Table 2.

Precision and accuracy of the determination of five alkaloids in cell lysates by LC–MS/MS analysis. RSD: relative standard deviation.

Compound	Nominal Concentration (ng/mL)	Intra-Day			Inter-Day
		Found Concentration (ng/mL)	RE (%)	RSD (%)	Found Concentration (ng/mL)	RE (%)	RSD (%)
Protopine	0.75	0.776	3.5	4.7	0.772	2.9	6.5
	1.875	1.978	5.5	3.4	1.954	4.2	4.1
	6.0	5.91	−1.5	4.2	5.934	−1.1	2.4
	22.5	21.02	−6.6	3.0	21.22	−5.7	3.8
Chelidonine	0.5	0.526	5.2	3.7	0.523	4.6	7.1
	1.25	1.295	3.6	4.1	1.319	5.5	2.2
	4.0	3.860	−3.5	2.9	3.916	−2.1	3.5
	15	13.74	−8.4	3.0	13.85	−7.7	2.8
Coptisine	12.5	12.74	1.9	4.8	12.96	3.7	5.9
	31.25	32.75	4.8	5.0	31.97	2.3	7.5
	100	97.9	−2.1	3.4	99.70	−0.3	4.1
	375	363.4	−3.1	3.7	367.1	−2.1	2.1
Sanguinarine	20	20.54	2.7	3.8	20.72	3.6	4.2
	50	52.45	4.9	2.6	51.85	3.7	3.9
	160	155.2	−3.0	4.3	156.2	−2.4	1.5
	600	567.6	−5.4	3.7	583.8	−2.7	6.0
Chelerythrine	6.0	5.604	−6.6	7.3	5.766	−3.9	6.7
	15	13.54	−9.7	3.2	13.43	−10.5	3.9
	48	43.78	−8.8	2.8	44.06	−8.2	1.3
	180	187.6	4.2	3.8	181.6	0.9	4.6