| The research used macro-fingerprint infrared spectroscopyic identification method to study caulis and lignum Chinese medicines systematically. Firsty two rattan stem medicines, two stem and branch medicines and three lignum medicines were compared and analyzed, and then organic chemical and inorganic chemistry compositions of seven caulis and lignum Chinese medicines carried onquantitative analysis. The results are as follows:Spatholobi Caulis (SpC) and Sargentodoxae Caulis (SaC) which are two kinds of rattan stem medicines were exactly similar, there were nine absorption peaks location in their infared (IR) spectra that differed 0-6 wavenumber. Mori Ramulus (MR) and Cinnamomi Ramulus (CR) which are two kinds of stem and branch medicines contained different characteristics in the range of 1700～1500 cm-1. Aquilariae Lignum Resinatum (ALR), Dalbergiae Odoriferae Lignum (DOL) and Sappan Lignum (SL) which are three kinds of lignum medicines had obvious fingerprint characteristics in their Fourier transform infrared (FT-IR) spectra, second derivative infrared (SD-IR) spectra and two-dimensional infrared (2D-IR) correlation spectroscopy. It turned out that seven cauiis and lignum Chinese medicines could achieve the purpose of the rapid identification by three-step identification.Using 1058 cm-1 which is the strongest peak in cellulose IR spectrum as a reference, seven caulis and lignum Chinese medicines all contained cellulose compositions and there was more cellulose compounds in SpC than other medicine. In addition, using 1508 cm-1 which is the strongest peak in lignin IR spectrum as a reference, they all contained lignin compositions and there were more lignin compounds in MR and SL than other medicine.Comparing calcium oxalate IR spectrum which used as a reference to seven caulis and lignum Chinese medicines, there were the characteristic absorption peaks of calcium oxalate in five medicines spectra expecting MR and ALR. In addition, there were the characteristic peaks of calcium oxalate in seven medicines SD-IR spectra, those further illustrated they all contained calcium oxalate. And then, DOL, SaC and SpC had more calcium oxalate, MR and ALR had less calcium oxalate. The analysis Results were consistent with the results of microscopic identification.SpC, SaC, MR, CR, ALR, DOL and SL all had the fingerprint characteristic peaks of aromatic compounds in their FT-IR spectra at room temperature, that stretching vibration of non-conjugated C=O and stretching vibration absorption peak of benzene ring skeleton, while ALR also had a strong peak at 1658 cm-1 referring to the conjugated carbonyl C=O. The differences of fingerprint characteristic peaks position of aromatic compounds were more apparent in SD-IR spectra. In 2D-ER. spectra, SpC had three obvious auto-peaks (1453,1543,1630 cm-1) and the strongest one is at 1630 cm-1, SaC had two obvious auto-peaks (1450,1629 cm-1) and the strongest one is at 1629 cm-1.The reason of the differences of two rattan stem medicines was that SpC contained much flavonoids compounds and SaC contained much anthraquinone compounds; the reason that the strongest auto-peak of SpC and SaC was similar was that they had the same medicinal part. MR had four obvious auto-peaks (1394,1467,1495,1641 cm-1) and the strongest one is at 1641 cm-1, CR had three obvious auto-peaks (1452,1493,1641 cm-1) and the strongest one is at 1641 cm-1. The reason of the differences of two stem and branch medicines was that MR contained much flavonoids compounds and CR contained much volatile oils compounds; the reason that the strongest auto-peak of NR and CR was similar was that they had the same medicinal part. ALR had eight obvious auto-peaks (1308,1390,1466,1491,1515,1599,1636,1660 cm-1) and the strongest one is at 1660 cm-1, DOL had four obvious auto-peaks (1468,1515,1622,1645 cm-1) and the strongest one is at 1645 cm-1, SL had five obvious auto-peaks (1398,1467,1491,1599,1642 cm-1) and the strongest one is at 1642 cm-1. The reason of the differences of three lignum medicines was that ALR contained much resin compounds, DOL contained much volatile oil and flavonoids compounds, SL contained much flavonoids compounds; the reason that the strongest auto-peak of DOL and SL was similar was that they had the same medicinal part. The above analysis results were the same as the references reported.The acceptance correlation threshold of the authentic ALRs was determined to be 0.9886 (p=0.01) by using the IR spectral correlation coefficients of 30 ALR samples, and many adulterations of ALR which were collected from the market were found by using the correlation coefficient identification method, and the main ways of making adulterations are parsed according to peaks at 1658±1 and 1610±1 cm-1 of resins in ALR In addition, according to the cross-peak symbol in synchronous spectrum and asynchronous spectrum, the response speed of the resin of ALR on the thermal perturbation is the fastest, followed by lignin, the response speed of cellulose is the slowest.Results of this research proved that macro-fingerprint infrared spectroscopic identification method not only provided organic chemical composition and relative content information of caulis and lignum Chinese medicines, but also quantitative evaluation of organic compounds. Meanwhile this method analyzed inorganic chemical composition and relative content information. So IR spectroscopy can provide a scientific and effective identification method for the research of caulis and lignum Chinese medicines. On the basis of the correlation coefficient calculation method which is ruled by ASTM standard, this research established an objective and standard identification method of authentic and adulterated ALRs. This presents a new idea and solution for quality control of traditional Chinese medicines, and provides a good method and means for the current classic methods. |
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