Table 4. Summary of the stability results.

	Donepezil concentration (ng/mL)
	LoQC (0.3 ng/mL)	HiQC (35 ng/mL)
Re-injecta	4.55	−0.25
Processed sampleb	2.25	1.01
Freeze-thawc	1.10	−1.20
Short-termd	0	−0.89
Stock short-terme	−4.26	−1.14
Stock long-termf	0	0.43

^aafter three re-injections, ^bafter 24 h in the autosampler at 10℃, ^cafter three freeze-thaw cycles, ^dafter 20 h at room temperature, ^eafter 24 h at room temperature, ^fafter 24 days at 4℃; LoQC, low concentration of the quality control (QC) sample; HiQC: high concentration of the QC sample; Data are represented as the mean % change.