Monitoring EDTA and endogenous metabolite biomarkers from serum with mass spectrometry

Article type: Research Article

Authors: Lowe, Rachel^; | Go, Eden P. | Tong, Grace C. | Voelcker, Nicolas H. | Siuzdak, Gary^;

Affiliations: Department of Molecular Biology, The Scripps Center of Mass Spectrometry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA | School of Chemistry Physics and Earth Sciences, Flinders University, Bedford Park, South Australia, 5042

Note: [] Corresponding author. E-mail: siuzdak@scripps.edu.

Abstract: We describe a quantitative method for the determination of ethylenediaminetetraacetic acid (EDTA) in human serum by gas chromatography mass spectrometry (GC-MS), liquid chromatography electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS), and desorption ionisation on silicon mass spectrometry (DIOS-MS). In the initial stages of the analysis, endogenous metabolites (1-palmitoyl-sn-glycero-3-phosphocholine and 1-stearoyl-sn-glycero-3-phosphocholine) were readily observed in LC-ESI-MS and DIOS-MS however, direct analysis of the EDTA free acid had limited sensitivity. In order to improve EDTA detection we employed a straightforward esterification derivatization. The most successful derivatization procedure converted EDTA to its methyl ester and, since 13C isotopes of these reagents are readily available, internal standards could be easily generated for quantitative analysis. This approach provided a limit of detection of 0.5 and 0.1 μM for GC-MS and LC-ESI-MS, and offers a viable method for the EDTA detection.

Journal: Spectroscopy, vol. 19, no. 3, pp. 137-146, 2005