RESUMEN
Interference of P with determination of Ca in food and the effect of interference suppressing agents of La, Sr and 8-hydroxyquinoline were studied. The results showed that 1) interference of P with Ca related to P/Ca ratio, the relative absorbance of Ca were getting increase along with, the decrease of P/Ca ratio if P/Ca ratio about 0.6; 2) La was more effective than the other interference suppressing agents. The relative absorbance of calcium reached to about 90% when 0.5% or 1% La was used in the P/Ca ratio of 30; 3) Sr had two actions. On one hand Sr had some suppressing action on P interference, and on the other hand Sr depressed the Ca absorption signal obviously; and 4) 8-hydroxyqui-noline had some but not very effective interference suppressing action. The content of Ca determined in food SRM were lower than certified value using 0.1% 8-hydroxyquinoline as interference suppressing agent.