CV % Recovery %     Colorimetric Luminescent Colorimetric Luminescent Log-log fit Mean ± SD 20.29 ± 9.12 11.79 ± 3.67 102.66 ± 18.77 100.65 ± 9.12   P value (one tail) 0.03   0.41   4-parameter fit Mean ± SD 25.50 ± 14.27 13.65 ± 4.58 97.97 ± 13.59 94.68 ± 14.91   P value (one tail) 0.04   0.35

Table 3: Comparison of mean CV% and recovery% of colorimetric method to that of luminescent method using different fitting method (n=6, for standards ranging from 0.91 to 222.22 ng/ml).