Table 9.

3-Epi-1,25(OH)₂D₃ retention time validation

3-Epi-1,25(OH)2D3
Solution	Sample name	Retention time (min)	Peak area	Signal/noise ratio
Spiked acetonitrile (1.25 ng)	Standard 1	7.542	4356	61
	Standard 2	7.615	2084	100
	Standard 3	7.495	3510	55
	Standard deviation	0.06
	Mean	7.55
	% RSD	0.80
Spiked brain homogenate (1.25 ng)	Endogenous 1	7.52	1797	15
	Endogenous 2	7.64	1820	18
	Endogenous 3	7.66	3548	31
	Standard deviation	0.07
	Mean	7.61
	% RSD	0.95
Spiked brain homogenate calibration (ng)	1.6	7.47	7094	59
	3.125	7.39	21,260	140
	6.25	7.43	54,577	260
	12.5	7.42	120,320	860
	25	7.40	267,640	1432
	50	7.40	526,309	2164
	100	7.31	1,003,098	2206
	Standard deviation	0.04
	Mean	7.36
	% RSD	0.58
Average retention time, standard deviation		0.05
Average retention time, mean		7.50
Average retention time, % RSD		0.77

This table provides parameters of an unknown peak we later validated and identified as the 3-epi-1,25(OH)2D3 metabolite