Distributions and Sources of Sedimentary Sterols as well as Their Indications of Sewage Contamination in the Guanting Reservoir, Beijing

Table 2

Peak time and characteristic ions of sterols for GC-MS.

Sterols	Systematic name	Number of carbon	Molecular weight	Retention time/min	m/z for quantification and identification
Cholesterol	(3β)-Cholest-5-en-3-ol	27	386.65	29.60	73,129,329
Cholestanol	(3β, 5α)-Cholestan-3-ol	27	388.67	29.91	75,129,215
Coprostanol	(3β, 5β)-Cholestan-3-ol	27	388.67	26.89	73.75,370
Epicoprostanol	(3α, 5β)-Cholestan-3-ol	27	388.67	27.19	75,215,370
Campesterol	(3β, 24R)-Ergost-5-en-3-ol	28	400.68	28.34	43,73,129
Sitosterol	(3β)-Stigmast-5-en-3-ol	29	412.69	36.04	57,73,129
Stigmasterol	(3β, 22E)-Stigmasta-5,22-dien-3-ol	29	414.71	34.03	55,83,370
5α-Androstan-3β-ol		19	276.46	14.831	75,258,333