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<br />A 5 C <br />'. <br />' the WAD cyanide analyses are less than the total cyanide values, (e.g., <br />sample 4, TCN = 126 mg/L; WAD CN = 112 mg/LI; <br />• the WAD cyanide analyses are less than the total cyanide IevelS by something <br />in excess of the calculated iron and cobalt cyanide complexes equivalent <br />' cyanide values (e.g., sample 4, TCN = 126 mg/L, WAD CfJ~ = 112 mg/L <br />giving a differepce of 14 mg/L. Iron, as Fe(CN)6 and cobalt, as Co(CN~ , <br />require about 3 mg/L cyanide and 3 mg/L cyanide to account for their <br />' presence in the total cyanide analysis over and above the WAD cyanide <br />analysis); and <br />' the WAD cyanide analyses exceed the overall cyanide requirement for <br />complexing those metals which would report to analysis. Thils must be the <br />' case if there is any free cyanide in the samples at all. (e.g., sample 4, WAD <br />CN = 112 mg/L. Copper, as Cu(CN)2 requires 78 mg/L cyanide, and the <br />remaining WAD cyanide metals (Zn, Ni and Mnl require about 2 mg/L <br />' cyanide, giving a total of 80 mg/L cyanide needed in the WAD cyanide <br />analysis at a minimum. <br />' 4.4 'FREE CYANIDE' <br />' None of the free cyanide determinations by either laboratory are correct, (Laboratory <br />"C" reported the data were incorrect and noted that high levels of thiocyanate, a <br />known interferent, were present.) The following observations substantiate this <br />' position: <br />• all Laboratory "C" free cyanide values exceed the WAD cyanide values which <br />' is not possible, particularly considering the levels of cyanide complexable <br />metals in these samples le.g., sample 4: WAD CN 112 mg/L, FCN = <br />' 149 mg/L); <br />• if Laboratory "A" free cyanide values are substituted for Laboratory "C" WAD <br />' cyanide values (Laboratory "A" WAD cyanide value are incorrect and cannot <br />be use for computation, see above), the residual cyanide "available" is <br />insufficient to account for the metallo-cyanide complexes present in the <br />' solutions, even taking the lowest oxidation state for those complexes (e.g., <br />sample 4: Laboratory "A" FCN = 93 mg/L, Laboratory "C" WAD CN = <br />' 112 mg/L, a difference of 21 mg/L cyanide. A minimurm of 80 mg/L <br />difference between the FCN and WAD cyanide is required to account for the <br />presence of the WAD metallo-cyanide species); <br />6 <br />1 <br />