Method for comparison of similar samples in liquid chromatography/mass spectrometry

A method of identifying and quantifying the chemical components of a mixture of organic materials comprising:

• a first step of subjecting said organic material to chromatography to separate components of said mixture and a second step of subjecting the separated materials to spectrometry to detect and identify said components, wherein said chromatography and spectrometry is performed by
• a) injecting a sample into a column;
• b) separating components by partitioning at different rates in the column;
• c) passing separated components into a spectrometer;
• d) obtaining a series of spectra to detect all species present;
• and
• e) storing the spectra in a computer file and reducing the number of mass chromatograms;
• the improvement comprising enhancing the spectral data by a variable selection using the following steps:
• i) selecting mass chromatograms for which at least one has an MCQ level above a certain level;
• ii) selecting mass chromatograms for which at least one has a maximum intensity above a level of about 20 times the smallest intensity increase in the data to avoid noise and broad peaks;
• iii) selecting a difference of more than three in the scan position of any pair of the chromatograms;
• and
• iv) ensuring that the ratio between intensities of peaks exceeds a factor of two in any pair of the chromatograms.