Hanna Instruments HI 901 - Manual (Page 131)

A2-5
APPENDIX 2
A2.3.3 Preparing the Sample
For this analysis can use commercial antacid pills.
• Crush a few pills in a mortar and separate a quantity weighting around 0.5 mg from
the resulting powder.
• Pour about 20 mL distilled and deionized water into a 150 mL beaker and then add
the sample powder.
• Raise the stirrer assembly.
• Place the beaker under the stirrer assembly.
• Lower the stirrer assembly until it rests on its positioning collar.
• Adjust the height of the stirrer by using the positioning screw of the positioning
collar to have the propeller as close as possible to the bottom of the beaker.
• Adjust the level of the sample solution so that the pH electrode bulb is completely
immersed in the sample and the reference junction of the electrode is 5-6 mm
below the surface.
A2.3.4Perform the Titration
• If the method is selected (the main screen displays “Antacid Power” at method
name) press .
• The titrator will prompt for the sample weight. Enter the exact weight value (with 4
digits) and press .
• The calculated volume of titrant 1 is displayed (this value can be modified by the
user). The displayed volume will be dispensed during the first phase of back-titration.
• Press to proceed with the next step.
• The titrator will start to dispense the titrant 1 (HCl).
• When this phase is completed, the titrator will stop and the Continue Back Titration
screen is displayed.