Table 4.

Assay linearity in different matrices of song sparrow

	Brain Δ slope (%)	Blood Δ slope (%)	Plasma Δ slope (%)
E1	7	3	0
17β-E2	2	1	6
E3	7	5	1
4OH-E2	2	n.d.	14
2Me-E2	1	3	1
4Me-E2	19	3	2

Difference in slope (Δ slope) was calculated by subtracting the slope of the sample with increasing amount with the slope of the standard curve in neat solution, and then dividing by the slope of the standard curve in neat solution multiplied by 100 and expressed in percentage (%). n.d. is defined as nondetectable.