| With the development of the traditional Chinese medicine,its safety problem is increasingly subjected to a domestic and oversea widespread concern.In recent years,the problem of heavy metals in traditional Chinese medicine aroses a high international recognition.The excess content of heavy metals in traditional Chinese medicine not only influenced its quality and its medication safety,but also restricted the export of traditional Chinese medicine.Therefore,to control the content of heavy metals in traditional Chinese medicine has become one of the important problems which need solving urgently at present. It has an important meaning in ensuring the quality and the medication safety of traditional Chinese medicine,it is also important to expand the international market of traditional Chinese medicine.In order to control the heavy metals in traditional Chinese medicine,we should firstly establish a scientific analytical method of heavy metals in traditional Chinese medicine. According to the current international standard,the harmful heavy metals controlled in traditional Chinese medicine mainly includes lead(Pb),cadmium(Cd),mercury(Hg), copper(Cu),arsenic(As),etc..When we analyse the heavy metals in traditional Chinese medicine,we should process the sample properly and then use instrument determine the contents of heavy metal elements.At present,the sample pre-processing methods mainly include wet digestion,dry digestion and microwave digestion and so on;and the determination methods mainly include inductively coupled plasma mass spectrometry (ICP-MS),atomic absorption spectrometry(AAS) and atomic fluorescence spectrometry (AFS),etc..To control the heavy metals in traditional Chinese medicine,we should also carry it out in a series of process like herbal planting.Heavy metal contamination in traditional Chinese medicine has something to do with many factors.In order to control the contents of heavy metals in traditional Chinese medicine originally,we put into effect Good Agricultural Practice(GAP) of Chinese medicinal materials.The contents of heavy metals in medicinal materials mainly depends on two factors:one is the contents of heavy metals in the soil in which the medicinal materials grows and the soil property;the other is the accumulation capability of the medicinal materials,and different kinds of medicinal materials have different accumulation capability to different heavy metals.The research on correlation of heavy metals in Chinese medicinal materials and their soils has a very important instruction meaning to control the contents of heavy metals originally,so is the study on absorption and accumulation characteristics of heavy metals in Chinese medicinal materials.And at the same time,they will also provide scientific basis to further perfect soil environment quality evaluation standard of Chinese medicinal materials production base.Fructus Amomi,Fructus Citri Sarcodactylis,Radix Morindae Officinalis,Herba Andrographis and Herba Pogostemonis are commonly used clinical medication and the main breed of south medicines,they are demanded greatly in the market.The medicinal parts of the five Chinese medicinal materials are not same,and their matrix nature are different.Therefore,we choosed the five Chineses medicinal materials as study objects, choosed copper,arsenic,cadmium,lead and mercury as study targets,we studied the sample pre-processing methods systemly,compared the different determination methods, and established the analytical method of heavy metal in Chinese medicinal materials which was accurate,rapid and convenient.Furthermore,we studied the correlation of heavy metals in Chinese medicinal materials and its soils,this study will provide scientific basis to discuss the source of heavy metal in Chinese medicinal materials.We also studied the absorption and accumulation characteristics of heavy metals in Herba Pogostemonis which is one of the famous-region drugs in Guangdong province,this study will provide scientific basis to administer the soil environment quality of the Chinese medicinal materials growth base and to control the production quality.The main contents and results of the study are as follows:1.Study on sample pre-processing method1.1 Study on pre-processing method of copper,arsenic,cadmium and lead in Chinese medicinal materialsWe processed the sample with wet digestion,dry digestion and microwave digestion respectively,and used ICP-MS determine the contents of copper,arsenic,cadmium and lead.Then we analysed the results with analysis of variance in order to discuss the influence of different pre-processing methods.By doing this we wanted to find an optimal pre-processing method for the four heavy metal elements in Chinese medicinal materials.In wet digestion method,we compared the different digestion systems.We digested the samples with nitric acid,nitric acid-hydrogen peroxide and nitric acid-perchloric acid respectively,the results showed that the effect of nitric acid-perchloric acid as the digestion systemwas better.In dry digestion method,we compared different ash temperatures.We processed the samples with the temperatures that were 400℃,500℃and 600℃,the results showed that the optimal ash temperature of copper and lead was 500℃,arsenic and cadmium were not suitable for the dry digestion.In microwave digestion method,we optimized the microwave digestion conditions with the orthogonal experiment and got the optimal microwave digestion process of the four elements.By comparing the three methods, we concluded that the microwave digestion was the best pre-processing method.So we choosed the microwave digestion as the sample pre-processing method in this study,and the optimal microwave digestion process we got in the experiment could be applied for the pre-processing of the four elements in Chinese medicinal materials.1.2 Study on pre-processing method of mercury in Chinese medicinal materialsWe processed the sample with wet digestion and microwave digestion respectively, and used cold-vapor atomic absorption spectrometry(CVAAS) determine the content of mercury.Then we analysed the results with analysis of variance in order to discuss the influence of different pre-processing methods of mercury to the results.By doing this we wanted to find an optimal pre-processing method for mercury in Chinese medicinal materials.In wet digestion method,we choosed nitric acid-perchloric acid and vanadium pentoxide- nitric acid-sulphuric acid respectively as the digestion systems.In microwave digestion method,we optimized the microwave digestion conditions with the orthogonal experiment and got the optimal microwave digestion process of mercury.By comparing the different pre-processing methods,we concluded that the microwave digestion was the optimal pre-processing method of mercury.So we choosed the microwave digestion as the sample pre-processing method in this study,and the optimal microwave digestion process we got in the experiment could be applied for the pre-processing of mercury in Chinese medicinal materials.2.Study on different determination methods of heavy metals in Chinese medicinal materials2.1 Study on determination of copper,arsenic,cadmium and lead in Chinese medicinal materials by comparing AAS with ICP-MSThe samples were processed with microwave digestion,then we used AAS and ICP-MS determine the contents of copper,arsenic,cadmium and lead.We analysed the results in order to compare whether the two methods had difference or not.The paired t-test results showed that the two methods didn't have significant difference(P>0.05).The two determination methods were accurate,but ICP-MS was faster and more convenient than AAS.So we choosed ICP-MS firstly as the determination method of the four elements in Chinese medicinal materials in this study.2.2 Study on determination of mercury in Chinese medicinal materials by comparing CVAAS with AFSThe samples were processed with microwave digestion,then we used CVAAS and AFS determine the content of mercury.We analysed the results in order to compare whether the two methods had difference or not.The paired t-test results showed that the two methods didn't have significant difference(P>0.05).The two determination methods were accurate,but CVAAS was more convenient and faster.So we choosed CVAAS firstly as the determination method of mercury in Chinese medicinal materials in this study.3.Establishment of analytical method of heavy metals in Chinese medicinal materials3.1 Establishment of determination of copper,arsenic,cadmium and lead in Chinese medicinal materials by microwave digestion- ICP-MSWe processed the samples with microwave digestion,then used ICP-MS determine the contents of copper,arsenic,cadmium and lead,and established the analytical method of the four harmful elements.The linear range of copper,arsenic,cadmium and lead were 0～500μg·L-1,0～50μg·L-1,0～10μg·L-1,0～100μg·L-1,their correlation coefficient were 0.9995, 0.9997,0.9996,0.9995;their detection limit were 0.013μg·L-1,0.065μg·L-1,0.004μg·L-1, 0.010μg·L-1,their determination limit were 0.045μg·L-1,0.216μg·L-1,0.012μg·L-1,0.033μg·L-1;the results of their reproducibility were 1.2%,2.0%,3.5%,1.6%(n=5);their recovery rates were 103.0%,96.5%,95.8%,98.7%,the values of their RSD were 2.0%, 2.7%,3.5%,3.2%(n=6).The results showed that the method was accurate,rapid and convenient,it can be applied to the determination of heavy metals in Chinese medicinal materials.3.2 Establishment of determination of mercury in Chinese medicinal materials by microwave digestion-CVAASWe processed the samples with microwave digestion,then used CVAAS determine the contents of mercury,and established the analytical method of mercury.The linear range of mercury was 0～6 ng·mL-1,the correlation coefficient was 0.9997;the detection limit was 0.204 ng·mL-1,the determination limit was 0.679 ng·mL-1;the reproducibility of the method was 3.0%(n=5);the recovery rate was 93.6%,RSD was 3.5%(n=6).The results showed that the method was accurate,rapid and convenient,it can be applied to the determination of mercury in Chinese medicinal materials.4.Study on correlation analysis of heavy metals in Chinese medicinal materials and their soilsWe determined the contents of copper,arsenic,cadmium,lead and mercury in Fructus Amomi,Fructus Citri Sarcodactylis,Radix Morindae Officinalis,Herba Andrographis, Herba Pogostemonis and the soils they growed.Then we discussed their correlativity by adopting correlation analysis.The results showed that the contents of copper,arsenic, cadmium,lead and mercury in Fructus Amomi and its soil didn't have significant correlativity;the content of copper in Fructus Citri Sarcodactylis and its soil had significant correlativity,but the contents of the other four elements in Fructus Citri Sarcodactylis and its soil didn't have significant correlativity;the contents of copper, arsenic,cadmium and mercury in Radix Morindae Officinalis and its soil had significant correlativity,but the content of lead in Radix Morindae Officinalis and its soil didn't have significant correlativity;the contents of copper,arsenic,cadmium in Herba Andrographis,Herba Pogostemonis and their soils had significant correlativity,but the contents of lead,mercury in the two medicinal materials and their soils didn't have significant correlativity.The results of the study revealed that different medicinal materials had selective absorption to heavy metals in the soil.The study also revealed that the transfer character of different heavy metals in plant-soil system was different,the copper in the soil was easily absorbed and accumulated by the medicinal materials,arsenic and cadmium took second place,but lead and mercury in the soil were difficult to be absorbed and accumulated by the medicinal materials.5.Study on the absorption and accumulation characteristics of heavy metals in Herba PogostemonisWe determined the contents of copper,arsenic,cadmium,lead and mercury in Herba Pogostemonis that grew at different time.By doing this we wanted to study the dynamic absorption and accumulation characteristics of heavy metal elements in Herba Pogostemonis.The results showed that the contents of the five heavy metal elements in the aerial parts of Herba Pogostemonis increased along with its growth period;the contents of copper and mercury in the root of Herba Pogostemonis also increased along with its growth period,but the contents of arsenic and cadmium in the root decreased along with growth period,and the content of lead in the root didn't have distinct change along with time.We studied the accumulation capability of Herba Pogostemonis to heavy metals in soil.The results showed that the accumulation capability of different parts to heavy metals was different,the leaf of Herba Pogostemonis had a relatively big accumulation capability to heavy metals in the soil.By analysing the accumulation coefficients,we found that the accumulation capability of Herba Pogostemonis to copper was relatively bigger,but it had a small accumulation capability to arsenic,cadmium,lead and mercury.We also studied the relation of the contents of heavy metals in Herba Pogostemonis and its soil property.The results of multiple linear regression showed that the absorption and accumulation of copper, arsenic,cadmium in every part of Herba Pogostemonis was influenced by the the soil property,so was lead in its root.The regression equations we got could be applied to calculate the contents of heavy metal elements in Herba Pogostemonis according to the contents of heavy metals in the soil and the soil property.But the absorption and accumulation of mercury in every part of Herba Pogostemonis had nothing to do with the content of mercury in the soil and the soil property,so did lead in its aerial parts.This revealed that there were other influencing factors besides the contents of heavy metals in the soil and the soil property,so the reason need further studying.
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