For the quality assurance of plant analysis,the certified
reference CTA-OTL-1 (OrientalTobacco Leaves fromthe BulgarianInsti-
tute for Plant Protection) was employed. Average recoveries (n = 6)
were 91, 87, 66, 98, 85, 58, and 79% for As, Cd, Cr, Cu, Ni, Pb and Zn,
respectively.