Detremination of the Saponification Number with Potentiometric Method

Determination of the Saponification Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0232.100 combined pH glass electrode; input 1

Reagents
c(HCl) = 1 mol/L; D0

Sample
app. 2 g sunflower oil
25 mL c(KOH) = 0.5 mol/L in ethanol
app. 10-20 mL dist. water

Remarks
· Calculations:

Sapon.No=(C01-EP1)*C02/C00;1;mg/g

Sapon.No = saponification number in mg KOH per g of sample
C01 = consumption of blank sample (12.199 mL)
C02 = mg KOH / 1 mL titrating agent (56.1)

. Answer

Sapon.No = (12.199-5.271) x 56.1 / 2.0224 = 192.2 mg/g

EP1 = 5.271 mL
C00 = 2.0224 g

· Sample preparation:
Weigh out approx. 2 g sample in a round-bottomed flask. Add 25 mL
alcoholic KOH solution plus a few boiling beads and allow to boil
lightly for at least 30 min. Shake from time to time. Finally rinse the
content of the round-bottomed flask into a beaker with a small
quantity of dist. water and back titrate the excess of potassium
hydroxide with HCl. A blank control sample should be prepared and
treated identically. Enter the blank value as C01.

Literature
· Metrohm Application Bulletin No. 141: Analysis of edible oils and fats.

Method documentation
'pa
751 GPD Titrino 15215 751.0010
DET U Sapon.No
parameters
>titration parameters
meas.pt.density… 4
min.incr. …10.0 ml
dos.rate max….. ml/min
signal drift ….50 mV/min
equilibr.time ….26 s
start V:….. OFF
pause …0 s
dos.element:… internal D0
meas.input: ….1
temperature ….25.0 °C
>stop conditions
stop V: ….abs.
stop V …99.99 ml
stop U…. OFF mV
stop EP ….1
filling rate max…. ml/min
>statistics
status: ….OFF
>evaluation
EPC …5
EP recognition:… all
fix EP1 at U… OFF mV
pK/HNP: …OFF
>preselections
req.ident: …OFF
req.smpl size: ….value
activate pulse:… OFF
------------
'fm
751 GPD Titrino 15215 751.0010
DET U Sapon.No
>calculations

Sapon.No=(C01-EP1)*C02/C00;1;mg/g

C00= 2.0224
C01= 12.199
C02= 56.1
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) -357 mV DET U.... Sapon.No
smpl size…. 2.0224 g
EP1 ….5.271 ml…. -203 mV
Sapon.No ….192.2 mg/g
stop #EP reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Sapon.No
1.0 ml/div dU=50.0 mV/div
============

Determination of Peroxide Number with Potentiometric Method

Determination of Peroxide Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(Na2S2O3) = 0.01 mol/L; D0
Prepared daily from c = 0.1 mol/L

Sample
app. 5 g sunflower oil
50 mL glacial acetic acid / chloroform (3 : 2)
1 mL KI saturate
100 mL dist. water

Remarks
· Calculations:

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

Perox.No = peroxide number in meq.O2/kg
C01 = consumption of blank sample (0 mL)
C02 = factor (10)

. Answer

Perox.No = 0.8874 x 10 / 5.0188 = 1.77 meq/Kg

EP1 = 0.8874 mL
C00 = 5.0188 g

· Sample preparation:
Weigh out accurately 5 g sample in an Erlenmeyer flask and add 50
mL of the glacial acetic acid / chloroform mixture. Then add 1 mL of
the KI solution and shake during 5 s. Now allow the mixture to stand
for about 1 min. in a dark place. After this, rinse the contents of the
Erlenmeyer flask out into a beaker with 100 mL dist. water and
immediately back-titrate the iodine thus liberated with sodium
thiosulphate. A blank control sample should be prepared and treated
in the same way. Enter the blank value as C01.
· The sample must be stirred well during the titration, in order to obtain
a good emulsion.

Literature
· Metrohm Application Bulletin No. 141: Analysis of edible oils and fats.

Method documentation

'pa
751 GPD Titrino 15215 751.0010
date 97-02-25 time 14:25 4
DET U Perox.No
parameters
>titration parameters
meas.pt.density 4
min.incr. 10.0 ml
dos.rate max. ml/min
signal drift 50 mV/min
equilibr.time 26 s
start V: OFF
pause 0 s
dos.element: internal D0
meas.input: 1
temperature 25.0 °C
>stop conditions
stop V: abs.
stop V 99.99 ml
stop U OFF mV
stop EP 1
filling rate max. ml/min
>statistics
status: OFF
>evaluation
EPC 5
EP recognition: all
fix EP1 at U OFF mV
pK/HNP: OFF
>preselections
req.ident: OFF
req.smpl size: value
activate pulse: OFF
------------
'fm
751 GPD Titrino 15215 751.0010
date 97-02-25 time 14:25 4
DET U Perox.No
>calculations

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

C00= 5.0188
C01= 0.0
C02= 10
------------
'fr
751 GPD Titrino 15215 751.0010U(init) 20 mV DET U Perox.No
smpl size 5.0188 g id#1 Suprema id#2 Oil
EP1 0.8874 ml 80 mV
Perox.No 1.77 meq/kg
stop #EP reached
============
'cu
751 GPD Titrino 15215 751.0010
date 97-02-25 time 14:24 4
start V 0.0000 ml DET U Perox.No
0.5 ml/div dU=20.0 mV/div
============

Determination of Peroxide Number with Potentiometric Method

Determination of Peroxide Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(Na2S2O3) = 0.01 mol/L; D0
Prepared daily from c = 0.1 mol/L

Sample
app. 5 g sunflower oil
50 mL glacial acetic acid / chloroform (3 : 2)
1 mL KI saturate
100 mL dist. water

Remarks
· Calculations:

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

Perox.No = peroxide number in meq.O2/kg
C01 = consumption of blank sample (0 mL)
C02 = factor (10)

. Answer

Perox.No = 0.8874 x 10 / 5.0188 = 1.77 meq/Kg

EP1 = 0.8874 mL

C00 = 5.0188 g

· Sample preparation:

Weigh out accurately 5 g sample in an Erlenmeyer flask and add 50

mL of the glacial acetic acid / chloroform mixture. Then add 1 mL of

the KI solution and shake during 5 s. Now allow the mixture to stand

for about 1 min. in a dark place. After this, rinse the contents of the

Erlenmeyer flask out into a beaker with 100 mL dist. water and

immediately back-titrate the iodine thus liberated with sodium

thiosulphate. A blank control sample should be prepared and treated

in the same way. Enter the blank value as C01.

· The sample must be stirred well during the titration, in order to obtain

a good emulsion.

Literature

· Metrohm Application Bulletin No. 141: Analysis of edible oils and fats.

Method documentation

'pa

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:25 4

DET U Perox.No

parameters

>titration parameters

meas.pt.density 4

min.incr. 10.0 ml

dos.rate max. ml/min

signal drift 50 mV/min

equilibr.time 26 s

start V: OFF

pause 0 s

dos.element: internal D0

meas.input: 1

temperature 25.0 °C

>stop conditions

stop V: abs.

stop V 99.99 ml

stop U OFF mV

stop EP 1

filling rate max. ml/min

>statistics

status: OFF

>evaluation

EPC 5

EP recognition: all

fix EP1 at U OFF mV

pK/HNP: OFF

>preselections

req.ident: OFF

req.smpl size: value

activate pulse: OFF

------------

'fm

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:25 4

DET U Perox.No

>calculations

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

C00= 5.0188

C01= 0.0

C02= 10

------------

'fr

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:24 4

U(init) 20 mV DET U Perox.No

smpl size 5.0188 g id#1 Suprema

id#2 Oil

EP1 0.8874 ml 80 mV

Perox.No 1.77 meq/kg

stop #EP reached

============

'cu

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:24 4

start V 0.0000 ml DET U Perox.No

0.5 ml/div dU=20.0 mV/div

============

Determination of Peroxide Number with Potentiometric Method

Determination of Peroxide Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(Na2S2O3) = 0.01 mol/L; D0
Prepared daily from c = 0.1 mol/L

Sample
app. 5 g sunflower oil
50 mL glacial acetic acid / chloroform (3 : 2)
1 mL KI saturate
100 mL dist. water

Remarks
· Calculations:

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

Perox.No = peroxide number in meq.O2/kg

C01 = consumption of blank sample (0 mL)

C02 = factor (10)

. Answer

Perox.No = 0.8874 x 10 / 5.0188 = 1.77 meq/Kg

EP1 = 0.8874 mL

C00 = 5.0188 g

· Sample preparation:

Weigh out accurately 5 g sample in an Erlenmeyer flask and add 50

mL of the glacial acetic acid / chloroform mixture. Then add 1 mL of

the KI solution and shake during 5 s. Now allow the mixture to stand

for about 1 min. in a dark place. After this, rinse the contents of the

Erlenmeyer flask out into a beaker with 100 mL dist. water and

immediately back-titrate the iodine thus liberated with sodium

thiosulphate. A blank control sample should be prepared and treated

in the same way. Enter the blank value as C01.

· The sample must be stirred well during the titration, in order to obtain

a good emulsion.

Literature

· Metrohm Application Bulletin No. 141: Analysis of edible oils and fats.

Method documentation

'pa

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:25 4

DET U Perox.No

parameters

>titration parameters

meas.pt.density 4

min.incr. 10.0 ml

dos.rate max. ml/min

signal drift 50 mV/min

equilibr.time 26 s

start V: OFF

pause 0 s

dos.element: internal D0

meas.input: 1

temperature 25.0 °C

>stop conditions

stop V: abs.

stop V 99.99 ml

stop U OFF mV

stop EP 1

filling rate max. ml/min

>statistics

status: OFF

>evaluation

EPC 5

EP recognition: all

fix EP1 at U OFF mV

pK/HNP: OFF

>preselections

req.ident: OFF

req.smpl size: value

activate pulse: OFF

------------

'fm

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:25 4

DET U Perox.No

>calculations

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

C00= 5.0188

C01= 0.0

C02= 10

------------

'fr

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:24 4

U(init) 20 mV DET U Perox.No

smpl size 5.0188 g id#1 Suprema

id#2 Oil

EP1 0.8874 ml 80 mV

Perox.No 1.77 meq/kg

stop #EP reached

============

'cu

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:24 4

start V 0.0000 ml DET U Perox.No

0.5 ml/div dU=20.0 mV/div

============

Determination of Peroxide Number with Potentiometric Method

Determination of Peroxide Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(Na2S2O3) = 0.01 mol/L; D0
Prepared daily from c = 0.1 mol/L

Sample
app. 5 g sunflower oil
50 mL glacial acetic acid / chloroform (3 : 2)
1 mL KI saturate
100 mL dist. water

Remarks
· Calculations:

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

Perox.No = peroxide number in meq.O2/kg

C01 = consumption of blank sample (0 mL)

C02 = factor (10)

. Answer

Perox.No = 0.8874 x 10 / 5.0188 = 1.77 meq/Kg

EP1 = 0.8874 mL

C00 = 5.0188 g

· Sample preparation:

Weigh out accurately 5 g sample in an Erlenmeyer flask and add 50

mL of the glacial acetic acid / chloroform mixture. Then add 1 mL of

the KI solution and shake during 5 s. Now allow the mixture to stand

for about 1 min. in a dark place. After this, rinse the contents of the

Erlenmeyer flask out into a beaker with 100 mL dist. water and

immediately back-titrate the iodine thus liberated with sodium

thiosulphate. A blank control sample should be prepared and treated

in the same way. Enter the blank value as C01.

· The sample must be stirred well during the titration, in order to obtain

a good emulsion.

Literature

· Metrohm Application Bulletin No. 141: Analysis of edible oils and fats.

Method documentation

'pa

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:25 4

DET U Perox.No

parameters

>titration parameters

meas.pt.density 4

min.incr. 10.0 ml

dos.rate max. ml/min

signal drift 50 mV/min

equilibr.time 26 s

start V: OFF

pause 0 s

dos.element: internal D0

meas.input: 1

temperature 25.0 °C

>stop conditions

stop V: abs.

stop V 99.99 ml

stop U OFF mV

stop EP 1

filling rate max. ml/min

>statistics

status: OFF

>evaluation

EPC 5

EP recognition: all

fix EP1 at U OFF mV

pK/HNP: OFF

>preselections

req.ident: OFF

req.smpl size: value

activate pulse: OFF

------------

'fm

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:25 4

DET U Perox.No

>calculations

Perox.No=(EP1-C01)*C02/C00;2;meq/kg

C00= 5.0188

C01= 0.0

C02= 10

------------

'fr

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:24 4

U(init) 20 mV DET U Perox.No

smpl size 5.0188 g id#1 Suprema

id#2 Oil

EP1 0.8874 ml 80 mV

Perox.No 1.77 meq/kg

stop #EP reached

============

'cu

751 GPD Titrino 15215 751.0010

date 97-02-25 time 14:24 4

start V 0.0000 ml DET U Perox.No

0.5 ml/div dU=20.0 mV/div

============

Potentiometric Titration of the Calcium/Mg in Milk Products

Potentiometric Titration of the Calcium/Mg in Milk Products

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0502.140 Cu2+ sensitive indicator electrode; input 1
6.0726.100 Ag/AgCl double junction reference electrode (KNO3 sat.)

Reagents
c(EGTA) = 0.1 mol/L; D0
c(Cu complex) = 0.100 mol/L; D1
Buffer solution pH = 10; D2

Sample
app. 10 g milk

Remarks
· Calculations:

Calcium=C70*C01*C02*C03/C00;3;%

Calcium = content of calcium in %
C01 = concentration of titrating agent (0.1 mol/L)
C02 = molecular mass of calcium (40.08 g/mol)
C03 = factor for % (0.1)
C70 = EP1 from submethod Milk-Ca3

. Answer

Calcium = 3.008 x 0.1 x 40.08 x 0.1 / 10.0516 = 0.12%

C70 = 3.008

· Reagents:
c(EGTA) = 0.100 mol/L:
38.04 g EGTA - ethylene glycol-0,0’-bis-(2-aminoethyl)-N,N,N’,N’-
tetraacetic acid are added to a 1 liter volumetric flask, dissolved in
250 mL c(NaOH) = 1 mol/L and the solution made up to the mark
with dist. water.
Cu complex:
EGTA titrant (100 mL) is mixed with 100 mL of a solution containing
0.2 mol/L NH4Cl and exactly 0.100 mol/L Cu(II)nitrate. Titration can
used to check that this solution contains no excess of Cu(II) or EGTA.

Buffer solution pH = 10:
54 g NH4Cl is dissolved in ca. 400 mL dist. water in a volumetric
flask, 300 mL w(NH3) = 0.25 (25%) added and the solution made up
to 1 liter with dist. water.
· The method „Milk-Ca3“ can also be used as work-alone method
(without TIP). Add the Cu complex-solution and the buffer solution
manually.

Literature
· Metrohm Application Bulletin No. 235: Potentiometric titration of Ca
(Mg) in milk products

Method documentation

'pa

751 GPD Titrino 15215 751.0010
TIP Milk…-Ca
parameters
>sequence
1.stirrer: N
2.method:… Milk-Ca1
3.pause …40 s
4.method:… Milk-Ca2
5.pause …10 s
6.method:… Milk-Ca3
>statistics
status: …OFF
>preselections
req.ident:… OFF
req.smpl size: value
meas.mode:… OFF
temperature …25.0 °C
------------
'fm
751 GPD Titrino 15215 751.0010
TIP Milk…-Ca
>calculations

Calcium=C70*C01*C02*C03/C00;3;%

C00= 10.0516
C01= 0.1
C02= 40.08
C03= 0.1
C70= 3.008
------------'fr
751 GPD Titrino 15215 751.0010
TIP Milk…-Ca
smpl size 10.0516 g
C70 3.008
Calcium 0.120 %
TIP terminated
============

Potentiometric Titration of the Calcium/Mg in Milk Products

Potentiometric Titration of the Calcium/Mg in Milk Products

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0502.140 Cu2+ sensitive indicator electrode; input 1
6.0726.100 Ag/AgCl double junction reference electrode (KNO3 sat.)

Reagents
c(EGTA) = 0.1 mol/L; D0
c(Cu complex) = 0.100 mol/L; D1
Buffer solution pH = 10; D2

Sample
app. 10 g milk

Remarks
· Calculations:

Calcium=C70*C01*C02*C03/C00;3;%

Calcium = content of calcium in %
C01 = concentration of titrating agent (0.1 mol/L)
C02 = molecular mass of calcium (40.08 g/mol)
C03 = factor for % (0.1)
C70 = EP1 from submethod Milk-Ca3

. Answer

Calcium = 3.008 x 0.1 x 40.08 x 0.1 / 10.0516 = 0.12%

C70 = 3.008

· Reagents:

c(EGTA) = 0.100 mol/L:

38.04 g EGTA - ethylene glycol-0,0’-bis-(2-aminoethyl)-N,N,N’,N’-

tetraacetic acid are added to a 1 liter volumetric flask, dissolved in

250 mL c(NaOH) = 1 mol/L and the solution made up to the mark

with dist. water.

Cu complex:

EGTA titrant (100 mL) is mixed with 100 mL of a solution containing

0.2 mol/L NH4Cl and exactly 0.100 mol/L Cu(II)nitrate. Titration can

used to check that this solution contains no excess of Cu(II) or

EGTA.

Buffer solution pH = 10:

54 g NH4Cl is dissolved in ca. 400 mL dist. water in a volumetric

flask, 300 mL w(NH3) = 0.25 (25%) added and the solution made up

to 1 liter with dist. water.

· The method „Milk-Ca3“ can also be used as work-alone method

(without TIP). Add the Cu complex-solution and the buffer solution

manually.

Literature

· Metrohm Application Bulletin No. 235: Potentiometric titration of Ca

(Mg) in milk products

Method documentation

'pa

751 GPD Titrino 15215 751.0010

TIP Milk…-Ca

parameters

>sequence

1.stirrer: N

2.method:… Milk-Ca1

3.pause …40 s

4.method:… Milk-Ca2

5.pause …10 s

6.method:… Milk-Ca3

>statistics

status: …OFF

>preselections

req.ident:… OFF

req.smpl size: value

meas.mode:… OFF

temperature …25.0 °C

------------

'fm

751 GPD Titrino 15215 751.0010

TIP Milk…-Ca

>calculations

Calcium=C70*C01*C02*C03/C00;3;%

C00= 10.0516

C01= 0.1

C02= 40.08

C03= 0.1

C70= 3.008

------------

'fr

751 GPD Titrino 15215 751.0010

TIP Milk…-Ca

smpl size 10.0516 g

C70 3.008

Calcium 0.120 %

TIP terminated

============