical.
• mz: m/z of an ion.
• abundance: abundance of a chemical among natural isotopes.
• isotopic_abundance: formula and abundance of possible natural isotopes of a chemical.
• getisotopes: formula of possible natural isotopes of a chemical.
• isobar_rt_mz1: coeluting isobars as a table.
• getisobars: coeluting isobars as a vector.
• acrit: create absolute criterion.
• rcrit: create relative criterion.
• crit: create both absolute and relative criterion.
• @ri_str: real number interval.

This submodule defines multiple biology related molecules, including aminoacids, lipids, glycans, etc. (still in active development)