To prepare a 0.1M citrate buffer at pH 5.4, start by dissolving 21.0 grams of citric acid (C6H8O7) in 800 mL of distilled water. Then, adjust the pH to 5.4 by gradually adding sodium citrate (Na3C6H5O7) while continuously stirring, and check the pH using a pH meter. Once the desired pH is achieved, dilute the solution to a final volume of 1 liter with distilled water. The buffer is now ready for use with Streptozotocin.