Application of high-resolution MS in the quantification of a therapeutic monoclonal antibody in human plasma.

Background: Monoclonal antibodies are the fastest growing class of protein therapeutics. Ligand-binding assays have been the technique of choice for the quantification of these large proteins; however, LC-MS and more recently LC-HRMS have been gaining momentum as robust alternatives for the bioanalysis of antibodies in biological matrices.

Results: Optimization of sample preparation and LC-HRMS analysis in MRM(HR) mode has allowed us to develop a highly specific dual-peptide targeted assay for the quantification of Rituximab, in human plasma.

Choosing the appropriate matrix to perform a scientifically meaningful lipemic plasma test in bioanalytical method validation.

Laurence Mayrand-Provencher has obtained a Master of Science in Chemistry from Université de Montréal. With over 3 years of experience as a scientist in the bioanalysis industry, he is now a scientist in method development at Algorithme Pharma. His experiences have led him to conduct robust and effective method development of bioanalytical assays, specifically in the LC-MS/MS field.

Impact of organic solvent additive on the integrity of plasma samples in bioanalysis by LC-MS/MS.

Background: Matrix effects are one of the major drawbacks of ESI-MS/MS. It is majorly caused by lipids in plasma, which can be overcome by using different extraction techniques.

Results: In this investigation, a major matrix effect was observed in samples containing a co-administered drug.

Large-molecule quantification: sensitivity and selectivity head-to-head comparison of triple quadrupole with Q-TOF.

Background: Bioanalysts are continuously looking for innovative ideas or instruments to increase the sensitivity and selectivity of their assays. Research for better mass spectrometers is becoming crucial with the emerging trend of large-molecule quantification. This study lists the different advantages of high-resolution MS (HRMS) over standard triple quadrupole instruments and proposes basic guidelines on how to use HRMS for large-molecule quantification in a regulated environment.

Dried blood spot on-card derivatization: an alternative form of sample handling to overcome the instability of thiorphan in biological matrix.

Thiorphan, the active metabolite of racecadotril, can undergo oxidation in biological matrices such as blood and plasma. In bioanalysis, a general approach for the stabilization of such a molecule is to derivatize the thiol group to a more stable thioether, often requiring complex handling procedures at the clinical site. In this research, the concept of dried blood spot (DBS) on-card derivatization was evaluated to stabilize thiorphan.

A practical approach to reduce interference due to in-source collision-induced dissociation of acylglucuronides in LC-MS/MS.

Background: In LC-MS/MS, glucuronide conjugated metabolites may convert back to the parent drug due to in-source collision-induced dissociation (CID).

Results: During the bioanalysis of naproxen, it was noticed that naproxen acylglucuronide exhibited intense in-source CID to the naproxen [M+H](+) ion under positive ESI. However, no in-source CID of the acylglucuronide to the naproxen [M+NH(4)](+) adduct was observed.

Reliable procedures to evaluate and repair crosstalk for bioanalytical MS/MS assays.

Louis-Philippe Morin is a senior instrument application specialist at Algorithme Pharma, a CRO located in Laval, Canada. He has been working in the bioanalysis industry for the past 10 years where he became a subject matter expert in analytical instrumentation, especially in the MS field. His responsibilities in his current position are to optimize the workflow of the laboratory and to find new procedures, or approaches, to fix complex analytical problems.

Determination of naproxen using DBS: evaluation & pharmacokinetic comparison of human plasma versus human blood DBS.

Background: Dried blood spots (DBS) sampling is a well-known technology for qualitative determination such as DNA analysis and screening of newborn metabolic disorders. The scientific community has recently expressed interest in applying the DBS technique for quantitative determination of drugs in biological fluid.

Results: Two new bioanalytical assays were developed and validated for the determination of naproxen in human plasma and in DBS samples using liquid chromatography coupled with tandem MS.

Elimination of LC-MS/MS matrix effect due to phospholipids using specific solid-phase extraction elution conditions.

Background: The objective is to find elution conditions using different solid-phase extraction chemistries to reduce the amount of phospholipids in plasma extract, which is associated with matrix effect in LC-MS.

Results: Phospholipids' recovery was reduced by decreasing the eluents' methanol content applied to silica-based and polymer-based reversed-phase solid-phase extraction cartridges while 100% acetonitrile applied to the silica-based cartridges drastically minimized the phospholipids' elution. Silanol interactions are involved in the increased retention of phospholipids with silica-based reversed-phase cartridges when using high percentages of ACN in eluents.

Effect of high pH mobile phase on the sensitivity of multiple drugs by LC positive electrospray ionization MS/MS.

Background: In this study, the postcolumn addition approach was used to evaluate the impact of high pH modifiers on the sensitivity of 25 compounds by LC-MS/MS under positive ESI (ESI+).

Results: None of the compounds were significantly suppressed by the use of high pH modifiers. Most of them showed a signal enhancement by at least twofold compared with acidic modifiers.

Matrix effect elimination during LC-MS/MS bioanalytical method development.

Due to the presence of endogenous components in biofluids, ionization suppression or enhancement may occur for bioanalytical assays using LC-MS or LC-MS/MS technologies. The matrix effect may affect the precision and accuracy of a bioanalytical method and, therefore, compromise the quality of the results. Protein precipitation sample preparation along with LC-MS/MS is a high-throughput method most commonly used in bioanalysis and is largely affected by the matrix effect.

Selection of HILIC columns to handle matrix effect due to phospholipids.

Background: Phospholipids from biological samples are a source of matrix effect in liquid chromatography mass spectrometry. While the behavior of phospholipids has been documented under reversed-phase chromatography, there is a lack of information concerning the selectivity of hydrophilic interaction chromatography (HILIC) towards phospholipids.

Results: Human plasma extracts were used to evaluate retention times and matrix effects associated with phospholipids under HILIC conditions.

A "Whirly" transcription factor is required for salicylic acid-dependent disease resistance in Arabidopsis.

Transcriptional reprogramming is critical for plant disease resistance responses; its global control is not well understood. Salicylic acid (SA) can induce plant defense gene expression and a long-lasting disease resistance state called systemic acquired resistance (SAR). Plant-specific "Whirly" DNA binding proteins were previously implicated in defense gene regulation.