title: Preliminary evaluation of a microwave-assisted metal-labeling strategy for quantification of peptides via RPLC-ICP-MS and the method of standard additions.
abstract: NIST has performed preliminary research on applying a calibration methodology based on the method of standard additions to the quantification of peptides via reverse-phase liquid chromatography coupled to inductively coupled plasma mass spectrometry (RPLC-ICP-MS). A microwave-assisted lanthanide labeling procedure was developed and applied to derivatize peptides using the macrocyclic bifunctional chemical chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), which significantly improved the lanthanide labeling yield and reduced reaction times compared to benchtop labeling procedures. Biomolecular MS technologies of matrix-assisted laser desorption ionization (MALDI)-MS and electrospray ionization (ESI)-MS/MS were used in concert with ICP-MS to confirm the results of microwave labeling, sample cleanup and standard additions experiments for several test peptides. The calibration scheme is outlined in detail and contextualized against complementary high accuracy calibration strategies currently employed for ICP-MS detection of biomolecules. Standard additions experiments using native, non-isotopic peptide calibrants confirm the simplicity of the scheme and the potential of applying a blending (recombined sample and spike) procedure, facilitating calibration via co-elution of lanthanide labeled peptides. Ways to improve and fully leverage the analytical methodology are highlighted.
authors.affiliation: National Institute of Standards and Technology, Material Measurement Laboratory, Analytical Chemistry Division, 331 Fort Johnson Road, Charleston, SC 29412, United States. steven.christopher@nist.gov
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Christopher
authors.forename: Eric L
authors.initials: EL
authors.lastname: Kilpatrick
authors.forename: Lee L
authors.initials: LL
authors.lastname: Yu
authors.forename: W Clay
authors.initials: WC
authors.lastname: Davis
authors.forename: Blakely M
authors.initials: BM
authors.lastname: Adair
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D056148:Chromatography, Reverse-Phase; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry; D007553:Isotope Labeling; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008872:Microwaves; D010455:Peptides / Q000032:analysis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013054:Spectrophotometry, Atomic; D013194:Staining and Labeling
chemical_list: D002614:Chelating Agents; D006573:Heterocyclic Compounds, 1-Ring; D028581:Lanthanoid Series Elements; D010455:Peptides; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid