Study on the Determination of Heavy-Metal Ions in Tobacco and Tobacco Additives by Microwave Digestion and HPLC with PAD Detection

Abstract

A new method for the simultaneous determination of heavy-metal ions in tobacco and tobacco additive by microwave digestion and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The tobacco and tobacco additive samples were digested by microwave digestion. The lead, cadmium, mercury, nickel, copper, and tin ions in the digested samples were precolumn derivated with tetra-(4-aminophenyl)-porphyrin (T4-APP) to form color chelates; the Hg-T4-APP, Cd-T4-APP, Pb-T4-APP, Ni-T4-APP, Cu-T4-APP, and Sn-T4-APP chelates were then enriched by solid-phase extraction with C18 disks and the retained chelates were eluted from the disks using tetrahydrofuran (THF). The chelates were separated on a Waters Xterra™ RP18 column by gradient using methanol (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH 10.0) as a mobile phase at a flow rate of 0.5 mL/min and detected with a photodiode array detector in the range 350–600 nm. The detection limits of lead, cadmium, mercury, nickel, copper, and tin were 5, 4, 2.5, 5, 8, and 4 ng/L, respectively, in the original samples. The method was applied to the determination of lead, cadmium, mercury, nickel, copper, and tin in tobacco and tobacco additive with good results.