Comparative study on the efficiency of ruthenium, rhodium and palladium as chemical modifiers for thermal stabilization of 18 analyte elements with high and moderate volatility has been performed. Addition of ascorbic acid provided higher temperatures of thermal pretreatment by +50 to +250-degrees-C for the analytes: As, Ge, P, Pb, Se, Sn and Tl, as well as better performence for Ga, In and Tl. Possible mechanisms and trends in stabilization are discussed.