Taking the preparation of 250mL pH=6.86 standard buffer solution as an example to illustrate the preparation method：
1.Uses two AAA batteries (1.5V) Battery compartment contains aprotective cover. To remove cover,slide fingernail into opening located on base, directly below the on/off button.Gently remove the black rubber cover.Insert batteries to match thepolarity as shown on inside of base where the batteries are inserted.To replacecover, push down until it is firmly seatedon all sides.
2.Take out a small plastic bag of pH=6.86 (green) buffer, tear it open, and pour the white powder inside into the Preparation Device. Rinse the residual powder in the bag with distilled water into the container and rinse repeatedly, making sure to rinse thoroughly.
3. Add 250mL of distilled water (The total water volume can not exceed or be less than 250ml). If there is no distilled water available, 250mL of purified water can be used as a substitute in a commercially available bottle.
4.To operate, push the button on the base until the powders are thoroughly dissolved.
5.Pour the prepared buffer solution into the corresponding labeled cup (PH6.86) and use it is complete.
The method for preparing 4.01 and 9.18 standard buffer solutions is the same as above.