Chloroform is an internal standard in the determination of the pesticide DDT in a polarographic analysis in which each compound is reduced at an electrode surface. A mixture containing 0.500 mM chloroform and 0.800 mM DDT gave signals of 15.3 µA for chloroform and 10.1 µA for DDT. An unknown solution (10.0 mL) containing DDT was placed in a 100-mL volumetric flask and 10.2 µL of chloroform (FM 119.39, density µ 1.484 g/mL) were added. After dilution to the mark with solvent, polarographic signals of 29.4 and 8.7 µA were observed for the chloroform and DDT, respectively. Find the concentration of DDT in the unknown.