AA-1800 Atomic Absorption Spectrometer for the Determination of Lead, Cadmium, Arsenic, Mercury and Copper in Salvia Miltiorrhiza - Master's thesis - Dissertation

Determination of lead, cadmium, arsenic, mercury and copper in Radix Salviae Miltiorrhizae by AA-1800 atomic absorption spectrometry

Key words: atomic absorption spectrophotometry; salvia miltiorrhiza; heavy metals; aesthetic instrument ; AA-1800 With the accelerating process of internationalization of traditional Chinese medicine, the therapeutic and health effects of traditional Chinese medicine have been increasingly More recognition and admiration, but at the same time its adverse reactions have gradually been highly valued by countries around the world. Excessive levels of heavy metals are one of the important factors causing adverse reactions of traditional Chinese medicines, which is an important cause of the decline in the quality of Chinese herbal medicines, which seriously hinders the pace of Chinese herbal medicines and other agricultural and sideline products entering the international market. Heavy metals are enriched in the body. When the content is too high, it will cause multiple organs and systemic diseases in the human body, which will seriously damage human health. In this paper, the content of lead, cadmium, arsenic, mercury and copper in Danshen medicinal materials from different producing areas was determined by reference to the Chinese Pharmacopoeia method, which provided a reference for the screening of high quality Salvia miltiorrhiza medicinal materials and the establishment of quality standards for such Chinese medicinal materials. . 1 Instruments and reagents 1.1 Instrument AA-1800 atomic absorption spectrophotometer (America China), flow injection hydride generator, the glass instruments used are soaked overnight with 20% nitric acid, washed repeatedly with water, and finally rinsed with deionized water . 1.2 Reagents Nitric acid, perchloric acid, hydrochloric acid, concentrated sulfuric acid are all excellent grade, lead, cadmium, arsenic, mercury, copper single element standard solution 2 Methods and results 2.1 Determination conditions 2.1.1 Graphite furnace heating conditions Element detection wavelength (nm Drying temperature (°C) Ashing temperature (°C) Atomization temperature (°C) Purification temperature (°C) Lead 283.311050017001800 Cadmium 228.8110400170018002.1.2 Determination of arsenic (Hydride method): The detection wavelength is 193.7 nm. Reducing agent: a mixed solution containing 1% sodium borohydride and 0.3% sodium hydroxide (prepared immediately before use), carrier liquid: 1% hydrochloric acid solution, carrier gas: nitrogen. 2.1.3 Determination of mercury (cold atomic-hydride method): The detection wavelength is 253.6 nm. Reducing agent: mixed solution containing 0.5% sodium borohydride and 0.1% sodium hydroxide (prepared immediately before use), carrier liquid: 1% hydrochloric acid solution, carrier gas: nitrogen. 2.1.4 Determination of copper (flame method): air-acetylene flame, gas flow: 1500 mL / min. The detection wavelength is 324.7 nm. 2.2 Preparation of the test solution 2.2.1 Take about 1g of the test sample coarse powder (passing through the No. 5 sieve), accurately weigh it, place it in the Kjeldahl flask, add 10mL of nitric acid-perchloric acid (4:1) mixed solution, Mix well, add a small funnel to the mouth and soak overnight. Heat the digestion in the next day's electric heating set, until the digestion is complete, let cool, transfer to a 50mL volumetric flask, dilute to the mark with 2% nitric acid solution, shake well, that is. A reagent blank solution was prepared simultaneously with the same method. This method is used for the determination of arsenic, cadmium, lead and copper. 2.2.2 Take about 1g of the test sample coarse powder, accurately weigh it, place it in a Kjeldahl flask, add 10mL of nitric acid-perchloric acid (4:1) mixed solution, mix well, add a small funnel to the bottle mouth, soak overnight. The next day, the electric heating sleeve is heated and digested at 120-140 °C, until the digestion solution is a small amount of colorless or slightly, and it is allowed to cool. Add 4 mL of 4% sulfuric acid solution, 0.5 mL of 0.5% potassium permanganate solution, shake well, add 5 % Hydrochloric acid hydrochloride solution disappeared into purple red, transferred to a 25mL volumetric flask, diluted to the mark with 4% sulfuric acid solution, shake well, that is. A reagent blank solution was prepared simultaneously with the same method. This method is used for the determination of mercury. 2.2 Drawing of the standard curve According to the method prescribed in the Chinese Pharmacopoeia, standard solutions of lead, cadmium, arsenic, mercury and copper were prepared. The absorbance was plotted on the ordinate and the concentration was plotted on the abscissa. The standard curve was drawn and the following equation was obtained (see Table 2). . Table 2 Element concentration range Standard curve equation R value lead 0 ~ 80ng / mLC = 516.8685A + 6.77260.99204 Cadmium 0 ~ 16ng / mLC = 97.7319A - 0.64090.99839 Arsenic 0 ~ 40ng / mLC = 338.1464A + 0.48000.99903 Mercury 0～18ng/mLC=608.6957A+0.11590.99905 Copper 0～0.8μg/mLC=5.2352A-0.0086 0.999552.3 Determination of lead, cadmium, arsenic, mercury and copper in different parts of Salvia miltiorrhiza The test solution is prepared according to the method of preparation of the standard curve and the absorbance is calculated according to the standard curve equation. (Results are shown in Table 3) Table 3 Determination results Unit: μg/g medicinal source Lead cadmium arsenic mercury copper Anhui Xinghua Administrative Village, Huayu Town, Zhangzhou, China 3.599 0.801 0.845 0.064 19.521 Lumiao Village, Lumiao Town, Luzhou, Anhui Province 2.659 0.664 0.635 0.042 17.707 Anhui Zhaomiao Village, Xiaonai Town, Zhangzhou 3.543 0.520 0.513 0.014 21.485 Wangdian Village, Chengbei Township, Yinzhou, Anhui Province 5.968 0.674 0.792 0.095 17.307 Chengyu Village, Dawu Township, Yinzhou, Anhui Province 3.043 0.696 0.648 0.062 16.325 Wangxin Village, Chengbei Township, Yinzhou, Anhui Province 3.727 0.580 0.663 0.042 33.786 Anhui Huzhuang Village, Beibei Township, Zhangzhou City 2.946 0.785 0.818 0.019 16.416 Duzhuang Village, Lumiao Town, Zhangzhou, Anhui Province 1.023 0.474 1.153 0.111 16.704 Fangzhuang Village, Xiaonai Town, Yinzhou, Anhui Province 2.442 0.588 0.621 0.066 8.849 Zhangzhuang Village, Xiaonai Town, Zhangzhou, Anhui Province 2.541 0.576 0.547 0.116 10.695 Henan Shangluo 2.261 1.459 0.726 0.158 15.167 Shandong 1.668 0.739 0.278 0.123 9.077 Shanxi 2.890 0.634 0.487 0.168 22.131 Inner Mongolia 3.196 0.704 0.767 0.136 24.102 Anhui 3.260 0.839 0.799 0.138 21.023 Shandong Wild Danshen 2.339 0.827 0.199 0.114 15.165 Over-standard rate 6.25% 100% 0 0 31.25%3 Analysis and discussion 3.1 According to the "medicinal plants and systems Import and export green industry standards: lead ≤ 5.0 mg ̇ kg-1, cadmium ≤ 0.3 mg ̇ kg-1, mercury ≤ 0.2 mg ̇ kg-1, arsenic ≤ 2.0 mg ̇ kg–1, copper ≤ 20 mg ̇ Kg–1, compared with the measured results, can obtain the content of five heavy metals in different parts of Danshen and the exceeding standard. It can be seen that the content of arsenic and mercury in Danshen medicinal materials from different producing areas is not high, the content of lead and copper exceeds the standard, and the cadmium content is seriously exceeded. 3.2 Wet digestion and dry digestion have their own advantages and disadvantages. Wet digestion has strong applicability and less volatile loss, but the reagent dosage is large, the blank value is large, and the time required for processing the sample is long; the dry digestion method is simple. , reagent contamination is small, blank value is low. However, its higher ashing temperature tends to cause loss of volatile elements, resulting in lower measurement results. In this test, the content of lead, cadmium and copper were determined by wet method and dry method. The results are not much different. Considering the volatility of arsenic and mercury, it is not suitable for dry digestion. With consistency, wet digestion is used. In this experiment, the electric heating sleeve is used for heating digestion, so that it is heated as much as possible, which is convenient for sample processing and temperature control, and the digestion time is shorter than when using the electric heating plate. 3.3 In this experiment, the graphite furnace heating procedure was discussed. Different ashing temperatures and atomization temperatures were set. Considering the life of the graphite tubes and the accuracy of the measured values, the ashing temperature of lead and cadmium was finally determined. The atomization temperatures were 500 ° C, 1700 ° C and 400 ° C, and 1700 ° C, respectively. 3.4 The content of heavy metal elements in traditional Chinese medicine is too high, which is easy to accumulate in the human body, leading to various diseases. As the source of traditional Chinese medicine preparations, Chinese herbal medicines are the primary link for monitoring and controlling heavy metal elements. Therefore, when selecting the standardized planting bases for Chinese herbal medicines, we should respect the history of the formation of Chinese herbal medicine production areas, and on this basis, the soil environment of the planting bases. Water quality monitoring and analysis should select areas with clean air, pure water, uncontaminated soil, good agro-ecological environment, full implementation of GAP and certification, establishment of a green Chinese herbal medicine production base, rational use of pesticides, fertilizers, and avoidance of traditional Chinese medicines. The materials are polluted during harvesting, transportation and processing, and the content of heavy metals is strictly controlled to improve the quality of Chinese herbal medicines. Key words: atomic absorption spectrophotometry; salvia miltiorrhiza; heavy metals; aesthetic instrument ; AA-1800

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