大致分为：水相LiCl沉淀法；LiCl+乙醇法
一、水相LiCl沉淀法：
原理：
Lithium Chloride (LiCl) precipitation is a convenient and effective way to remove unincorporated nucleotides and most proteins. Lithium chloride precipitation, however, does not precipitate transfer RNA and may not efficiently precipitate RNAs smaller than 300 nucleotides. Also, the concentration of RNA should be at least 0.1 鸭子英语怎么说μg/μL to assure efficient precipitation.
特点：
1、 要求RNA浓度>100ng/μL, 才能做到有效的沉淀; >400ng/μL,茉莉花的寓意效果最好 (对于高效的体外转录体系以及除去高RNA五年级下册教学计划含量样品中的RNA污染适合)扩展屏幕
2、 对于小片断(<300bp)的沉淀效率较低（适用于RPA的探针纯化）。
试剂：
RNA Precipitation Solution：7.5 M Lithium Chloride, 50 mM EDTA, pH 8.0；
方法：
Precipitation of RNA from Solution at a Concentration ≥400 ng/μL
1. Bring the final concentration of LiCl in the RNA solution to 2.5 M.
2. Chill the solution at –20°C for 30 min.
3. Centrifuge at top speed in a microcentrifuge for 15 min.
4. Discard the supernatant, and wash the pellet with ice-cold 70% EtOH to remove residual salt.茶叶保质期一般多久
5. Resuspend in nuclea-free water or 10 mM Tris, 1 mM EDTA.（DEPC水）
设备安装合同
二、LiCl/ethanol 沉淀法
原理：
即为普通的盐离子/醇法，降低核酸分子间的同电相斥，导致沉淀。
特点：
1、 高效沉淀，无明显的片断选择性，因而对<500bp的探针较为适合；
2、 较低浓度的RNA沉淀效率要略高于水相沉淀法；
3、 对RNA的沉淀特异性略低，因而沉淀产物混杂有蛋白和DNA，因而在探针制备试验中，应在沉淀前进行DNa I处理。
试剂
4M LiCl
Ethanol
方法：
1、 in vitro transcription（20μL）；
2、 (Optional) Add 1 µL of DNa to the reaction and incubate for 15 min at 37最闪耀的那颗星°C to digest the template DNA. Add 1 µL of 0.5 M EDTA to stop the reaction.
3、 言传身教Precipitate the RNA probe by adding 2.5 µL of 4 M LiCl,（5M加2µL，7.5M1.5µL） and 100 µL of 100% ethanol.
Optionally, add 1µL of 50 mg/mL tRNA.
4、 Incubate the reaction for at least 1 h at -80°C.（Centrifuge at top speed in a microcentrifuge for 15 min.Discard the supernatant, and wash the pellet with ice-cold 70% EtOH to remove residual salt Remove the ethanol.
5、 Resuspend the RNA pellet in 50 µL of RNa-free H2O (or 25 µL if the probe was synthesized using half-volumes). Store probe at -80°C.
Do not allow the pellet to dry completely after precipitating, or it will become difficult to resuspend. Probes stored at -80°C are stable for years.
