Quantitative analysis of proteins via sulfur determination by HPLC coupled to isotope dilution ICPMS with a hexapole collision cell

Meng Wang, Weiyue Feng, Wenwei Lu, Bai Li, Bing Wang, Motao Zhu, Yun Wang, Hui Yuan, Yuliang Zhao, Zhifang Chai

Research output: Contribution to journalArticle

79 Scopus citations

Abstract

Quantitative analysis of proteins is an essential part and also constitutes a major challenge in modern proteomics. Quantification of proteins by inductively coupled plasma mass spectrometry (ICPMS) offers an alternative method for quantitative proteomics. In this study, we developed a method of absolute quantification of proteins via sulfur by size exclusion chromatography (SEC) coupled to ICPMS with a collision cell (ICP-CC-MS) and postcolumn isotope dilution. Bovine serum albumin (BSA), superoxide dismutase (SOD), and metallothionein-II (MT-II) served as model proteins. Enriched 34S, 65Cu, and 67Zn isotopic solutions were continuously mixed with the eluate from the SEC. Oxygen was added as a reactive gas into the collision cell where sulfur reacts with oxygen to form sulfur-oxygen ion, the ratio of 32S16O+/34S 16O+ thus representing 32S+/ 34S+. The absolute quantity of proteins could be calculated by the isotopic dilution equation and the content of sulfur in the proteins. The detection limits for BSA, SOD, and MT-II are 8, 31, and 15 pmol, respectively. The relative standard deviations for the proteins are less than 3%. The ratios of S/Cu and S/Zn in the proteins were also determined. The quantitative method was validated by comparing with gravimetric results.

Original languageEnglish (US)
Pages (from-to)9128-9134
Number of pages7
JournalAnalytical Chemistry
Volume79
Issue number23
DOIs
StatePublished - Dec 1 2007

ASJC Scopus subject areas

  • Analytical Chemistry

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