A robustness test was performed on a chromatographic method to identify and
assay an active substance and two related compounds in film-coated tablet.
For a number of responses the originally applied system suitability criter
ia were evaluated based on the results of the robustness test. Ambiguous si
tuations can occur in situations where a method is found to be robust to as
say the substances, as was the case here, but when system suitability crite
ria for some responses are violated. To avoid this, a proposal is made to d
efine or re-define system suitability limits based on the results of the ro
bustness test. From the effects found in the robustness test, the experimen
tal conditions giving the worst result that still is acceptable and probabl
e to occur are predicted and the system suitability limits are defined from
replicated experiments in these conditions. (C) 1999 Elsevier Science B.V.
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