Classification and identification of TCM by macro-interpretation based on FT-IR combined with 2DCOS-IR

An approach, macro-interpretation based on FT-IR and 2DCOS-IR, has been developed for TCM classification and identification. It has been noted that every TCM has respective unique IR and 2DCOS-IR macro-fingerprints, every category (protein-rich, oil-rich, tannin-rich, inulin-rich, starch-rich, sucrose-rich and stachyose-rich) of TCMs, however, has common macro-fingerprints in specific wavenumber regions. Particularly, protein-rich TCMs have two strong absorption bands of amide I (similar to 1630 cm(-1)) and amide II (similar to 1560 cm(-1)) in the range of 1680-1500 cm(-1); oil-rich TCMs generally have characteristic regions with strong autopeaks around 2920 cm(-1), 2852 cm(-1) and 1740 cm(-1); starch-rich TCMs have a common pattern of positively correlated strong autopeak cluster (1139 cm(-1), 1120 cm(-1), 1102 cm(-1), 1070 cm(-1), 955 cm(-1), 907 cm(-1), 887 cm(-1)) in the saccharide vibration regions; inulin-rich TCMs have a tower-like fingerprint with the strongest peak around 1033 cm(-1) in the region of 1200-800 cm(-1) in IR spectra and a 3 * 3 positively correlated strong autopeak cluster (1006 cm(-1), 954 cm(-1), 893 cm(-1)) in 2DCOS-IR spectra. 2DCOS can enhance the spectral resolution in discriminating TCMs with high similarity in IR spectra. Based on the results of IR and 2DCOS-IR spectral macro-interpretation, TCM classification and identification can be achieved as general character for classification, specific character for identification.