. 2015 Feb 13;10(2):e0117984. doi: 10.1371/journal.pone.0117984

Table 2. Selected reaction monitoring transitions and the optimum LC-MS/MS conditions for the internal standard testosterone, progesterone and its metabolites.

Number	Steroid	Q1 (Da)	Q3 (Da)	Rt (min)	DP (Volts)	EP (Volts)	CE (Volts)	CXP (Volts)
1	Testosterone	289.2 [M+H]⁺	109.2	9.2	120	10	47	23
2	(20S)-Pregn-4-ene-3β,20-diol	301.1 [M-H₂O+H]⁺	79.1	15.4	70	12	60	28
3	(20S)-20-Hydroxy-pregn-4-ene-3-one	317.1 [M+H]⁺	96.9	17.6	70	10	20	16
4	(20S)-5α-Pregnane-3β,20-diol	285.1 [M-2 H₂O+H]⁺	66.9	18.2	110	8	30	10
5	(20S)-Pregn-4-ene-3α,20-diol	301.1 [M-H₂O+H]⁺	79.1	19.4	70	12	60	28
6	(20R)-Pregn-4-ene-3β,20-diol	301.1 [M-H₂O+H]⁺	77.0	19.8	70	12	80	28
7	(20R)-20-Hydroxy-pregn-4-ene-3-one	299.2 [M-H₂O+H]⁺	81.0	21.7	90	10	20	10
8	(20S)-5α-Pregnane-3α,20-diol	285.1 [M-2 H₂O+H]⁺	78.9	22.7	110	8	30	10
9	Progesterone	315.1 [M+H]⁺	109.1	22.8	110	10	30	10
10	(20S)-20-Hydroxy-5α-pregnane-3-one	319.2 [M+H]⁺	91.0	22.9	150	8	60	10
11	(20R)-Pregn-4-ene-3α,20-diol	301.1 [M-H₂O+H]⁺	77.0	23.2	70	12	80	28
12	3α-Hydroxy-pregn-4-ene-20-one	299.1 [M-H₂O+H]⁺	81.0	23.3	90	10	20	10
13	3β-Hydroxy-pregn-4-ene-20-one	317.1 [M+H]⁺	96.9	23.8	70	10	20	16
14	3β-Hydroxy-5α-pregnane-20-one	319.2 [M+H]⁺	91.0	23.8	150	8	60	10
15	(20R)-5α-Pregnane-3α,20-diol	285.1 [M-2 H₂O+H]⁺	78.9	25.9	110	8	30	10
16	3α-Hydroxy-5α-pregnane-20-one	319.2 [M+H]⁺	77.0	26.1	150	8	80	10
17	(20R)-20-Hydroxy-5α-pregnane-3-one	319.2 [M+H]⁺	77.0	27.0	150	8	80	10
18	5α-Pregnane-3,20-dione	317.1 [M+H]⁺	91.1	27.4	90	10	60	10

Q1, first quadrupole; Q3, third quadrupole; Rt, retention time

DP, declustering potential; EP, entrance potential; CE, collision energy; CXP, collision cell exit potential