A Comparison of Mineral Extraction Techniques of Citrus Juices as Analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry

Two methods of mineral extraction for citrus juices were investigated: dry ashing in a muffle furnace and wet ashing in a microwave oven. Elemental concentrations were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). For reference, a synthetic multielement mixture was prepared and analyzed. Results for the multielement solution using wet ashing in a microwave oven or dry ashing in a muffle furnace differed by less than 10% from those for an undigested, but diluted solution. An exception was boron, of which 96% was lost in the muffle furnace. Grapefruit juice analysis showed differences in concentration of less than 10% for all elements. Orange juice samples, however, showed greater losses for Na (16%), Si (13%), and Sn (11%) with the dry ashing method.