Feasibility assessment of a novel selective peptide derivatization strategy for sensitivity enhancement for the liquid chromatography/tandem mass spectrometry bioanalysis of protein therapeutics in serum

Optimizing oxytocin LC-MS/MS sensitivity by choosing the right column

Objective

Sensitivity is often an issue in bioanalytical LC-MS/MS applications. Commonly investigated parameters to improve it include additives to mobile phase, derivatization and sample-preparation. The nature of the column, however, is not frequently evaluated.

Design and Methods

The sensitivity is compared for 18 different reversed phase and 2 different HILIC columns using 2 different mobile phase compositions. Sensitivity was evaluated in terms of S/N for 1,5 pg oxytocin on column, using a scouting gradient.

Results

The measured signal to noise ranged from 55 to 1473, indicating a substantial difference in sensitivity. The most sensitive columns were the Synergi Hydro RP (reversed phase) and the Atlantis HILIC (HILIC).

Conclusions

This study shows that choosing the right column contributes to the sensitivity of the method.

Quantitative analysis of factor P (Properdin) in monkey serum using immunoaffinity capturing in combination with LC–MS/MS

Aim: Factor P (Properdin), an endogenous glycoprotein, plays a key role in innate immune defense. Its quantification is important for understanding the pharmacodynamics (PD) of drug candidate(s). Results: In the present work, an immunoaffinity capturing LC–MS/MS method has been developed and validated for the first time for the quantification of factor P in monkey serum with a dynamic range of 125 to 25,000 ng/ml using the calibration standards and QCs prepared in factor P depleted monkey serum. The intra- and inter-run precision was ≤7.2% (CV) and accuracy within ±16.8% (%Bias) across all QC levels evaluated. Results of other evaluations (e.g., stability) all met the acceptance criteria. Conclusion: The validated method was robust and implemented in support of a preclinical PK/PD study.

Recent development of chemical derivatization in LC–MS for biomedical approaches

LC–MS/MS is currently the most powerful system in biomedical analysis. At the same time, chemical derivatization is a useful technique to enhance the detection sensitivity of nonionizable or poorly ionizable molecules in LC–MS/MS. Derivatization improves the ionization efficiency, the chromatographic separation and/or the chemical stability. This article presents an overview of the recent development of chemical derivatization reagents and reactions for the quantitative analysis of xenobiotic and endogenous molecules such as pharmaceuticals, amino acids, peptides, proteins, steroids, biomarkers and industrial products by LC–MS.