Table 2.

Regression equations, linear ranges, and LLOQs of the three compounds.

Compound	Regression equation	R 2	Linear range (ng/mL)	Limit of quantification (ng/mL)
Promethazine	Y = 0.016464X + 0.001150	0.9983	0.5–200	0.5
Promethazine sulfoxide	Y = 0.041898X + 0.001187	0.9961	0.5–200	0.5
Schisandrin	Y = 0.054003X + 0.001437	0.9986	0.5–200	0.5