QPrEST White Papers

Discover the QPrEST standards for absolute protein quantification using mass spectrometry. In our white papers, you can learn more about QPrEST technology and unique features.

QPrEST Case Study
In a recent study, the performance of PSAQ, SIL-peptide, WiSIL-peptide, and QPrEST internal standards in monitoring the CSF levels of αSynuclein (αSyn) was evaluated. The authors concluded that, “QPrEST showed better accuracy in CSF than SIL and WiSIL peptides, indicating that it better reflects digestion conditions and is an improved alternative to them”.
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ELISA and LC-MS/MS supported by robust QPrEST standards are valuable cross validation partners.

Summary:

  • Direct comparison of ELISA and LC-MS/MS shows that the two methods are very valuable as cross-validation partners.
  • Case Study: Measurement of apolipoproteins in plasma samples using ELISA and LC-MS/MS + QPrEST standards
  • The data in this white paper was generated by Atlas Antibodies AB in collaboration with MABTECH AB.
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A robust method for the quantification of multiple apolipoproteins in human plasma based on MRM-LC/MS and QPrEST internal standards.

Summary:

  • QPrEST standards in combination with ProteinWorks™ eXpress Direct Digest Kit (Waters Corporation) can be used to accurately quantify apolipoproteins in human plasma.
  • The high correlation between LC-MS/MRM and ELISA data demonstrates that these methods can be used for cross-validation with confidence in the LC-MS/MRM results.
  • The data in this application note was generated by Atlas Antibodies AB in collaboration with Waters Sverige AB.
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Validated Isotope-Labeled Protein Standard for Absolute Quantification Using Mass Spectrometry

Summary

  • The QPrEST+ protein standards are readily available and contain peptides validated according to the CPTAC assay criteria
  • The QPrEST+ protein standard provides quantotypic peptides comparable to stable isotope-labeled full-length proteins
  • QPrEST+ shows good linear responses for quantotypic peptides and are suitable for single-point calibration
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Using the QTag for LC Retention Time Normalization

Summary

  • The QTag present in all QPrEST standards consists of a set of theoretical tryptic peptides which can be used for retention time normalization
  • Retention times of QTag peptides can be accurately predicted using iRT coordinates
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QPrEST High Accuracy Targeted Proteomics

Summary

  • Stable Isotope-Labeled Protein Standards for absolute quantification using mass spectrometry. 
  • Spiked in early and show a similar digestion efficiency to the endogenous proteins.
  • Used to determine absolute protein amounts in multiple sample types
  • Pre-quantified and ready-to-use
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High Accuracy Targeted Proteomics

Learn more about QPrEST standards for targeted proteomics and browse products. 

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