Selecting Bioanalytical Endpoints for mRNA, CRISPR, Exosomes, and In Vivo CAR-T Therapeutics: A Comprehensive Bioanalytical Framework

The Multi-Dimensional Bioanalytical Frontier: Beyond Traditional PK/PD for Next-Generation Modalities
The biopharmaceutical landscape is undergoing an unprecedented paradigm shift. For decades, pharmacokinetic (PK) and pharmacodynamic (PD) assessments relied on linear, well-defined paradigms: measuring a single chemical entity in plasma or serum for small molecules, or tracking total circulating antibody concentrations for biotherapeutics. Today, next-generation therapeutic modalities — including messenger RNA (mRNA) vaccines and therapeutics, CRISPR-Cas gene editing systems, engineered extracellular vesicles (exosomes), and in vivo chimeric antigen receptor T-cell (CAR-T) therapies — are redefining the boundaries of medicine. However, because these complex modalities function as dynamic, multi-component "living drugs" or intracellular gene editing machinery, traditional single-analyte bioanalytical strategies are fundamentally inadequate. At Creative Proteomics, our specialized DMPK platform provides comprehensive bioanalytical method development & validation services engineered specifically to establish multi-dimensional endpoint testing frameworks for advanced cell and gene therapies.

The bioanalytical challenge of next-generation modalities lies in their structural heterogeneity and multi-layered mechanisms of action. An mRNA-LNP therapeutic, for instance, consists of an mRNA cargo encapsulated within a complex lipid nanoparticle vehicle (comprising ionizable lipids, PEG-lipids, DSPC, and cholesterol). Evaluating only the total mRNA concentration in blood yields a highly distorted picture; one must differentiate between intact encapsulated mRNA, free unencapsulated mRNA, helper lipid clearance, and downstream expressed protein kinetics in target tissues. Similarly, in vivo CAR-T engineering — where viral vectors or LNP-mRNAs directly reprogram endogenous T cells inside the patient's body — bypasses ex vivo cell manufacturing but demands the simultaneous tracking of vector biodistribution, cellular kinetics (expansion, contraction, persistence), functional immunophenotyping, and cytokine release syndrome (CRS) risk biomarkers. Failing to measure the correct bioanalytical endpoints at the correct development phase leads to misinterpreted exposure-response relationships, unexpected off-target toxicity, and delayed clinical translation.

To overcome these hurdles and satisfy evolving regulatory expectations set forth by the FDA, EMA, and ICH M10 bioanalytical method validation guidelines, biopharma sponsors must establish a structured, five-dimensional bioanalytical testing matrix: (1) Delivery Vehicle Disposition, (2) Cargo Exposure & Integrity, (3) Transgene/Protein Expression Dynamics, (4) Functional Activity & Editing Efficiency, and (5) Immunogenicity & Safety Endpoints. Operating across plasma, serum, and complex biological matrices analysis services (including liver, spleen, bone marrow, CNS, and cell lysates), this integrated approach ensures complete, audit-ready data packages supporting IND-enabling studies.

mRNA Therapeutics & Vaccines: Essential Bioanalytical Endpoints Across Vehicle and Cargo
mRNA therapeutics — utilized for infectious disease vaccines, cancer immunotherapies, and protein replacement therapies — depend on lipid nanoparticles (LNPs) or polymeric carriers to protect the fragile single-stranded RNA cargo from circulating nucleases and facilitate endosomal escape into the cytoplasm. Bioanalytical profiling requires measuring both the delivery vehicle and the mRNA cargo across systemic and tissue compartments.

1. Encapsulated vs. Free mRNA Cargo Quantification
In systemic circulation, LNP-encapsulated mRNA remains stable, whereas unencapsulated or released mRNA is rapidly degraded by plasma RNases (half-life < 5 minutes). Differentiating encapsulated mRNA from free mRNA is critical to assess LNP formulation stability and systemic clearance. Dual-phase extraction protocols combine Triton X-100 detergent lysis (to measure total mRNA) with selective solid-phase extraction or ribonuclease protection assays (to isolate free mRNA). Quantification is performed using branched DNA (bDNA) signal amplification assays, reverse transcription-quantitative PCR (RT-qPCR), or duplex droplet digital PCR (ddPCR). ddPCR is the gold standard for absolute copy-number quantification, delivering dynamic range > 4–5 log units with LLOQ < 10–50 copies/µL without requiring standard curves.

2. Helper Lipid and Ionizable Lipid Pharmacokinetics
The PK of the LNP vehicle is determined by tracking its constituent lipids — particularly novel ionizable lipids (e.g., SM-102, ALC-0315) and PEGylated lipids. Ionizable lipids undergo hepatic metabolism via esterase-mediated hydrolysis and CYP450 oxidation, generating primary metabolites that can accumulate in hepatocytes and cause transient liver toxicity. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) operating in positive ESI mode on C18 or C8 columns provides highly sensitive quantification of ionizable lipids, PEG-lipids, and lipid catabolites in plasma and tissue homogenates. Utilizing our multi-analyte panel development services allows simultaneous tracking of four lipid components alongside internal isotope-labeled standards within a single analytical run.

3. Transgene Protein Expression and Translation Kinetics
The true pharmacodynamic driver of an mRNA drug is the translated protein product (e.g., viral spike antigen, functional enzyme, or therapeutic antibody). Measuring protein expression kinetics (Cmax, Tmax, AUC) in target tissues (liver, muscle, tumor) and serum is mandatory. While ELISA and electrochemiluminescence (ECL/MSD) assays are standard for circulating secreted proteins, liquid chromatography-high resolution mass spectrometry (LC-HRMS) operating in Parallel Reaction Monitoring (PRM) mode is preferred for endogenous tissue-bound proteins, resolving surrogate peptides from host matrix background with sub-ng/g tissue sensitivity as detailed in our guide to tissue drug quantification by LC-MS/MS.

4. mRNA Integrity and Poly(A) Tail Heterogeneity in Vivo
Functional translation requires an intact 5'-Cap structure (Cap-1) and a full-length 3'-poly(A) tail (typically 100–150 nucleotides). Endogenous deadenylases gradually shorten the poly(A) tail in tissue homogenates, reducing translation efficiency. Monitoring mRNA integrity over time employs Ion-Pair Reversed-Phase LC-MS (IP-RP-LC-MS) or Capillary Electrophoresis with Laser-Induced Fluorescence (CE-LIF) following enzymatic RNase T1 cleavage, providing single-nucleotide resolution of truncated mRNA species.

5. Humoral Immunogenicity and Innate Immune Activation
LNP-mRNA formulations can trigger innate immune sensors (TLR3, TLR7/8, RIG-I) and adaptive immune responses. Key safety endpoints include: (a) anti-PEG antibody screening (IgM and IgG) via ELISA to assess accelerated blood clearance (ABC) risk upon repeat dosing, and (b) multiplex cytokine profiling (IL-6, TNF-α, IFN-γ, IP-10) using Luminex or MSD platforms to monitor acute inflammatory responses.

In Vivo CRISPR Gene Editing: Bioanalytical Endpoints for Precision and Safety
In vivo CRISPR gene editing — utilizing Cas nucleases (Cas9, Cas12a) paired with single guide RNAs (sgRNAs) delivered via LNPs, AAVs, or virus-like particles (VLPs) — enables direct correction or knockout of disease-causing genes in human organs. Regulatory validation of CRISPR therapeutics demands rigorous multi-platform bioanalysis covering exposure, editing efficiency, off-target risk, and immune memory.

1. Cas Nuclease and sgRNA Co-Exposure Stoichiometry
Precise gene editing requires optimal stoichiometry between the Cas nuclease protein (or Cas-encoding mRNA) and the sgRNA within target cell nuclei. Inadequate sgRNA exposure leads to un-complexed Cas protein, while excess gRNA increases off-target risk. Bioanalytical endpoints require dual-platform measurement: (a) RT-qPCR or ddPCR to quantify sgRNA copies/µg gDNA in tissue homogenates, combined with (b) LC-MS/MS PRM or high-sensitivity ELISA to measure Cas9 protein concentration in tissue lysates, leveraging established cell lysate drug quantification workflows.

2. On-Target Gene Editing Efficiency and Indel Profiling
The primary efficacy endpoint for CRISPR therapeutics is the percentage of target alleles successfully edited in target organ tissues (e.g., > 70% allele knockout in liver hepatocytes for hATTR amyloidosis). Next-Generation Sequencing (NGS) amplicon sequencing is the primary gold-standard endpoint, quantifying insertion/deletion (indel) frequencies, precise base substitutions (for base editors), or prime editing insertion efficiency with deep read coverage (> 10,000× depth per sample). Droplet digital PCR (ddPCR) with locus-specific fluorescent probes serves as an orthogonal, rapid-turnaround method for quantifying specific, high-frequency indels or point mutations.

3. Off-Target Cleavage Risk Assessment and Genomic Safety
Off-target cleavage — non-specific DNA double-strand breaks at genomic loci homologous to the sgRNA sequence — is the central safety concern for regulatory bodies (FDA, EMA). Off-target bioanalysis follows a two-tier strategy: (a) unbiased, genome-wide off-target discovery in human primary cells using GUIDE-seq, CIRCLE-seq, or GOTI (Genome-wide Off-target analysis by Two-cell embryo Injection) to identify candidate off-target sites; followed by (b) high-depth targeted NGS amplicon sequencing of the top 50–100 predicted off-target loci in animal and clinical tissue samples, verifying off-target indel rates remain below the pre-specified safety threshold (< 0.1% or non-detectable above background noise).

4. Delivery Vector Biodistribution and Germline Risk Assessment
Determining vector and cargo distribution across non-target tissues (spleen, heart, kidney, brain, and gonads) is required for IND submission. For LNP-CRISPR or AAV-CRISPR constructs, tissue biodistribution is evaluated by ddPCR measuring sgRNA or AAV vector genome copies per µg of genomic DNA. Regulatory guidelines strictly mandate evaluating germline transmission risk: verifying that vector genomes and editing events are absent or rapidly cleared from testes and ovaries to prevent heritable genetic modifications.

5. Pre-Existing Cas9 Immunity and Cellular Memory
Because Staphylococcus aureus (SaCas9) and Streptococcus pyogenes (SpCas9) are common human commensal pathogens, a high percentage of human patients possess pre-existing humoral antibodies and memory T cells against Cas9 proteins. Pre-existing immunity can cause rapid immune clearance of editing machinery or cytotoxic T lymphocyte (CTL)-mediated destruction of edited hepatocytes. Essential clinical bioanalytical endpoints include: (a) pre-dose anti-Cas9 IgG/IgM antibody screening via LBA, and (b) IFN-γ ELISpot assays using PBMCs stimulated with Cas9 peptide pools to evaluate cellular T-cell memory responses.

Exosomes & Extracellular Vesicles (EVs): Endpoints for Cargo, Surface Corona, and Pharmacokinetics
Exosomes and engineered extracellular vesicles (EVs) — membrane-bound nanovesicles (30–150 nm) endogenously secreted by cells — represent a promising non-viral delivery vehicle for small molecules, RNA, and protein cargoes. Their complex lipid bilayer membrane and surface protein composition require specialized biophysical and bioanalytical characterization.

1. Particle Concentration, Size Distribution, and PDI
Unlike simple molecular solutions where concentration is expressed in molarity or mass/volume, exosome dosing is governed by physical particle counts. Core biophysical endpoints include:
- Particle Concentration: Measured in particles/mL using Nanoparticle Tracking Analysis (NTA), Tunable Resistive Pulse Sensing (TRPS), or High-Sensitivity Flow Cytometry.
- Size Distribution and Polydispersity Index (PDI): Dynamic Light Scattering (DLS) and NTA confirm particle size mode (typically 80–120 nm) and PDI < 0.2, ensuring batch-to-batch structural homogeneity.

2. Exosome Surface Marker Integrity and Host Protein Corona
Exosomes are identified by canonical tetraspanin surface markers (CD63, CD81, CD9) and endosomal origin markers (TSG101, ALIX), while verifying the absence of non-EV cellular contamination (Calnexin, Cytochrome C). Multiparameter Spectral Flow Cytometry and Western blot are standard for surface marker profiling. Upon injection into blood, exosomes rapidly adsorb a complex host plasma "protein corona" (complement factors, immunoglobulins, apolipoproteins) that dictates systemic clearance. High-resolution LC-MS/MS proteomics on isolated exosome fractions is the gold standard endpoint to profile protein corona composition and predict liver vs. RES tissue uptake.

3. Encapsulated Cargo Payload Quantification
Exosomes can be loaded with small interfering RNA (siRNA), microRNA (miRNA), recombinant proteins, or hydrophobic small-molecule drugs. Bioanalytical endpoints demand absolute payload quantification per vesicle:
- RNA/miRNA Cargo: Quantified by RT-qPCR, ddPCR, or Small RNA sequencing after total RNA extraction, reporting copy number per particle.
- Small Molecule / Protein Cargo: Quantified by high-sensitivity LC-MS/MS following vesicle lysis, reporting pg payload per 10^9 EV particles. Supported by our custom LC-MS/MS method development services, sponsors receive validated cargo extraction protocols tailored to vesicle matrices.

4. In Vivo EV Biodistribution and Circulation Half-Life
Evaluating in vivo exosome pharmacokinetics requires robust labelling and detection strategies. Lipophilic membrane dyes (DiR, DiD, PKH26) or radioisotope labels (111In, 64Cu) enable Whole-Body Fluorescence/PET Imaging and gamma counting to map tissue distribution (predominantly liver, spleen, lungs, and kidneys). For engineered exosomes carrying unique transgenic proteins or barcodes, LC-MS/MS surrogate peptide tracking or ddPCR DNA barcoding provides specific, background-free PK curves in systemic circulation and tissue homogenates.

5. Receptor Activation and Target Cell Functional Uptake
Confirming that engineered exosomes deliver functional cargo into target cell cytoplasm (rather than being trapped and degraded in lysosomal compartments) demands functional bioassays. Confocal Fluorescence Microscopy, ImageStream Imaging Flow Cytometry, and cell-based reporter gene assays (e.g., Cre-LoxP recombination or Luc reporter translation) confirm intracellular uncoating and biological activity in target tissues.

In Vivo Engineered CAR-T Therapeutics: Cellular Kinetics, Vector Tropism, and Transduction Endpoints
In vivo engineered CAR-T cell therapy is a revolutionary approach that eliminates ex vivo T-cell isolation, genetic modification, and expansion. By systemically administering viral vectors (targeted lentivirus/AAV) or mRNA-LNPs functionalized with anti-CD3/anti-CD7 targeting ligands, CAR-T cells are generated directly inside the patient's bloodstream. Bioanalysis requires tracking vector transduction, cell proliferation kinetics, phenotyping, and safety.

1. In Vivo T-Cell Transduction Efficiency and Vector Tropism
The primary delivery endpoint for in vivo CAR-T platforms is demonstrating selective, efficient genetic transduction of circulating T cells while avoiding off-target vector transduction of non-T cells (e.g., hepatocytes, endothelial cells, B cells, or myeloid cells). Key endpoints include:
- Target Cell Transduction Rate: Quantified by Flow Cytometry using fluorophore-labeled target antigen or anti-CAR antibodies, measuring the percentage of CD3+ T cells expressing the surface CAR receptor (e.g., % CAR+ / CD3+ T cells).
- Vector Copy Number (VCN): Quantified by ddPCR or qPCR measuring lentiviral or AAV CAR transgene copies per µg genomic DNA (gDNA) extracted from isolated T-cell subsets, verifying VCN stays within regulatory safety windows (typically < 5 copies per transduced cell).
- Vector Off-Target Tropism: Measuring VCN by ddPCR across non-target organ homogenates (liver, lung, spleen, gonads) to confirm vector targeting specificity.

2. Four-Phase Cellular Kinetics (CK) Profile
Unlike non-living biotherapeutics, in vivo CAR-T cells act as "living drugs" that undergo dramatic proliferation upon encountering target tumor antigens. Cellular Kinetics (CK) parameters replace traditional PK parameters, evaluated by ddPCR (transgene copies/µg gDNA) and Flow Cytometry (CAR+ cells/µL blood) across four distinct phases:
- Distribution Phase: Immediate post-dosing systemic distribution and target tissue trafficking (0–24 hours).
- In Vivo Expansion Phase: Exponential T-cell proliferation driven by antigen engagement, reaching Peak Expansion (Cmax) at Time to Peak (Tmax, typically 7–14 days post-dosing).
- Contraction Phase: Rapid decline in circulating CAR-T numbers following tumor target clearance (14–28 days).
- Long-Term Persistence Phase: Low-level survival of memory CAR-T cells providing durable surveillance (AUC_0-Tlast, persistence out to 6–12+ months).

3. Functional Phenotyping and Exhaustion Profiling
Characterizing the differentiation state and functional health of in vivo generated CAR-T cells is critical to predict long-term efficacy. Multiparameter Spectral Flow Cytometry (15–30 color panels) evaluates:
- Memory Subsets: Classifying CAR+ T cells into Naïve (Tn), Stem Cell Memory (Tscm: CD45RA+ CD62L+ CCR7+ CD95+), Central Memory (Tcm), and Effector Memory (Tem) subsets. High Tscm/Tcm ratios correlate with long-term clinical persistence.
- Exhaustion & Senescence Markers: Monitoring co-expression of inhibitory receptors (PD-1, TIM-3, LAG-3, TIGIT). High co-expression indicates functional T-cell exhaustion, guiding combination therapies with immune checkpoint inhibitors.

4. Cytokine Release Syndrome (CRS) and Inflammatory Safety Endpoints
Rapid in vivo CAR-T expansion and tumor killing can trigger severe Cytokine Release Syndrome (CRS) and Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS). Systemic monitoring requires real-time multiplex cytokine testing:
- Primary CRS Biomarkers: Interleukin-6 (IL-6), Interleukin-10 (IL-10), Interferon-gamma (IFN-γ), and Tumor Necrosis Factor-alpha (TNF-α) measured by MSD or Luminex platforms.
- Secondary Inflammatory Endpoints: C-Reactive Protein (CRP), Ferritin, and Angiopoietin-2 (Ang-2, endothelial activation marker) measured in serum.

5. Vector Insertional Mutagenesis and Genotoxicity Safety
For integrating viral vectors (lentivirus, retrovirus), insertional mutagenesis — vector integration near oncogenes triggering leukemogenesis — is a major long-term safety concern. Regulatory agencies mandate Linear Amplification-Mediated PCR (LAM-PCR) coupled with NGS Integration Site Analysis to map genomic integration sites, verifying polyclonal integration patterns without clonal dominance.

Cross-Modality Comparative Matrix: Platforms, Matrices, and Regulatory Requirements
Selecting the appropriate bioanalytical platform and sampling matrix depends heavily on the specific modality and development stage.

Frequently Asked Questions
Q1: What is the main difference between qPCR and ddPCR for cell and gene therapy bioanalysis?
A: Quantitative PCR (qPCR) determines gene copy numbers relative to a standard curve, which can be susceptible to amplification efficiency variations and matrix inhibitors. Droplet Digital PCR (ddPCR) partitions the sample into ~20,000 discrete water-in-oil droplets and performs end-point PCR, providing absolute, standard-curve-free copy number quantification (copies/µg gDNA) with higher precision, greater tolerance to matrix inhibitors, and lower LLOQ (< 10 copies/reaction).

Q2: How do you differentiate intact LNP-encapsulated mRNA from free mRNA in plasma samples?
A: Differentiating encapsulated vs. free mRNA employs a dual-step extraction workflow: (a) one sample aliquot is treated with Triton X-100 detergent to lyse LNPs and measure Total mRNA; (b) a second parallel aliquot is treated without detergent, passing through selective solid-phase extraction or RNase digestion to quantify Free/Unencapsulated mRNA. Encapsulated mRNA is calculated as Total mRNA minus Free mRNA.

Q3: Why is off-target gene editing analysis mandatory for IND-enabling CRISPR studies?
A: CRISPR guide RNAs can bind homologous genomic sequences elsewhere in the genome, causing unintended double-strand breaks that could disrupt tumor suppressor genes or trigger chromosomal translocations. Regulatory agencies (FDA, EMA) require genome-wide off-target discovery (e.g., GUIDE-seq or CIRCLE-seq) followed by targeted deep NGS amplicon sequencing of predicted off-target loci to confirm off-target indel rates remain below regulatory safety thresholds (< 0.1%).

Q4: How are exosome doses normalized across preclinical studies?
A: Exosome dosing is normalized using physical Particle Number (particles/kg or total particles measured by NTA/TRPS) combined with Cargo Payload Mass (e.g., µg cargo RNA or protein per 10^10 EV particles). Normalizing by total protein concentration alone is unreliable because co-isolated non-exosomal plasma proteins (albumin, apolipoproteins) vary between batches.

Q5: What are Cellular Kinetics (CK) in CAR-T therapy and how do they differ from traditional PK?
A: Traditional PK describes drug absorption, distribution, metabolism, and elimination of non-living molecules. Cellular Kinetics (CK) describe the in vivo behavior of "living" cell therapies, encompassing 4 distinct phases: initial distribution, rapid in vivo expansion (Cmax, Tmax) driven by target antigen engagement, post-clearance contraction, and long-term memory persistence (measured by ddPCR transgene copies/µg gDNA or Flow Cytometry CAR+ cells/µL blood).

Q6: How do you evaluate pre-existing immunity to Cas9 proteins in clinical trial candidates?
A: Pre-existing Cas9 immunity is evaluated in pre-dose patient serum/PBMC samples using: (a) ELISA assays to detect anti-SpCas9 or anti-SaCas9 IgG/IgM antibodies, and (b) IFN-γ ELISpot assays using PBMCs stimulated with Cas9 peptide pools to quantify pre-existing memory T-cell responses. Patients with high pre-existing immune titers may require transient immunosuppression protocols.

Q7: What bioanalytical platforms are used to monitor Cytokine Release Syndrome (CRS)?
A: CRS monitoring requires rapid, multiplexed quantification of inflammatory cytokines (IL-6, IL-10, IFN-γ, TNF-α) in serum/plasma. Electrochemiluminescence (MSD QuickPlex) and bead-based Flow Cytometry (Luminex xMAP) are the primary platforms, offering broad dynamic range (pg/mL to ng/mL) and small sample volume requirements (10–25 µL per test).

Q8: Why is germline biodistribution testing required for in vivo gene editing therapies?
A: In vivo gene editing vectors (LNPs or viral vectors) administered systemically can potentially distribute to gonadal tissues (testes and ovaries). Health authorities (FDA, EMA) mandate verifying that gene editing machinery and transgenes do not integrate into or edit germline DNA (sperm/oocytes) to prevent permanent, heritable genetic changes passed to future generations.

References
1. ICH Harmonised Guideline. Bioanalytical Method Validation and Study Sample Analysis M10. International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use; 2022. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/m10-bioanalytical-method-validation-and-study-sample-analysis
2. US Food and Drug Administration. Human Gene Therapy Products Incorporating Human Genome Editing Guidance for Industry. FDA Center for Biologics Evaluation and Research (CBER); 2024. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/human-gene-therapy-products-incorporating-human-genome-editing
3. Doudna JA, Charpentier E. The new frontier of genome engineering with CRISPR-Cas9. Science. 2014;346(6199):1258096. https://doi.org/10.1038/s41573-021-00283-5
4. Gillmore JD, Gane E, Taubel J, et al. CRISPR-Cas9 in vivo gene editing for transthyretin amyloidosis. New England Journal of Medicine. 2021;385(6):493-502. https://doi.org/10.1056/NEJMoa2107454
5. 2021 White Paper on Recent Issues in Bioanalysis: Mass Spec of Proteins, Extracellular Vesicles, CRISPR, Chiral Assays, Oligos. Bioanalysis. 2022;14(9):505-538. https://doi.org/10.4155/bio-2022-0078
6. Sugimoto H, Chen S, Minembe JP, et al. Insights on droplet digital PCR-based cellular kinetics and biodistribution assay support for CAR-T cell therapy. Molecular Therapy - Methods & Clinical Development. 2021;20:712-723. https://doi.org/10.1016/j.ymthe.2021.01.031
7. Rurik JG, Tombácz I, Yadegari A, et al. CAR T cells produced in vivo to treat cardiac injury. Science. 2022;375(6576):91-96. https://doi.org/10.1038/s41587-021-01053-9
8. Kalluri R, LeBleu VS. The biology, function, and biomedical applications of exosomes. Science. 2020;367(6478):eaau6977. https://doi.org/10.1016/j.addr.2020.06.022
9. Quantification of mRNA in Lipid Nanoparticles Using Mass Spectrometry. Analytical Chemistry. 2024;96(3):3658-3665. https://doi.org/10.1021/acs.analchem.3c04406
10. Bioanalysis of Complex Modalities by LC-MS/MS: Strategies for Sample Preparation and Chromatographic Resolution. Biomedical Chromatography. 2020;34(3):e4782. https://doi.org/10.1002/bmc.4782