原子吸收法测定食品中钙时磷的干扰及干扰抑制剂效果观察

PHOSPHORUS INTERFERENCE AND EFFECT OF DIFFERENT INTERFERENCE SUPPRESSING AGENTS ON THE DETERMINATION OF CALCIUM IN FOOD BY ATOMIC ABSORPTION SPECTROMETRY

本文研究了原子吸收法测定钙时磷的干扰以及镧、锶和8-羟基喹啉的抗干扰效果。实验表明:1)磷对钙的干扰与P/Ca比值有关,当P/Ca比(w/w)<约0.6时,钙的吸光度随着P/Ca比的减小而增大,当P/Ca比>约0.6时,钙的吸光度基本保持不变,相对吸光度保持在60％左右。2)干扰抑制剂的效果以镧较好,在P/Ca比为30时,使用0.5％或1％的镧作干扰抑制剂,钙的相对吸光度可达90％左右。3)锶具有二重性,一方面对样品中的磷有一定的抗干扰作用,另一方面明显抑制钙的吸收信号。4)8-羟基喹啉对溶液中磷的干扰具有一定的拮抗作用,但效果较差,使用0.1％8-羟基喹啉作干扰抑制剂,食品标样钙的测定结果较证书值低。

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(w/w) and the relative absorbance decreased to about 60% and kept this value 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.