23266-Fluor-Prot-Assay-230

Fluorescence-based protein quantification detection methods provide superior sensitivity, which means you use less of your protein samples for quantitation and have more samples available for your experiment. For the assays described below, few steps are required and timing is not critical so the assays can be adapted for automated handling in high-throughput applications. The fluorescence signal can be detected using a fluorometer or microplate reader.

Fluorescence-based protein quantitation assay selection guide

Each assay has its own advantages. Use the table and information below to help select the best protein assay for your application.

Product Quant-iT™ Protein Assay  Qubit® Protein Assay 100 assays Qubit® Protein Assay 500 assays NanoOrange® Protein Quantification Assay CBQCA Protein Quantification Assay EZQ™ Protein Quantification Assay
Applications Best for more than 20 samples Best for 1–20 samples

Compatible with Qubit® Fluorometer 
Best for 1–20 samples
Compatible with Qubit® Fluorometer 
Ideal for quantitating protein samples before gel electrophoresis and western blot analysis Better suited for accurate quantitation of proteins in the presence of lipids, membrane fractions, or detergents, and for lipoproteins and small peptides  Ideal for determining protein concentration prior to electrophoresis

Solid-phase format designed for high-throughput analysis
Detection wavelength (nm) 470/570 470/570 470/570 470/570 450/550 280 and 450/618
Sensitivity and effective range Quasi-linear from 0.5 to 4 µg in a 200 µL assay volume, with a sample volume of 1–20 µL Quasi-linear from 0.5 to 4 µg in a 200 µL assay volume, with a sample volume of 1–20 µL Quasi-linear from 0.5 to 4 µg in a 200 µL assay volume, with a sample volume of 1–20 µL 10 ng/mL to 10 µg/mL 10 ng/mL to 150 µg/mL 50 µg/mL to 5 mg/mL, with a sample volume of 1 µL
Mechanism of action Binds to detergent coating on proteins and hydrophobic regions of proteins; the unbound dye is nonfluorescent Binds to detergent coating on proteins and hydrophobic regions of proteins; the unbound dye is nonfluorescent Binds to detergent coating on proteins and hydrophobic regions of proteins; the unbound dye is nonfluorescent Binds to detergent coating on proteins and hydrophobic regions of proteins; the unbound dye is nonfluorescent Reacts with primary amine groups on proteins in the presence of cyanide or thiols; the unreacted dye is nonfluorescent Binds electrostatically to basic amino acids, supplemented by additional hydrophobic interactions
High sensitivity

 
Little protein-to-protein variation

 

Signal duration 3 hours 3 hours 3 hours 6 hours 5 hours ---
Shelf life 6 months 6 months 6 months 6 months 6 months 6 months
Size I kit 100 assays 500 assays 1 kit 1 kit 2,000 assays
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Sample compatibilities

  Quant-iT™ Protein Assay  Qubit® Protein Assay NanoOrange® Protein Quantification Assay CBQCA Protein Quantification Assay* EZQ™ Protein Quantification Assay
Salts

 
Solvents

     
1-mecaptoethanol

 
Amino acids

     
DNA

 
Reducing agents    

 

Lipophillic proteins

 
Urea        

Tracking dye

Detergent      

✓*

* CBQCA Protein Quantification Assay is not compatible with buffers containing amines or thiols.

We offer easy-to-use colorimetric or fluorescent peptide assays that are designed specifically to improve the sensitivity and reproducibility of quantitation of peptide mixtures. The kits include simple protocols with a representative standard enclosed. The kits have been fully validated with representative samples that have been processed and analyzed using Thermo Scientific™ Mass Spectrometers