Determination of 7 Metals Impurities in Pure Terephthalic Acid Products by GF-AAS

GF-AAS was applied to the determination of 7 metals impurities,i.e.titanium,molybdenum,chromium,nickel,cobalt,manganese and iron in pure terephthalic acid products.The ashing temperature of GF was 750 ℃,and the ashing time was 45 min.Sulfuric acid (1+1) solution was used to dissolve the residue.The linearity ranges of iron and nickel were within 20 μg·L-1,and those of titanium,molybdenum,chromium,cobalt and manganese were within 120 μg·L-1.The detection limits (3S/N) were in the range of 0.5-1.6 μg·L-1.Recovery rates measured by standard addition method were in the range of 92.0%-105% and RSD′s (n=6) were less than 5%.The method was used for determination of cobalt,manganese and iron in samples,giving results consistent with those obtained by the standard method.