title: The influence of salt matrices on the reversed-phase liquid chromatography behavior and electrospray ionization tandem mass spectrometry detection of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid in water.
abstract: The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography-heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI-MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na+, K+) or trivalent (Al3+, Fe3+) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu2+, Co2+, Zn2+, and Mn2+prevented glyphosate detection whereas Ca2+, Mg2+, and Sr2+altered the retention time. At certain tested concentrations of Ca2+and Sr2+glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca2+, Mg2+, and Sr2+can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI-MS/MS analysis.
authors.affiliation: Leibniz Institute for Baltic Sea Research Warnemuende, Department of Marine Chemistry, Seestrasse 15, 18119 Rostock, Germany. Electronic address: wael.skeff@io-warnemuende.de.
authors.forename: Wael
authors.initials: W
authors.lastname: Skeff
authors.affiliation: Leibniz Institute for Baltic Sea Research Warnemuende, Department of Marine Chemistry, Seestrasse 15, 18119 Rostock, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Recknagel
authors.affiliation: Leibniz Institute for Baltic Sea Research Warnemuende, Department of Marine Chemistry, Seestrasse 15, 18119 Rostock, Germany.
authors.forename: Detlef E
authors.initials: DE
authors.lastname: Schulz-Bull
mesh_terms: D000613:Aminobutyrates / Q000032:analysis*; D000615:Aminoethylphosphonic Acid / Q000032:analysis; D002413:Cations, Divalent; D002853:Chromatography, Liquid; D056148:Chromatography, Reverse-Phase; D005449:Fluorenes / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry; D007555:Isoxazoles; D063065:Organophosphonates / Q000032:analysis; D012492:Salts / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D013777:Tetrazoles; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D000097797:Glyphosate
chemical_list: D000613:Aminobutyrates; D000615:Aminoethylphosphonic Acid; D002413:Cations, Divalent; D005449:Fluorenes; D005998:Glycine; D006540:Herbicides; D007555:Isoxazoles; D063065:Organophosphonates; D012492:Salts; D013777:Tetrazoles; D014867:Water; D014874:Water Pollutants, Chemical; D000097797:Glyphosate; C003121:phosphinothricin; C054007:1-(9-fluorenyl)methyl chloroformate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid
keywords: 2-AEP; Complexes; Herbicides; MS/MS; Metabolite; RP-LC-HESI-; Salt matrix