Hanna Instruments HI 903 - Manual (Page 179)

Method ID: HI8105EN
Moisture Determination in Cooking Oil
Titrator Application Methods: General Methods - r. 0.4
Description:
Method for the determination of moisture in cooking
oil. The results are expressed in ppm and should be
between 200 and 800 ppm.
Electrode:

HI 76320 Double Platinum Pin Electrode
Reagents:

1 mg/mL One-Component KF Volumetric Titrant

Dry Methanol

Dry Chloroform
Other Accessories:

A clean, dry 25-mL syringe

A clean, dry 18-gauge , 6” non-coring septum
penetration needle

GL 45-Thread Solvent Bottle
Procedure:

Setup titrator according to the instruction manual.
 Press “Select Method” from the main screen. Use
the arrow keys to highlight ‘HI8105EN Moisture in
Cooking Oil
’ and press “Select”.

Install a 5-mL burette filled with 1 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 HI8003EN 1.0 mg/mL Titrant
Standardization using Liquid Water Standard.

Prepare at least 200 mL of solvent by adding 1
part dry chloroform to 1 part dry methanol in a
solvent bottle. Attach the solvent bottle top
assembly to the bottle according to the instruction
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 solvent and the
titration vessel moisture. Allow the background
drift rate to stabilize before proceeding to the next
step.

Fill the syringe and needle with sample.

Weigh the syringe, needle and oil.
 Press “Start Analysis”. You will be prompted to
enter the sample size.

Dispense 3 g to 5 g of cooking oil 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 ppm of water.

Change the solvent after every 3 to 4 titration or if
phase-separation occurs.
Method Parameters:
Name: Moisture in Cooking Oil
Method Revision: 1.0
Type: Sample Analysis
Predispensing Amount: None
Pre-Analysis Stir Time: 15 Sec
Stirring Speed: 900 RPM
Stirbar Type: Medium
Drift Entry: Automatic
Solvent: CHCl3 MeOH 1:1
Sample Parameters:
Sample Determ.: Normal
Sample Name: Oil
Sample Type: Mass
Sample Size: 4.0000 g
Titrant: Composite 1
Titrant Type: One Component
Nominal Titrant Conc.: 1.0000 mg/mL
Std. Titrant Conc.: 1.0000 mg/mL
Date/Time: Jan 1, 2010 12:01
Titrant Age Reminder: 2d:00h:00m
Control Parameters:
Start Mode: Cautious
Standby Mode: Enabled
Standby Duration: 720 minutes
Imposed Current: 20 uA
Minimum Dose: 1.000 uL
Maximum Dose: 30.000 uL
Timed Increment: 1 second
End Point Value: 180.0 mV
Signal Averaging: 3 Readings
Flow Rate: 10.0 mL/min
Termination Parameters:
Maximum Duration: 900 sec
Maximum Titrant Volume: 10.0000 mL
Term. Criterion: Relative Drift
Relative Drift: 10.0 ug/min
Result Unit: ppm
Calculations:
Calculations:
Titrant units:
mg/mL
Titrant volume consumed: V (mL)
Final results units: ppm
Titrant concentration: 1.0000 mg/mL
Sample mass: 4.0000 g