Determination of steryl sulphates in invertebrate tissue by liquid chromatography-tandem mass spectrometry.
A method for the identification and quantification of underivatised steryl sulphates in invertebrates by liquid chromatography (LC) coupled with tandem mass spectrometry (MS) involving a single cleanup step has been developed. Negative electrospray ionisation and positive and negative atmospheric-pressure chemical ionisation (APCI) spectra of steryl sulphate showed pseudomolecular ions ([M+H-H2SO4]+ or [M-H]-). Collision-induced dissociation (CID) was efficient only in positive APCI. LC-MS in negative APCI was least susceptible to interference and possible differences in response factors. The detection limits (signal-to-noise ratio of 3) based on cholest-5-enyl-3-sulphate in positive and negative APCI modes are 3.66 and 0.73 pmol microL(-1), respectively. Calibration plots and response factors for cholest-5-enyl-3-sulphate relative to the internal standard, cholecalciferyl-3-sulphate, in both positive and negative polarities, were linear in the concentration range from 1.22 to 16.4 pmol microL(-1) with good coefficients of determination (R2 > 0.98). It is suggested that the structure elucidation of steryl sulphates is best achieved in CID positive APCI mode, whereas their quantification should be carried out using negative APCI.
Neto
Renato R
RR
Organic Biogeochemistry Group, Oceanography Laboratories, Department of Earth and Ocean Sciences, University of Liverpool, Liverpool, L69 3GP, UK. rrneto@dern.ufes.br
Thompson
Anu
A
Wolff
George A
GA
D002784:Cholesterol / Q000031:analogs & derivatives* / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D047332:Holothuria / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization
D002784:Cholesterol