. Author manuscript; available in PMC: 2011 Aug 1.

Published in final edited form as: J Steroid Biochem Mol Biol. 2010 Jan 18;121(3-5):546–555. doi: 10.1016/j.jsbmb.2010.01.005

Table 2.

Limits of Detection Using APCI and ECAPCI for Selected Estrogen Metabolites.

Analyte	Negative APCI^a LOD (fmol)	ECAPCI^b LOD (amol)	Increased^c Sensitivity
estrone	18.52	740	25-fold
2-methoxyestrone	8.33	170	50-fold

underivatized analyte;

PFB derivative,

negative ion APCI of underivatized sample compared with ECAPCI of PFB-derivative.