Isotope-labeled mass spectrometry-based absolute quantification of multiple proteins

Unlock True Protein Concentrations: Absolute Quantification Service

Our Absolute Protein Quantification service utilizes Stable Isotope Labeling combined with Tandem Mass Spectrometry (LC-MS/MS) to determine the exact molar concentration of target proteins within complex biological matrices. Unlike relative quantification methods that only provide fold-changes, or antibody-based assays that often suffer from cross-reactivity and matrix effects, this approach employs synthetic heavy isotope-labeled internal standards to ensure superior specificity and accuracy. By directly comparing the ion intensity of endogenous peptides against these strictly quantified standards, we provide researchers with definitive data that is entirely independent of antibody availability or variability.

This transition from simple identification to precise absolute quantification is a critical leap for advancing scientific research. The service allows scientists to rigorously validate potential biomarkers by establishing the exact concentration thresholds necessary for clinical diagnostics, as well as to decipher the specific stoichiometry of protein complexes for accurate kinetic modeling and systems biology. By offering a direct, sequence-specific measurement, this technology resolves the reproducibility issues common in traditional immunoassays, providing the high-fidelity data required for metabolic engineering, pharmacokinetic studies, and the development of robust diagnostic tests.

Why choose isotope-labeled tandem mass spectrometry for absolute quantification of multiple proteins?

Isotope-labeled tandem mass spectrometry (MS/MS) is a highly precise and reliable method for absolute protein quantification, offering unparalleled sensitivity, accuracy, and reproducibility. By incorporating stable isotope-labeled peptides as internal standards, this technique ensures accurate measurement of even low-abundance proteins across a broad dynamic range, without the need for external calibration curves. The high specificity of MS/MS minimizes interference from complex biological matrices, making it ideal for analyzing diverse sample types such as plasma, serum, and cerebrospinal fluid. When paired with our expert testing services, this powerful technology allows us to deliver highly reproducible, quantitative data tailored to your research needs, ensuring that your protein quantification is not only accurate but also streamlined and efficient, with professional analysis and interpretation included.

Absolute Protein Quantification at Creative Proteomics

We provide both test kits and testing services, allowing you to select the option that best fits your requirements.

• CP PolyQuantification 47 CVD-related Proteins Testing Service
  This specialized service provides a streamlined solution for translational cardiovascular research, offering absolute quantification of 47 clinically relevant plasma proteins associated with heart disease and vascular pathology. What sets this panel apart is its cross-species compatibility: it utilizes a set of 212 reference peptides specifically selected for their sequence conservation across Human, Mouse, and Rat genomes. This unique feature allows researchers to use a single analytical platform to bridge the gap between preclinical animal models and human clinical trials, ensuring data consistency throughout the drug development pipeline.
  To address the challenge of plasma complexity, we employ a sophisticated workflow where targets are organized into four distinct analytical arrays based on their native plasma abundance. This stratification ensures optimal sensitivity for every target, preventing high-abundance proteins from masking lower-abundance biomarkers. Requiring only a minimal sample volume (typically 10-20 µL), this service is ideal for longitudinal animal studies or valuable clinical biobank samples. Whether you are profiling atherosclerosis markers or validating cardiac toxicity panels, this service delivers the precise, cross-species data needed to accelerate biomarker discovery.
• CP PolyQuantification 29 CHO Proteins Testing Service
  Tailored specifically for the biopharmaceutical industry, this service addresses the critical challenge of monitoring impurities in biologic drug production. We provide absolute quantification for 29 specific Chinese Hamster Ovary (CHO) host cell proteins (HCPs)—contaminants that can compromise drug safety and efficacy if not properly cleared. Unlike non-specific ELISA methods, our targeted approach utilizes nanoflow LC-MS/MS to positively identify and quantify these specific targets. By employing stable ^15N-labeled isotope standards, we ensure rigorous accuracy, allowing process engineers to track the presence of these proteins with confidence throughout the manufacturing cycle.
  This service is optimized for cell culture supernatants and process intermediates derived from CHO cell lines, the industry standard for therapeutic protein production. The analysis utilizes 86 reference peptides, scientifically grouped by abundance to handle the wide dynamic range found in harvest media. With a minimal sample requirement (typically 10-20 μL), this workflow is an invaluable tool for Process Analytical Technology (PAT) and downstream process development. It enables researchers to precisely monitor HCP clearance steps, optimize purification protocols, and ensure the final product meets the stringent purity standards required for regulatory approval.
• CP PolyQuantification Human Biofluid Protein Profiling Service
  Our Human Biofluid Absolute Quantification Service offers a flexible, high-precision solution for proteomic analysis. By utilizing advanced LC-MS/MS technology (MRM/PRM and Hybrid DIA) paired with stable isotope-labeled internal standards, we ensure rigorous reproducibility and definitive concentration data.
  Unlike standard assays often overwhelmed by high-abundance proteins like albumin, our workflow is calibrated to detect the medium-to-low abundance "functional tier" of the proteome—critical for monitoring inflammatory, metabolic, and signaling markers.
  We understand that different research stages require different levels of depth. We offer three distinct panels to balance throughput with granular focus:
  • 125-Protein Panel (Targeted Pathway Focus): Ideal for studies requiring a balance between screening and pathway specificity. This panel quantifies 125 key plasma proteins, making it a versatile choice for investigating specific disease mechanisms (such as cardiovascular pathology or cancer) and monitoring therapeutic efficacy over time.
  • 270-Protein Panel (Deep Profiling): Designed to capture a deeper view of the human proteome in a single run, this panel is the preferred choice for large-scale cohort profiling and biomarker verification. It provides the high-throughput data necessary for clinical research in oncology and systemic pathology.
  • 500-Protein Panel (High-Throughput Discovery): Representing the pinnacle of our capabilities, this premium workflow integrates broad-spectrum Data-Independent Acquisition (DIA) with the precision of MRM/PRM. Using a library of over 800 stable isotope-labeled standards, this hybrid approach offers a massive snapshot of complex biological networks, identifying subtle dysregulations with unmatched confidence.
• CP PolyQuantification 375 Mouse Plasma Profiling Service
  Tailored specifically for preclinical research and animal model validation, this service provides the most comprehensive targeted analysis available for the mouse proteome. We deliver absolute quantification for a vast panel of 375 mouse plasma proteins in a single run. Utilizing high-fidelity MRM-MS technology paired with stable isotope-labeled peptides, this workflow is engineered to detect low-abundance signaling and metabolic proteins that are critical for understanding disease progression in mice—proteins often missed by less sensitive methods. This depth makes it an essential resource for mapping the molecular mechanisms of cancer, cardiovascular defects, and metabolic disorders within a controlled model system.
  A major challenge in mouse studies is the limited volume of blood available per subject; our service addresses this by requiring only a minimal sample input (typically 10-20 µL). This efficiency allows researchers to perform longitudinal studies on the same animal or maximize data output from precious terminal samples. By choosing this service, you gain access to high-throughput, reproducible data that facilitates robust comparison between wild-type and disease models. It is the ideal solution for screening drug candidates and validating biomarkers before moving to human clinical trials, bridging the gap between basic science and translational medicine.

Below is a detailed table listing the applicable species, analytical techniques, and applicable proteins for each service for your reference.

Advantages of Absolute Quantification Using Isotope Labeling Tandem Mass Spectrometry

• Unmatched Accuracy and Precision

Using LC-MS/MS and MRM/MS with isotopically labeled internal standards for highly accurate, reproducible protein quantification.

• High Sensitivity for Low-Abundance Proteins

Identifying even low-abundance proteins in complex samples, ideal for biomarker discovery and sensitive analyzes.

• Comprehensive Sample Compatibility

Processing plasma, serum, tissues, and cell cultures to meet diverse research needs.

• Wide Dynamic Range and Quantification Flexibility

Measuring both high and low-abundance proteins in a single analysis, delivering comprehensive data.

• Scalable and High-Throughput Analysis

Managing projects of any scale, from single protein analysis to high-throughput, large-sample studies.

• Customizable Protocols

Tailoring workflows to meet research objectives, including custom sample preparations and data analysis methods.

• Comprehensive Data Analysis and Reporting

Delivering advanced data analysis and clear, actionable reports along with precise quantification.

• Expert Support and Consultation

Assisting from experiment design to data interpretation, ensuring smooth project progression.

• Confidentiality and Data Security

Protecting your research and intellectual property through secure data handling.

FAQs

What is the fundamental difference between the output of your service and standard "discovery" proteomics?

Standard discovery proteomics (or "shotgun" proteomics) provides relative quantification (e.g., "Sample A has a 2.5-fold increase in Protein X compared to Sample B"). Our absolute quantification service utilizes external standards to provide a specific molar or mass concentration (e.g., 25 ng/mL). This data is necessary for kinetic modeling, biomarker validation, and determining stoichiometry.

What methods do you use for absolute protein quantification?

We deliver absolute protein quantification using isotope-labeled peptides and liquid chromatography-mass spectrometry (LC-MS). Understanding that every project is unique, we tailor our methodology—selecting from LC-MS/MS, PRM, or DIA techniques—to meet your specific goals. Our analysis is powered by industry-leading instrumentation, including the Thermo Orbitrap Astral, and Agilent 1260 AB SCIEX API6500+.

What types of samples can be analyzed?

We can analyze a wide range of sample types, including biological fluids (e.g., plasma, serum), tissues, cell cultures, and more. We handle both complex and straightforward samples, ensuring accurate quantification regardless of sample complexity.

What is the role of isotopically labeled standards in absolute quantification?

Isotopically labeled standards, also known as internal standards, are used to account for sample variability and instrument fluctuations. These labeled peptides or proteins mimic the target analyte but have a different isotope mass, allowing for more accurate quantification by compensating for any potential analytical variations.

What is the limit of detection (LOD) for your protein quantification service?

The limit of detection (LOD) varies depending on the protein and sample type. However, using LC-MS/MS and MRM/MS, we can achieve detection levels as low as femtomolar concentrations, allowing for the quantification of even low-abundance proteins in complex biological samples.

Can you quantify post-translational modifications (PTMs) using this method?

Yes, our LC-MS/MS and MRM/MS techniques can quantify proteins with specific post-translational modifications (PTMs) such as phosphorylation, glycosylation, and acetylation. This provides deeper insights into protein function and regulation, which is critical for understanding cellular processes and disease mechanisms.

How do you ensure the reproducibility of protein quantification results?

Reproducibility is ensured through the use of multiple technical replicates, stringent sample preparation protocols, and stable isotopic labeling. Additionally, our advanced analytical platforms undergo regular calibration and maintenance to guarantee consistent performance.

What kind of data analysis tools do you use for protein quantification?

We use advanced software tools for data processing and analysis, including proprietary algorithms for protein identification, quantification, and statistical analysis. Tools like Skyline or OpenMS are often employed for MRM/MS analysis, providing accurate and reproducible quantification results with clear, interpretable outputs.

For research purposes only, not intended for clinical diagnosis, treatment, or individual health assessments.