Evaluation of OptiFlow™-MS/MS for bioanalysis of pharmaceutical drugs and metabolites

Aim: Microflow tandem mass spectrometry-based methods have been proposed as options to improve sensitivity and selectivity while improving sample utility and solvent consumption. Here, we evaluate a newly introduced microflow source, OptiFlow™, for quantitative performance. Results/methodology: We performed a comparison of the OptiFlow and IonDrive™ sources, respectively, on the same triple quadrupole mass spectrometer. The comparison used a neat cocktail of commercially available drugs and extracted plasma samples monitoring midazolam and alprazolam metabolites. Microflow produced a 2–4× signal increase for the neat drug cocktail and a 5–10× increase for extracted plasma samples. Conclusion: The OptiFlow method consistently gave increased signal response relative to the IonDrive method and enabled a better lower limit of quantitation for defining phamacokinetics.

Protein quantification by LC–MS: a decade of progress through the pages of Bioanalysis

Over the past 10 years, there has been a remarkable increase in the use of LC–MS for the quantitative determination of proteins, and this technique can now be considered an established bioanalytical platform for the quantification of macromolecular drugs and biomarkers, next to the traditional ligand-binding assays. Many researchers have contributed to the field and helped improve both the technical possibilities of LC–MS-based workflows and our understanding of the meaning of the results that are obtained. As a tribute to Bioanalysis, which has published many important contributions, this report gives a high-level overview of the most important trends in the field of protein LC–MS, as published in this journal since its inauguration a decade ago. It describes the major technical developments with regard to sample handling, separation and MS detection of both digested and intact protein analysis. In addition, the relevance of the complex structure and in vivo behavior of proteins is discussed and the effect of protein–protein interactions, biotransformation and the occurrence of isoforms on the analytical result is addressed.

Qualitative and quantitative characterization of protein biotherapeutics with liquid chromatography mass spectrometry

In the last decade, the advancement of liquid chromatography mass spectrometry (LC/MS) techniques has enabled their broad application in protein characterization, both quantitatively and qualitatively. Owing to certain important merits of LC/MS techniques (e.g., high selectivity, flexibility, and rapid method development), LC/MS assays are often deemed as preferable alternatives to conventional methods (e.g., ligand-binding assays) for the analysis of protein biotherapeutics. At the discovery and development stages, LC/MS is generally employed for two purposes absolute quantification of protein biotherapeutics in biological samples and qualitative characterization of proteins. For absolute quantification of a target protein in bio-matrices, recent work has led to improvements in the efficiency of LC/MS method development, sample treatment, enrichment and digestion, and high-performance low-flow-LC separation. These advances have enhanced analytical sensitivity, specificity, and robustness. As to qualitative analysis, a range of techniques have been developed to characterize intramolecular disulfide bonds, glycosylation, charge variants, primary sequence heterogeneity, and the drug-to-antibody ratio of antibody drug conjugate (ADC), which has enabled a refined ability to assess product quality. In this review, we will focus on the discussion of technical challenges and strategies of LC/MS-based quantification and characterization of biotherapeutics, with the emphasis on the analysis of antibody-based biotherapeutics such as monoclonal antibodies (mAbs) and ADCs. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:734-754, 2017.

A novel sequential electrostatic-HILIC SPE within a quantitative method for bivalirudin in human plasma by LC–SRM

Aim: This work set out to realize an idea for a novel means of extracting the peptide therapeutic bivalirudin from human plasma in what would be a uniquely selective means of SPE, a mixed-mode protocol involving electrostatic interactions followed by HILIC. Results: Inter and intra-assay relative error ranged from 3.52 to 8.23%, and 2.37 to 6.90%, respectively. Inter and intra-assay precision ranged from 2.64 to 7.12%, and 0.855 to 2.90%, respectively. Recoveries of 80% were attained, and there was no hint of discernible manifestation of matrix effects. Conclusion: The method was shown to perform excellently in the assessment tantamount to method validation. The essence of the extraction method presents a new option for highly selective extraction of peptides from biological matrices.

Practical applications of integrated microfluidics for peptide quantification

Background: Increased pressure to obtain more, higher sensitivity data from less sample is especially critical for large peptides, whose already optimized LC–MS methods are heavily challenged by traditional ligand-binding assays. Results: Critical bioanalytical assays were adapted to integrated microscale LC to reduce sample volumes while increasing sensitivity. Assays for teriparatide, glucagon and human insulin and five analogs were transferred from 2.1 mm analytical scale LC to a 150 µm scale system. This resulted in a 15–30 fold overall improvement in sensitivity derived from increased signal to noise, three to six fold reduction in injection volumes, and a two to five fold reduction in sample consumption. Conclusion: Integrated microscale LC reduces sample consumption while enabling single picomolar quantification for therapeutic and endogenous peptides.