Amino acid analysis using FTIR protein quantitation
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Direct Detect™ FTIR Protein Quantitation Matches Results of Amino Acid Analysis

The Direct Detect™ system provides protein quantitation in agreement with amino acid analysis (AAA). Direct Detect™ concentration determination performed within system dynamic range and compared to reference method (AAA). Error bars represent standard deviations of triplicate sample spots (Direct Detect™) or readings (AAA).

* For complete data and experimental details, read our application note.

Direct Detect outperforms Bradford assay, BCA protein assay, and lowry assay for protein quantitation
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Direct Detect™ FTIR Quantitation Outperforms Bradford and BCA Protein Assays in Samples Containing Detergents and Reducing Agents

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

* For complete data and experimental details, read our application note.

More compatible with buffer components than Bradford, BCA and Lowry protein assays

Quantitation Approach Assay Range Sample Volume
(tube/plate)		 Amount Protein
Required to
Measure 1 mg/mL		 Compatible
Direct Detect™ 250-5,000 μg / mL 2 μL 6 μg Detergents
Reducing agents
SDS
Chelators
Bradford Assay 100-1,500 μg / mL 35 μL / 7 μL 21 μg Most reducing agents
Chelators
BCA Assay 20-2,000 µg / mL 50 µL / 25 µL 30 μg Detergents
Micro BCA™ Assay 2-40 µg / mL 500 µL / 150 µL 450 μg Detergents
Lowry Assay 10-1,500 μg / mL 200 μL / 40 μL 120 μg SDS