Sodium citrate, or trisodium citrate, can buffer solutions in the pH range of about 3 to 6.2. Sodium citrate buffer, or citric acid buffer, is used for RNA isolation because it minimizes base hydrolysis of the RNA strands. This makes it an important step in the mRNA purification, during genomic research or for studying transcription. Citrate-based buffers can also aid the detection of antigens in fixed tissue preparations, because they break the cross-links formed between the antigens and the fixation media.