Table 3. Linearity, LOD, correlation coefficient and linear range for the four target barbiturates

Compound	Regression equation	LOD(ng/mL)	LOQ(ng/mL)	Correlation coefficient(r2)	Linear range(ng/mL)	Replicate number
Phenobarbital	A = 11.05C + 271.55	5	10	0.9986	10–1000	6
Pentobarbital	A = 33.67C + 850.54	5	10	0.9952	10–1000	6
Amobarbital	A = 34.50C + 651.37	5	10	0.9978	10–1000	6
Secobarbital	A = 23.12C + 318.93	5	10	0.9993	10–1000	6