sorbance difference of 0.005 unit from t h a t containing 5 p.p.m. of uranium and no diverse ion; that concentration which caused a n error of 1 2 % based on 5 p.p.m. of uranium; and t h a t concentration which caused a n error of k5% also based on 5 p.p.m. of uranium. The results are listed in Table 111. The interferences were somewhat similar to those in the dibenzoylmethane method (84). These results indicate t h a t many elements interfere with the color reaction, as is true for the dibenaoylmethane method, and hence, must be removed before uranium can be determined with arsenazo.
Limiting Concentration Ion
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