dische

Dische, also known as the Dische reaction or the Dische diphenylamine reaction, is a colorimetric method used for the quantitative determination of deoxyribonucleic acid (DNA). Developed by Z. Dische in 1930, the reaction relies on the dehydration of sugars in the presence of concentrated sulfuric acid and diphenylamine to form a blue-colored complex. Deoxyribose, a key component of DNA, reacts specifically under these conditions.

The procedure involves heating a sample containing DNA with a solution of diphenylamine in glacial acetic acid and a small amount of concentrated sulfuric acid. Upon heating, the deoxyribose sugar residues in the DNA molecule undergo dehydration, forming a reactive intermediate that then reacts with diphenylamine. This reaction yields a characteristic blue-colored product, the intensity of which is proportional to the concentration of DNA present in the original sample. Spectrophotometry is then used to measure the absorbance of this blue color, typically at a wavelength of 600 nm, allowing for the calculation of DNA concentration by comparing it to a standard curve prepared with known concentrations of DNA.

While the Dische reaction is a classic method for DNA quantification, it is not entirely specific for DNA. RNA and other carbohydrates can also react, though to a lesser extent. Contamination with RNA can lead to overestimation of DNA concentration. Despite this limitation, the Dische reaction remains a useful and relatively simple technique, particularly in laboratories where more sophisticated instruments are unavailable. It is often employed in basic research and educational settings for routine DNA estimations.