AbstractA procedure for fractionation of phosphorus compounds in leaves has been studied. Serial extractions with 85 ethanol, 0.2N‐HCl, IN‐HClO4at 4°, 0.5N‐HClO4at 70° and 2N‐NaOH removes 99.8 of the total phosphorus from tomato or cauliflower leaves. A method, involving preliminary treatment of fractions with isobutanol, was designed to eliminate interfering effects of unknown compounds on the determination of inorganic and acid‐labile phosphorus by the phosphomolybdic acid method used.Several extractions with ethanol and 0.2N‐HCl are required for exhaustive removal of phosphorus compounds by each of these reagents. Single extractions by these reagents remove about 75 of the respective fractions. A major part of the organic phosphorus remaining after exhaustive ethanol extraction is readily removed by 0.2N‐HCl. By using 32P‐labelled inorganic phosphorus it was shown that whereas ribonucleic acids (RNA) are not decomposed during extraction in IN‐HClO4at 4° for 18 h. there is appreciable decomposition of nucleic acids including deoxyribose nucleic acid (DNA) during subsequent extraction by 0.5N‐HClO4at 70° for 20 min. RNA is estimated as organic phosphorus in the IN‐HClO4extract and DNA as total phosphorus in the 0.5N‐HClO4extract. Light extinction values at 260 mμ tend to be higher than expected in relation to phosphorus contents, especially for DNA.The distribution of organic phosphorus by single consecutive extractions into the fractions described above was determined for seven different species or varieties of
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