pH Calibration Solutions3 40ml. bottles Sper Scientific offers a wide selection of pH calibration and buffer solutions. Always choose a pH 7 buffer plus at least one other pH value close to your expected measurement range. Using solutions of known pH value allow you to adjust the system to read accurate measurements. Calibration should be performed before each reading or each set of readings. pH buffers allow you to adjust your testing system to measure your samples’ unknown pH more precisely.For best accuracy:• Perform standardizations with fresh buffer solutions.• Never pour used buffer back into the bottle; always discard after using.• Use buffers that frame the pH range of the samples you are testing i.e. directly above and below the expected value of your sample.• Match the temperature of the buffer to the temperature of the samples. For example, if your samples are at 50 degrees Celsius, warm your buffers to 50 degrees Celsius using a beaker in a water bath.