Hanna Instruments HI 903 - Manual (Page 185)

Method ID: HI8108EN
Moisture Determination in Mayonnaise
by external extraction
Titrator Application Methods: General Methods - r. 0.4
Description:
Method for the determination of moisture in
Mayonnaise by external extraction. The results are
expressed in % mass and should be between 40
and 60 %.
Electrode:

HI 76320 Double Platinum Pin Electrode
Reagents:

5 mg/mL One-Component KF Volumetric Titrant

Solvent for KF Volumetric Titration

Dry Methanol
Other Accessories:

A clean, dry 1-mL syringe

A clean, dry 22-gauge , 6” non-coring septum
penetration needle

GL 45-Thread Solvent Bottle

100-mL extraction bottle with septum

Magnetic stirrer and stirbar
External Extraction Procedure:

To an external extraction bottle with septum add
magnetic stir bar. Weigh the bottle and record this
value.

Add 40 g of dry methanol to the bottle and stir for
5 minutes.

Determine the moisture content of the solvent mix.
For the determination of the exact concentration of
the solvent mix, follow HI8301EN Solvent w/
5mg/mL 1-comp.

Enter the solvent moisture concentration by
pressing Method Options, then Sample
Parameters, then External Solvent Concentration.
Use the numeric keypad to enter the exact
concentration. Press Accept or Enter.

Weigh the extraction bottle to determine the
weight of the remaining solvent (by subtracting the
empty bottle mass). Enter the exact mass by re-
entering Sample Parameters and selecting
External Solvent Size. Use the numeric keypad to
enter the exact mass. Press Accept or Enter.

Add 0.8 to 1.2 g of mayonnaise to the bottle.
Weigh the bottle to determine the exact extracted
sample weight. Enter the exact mass by re-
entering Sample Parameters and selecting
Extracted Sample Size. Use the numeric keypad
to enter the exact mass. Press Accept or Enter.

To extract the water from the mayonnaise, mix for
20 to 30 minutes. The resulting supernatant will
be used to determine the water content.
Note: Titrate the supernatant immediately.
Titration Procedure:

Setup titrator according to the instruction manual.
 Press “Select Method” from the main screen. Use
the
arrow keys to highlight ‘HI8108EN Moisture in
Mayonnaise ’ and press “Select”.

Install a 5-mL burette filled with 5 mg/mL One-
Component KF Volumetric Titrant and verify that
no air bubbles are present in the burette or tubing.
If necessary prime until all air has been removed
completely.
For the determination of the exact concentration of
the titrant follow HI8001EN 5.0 mg/mL Titrant
Standardization using Liquid Water Standard.

Connect the solvent bottle top assembly to the
bottle of methanol according to the manual.

Prepare the titration vessel according to the
manual. Dispense enough solvent from the solvent
bottle to fill the vessel to the “min” line (about 50
mL).
 Press “Start/Stop” to pre-titrate the titration solvent
and the titration vessel moisture. Allow the
background
drift rate to stabilize before
proceeding to the next step.

Stop stirring the sample in the extraction bottle
and allow any particulate matter to settle.

Fill the syringe and needle with the supernatant.
Do not draw particulate from the bottom.

Weigh the syringe, needle and supernatant.
 Press “Start Analysis”. You will be prompted to
enter the sample size.

Dispense 0.5000 g to 1.0000 g of supernatant into
the titration vessel through the septum using the
needle. Pay attention not to get any sample on
the electrode or beaker walls. If necessary swirl
the titration vessel by hand.

Clear the needle of residual sample by intaking a
small volume of air from the titration vessel. If a
“hanging drop” of sample is seen on the end of the
needle, dip the end of the needle briefly in the
solvent.

Remove the needle from the titration vessel and
weigh the syringe again in order to determine the
added sample mass (by difference of the two
measurements.)

Use the numeric keypad to enter the exact weight
and press “Enter” to start the analysis.
 At the end of the titration the “Sample Analysis
Result
” screen is displayed. The results are
expressed in % mass of water.

The use of external extraction increases the
precision and drastically lowers the load of the
solvent, allowing you to run more titrations without
changing the solvent. Use fresh solvent after
every 10 - 12 titrations.