Analysis of unsaturated compounds by Ag+ coordination ionspray mass spectrometry: studies of the formation of the Ag+/lipid complex.
Coordination ionspray mass spectrometry (CIS-MS) is a useful tool in the detection and identification of cholesterol ester and phospholipid hydroperoxides and diacyl peroxides. Extensive studies of a series of cholesterol esters using CIS-MS revealed the following: (1) Cholesterol esters with equal number of double bonds as the internal standard showed a linear relative response in the mass spectrometer while compounds with non-equal numbers of double bonds gave a nonlinear relative response. (2) Complex adducts containing cholesterol ester, silver ion, AgF, AgBF(4), and 2-propanoxide form when silver is in molar excess of cholesterol esters, reducing the [M + Ag](+) signal. (3) In a mixture of cholesterol esters where silver is limiting, Ch22:6 and Ch20:4 bind to silver at the expense of Ch18:2 and have a higher signal in the mass spectrometer. (4) In a mixture of cholesterol esters where silver concentration is twofold greater than total cholesterol ester concentration, Ch22:6 and Ch20:4 form large complex adducts more frequently than Ch18:2 and have a lower signal in the mass spectrometer.
Seal
Jennifer R
JR
Department of Chemistry, the Center in Molecular Toxicology, Vanderbilt University, Nashville, Tennessee 37235, USA.
Havrilla
Christine M
CM
Porter
Ned A
NA
Hachey
David L
DL
D002414:Cations, Monovalent / Q000737:chemistry*; D002788:Cholesterol Esters / Q000032:analysis / Q000737:chemistry; D005224:Fats, Unsaturated / Q000032:analysis / Q000737:chemistry*; D015227:Lipid Peroxidation; D012834:Silver / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D002414:Cations, Monovalent; D002788:Cholesterol Esters; D005224:Fats, Unsaturated; D012834:Silver