Table 3.

Short and long-term stability data of levonorgestrel under different conditions

Condition	QC	Nominal concentration (pg/mL)	Mean (pg/mL)	S.D. (pg/mL)	CV (%)	Bias (%)
Heat inactivation	LQC	134	128.48	4.57	3.56	−4.12
	MQC	420	406.28	19.43	4.78	−3.27
	HQC	1200	1248.05	66.86	5.36	4.00
Bench-top	LQC	134	116.01	7.74	6.67	−13.42
	MQC	420	415.89	14.67	3.53	−0.98
	HQC	1200	1303.72	18.15	1.39	8.64
Processed	LQC	134	120.45	10.01	8.31	−10.11
	MQC	420	415.66	26.82	6.45	−1.03
	HQC	1200	1278.22	31.39	2.46	6.52
Freeze-thaw	LQC	134	126.52	6.38	5.05	−5.59
	MQC	420	412.92	8.88	2.15	−1.69
	HQC	1200	1255.96	21.92	1.75	4.66
Long-Term	LQC	134	127.58	9.37	7.35	−4.79
	MQC	420	416.19	9.53	2.29	−0.91
	HQC	1200	1286.23	29.03	2.26	7.19
Re-injection	LQC	134	140.47	6.00	4.27	4.83
	MQC	420	453.90	8.67	1.91	8.07
	HQC	1200	1320.81	54.06	4.09	10.07

Abbreviations: LNG, levonorgestrel; LQC, low quality control; MQC, medium quality control; HQC, high quality control.