Practical Protein Chemistry - A. Darbre 1989
Analytical Methods
Determination of protein attached to a solid support
Colorimetric determination of carbodiimides
2 M pyridine hydrochloride and 1 M 1,2-diaminoethane hydrochloride (pH 7.0) for Water-soluble carbodiimides (measured at 400 nm).
2 M pyridine hydrochloride and 1 M piperazine hydrochloride (pH 7.0) for water-insoluble carbodiimides (measured at 420 nm).
Procedure. Add 0.1 mL of the water-soluble carbodiimide to 1 mL of the reagent solution. After 20 min, measure the absorbance at 400 nm. Analyze water-insoluble carbodiimides in dimethylformamide by measuring the absorbance at 420 nm.
Note. The reaction is specific for carbodiimides, and no Condensation side products are formed. The absorbance increases linearly (as a function of carbodiimide concentration) for up to 6 h, during which time the calibration curve is constructed. The determinable concentration range is 50 µmol/L to 50 mmol/L; for smaller amounts, the mixture is incubated at 45 °C to increase color intensity.
Last update: 06/08/2026
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