Table 3: Robustness and ruggedness.

ZMT taken, μg mL−1RobustnessRuggedness
Volume of acidaReaction timebInteranalysts (%RSD), Interinstruments (%RSD),
( )( )( )( )

20.01.151.781.831.97
40.01.432.191.642.13
60.02.012.851.551.89

aThe volumes of conc. H2SO4 solution were 0.9, 1.0, and 1.1 mL; breaction times were 9, 10, and 11 min.