Table 2.

Risk assessment and control strategy for AQbD-enabled development UHPLC-PDA method for Genkwa Flos.

Potential failure cause	Failure effect	Risk mitigation	P	S	D	RPN
Injection volume*	Change the peak resolutions and S/N	Optimized by DoE and control	3	2	3	18
Sample stability	Change in peak resolutions and S/N	Ascertain the stability of prepared sample solutions	1	1	2	2
Mobile phase	Change in peak symmetry and chromatography	At least four mobile phases were tested	2	2	2	8
Columns	Lot variability may change	At least three columns were tested	2	2	2	8
Vials	Exposure to light results in an increase of impurity	Amber vials to be used	1	2	1	2
Humidity	Change in weighing	Standard operating procedures to be followed to dry the samples	1	2	2	4
Column temperature*	Changes in peak resolutions, elute time, and S/N	Optimized by DoE and control	3	2	2	12
Sample temperature	May change the peak resolutions	Control autosampler temperature at 20℃	2	1	2	4
Misidentification of peaks	Incorrect values reported	Training, example chromatograph	3	2	1	6
Gradient slope*	Changes in whole chromatography	Optimized by DoE and control	4	2	3	24
Flow rate*	Changes in peak resolutions and elute time	Optimized by DoE and control	2	2	3	12
Instrument model	Changes in whole chromatography	UHPLC system was selected	2	2	2	8

S/N signal to noise, DoE design of experiments, P probability, S severity, D detectability.

Risk priority number (RPN) = Severity $\times$ Probability $\times$ Detectability.

*High risk factors selected by upper 10 RPN.