1)The ATP (Analytical Target Profile) lists the range over which the method parameters are validated.
The ATP as described in the enhanced approach for analytical procedures describes the requirements that the results generated from the procedure must meet in order to be fit for purpose. (For quantitative analysis this is usually expressed as allowable bias and uncertainty). Method parameters are rarely expressed in the ATP.
2)Stage 1 of the lifecycle approach is development using specialised software to develop the procedure. (often interpreted as QbD)
Although development software plays a key role in development of new procedures to optimise method parameters, it is only a small component of Stage 1 (used for Design of Experiments- DoE). Stage 1 also encompasses procedure understanding, knowledge gathering, documentation, risk assessment and defining an analytical control strategy. Stage 1 is also applicable to method transfers and verification of compendial procedures, neither of which generally require DoE.
3)Stage 2 (procedure performance) is just executing the current ICHQ2 guidance
Stage 2 provides the evidence that the results generated by the procedure and its control strategy, developed in stage 1, meets the requirements of the ATP thus showing the procedure is fit for purpose.It may not require all of the validation characteristics described in the current version of ICHQ2 which will have primarily been performed in Stage 1. It is also an opportunity to explore and refine the replication strategy.
4)Stage 3- Continual monitoring is demonstrating that the system suitability requirements pass each time the procedure is run.
Demonstrating system suitability passes prior to running samples is good practice and this is incorporated into the overall analytical control strategy. However, Stage 3 also includes, trending of data, performance charts, running control samples to challenge procedure performance and identifying if any changes to the procedure are required and need to be evaluated.