title: The benefits and limitations of reaction cell and sector field inductively coupled plasma mass spectrometry in the detection and quantification of phosphopeptides.
abstract: BACKGROUND
  The phosphorylation of proteins is one of the most important post-translational modifications in nature. Knowledge of the quantity or degree of protein phosphorylation in biological samples is extremely important. A combination of liquid chromatography (LC) and inductively coupled plasma mass spectrometry (ICP-MS) allows the absolute and relative quantification of the phosphorus signal.
  
  
  METHODS
  A comparison between dynamic reaction cell quadrupole ICP-MS (DRC-Q-ICP-MS) and high-resolution sector field ICP-MS (SF-ICP-MS) in detecting signals of phosphorus-containing species using identical capillary LC (reversed-phase technology) and nebulizer settings was performed.
  
  
  RESULTS
  A method to diminish the reversed-phase gradient-related signal instability in phosphorus detection with LC/ICP-MS applications was developed. Bis(4-nitrophenyl)phosphate (BNPP) was used as a standard to compare signal-to-noise ratios and limits of detection (LODs) between the two instrumental setups. The LOD reaches a value of 0.8 µg L(-1) when applying the DRC technology in Q-ICP-MS and an LOD of 0.09 µg L(-1) was found with the SF-ICP-MS setup. This BNPP standard was further used to compare the absolute quantification possibilities of phosphopeptides in these two setups.
  
  
  CONCLUSIONS
  This one-to-one comparison of two interference-reducing ICP-MS instruments demonstrates that absolute quantification of individual LC-separated phosphopeptides is possible. However, based on the LOD values, SF-ICP-MS has a higher sensitivity in detecting phosphorus signals and thus is preferred in phosphopeptide analysis.
authors.affiliation: Flemish Institute for Technological Research (VITO), Mol, Belgium; CFP-CeProMa, University of Antwerp, Antwerp, Belgium; KU Leuven, Research Group of Functional Genomics and Proteomics, Leuven, Belgium.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Maes
authors.forename: Wilfried
authors.initials: W
authors.lastname: Brusten
authors.forename: Filip
authors.initials: F
authors.lastname: Beutels
authors.forename: Geert
authors.initials: G
authors.lastname: Baggerman
authors.forename: Inge
authors.initials: I
authors.lastname: Mertens
authors.forename: Dirk
authors.initials: D
authors.lastname: Valkenborg
authors.forename: Bart
authors.initials: B
authors.lastname: Landuyt
authors.forename: Liliane
authors.initials: L
authors.lastname: Schoofs
authors.forename: Kristof
authors.initials: K
authors.lastname: Tirez
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D057230:Limit of Detection; D013058:Mass Spectrometry / Q000379:methods*; D009596:Nitrophenols / Q000737:chemistry; D010748:Phosphopeptides / Q000032:analysis* / Q000737:chemistry*; D059629:Signal-To-Noise Ratio
chemical_list: D009596:Nitrophenols; D010748:Phosphopeptides; C002887:bis(4-nitrophenyl)phosphate