Purity, concentration and molecular weight of nucleic acid

Mouse ELISA kit ethidium bromide is a fluorescent dye, in gel electrophoresis, EB molecules can be embedded in nucleic acid double stranded base pairs, which emit fluorescence under ultraviolet excitation, and its intensity is directly proportional to the amount of DNA At the same time, the absorption wavelength of nucleic acid Zui is 260nm At this wavelength, the absorbance 1a is equivalent to a certain concentration of nucleic acid The purity of nucleic acid can be determined by the ratio of a260 / A280 The experimental materials are DNA reagent, reagent kit, agarose TBE electrophoresis buffer, TE buffer ethidium bromide (EB) sample buffer instrument, consumable electrophoresis apparatus, electrophoretic tank, electronic balance, pipette gun head spot sample, microwave oven ultraviolet spectrophotometer gel image analyzer, experimental step 1., the spectrophotometer is turned on and preheated for 10 minutes 2 Take 2 μ l of nucleic acid solution, add (or pure water) to make the volume 100 μ L 3 Add the diluted solution into the quartz tube and pour it into another tube with te buffer (or pure water) as the standard 4 Measure the absorbance at the wavelength of 260 and 280 nm 5 Compare the readings at 260 nm and 280 nm Note for mouse ELISA Kit 1 A260 / A280 > 1.8 indicates high purity of DNA / RNA If the value is less than 1.8, it means the purity is low At this time, the DNA content measured by od260 is not credible, and there are more proteins in the nucleic acid solution Therefore, Zui is good to re extract the above-mentioned nucleic acid 2 Determine 260 nm absorbance value, OD = 1.0, the representative value is as follows: (1) double stranded DNA = 50 mg / ml (2) single stranded DNA or single stranded RNA = 40 mg / ml (3) oligonucleotide = 33 mg / ml.