Analysis Of Heavy Metals In Mainstream Cigarette Smoke And Migration Ratios Research

The heavy metals of tobacco products are a kind of harmful substances in the tobacco and those in the cigarette smoke that can enter the body with the suction process, causing disease. Heavy metals have a variety of forms. The effects of different forms on the human body are various. Among them, some are beneficial, some harmful, some of low toxicity while some of high toxicity. The physical and chemical properties of the different forms of heavy metals are different, thus the degree of difficulty of their migration is different. Currently, the study on heavy metals in tobacco mostly concentrates on the total amount of heavy metals, rarely involving the systematic separation detecting of different forms of heavy metals and their effects on their migration rates in the smoke. Therefore, it is of great significance for the safety evaluation and monitoring of heavy metals and the evaluation of the availability of the tobacco industry under the limiting amount of heavy metals to study the of separation and detection of different valences of heavy metals in cigarette smoke and the influence rule of different forms of heavy metals in tobacco leaves on their migration ratios in the smoke.The main research and achievements of this paper are as follows:1. Established the separation methods of different valences of arsenic in mainstream smokeThe toxicity of arsenic of different forms is various. Inorganic arsenic has high toxicity, whereas organic arsenic is of low toxicity. Among the inorganic arsenic, the toxicity of As (Ⅲ) is ten times as much as that of As (Ⅴ). We established a method of separating valences of arsenic in cigarette mainstream smoke based on the property of the selectively adsorbing As5+ of 717 strong basic anion exchange resin. The preferred conditions of this method are that the resin height is 10.0cm, the pH of sample solution is 7.0 and the eluent of As5+ is 0.5 mol/L HNO3, the relative standard deviation of this method is 3.5-4.7% and the recovery of As5+ is 90.6-102.4%, which demonstrates that the method is accurate and reliable.2. Studied the distribution of different forms of heavy metals in tobacco leaves of different production regions and in the mainstream smokeThe heavy metals of tobacco leaves come mainly from tobacco plant’s absorbing the heavy metals from soil and atmospheric particulate. The contents of different forms of five heavy metals (Cr、Ni、As、Se、Cd) in different parts of tobacco leaves from eight major tobacco-producing areas of China and in the mainstream smoke of corresponding unblended cigarette have been separated and detected. The results showed that the contents of different forms of heavy metals differ greatly in different parts of tobacco leaves from different areas and in the mainstream smoke. The contents of heavy metals in the bottom leaves are higher than that in the top and middle leaves while there is no unified law about the content of heavy metals in the top and middle leaves. The distribution of heavy metals in the mainstream smoke is different from that in the tobacco leaves, as demonstrates that the different forms of heavy metals in the tobacco leaves have different effects on their migration ratios in the mainstream smoke.3. Studied the rule of influence of the different forms of heavy metals in the tobacco leaves on their migration ratios in the mainstream smokeThe statistical analysis of the detection data of the amount of heavy metals and the contents of different forms in the tobacco leaves, the total amount of heavy metals in mainstream smoke of the corresponding unblended cigarette and the TPM detection data have been conducted by using the way of least square method and advantage analysis method and the influence rule of different forms of heavy metals on their migration ratios in the mainstream smoke has been revealed.The results showed that the significance orders of the effects of the different forms of heavy metals and the TPM on their migration rates in the mainstream smoke are as follows,Cr:fraction of soluble(inorganic state) state (+)> fraction of insoluble state (-)> TPM (+); Ni:fraction of organic state (+)> fraction of inorganic state (-)> fraction of insoluble state (+)> TPM (+); As:TPM (+)> fraction of organic state(+)> fraction of inorganic state(+)> fraction of insoluble state(-); Se:fraction of inorganic state (+)>TPM (+)> fraction of insoluble state (-)> fraction of organic state (-); Cd:TPM (+)> fraction of organic state (-)> fraction of insoluble state (+)> fraction of inorganic state (+)4. Compared and analyzed the contents of heavy metals in different types of domestic and foreign cigarette tobacco and in the corresponding mainstream smoke and their migration rates in the mainstream smoke as well as the contents of valences of arsenicThe contents of heavy metals in the cigarette tobacco and in the corresponding mainstream smoke of different brands and types of cigarettes are different because of the different types or the formulations of tobacco leaves being used. The contents of heavy metals in different types of domestic and foreign cigarette tobacco and in the corresponding mainstream smoke and their migration rates in the mainstream smoke as well as the contents of valences of arsenic have been detected by using the method established by ourselves and the data have been compared and analyzed. The results show that foreign cigarettes have an advantage over domestic cigarettes in the control of heavy metals, especially Cd and Pb. The contents of Cd and Pb in the domestic cigarette tobacco is about three times as much as that of the foreign cigarette tobacco. Moreover, the content of Cd in the mainstream smoke of domestic flue-cured tobacco even reaches about 10 times as much as that of foreign flue-cured tobacco because the migration rate of Cd in the mainstream smoke of domestic flue-cured tobacco is higher than that of foreign flue-cured tobacco. Therefore, it should be focused mainly on the research of the technology of reducing Cd and Pb in the domestic cigarettes. In addition, the proportion of As (Ⅲ) content in the inorganic arsenic in the mainstream smoke of cigarettes of different brands is all low, about less than 15%, which indicates that the arsenic of the mainstream smoke of different cigarettes mainly exists as As (Ⅴ), of which the toxicity is low while the content of high-toxicity As (Ⅲ) is at low level.