Parameter Bu /PA  Bu /BPR Bu /AR  Bu /BTB λmax (nm) 410 430 435 430 Beer’s law up to (µgmL-1)  42.5 105.5   73.8 29.5 Molar absorpitivity (ε) (Lmol-1 cm-1 )   1.8 x103  4.26 x103 6.67 x103  14.33 x103 Ringbom (µg mL-1) 2.68 8.06  8.20  1.61 Sandell sensitivity  (µg cm-2 )  0.039  0.099  0.063  0.0294 Limit of detection(µgmL-1) 0.53 2.24  0.70  0.21 Limit of quantification (µgmL-1)  1.67  0.96 2.34  0.699 Color of ion- associate Yellow Yellow Yellow Yellow Intercept 0.013   - 0.002 0.033 - 0.017 Slope 0.025 0.01 0.015  0.035 Correlation Coefficient  0.999  0.999 0.999 0.998

Table 1: Characteristics and analytical data of (Bu-HCl) ion-associates with PA, BPR, AR and BTB