Use of boiling point–Lee retention index correlation for rapid review of gas chromatography-mass spectrometry data

Abstract

Gas chromatographic (GC) retention indices are useful for reviewing mass spectral library searches for the tentative identification of organic compounds. If the known GC retention index (RI) of a compound that ranks high on the (gas chromatography-mass spectrometry) GC-MS library search “hit list” matches the RI of the unknown, there is a strong presumption that a correct identification has been made. If the Lee retention index of the “hit list” compound is not known from published data, and cannot be estimated by RI–boiling point correlation, its boiling point (°C) may be directly compared to the unknown’s Lee retention index. In general, an unknown compound with a particular RI will have a boiling point of RI−10 (°C) to RI+50 (°C). Some compound classes deviate predictably from this rule. Library matches for unknowns whose boiling points fall outside the RI−10 to RI+50 range may safely be rejected. Conversely, library matches whose boiling points fall within the range of RI−10 to RI+50 should be further considered as possibly correct identifications.