Table 5: Robustness and ruggedness of the proposed methods.

ParametersABCDE
2.0  g mL−14.0  g mL−16.0  g mL−13.0  g mL−13.0  g mL−1
Recovery (%) ± RSD%a

Robustness
No variationb
Oxidant ( )
 0.8 mL
 1.2 mL
Oxidation time
 2.0 min
 10 min
1,10-Phenanthroline (0.2%)
 0.8 mL
 1.2 mL
Ammonia (1 : 1)
 0.8 mL
 1.2 mL
FAS (5 × 10−3 mol L−1)
 1.3 mL
 1.7 mL
SCN (1.0 mol L−1)
 1.8 mL
 2.2 mL
Ruggedness
Interanalysis’
Interinstruments’

Average of three determinations.
bFollowing the general assay procedure conditions.