Fragmentation resilience energy mass spectrometry (FREMS)

A method of building a Liquid Chromatography Mass Spectrometry (LC-MS) library, comprising:

• scanning, by a LC-MS device, a sample to extract ion chromatograms including a fragmentation curve of a precursor ion;
• determining, for the fragmentation curve, a fragmentation point at which fifty percent of the precursor ion has fragmented;
• determining whether the ion chromatograms include a formation curve, of an observed ion, including a formation point equivalent to the fragmentation point, at which fifty percent of the observed ion has formed;
• responsive to determining that the formation curve includes the formation point equivalent to the fragmentation point, updating the LC-MS library to indicate that the observed ion is a product of fragmentation of the precursor ion;
• and
• responsive to determining that the formation curve does not include the formation point equivalent to the fragmentation point, updating the LC-MS library to indicate that the observed ion is not a direct product of the fragmentation of the precursor ion.

A method of building a Liquid Chromatography Mass Spectrometry (LC-MS) library, comprising:

• collecting, by a LC-MS device, a full scan of ion chromatograms of a sample;
• determining product (daughter) ions of interest as observed in the full scan of a precursor (parent) ion;
• using FREMS methodology to collect a fragmentation curve of the precursor ion as collision energy is increased;
• determining, for the fragmentation curve, a fragmentation point at which fifty percent of the precursor ion has fragmented;
• determining whether the ion or ions observed in the full scan exhibit formation curve(s);
• if not, then that ion is not a product of the precursor ion;
• it is contamination;
• responsive to determining that the formation curve includes a formation point equivalent to the fragmentation point, updating the LC-MS library to indicate the formation curve of the observed ion is a primary product of fragmentation of the precursor ion;
• and
• responsive to determining that the formation point occurs at lower energy than the fragmentation point representing loss of 50% of the precursor ion, then the observed ion is not a primary product resulting from fragmentation of the precursor ion;
• it is the product of a product of the precursor ion, i.e. a granddaughter ion.

A method of identifying a precursor ion using a Liquid Chromatography Mass Spectrometry (LC-MS) library, comprising:

• collecting, by a LC-MS device, a full scan of ion chromatograms of a sample;
• determining observed ions contained in the full scan, based on mass-to-charge ratios (m/z);
• determining, for a formation curve of an observed ion, a formation point at which fifty percent of the observed ion has formed;
• determining a fragmentation curve of a precursor ion, based on a fragmentation point of the fragmentation curve equivalent to the formation point at which fifty percent of the precursor ion has fragmented;
• identifying the ion by referencing the LC-MS library to confirm that the observed ion (m/z) is present in the LC-MS library;
• matching product(s) m/z from the LC-MS library, and matching 50% fragmentation points for precursor and fragment ions to the LC-MS library;
• and
• indicating a goodness of fit between the fragmentation curve, as observed, and a model fragmentation curve, as stored in the LC-MS library.