title: Matrix influence on derivatization and ionization processes during selenoamino acid liquid chromatography electrospray ionization mass spectrometric analysis.
abstract: Considering the importance of derivatization in LC/ESI/MS analysis, the objective of this work was to develop a method for evaluation of matrix effect that would discriminate between matrix effect due to the derivatization reaction yield and from the ESI. Four derivatization reagents (TAHS, DEEMM, DNS, FMOC-Cl) were studied with respect to matrix effects using two selenoamino acids and onion matrix as model system. A novel method for assessing matrix effects of LC/ESI/MS analyses involving derivatization is proposed, named herein post-derivatization spiking, that allows evaluating effect of matrix on ESI ionization without derivatization reaction yield contribution. The proposed post-derivatization spiking method allowed to demonstrate that the reason of reduced analytical signal can be signal suppression in ESI (as in case of DNS derivatives with matrix effects 38-99%), alteration of derivatization reaction yield (TAHS, matrix effects 92-113%, but reaction yields 20-50%) or both (FMOC-Cl, matrix effects 28-88% and reaction yields 50-70%). In case of DEEMM derivatives, matrix reduces reaction yield but enhances ESI/MS signal. A method for matrix effect evaluation was developed. It was also confirmed that matrix effects can be reduced by dilution.
authors.affiliation: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia. Electronic address: riin.rebane@ut.ee.
authors.forename: Riin
authors.initials: R
authors.lastname: Rebane
authors.affiliation: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.
authors.forename: Maarja-Liisa
authors.initials: ML
authors.lastname: Oldekop
authors.affiliation: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.
authors.forename: Koit
authors.initials: K
authors.lastname: Herodes
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D007477:Ions / Q000032:analysis / Q000737:chemistry*; D017279:Selenocysteine / Q000032:analysis / Q000737:chemistry*; D012645:Selenomethionine / Q000032:analysis / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D007477:Ions; D017279:Selenocysteine; D012645:Selenomethionine
keywords: Amino acids; Derivatization; LC/ESI/MS; Matrix effects