Figure 4.

A) Absorption spectra of ternary synthetic mixture of antituberculosis drugs (a) before and (b-e) after addition of 1.5,3,4.5 and 6 mg L-1 of rifampicin, isoniazid and pyrazinamide; B) Net analyte signal of rifampicin (a) before and (b-e) after standard addition;