Applications Of Inductively-Coupled Plasma Mass Spectrometry To Determinate Heavy Metals In Auxiliary Materials For Cigarette

The heavy metals in cigarettes are drawing more and more attention as peoplekeep a watchful eye on food security. It has become a consensus for both of tobaccomanufacturer and consumer that the content of metals in cigarettes and raw materialsshould be controlled in appropriate ranges. Auxiliary materials for cigarette,significant part of the products, are also an important source of heavy metals.Therefore, it’s very meaningful to establish an accurate method for heavy metals’determination in auxiliary materials for cigarette. However, few researches have beenreported in this area with ICP-MS, which is one of the most authoritative quantitativeanalysis technique for elements and widely used in food、geology and environics. Inthis paper, we developed a method to determinate heavy metals in seven auxiliarymaterials for cigarette with ICP-MS and microwave digestion. The work includes:1. The influence of acid effect、carbon effect、double charge ion interference、polyatomic ion interference and the differences between DRC mode and standardmode for Cr、Ni、As、Se in the ICP-MS determination was assessed first. The resultsshowed that the impact of acid effect、double charge ion interference was small，theformer of which could be corrected to a great extent by internal standard. Too muchcarbon would make the analytic results on the high side for the quantitation of Cr、As、Se. So it’s necessary to remove the carbon in samples as much as possible. DRC modewas always the better mode for Cr and Se, while standard mode was more suitable forAs. In the case of Ni, which mode should be used depends on Ca content.2. With microwave digestion as sample pretreatment approach, we determinedeight elements in tipping papers、cigarette papers、filter tips、reconstituted tobaccos.Hydrofluoric acid and hydrochloric acid were added for digestions because therewould be small particles left if the samples were digested with nitric acid andhydrogen peroxide only. As the results showed, both of hydrofluoric acid andhydrochloric acid were beneficial to dissolve the particles, and hydrofluoric acid wasmuch more effective. The amount of hydrofluoric acid used was little,0.4ml fortipping paper and0.15for others, so it wouldn’t bring any damage to ICP-MS. Therewere too much Ca in tipping papers and cigarette papers, which made Ni measuredunder standard mode higher than real contents. While no distinct difference wasobserved in the Ni quantitations between DRC mode and standard mode for filter tipand reconstituted tobacco. 3. It’s dangerous to digest triacetin、 water-based adhesive、 flavors usingmicrowave system directly, for there are usually explosive solvents in them.Pre-digest with nitric acid for over12hours could make digestion more safely. Todecrease carbon content in samples, the amount of nitric acid、hydrogen peroxide anddigest program were optimized. A negative correlation between carbon intensity anddigest temperature was found, and no one method worked well enough. Thephenomena might cause by the undigested organics which volatilized at high digesttemperature and condensed after the digestion. Heating the samples at140℃for40min just after the microwave digestion could remove majority of carbon without lossof elements, which was beneficial to the determination of Cr、As、Se greatly.