Study On The Application Of SBWE And SBWC On Chinese Traditional Medicine Extraction And Analysis

Organic solvents and water have been the most common fluid used for Chinese Traditional Medicine (CTM) extraction in conventional solvent extraction. Usually water has been the most efficient solvent for polarity substance extraction, but it often fails to efficiently extract many liposoluble substances because of its high polarity. Although, organic solvents are the excellent solvents for liposoluble substances, they are expensive, potentially harmful to the operator, and need to be disposed of. Meanwhile, they may debase the quality of extractants because of remains. Traditional methods of sample extraction tend to be tedious, laborious, waste producing, and therefore, time-consuming and expensive. Subcritical Water Extraction (SBWE) is a brand-new method. The ability of subcritical water (SBW) to extract nonpolar organics such as liposoluble substances is linked to the fact that the polarity (dielectric constant, ε) of water can be reduced significantly with increasing temperature (with enough pressure to maintain the liquid state). Therefore, the dielectric constant of water can be dramatically decreased to less than 10 at supercritical conditions, making it an extremely effective solvent for a wide range of substance which from moderately polar to nonpolar substances. The ability of SBW to dissolve nonpolar organics is similar to that of organic solvents. The reduction or total elimination of toxic organic solvents used in CTM extraction procedures, using SBWE instead is highly desirable from environmental and health perspectives, and the advantages of using SBW are its nontoxic nature, no organic solvents remained, low cost, and the fact that it can be readily obtained and disposed of. Compared with supercritical extraction (SFE) (CO2 used particularly), SBW can be used in extraction substances from moderately polar to heavy molecular weight in CTM. This just compensate for the disadvantages of SFE (CO2 used particularly, which can just extract nonpolar or light molecular weight substance). Recently, The uses of SBWE have been reported largely abroad. Most of these reports focused on extraction pollutants from environmental samples and extraction spice components from plants. SBWE-HPLC in CTM has not been reported yet. The innovation of this study is extraction CTM with SBW for the first time. The present study describes the use of a homemade SBWE apparatus to extraction Danshen, Radix Scutellariae and Radix Rhei, three kind of representative CTM. Compared with conventional organic solvent extraction, the SBWE shows lower handling time and solvent consumption, reducing the loss of heat-sensitive compounds. It totally eliminates the use of toxic organic solvents, with no organic solvent remain, with no waste produced at the same extraction efficiency. From water-solubility to liposoluble substances were successively extracted with this apparatus. The technique of selectively extracting polar, moderately polar, and nonpolar organics by altering extraction parameter, such as temperature, pressure and cosolvent may be achieved. More over, detection in real time, rapidly separation can be achievedwith the function of online HPLC analysis. The effects of various parameters, which included the temperature, pressure, extraction time on the yield were investigated. The optimal conditions of extraction of each kind of CTM with SBW were showed blow: Danshen, Radix Scutellariae, dissociated or total anthraquinone ramification in Radix Rhei were extracted dynamically for about 12min at 180℃5Mpa,at 130℃5Mpa,at 190℃5Mpa,and at 260℃5Mpa respectively. Other factors, such as particle size of the CTM, solvent/sample ratio as well as the manner of extraction also affect the yield. The yield will increase with a small particle size, moderate solvent/sample ratio and using dynamic extraction manner. Still more, add adequacy cosolvent, not only the yield will increased, the extraction temperature can also be decreased. Thereby, the hot decompose of extracted substance will reduce gradually. This study provided an earlier stage research datas to establish a rounded method for CTM SBWE. Subcriticasl Water chromatography (SBWC) was first explored in this study. SBWC was freshly developed recently. It was mainly used in moderate polar compound analysis. It was short of such researches. The polarity and viscidity of water are dramatically decreased when heated under pressure. Thus, by changing temperature and pressure, a tremendous range of polarity in the water can be achieved, which can simulate methanol-ambient water mixtures in different proportion. Moreover, SBWC can separate compounds in different polarity by temperature gradient, achieving the same efficiency as the solvent gradient of HPLC. Since SBW seperation requires elevatedtemperature and chramotograph columns that are thermally stable under the high temperature, we choose the poly styrene-divinglbenzene column (PS-DVB) (It's reported that this column can tolerate higher temperature) and study on the seperation of polyhydroxybenzenes using SBWC. Little molecular, middle polarity compounds are eluted by subcritical water instead of methanol-ambient water mixtures in this study. The chromatograms of the same mixtures are achieved using SBWC and conventional RP-LC. The column efficiency and peak symmetry study showed that SBWC was generally more efficient and more improved peak symmetry than traditional separations using organic solvent-ambient water mixtures for separations on the PRP-1 column. At present, the varieties of chromatograph columns used in SBWC are very limited. A plenty of compounds are remained strongly in PS-DVB kind of columns on general conditions. It causes that these compounds can't be eluted from the columns. The changes of chromatograph performance of columns in the higher temperature, the development of clumns that can tolerate the high temperature, the selection of cosolvent, the improvement in the temperature programme technique and so on, all of these problems need to be the further studied.