Science, Tech, Math › Science How to Make Sodium Citrate Buffer Share Flipboard Email Print Kevin Horan/The Image Bank/Getty Images Science Chemistry Biochemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Theresa Phillips Practice Leader, Environmental Risk Assessment at Pinchin Ltd. University of Guelph University of Waterloo Theresa Phillips, PhD, is a former writer for The Balance covering biotech and biomedicine. She has worked as an environmental risk consultant, toxicologist and research scientist. our editorial process Twitter Twitter LinkedIn LinkedIn Theresa Phillips Updated November 30, 2019 Sodium citrate buffer is frequently used for RNA isolation, because it minimizes base hydrolysis of the RNA strands, making it invaluable for mRNA purification during genomic research, and for studying transcription. Citrate-based buffers also aid the detection of antigens in fixed tissue preparations, because they break the cross-links formed between the antigens and the fixation media. With the following easy steps, one can create a sodium citrate buffer with a pH of 6 (acidic) in under 10 minutes. Materials for the Sodium Citrate Buffer Few materials are required to make the sodium citrate buffer. With citric acid, one only needs 1M of sodium hydroxide, distilled water, and a calibrated pH probe. Sodium citrate is optional. Making the buffer also requires a 1 liter graduated cylinder, a 1-liter volumetric flask, and three 1 liter media bottles. Finally, you'll need a magnetic stir bar and a magnetic stirrer. All of these materials may be found at school, work-site laboratories or be purchased online or at specialty goods stores. Two Options to Make the Buffer There are two methods of making sodium citrate buffers, depending on the materials accessible to you. If you have both citric acid and the conjugate base, create a stock solution of each by mixing 21 grams of citric acid in 1 liter of distilled water, and 29.4 grams of sodium citrate in 1 liter of distilled water.If you only have citric acid on hand, mix 2.1 grams in just under 1 liter of distilled water. Mixing Citric Acid and Sodium Citrate Solutions Mix 82 milliliters of the citric acid solution with 18 milliliters of the sodium citrate solution. To this, add enough distilled water to bring the volume of the mixture to slightly under 1 liter. Adjusting the pH While gently stirring the solution with a magnetic stirrer, use 1M sodium hydroxide to adjust the pH of the mixture to 6.0. Then, with a volumetric flask, add more distilled water to bring the final total volume of the solution up to exactly 1 liter.