Spectrophotometer in the field of medicine is mainly used in: the quantification of nucleic acids, direct quantification of proteins (UV method), colorimetric protein quantification.
1, the quantification of nucleic acids
The quantification of nucleic acids is the most frequently used function of the spectrophotometer. It can quantify oligonucleotides dissolved in buffer, single-stranded and double-stranded DNA, as well as RNA.The highest absorption peak of nucleic acids has an absorption wavelength of 260 nm.The molecular composition of each type of nucleic acid is different, so its conversion factor is different. To quantify different types of nucleic acids, the corresponding coefficients should be selected beforehand. For example
2, the direct quantification of protein (UV method)
This method is at 280 nm wavelength, directly test the protein. Select the Warburg formula, the photometer can directly display the concentration of the sample, or select the appropriate conversion method, the absorbance value will be converted to sample concentration. The protein determination process is very simple, first test the blank solution, and then directly test the protein.
3, colorimetric protein quantification
Protein is usually a mixture of proteins, colorimetric determination is based on the protein constituents: amino acids (such as tyrosine, serine) and the addition of color groups or dyes to react, resulting in colored substances. The concentration of the colored substance is directly related to the number of amino acids with which the protein reacts, thus responding to the protein concentration.
Expanded Information
The measurement range of a spectrophotometer generally includes the visible light region with a wavelength range of 380 to 780 nm and the ultraviolet light region with a wavelength range of 200 to 380 nm. Different light sources have their own unique emission spectra, so different luminophores can be used as the light source of the instrument.
Tungsten lamp emission spectrum: tungsten light source issued by the 380 ~ 780 nm wavelength of the spectral light refracted through the prism, can be obtained by the red, orange, yellow, green, blue, indigo, violet composition of the continuous chromatogram; the chromatogram can be used as a visible spectrophotometer light source.
Baidu Encyclopedia - Spectrophotometer