Quantitation of nucleic acids is the most frequently used spectrophotometer function. Oligonucleotides, single-stranded, double-stranded DNA, and RNA can be quantified in buffer. The absorption peak of the highest absorption peak of nucleic acid is 260 nm. The molecular makeup of each nucleic acid is different, so its conversion factor is different. To quantify different types of nucleic acids, select the corresponding coefficients in advance. Such as: 1 OD absorbance values corresponding to 50μg / ml dsDNA, 37μg / ml ssDNA, 40μg / ml RNA, 30μg / ml Olig. After the test absorbance value after the conversion of the above coefficients, resulting in the corresponding sample concentration. Before testing, select the correct procedure, enter the volume of stock solution and diluent, then test the blank solution and sample solution. However, the experiment is not easy. Unstable readings may be the biggest headache for experimenters. The more sensitive the instrument, the greater the absorbance shift exhibited.