A modified digestion mixture utilizing sodium molybdate as a catalyst is described for plant materials. In atomic absorption spectroscopy, special attention is given to calcium analyses using this mixture, because of various interfering ions. The digestion mixture is suitable for numerous other cation determinations. Also, a method of increasing the sensitivity for copper by adding methanol is described.
Merle Harrison and Charles Andre, "Digestion of Sugar Beet Leaves for Atomic Absorption Spectroscopy," Appl. Spectrosc. 23, 354-357 (1969)