Method LMT taken,
µg mL-1
Robustness Ruggedness
Parameter altered* Inter-analysts, (%RSD)
(n=4)
Inter-instruments, (%RSD)
(n=4)
H2SO4 concentration, (%RSD)
A 6.0 1.56 0.88 1.65
B 8.0 - 0.99 1.58
*In method A, concentration of H2SO4 were 0.08, 0.1 and 0.12 M
Table 3: Method robustness and ruggedness expressed as intermediate precision (% RSD).