Direct Detect® FTIR quantitation outperforms Bradford and BCA protein assays in samples containing detergents and reducing agents.
The Direct Detect® provides accurate and precise results, even in presence of detergent (SDS) and reducing agent (DTT). Using the Direct Detect® IR-based quantitation system, calculated concentrations for all the BSA samples matched the prediluted standard (Thermo BSA Standard). In comparison, the Coomassie Plus (Bradford) assay provided calculated concentrations that differed greatly in the presence of 1% SDS, and the MicroBCA assay could not provide data in the presence of 50 mM DTT.
Compare Direct Detect® FTIR quantitation with Bradford and BCA protein assays in samples.
Sample Volume (tube/plate)
Amount Protein Required to Measure 1 mg/mL
Direct Detect® Spectrometer
250-5,000 μg / mL
Detergents Reducing agents SDS Chelators
100-1,500 μg / mL
35 μL / 7 μL
Most reducing agents Chelators
20-2,000 µg / mL
50 µL / 25 µL
Micro BCA™ Assay
2-40 µg / mL
500 µL / 150 µL
10-1,500 μg / mL
200 μL / 40 μL
How FTIR Protein Quantitation Works in Complex Samples:
Protein quantitation in presence of lipids within a complex cell lysate is possible because the most intense regions of lipid absorbance are spectrally distinct from the protein’s Amide I and Amide II signals.