Hanna Instruments HI931, User Manual, Page: 173 / 218

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0.1N HYDROCHLORIC ACID TITRANT CONCENTRA
TION
0.1N HYDROCHLORIC ACID TITRANT CONCENTRATION
METHOD ID: HI0002EN
DESCRIPTION
Method for the standardization (titer determination) of 0.1N
Hydrochloric Acid (HCl) titrant solution against Sodium Hydroxide
(NaOH). The results are expressed in
N (eq/L) .
REFERENCE
AOAC Official Methods of Analysis, Official Method 936.15
ELECTRODE
• HI1131B Combination pH Electrode
• HI7662-T Temperature Probe
REAGENTS
• HI70463 0.1N Hydrochloric Acid (1 L)
• HI70456 0.1N Sodium Hydroxide (1 L)
• HI70436 Deionized Water (1 gal)
ACCESSORIES
• HI70300L Storage Solution (500 mL)
• HI7071
Electrode Fill Solution (30 mL x 4)
• HI7004L pH 4.01 Buffer Solution (500 mL)
• HI7007L pH 7.01 Buffer Solution (500 mL)
• HI7010L pH 10.01 Buffer Solution (500 mL)
• HI740036P 100 mL Plastic Beakers (10 pcs)
• 10 mL Class A Volumetric Pipette
DEVICE PREPARATION
• Connect the pH electrode and temperature probe to the titrator.
• Install a 25 mL burette filled with 0.1N hydrochloric acid (HI70463)
on pump one and verify that no air bubbles are present in the
burette or tubing. If necessary prime the burette until all the air has
been removed completely.
• Press from the main screen. Use the arrow keys
to highlight HI0002EN 0.1N Hydrochloric Acid and press
.
ELECTRODE PREPARATION
• Press from the main screen and press .
• Calibrate the electrode using pH 4.01, 7.01 and 10.01 buffers.
Refer to the instruction manual for calibration procedure.
SAMPLE PREPARATION
• Use a Class A volumetric pipette to transfer exactly 10.00 mL of
0.1N sodium hydroxide (HI70456) to a clean 100 mL beaker.
• Add deionized water to the 50 mL mark on the beaker.
ANALYSIS
• Place the beaker under the stirrer assembly and lower it to
immerse the pH electrode, temperature probe and stirrer. Ensure
that the reference junction of the pH electrode is 5 to 6 mm
below the surface. If necessary add extra deionized water.
Note:
The dispensing tip should be slightly submerged in the
sample.
• Press , the titrator start the analysis.
• At the end of the titration, after detection of the equivalence
point, “Titration Completed” will appear with the result. The
result is expressed in
N (eq/L) of hydrochloric acid .
• Remove the pH electrode, temperature probe and stirrer from the
sample and rinse them thoroughly with deionized water.
• Record the result.
Note:
For improved accuracy, repeat this procedure a minimum
of three times and calculate the average value.
For methods utilizing 0.1N hydrochloric acid titrant solution,
follow the steps below to enter the titer/standardized value.
• Select the method utilizing 0.1N hydrochloric acid.
• Press
from the main screen.
• Using the arrow keys, highlight Titrant Conc. and press
.
• Use the numeric keypad to enter the standardized (titer) value
of the titrant then press .
• Press to exit the View/Modify Method screen. Use
the arrow keys to highlight Save Method and press .