Omics Forecasting: Predictive Calculations Permit the Rapid Interpretation of High-Resolution Mass Spectral Data from Complex Mixtures

For some complex mixtures, chromatographic techniques
are insufficient
to separate the large numbers of compounds present. In addition, these
mixtures often contain compounds with similar or identical molecular
masses and shared fragmentation transitions. Advancements in mass
spectrometry have provided more and more detailed molecular profiles
with significant increases in resolution. This has led to a capacity
to distinguish a very large number of compounds in complex mixtures,
providing overwhelming data sets. The approach of calculating molecular
formulas from a mass list has become more and more problematic as
the number of signals has increased exponentially, to the point that
it has become impossible to manually interpret the thousands of mass
signals. The current approach is to calculate a list of possible formulas
that fall within a specific mass error of the observed signal. Then,
one must look for possible structures that can be derived from each
entry on the list of formulas. However, an alternative approach is
to anticipate the possible structures of a particular set of compounds,
such as red wine pigments, and then compare the ion signals against
a predicted list. To that end, starting with known wine pigment types,
we have generated a set of expected wine pigment variants based on
known derivatives of condensed tannin oligomers, anthocyanins, and
fermentation products. After the ability to distinguish compounds
by mass spectrometry was accounted for, over 1 million results were
generated consisting of known and anticipated wine pigments. A comparison
with a small sample of wine phenolic fractions show a large number
of matches, suggesting that this approach may be helpful.