Table 3: Method robustness and ruggedness expressed as intermediate precision.

Method Nominal concentrationRobustnessRuggedness
Reaction times* 
( )
Volumes of FC reagent#Volumes
of ferricyanide#
Interanalysts
( )
Interinstruments
( )

A 3.01.451.692.202.32
6.01.721.351.741.92
9.02.101.712.442.57

B 1.0 1.72 1.591.782.12
1.51.841.612.111.62
2.02.121.721.072.54

Reaction times were 10 ± 2 min for both methods. #Volumes of FC regent added were 2 ± 0.2 mL for method A; volumes of ferricyanide added were 1.5 ± 0.1 mL for method B.