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Liquid chromatography/tandem mass spectrometric method for the quantification of eight proteolytic fragments of ITIH 4 with biomarker potential in human plasma and serum
Author(s) -
van den Broek Irene,
Sparidans Rolf W.,
Schellens Jan H. M.,
Beijnen Jos H.
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3695
Subject(s) - chemistry , chromatography , protein precipitation , formic acid , selected reaction monitoring , detection limit , mass spectrometry , tandem mass spectrometry , electrospray ionization , triple quadrupole mass spectrometer , solid phase extraction
A liquid chromatography/tandem mass spectrometric (LC/MS/MS) analytical procedure for the quantification of eight proteolytic fragments from inter‐α‐trypsin inhibitor heavy chain 4 (ITIH 4 ) in human plasma and serum has been developed. The eight peptide fragments only differ in length at the N‐terminus, varying between 21 and 30 amino acid residues. Protein precipitation (PP) with acetonitrile was followed by solid‐phase extraction (SPE) on C 2 columns to provide clean extracts. Chromatographic separation of the peptides was performed on a Symmetry 300 C 18 column (50 mm × 2.1 mm i.d., particle size 3.5 µm), using a water/methanol gradient containing 0.25% v/v formic acid. The triple quadrupole mass spectrometer was operated in the positive electrospray ionization (ESI + ) mode, using multiple reaction monitoring (MRM) for detection. One stable‐isotope‐labeled analog and two structural analogs were used as internal standards. The method has been completely validated for plasma and partially for serum samples, yielding linear responses in a range up to 100 ng/mL. The lower limit of quantification (LLOQ) in plasma was ±2 ng/mL for four ITIH 4 ‐derived peptides and ±5 ng/mL for the others. The stabilities of the peptides in different environments have been extensively explored. Several peptides showed rapid degradation, especially in the biological matrix at ambient temperature, and preparation on ice was therefore required. The method has been applied for the analysis of several plasma and serum samples from patients with different cancer types. Copyright © 2008 John Wiley & Sons, Ltd.