Method ID: HI0001EN
0.1N Sodium Hydroxide Titrant Concentration
Titrator Application Methods: General Methods - r. 2.3
Description:
Method for the standardization (titer determination)
of 0.1N Sodium Hydroxide (NaOH) titrant solution
against Potassium Hydrogen Phthalate (KHP). The
results are expressed in N (eq/L).
Reference:
AOAC Official Methods of Analysis, Official Method
936.16
Electrode:
HI 1131B Combination pH Electrode
HI 7662-T Temperature Probe
Reagents:
HI 70456 0.1N Sodium Hydroxide solution (1 L)
HI 70401 Potassium Hydrogen Phthalate (20 g)
HI 70436 Distilled Water (1 gal)
Accessories:
HI 70300L Storage Solution (500 mL)
HI 7071 Electrode Fill Solution (4*30 mL)
HI 7004L pH 4.01 Buffer Solution (500 mL)
HI 7007L pH 7.01 Buffer Solution (500 mL)
HI 7010L pH 10.01 Buffer Solution (500 mL)
HI 740036P 100-mL Plastic Beaker (10 pcs)
Analytical Balance with a minimum resolution of
0.0001g is recommended
NOTE: A pH electrode calibration is not needed for
this method.
Procedure:
Connect the pH electrode and temperature probe
to the titrator.
Press “Select Method” from the main screen. Use
the arrow keys to highlight „HI0001EN 0.1N NaOH
Titr. Conc.‟ and press “Select”.
Install a 25-mL burette filled with 0.1N sodium
hydroxide solution (HI 70456) on pump-one and
verify that no air bubbles are present in the burette
or tubing. If necessary prime until all air has been
removed completely.
Crush approximately 3 grams of potassium
hydrogen phthalate (HI 70401) and dry it for 2
hours at 120°C. Cool to room temperature in a
desiccator.
Place a clean 100-mL plastic beaker on the
analytical balance.
Zero the balance.
Carefully weigh approximately 0.20 grams of dried
potassium hydrogen phthalate into the beaker.
NOTE: Ensure that all of the potassium hydrogen
phthalate is on the bottom of the beaker.
Record the exact weight of the sample once the
balance has stabilized with an accuracy of 0.0001
grams.
Remove the beaker from the balance and add
distilled water to the 50-mL mark on the beaker.
Place the beaker under the stirrer assembly and
immerse the pH electrode, temperature probe and
stirrer. Ensure that the reference junction of the
pH probe is 5-6 mm below the surface. If
necessary add extra distilled water.
Press “Start”. You will be prompted to enter the
analyte size (weight of KHP). Use the numeric
keypad to enter the exact weight and press
“Enter” to start the analysis.
NOTE: Ensure that the KHP dissolves completely
during the pre-titration stir time. Erroneous results
may occur if the sample does not dissolve
completely prior to titration. If necessary the pre-
titration stir time can be increased.
At the end of the titration, after detection of the
equivalence point, 'titration completed‟ will appear
with the titrant concentration. The result is
expressed in N (eq/L) of sodium hydroxide.
Remove the electrodes and stirrer from the
sample and rinse them thoroughly with distilled
water.
Record the result (titer concentration).
NOTE: For improved accuracy, repeat this
procedure a minimum of three times and calculate
the average value.
For methods utilizing 0.1N NaOH titrant solution,
follow the steps below to enter the
titer/standardized value.
Select the method utilizing 0.1N NaOH.
Select „Method Options‟ from the main screen.
Using the arrow keys, highlight „Titrant Conc.‟ and
press “Select”.
Use the numeric keypad to enter the standardized
(titer) value of the titrant then press „Accept‟.
Press „Escape‟ to exit the Method Options screen
and select „Save Method‟ option.
Method Parameters:
Name: 0.1N NaOH Titr. Conc.
Method Revision: 2.3
Titration Type: Standard Titration
Analog Board: Analog 1
Stirrer Configuration: Stirrer 1
Pump Configuration:
Titrant Pump: Pump 1
Dosing Type: Dynamic
min Vol: 0.030 mL
max Vol: 0.500 mL
delta E: 4.500 mV
End Point Mode: pH 1EQ point, 1st Der.
Recognition Options:
Threshold: 500 mV/mL
Range: No
Filtered Derivatives: No
Pre-Titration Volume: 5.000 mL
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