Your requirement: to analyse proteins using the CBQCA method
The CBQCA (3-(4-Carboxybenzoyl)quinoline-2-carboxaldehyde) method is a fluorescence-based protein assay technique that offers significantly higher sensitivity than conventional colorimetric methods such as BCA or Bradford.
Quantify your proteins with high fluorescent precision
In the pharmaceutical, cosmetic, chemical and natural ingredients industries, protein quantification is an essential step in controlling the quality, compliance and performance of finished products.
The CBQCA (3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde) method enables sensitive and specific quantification of proteins, even at very low concentrations, through fluorescence detection.
What is the CBQCA method?
The CBQCA method is based on a reaction between the CBQCA reagent and the primary amine groups of proteins and peptides, forming a fluorescent complex detected by spectrofluorimetry.
It is particularly suitable for samples with low protein concentrations or containing optical interferences that limit the use of conventional colorimetric methods (BCA, Bradford, Lowry).
Our protein services
The FILAB laboratory offers a wide range of analytical services related to proteins. These specialised services are aimed at manufacturers wishing to characterise their proteins of interest in detail.
FILAB performs protein analyses using the CBQCA method.
Why choose FILAB for protein analysis using the CBQCA method?
At the FILAB laboratory, we provide pharmaceutical, cosmetics and chemical manufacturers with comprehensive analytical expertise for protein quantification and characterisation. FILAB offers tailor-made solutions for protein analysis: dosage, contaminant identification and structural characterisation, supported by cutting-edge technologies (LC-MSMS, HPLC, UPLC-UV, etc.).
What are the main advantages of the CQBCA method?
The CBQCA method can detect extremely low quantities of proteins — down to a few nanograms per millilitre (ng/mL).
Ideal for:
- diluted samples,
- low-concentration proteins,
- matrices with low protein content (pharmaceutical formulations, natural extracts, etc.).
The CBQCA reagent reacts only with primary amine groups in proteins and peptides.
This selectivity greatly reduces interference from other matrix components (detergents, buffers, solvents, etc.).
Unlike certain colorimetric methods that are sensitive to the composition of the medium, CBQCA remains largely unaffected by additives:
Compatible with salt-rich buffers,
Compatible with organic solvents,
Compatible with certain detergents used in purification processes.
The fluorescent complex formed by the CBQCA-protein reaction is stable over time, ensuring good reproducibility of measurements and increased reliability when comparing samples.
The method requires little material — a major advantage when working with rare, expensive proteins or those produced in limited quantities.
CBQCA can be easily integrated into a multi-technique analytical strategy:
- Used in conjunction with BCA for different concentration ranges,
- In support of HPLC or LC-MS/MS for precise quantification prior to characterisation,
- As part of method development and validation in accordance with ICH Q2 (R2).
FAQ
Industrial teams use this analysis in several cases:
- Production issues: yield control, detection of protein loss, monitoring of a purification step.
- Compliance control: verification of a protein specification or validation of a dosage.
- Process optimisation: validation of an analytical method or technology transfer.
- Failure investigation: suspected degradation, interaction or contamination.
- Regulatory requirements: creation or updating of a dossier in accordance with ICH Q2 (R2).
The FILAB laboratory applies the CBQCA method to a wide variety of matrices:
- Pharmaceutical formulations: recombinant proteins, vaccines, enzymes, monoclonal antibodies
- Cosmetic products: active ingredients, protein extracts, peptide-based formulations
- Chemical and biotechnological raw materials
- Natural ingredients and extracts: plant proteins, enzyme extracts, hydrolysates
| Method | Principle | Sensitivity | Matrix compatibility | Type of detection | Typical applications |
|---|---|---|---|---|---|
| CBQCA | Fluorescent reaction with primary amines | Very high (ng/mL) | Large (stamps, solvents) | Fluorescence | Diluted samples, high sensitivity required |
| BCA | Coloured Cu⁺–BCA complex | Medium to high (µg/mL) | Good (detergents) | Absorbance | Production monitoring, quality control |
| Bradford | Coomassie complex–proteins | Average (µg/mL) | Limited (sensitive to additives) | Absorbance | Rapid assays, initial screening |
Our engineers select the most appropriate method based on the nature of your sample, the target concentration range and the purpose of the analysis.
R&D teams exploring new molecules, formulations or processes.
Quality Control departments ensuring batch release or compliance verification.
Production/Process departments dealing with changes in scale, yields or production incidents.
Regulatory Affairs departments required to document files or meet requirements.
Formulation/analytical project managers who coordinate the transition from innovation to industrialisation.
