This concentration calculation is automated in many instruments.ε=wavelength-dependent molar absorptivity coefficient (or extinction coefficient) in M -1cm -1.A=UV absorbance in absorbance units (AU).C= nucleic acid concentration in molar (M).Concentrations of nucleic acids can be directly calculated from their measured absorbance values at 260 nm, using the Beer-Lambert's equation:.How is the concentration of nucleic acids calculated? Wavelength separation can take place in various ways (for example with filters or with monochromators).Wavelength separation can take place before or after the light has passed the sample, and the optical light path can be horizontal or vertical.Sample is excited with filtered light (at the excitation wavelength, and the emitted light (at the emission wavelength) is recorded by a detector. The signal is measured by fluorometers.The attenuation in the light that reaches the detector after passing through the sample is measured in relation to the incident light and expressed as absorbance values of the sample in the solution. The signal is measured by spectrophotometers or spectrometers. Dyes only emit signal when bound to the target. The fluorometric measurement of nucleic acids is based upon the use of fluorogenic dyes that bind selectively to DNA or RNA.įluorescent dyes selectively bind to DNA, RNA or protein. When an absorption spectrum is measured, nucleic acids absorb light with a characteristic peak at 260 nm. The photometric measurement of nucleic acids is based on the intrinsic absorptivity properties of nucleic acids (DNA and RNA).
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