With more education and experience, accountants can become certified. Some financial documents, such as those submitted to the Securities and Exchange Commission, must be signed by a Certified Public Accountant.
Hyperchromicity is the increase of absorbance (optical density) of a material. The most famous example is the hyperchromicity of DNA that occurs when the DNA duplex is denatured. The UV absorption is increased when the two single DNA strands are being separated, either by heat or by addition of denaturant or by increasing the pH level.
DNA concentration can be determined measuring the intensity of absorbance of the solution at the 600 nm with a spectrophotometer and comparing to a standard curve of known DNA concentrations. Measuring the intensity of absorbance of the DNA solution at wavelengths 260 nm and 280 nm is used as a measure of DNA purity. DNA purification from detergents, proteins, salts and reagents used during cell lysis step. 2  The most commonly used procedures are: 3  Ethanol precipitation usually by ice-cold ethanol or isopropanol. 4  Since DNA is insoluble in these alcohols, it will aggregate together, giving a pellet upon centrifugation.