18 Pack pH Meter Buffer Solution Powder 6.86 4.00 9.18 pH Calibration Solution Packets for Precise PH Meter

Specifications: Accuracy: ±0.01pH at 77°F(25°C) ? 6 packets of pH 4.00 Solution powder ? 6 packets of pH 6.86 Solution powder ? 6 packets of pH 9.18 Solution powder Directions for use: Step 1:Completely empty the powder into a dry glass container. Step 2:Add 250mL deionized water (or distilled water) to the beaker. Step 3:Stir until the powder has completely dissolved. Step 4:Put the pH meter in the solution and gently stir and wait a few seconds for the result. CAUTION: Not a drinkable solution! The ph meter may need to be recalibrated mainly in these cases: -Inactivity for long period, for example over 3-4 weeks. -Very frequently used. -Can't get a stable meter reading. -After testing strong acid/alkline. -The testing accuracy requirement is high