Potentiometric Determination of the Anionic Surfactants in Shampoo

Potentiometric Determination of the Anionic Surfactants in Shampoo


Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0507.120 Ionic surfactant electrode; input 1
6.0733.100 Ag/AgCl reference electrode (c(KCl) = 3 mol/L)

Reagents
c(TEGOtrant A100) = 0.004 mol/L; D0
1,3-didecyl-2-methyl-imidazolium chloride (DDMICl)
Metrohm 6.2317.000

Sample
app. 0.2 g sample (shampoo)
5 mL Methanol puriss p.a.
10 mL Buffer solution pH = 3.0, citrate/HCl, e.g. Merck Tirisol No. 9883
60 mL dist. water

Remarks
Calculations:

Anionic=EP1*C01/C00;4;meq/g

Anionic = concentration of anionic Tensides in meq/g
C01 = concentration of titrating agent (0.004 mol/L)

Answer

Anionic = 12.638 x 0.004 / 0.2128 = 0.2376 meq / g

EP1 = 12.638 mL
C00 = 0.2128 g

Electrode preparation, maintenance and storage:
Store the Ionic Surfactant electrode dry. They are conditioned by two to three titrations. Rinse the electrode after several titrations with methanol or wipe it with a cloth moistend woth methanol and rinse with dist. water. If you use the electrode frequently, it may also be stored in a solution of 1% polyethyleneglycol 1000. In this case, the electrode is always ready to use.

Sample preparation:
Adjust the sample size in order to have a titrating agent consumption of at least 10 mL. The pH of buffer solution, the amount of added methanol may change according to the type of surfactant. See also Application Bulletin No. 233.

Literature
Metrohm Application Bulletin No. 233: Titrimetric / potentiometric determination of anionic and cationic detergents with the high-sense surfactant electrode.

Method documentation
'pa
751 GPD Titrino 15215 751.0010
DET U Tens.An
parameters
>titration parameters
meas.pt.density 3
min.incr…. 10.0 ml
dos.rate max….. ml/min
signal drift ….OFF mV/min
equilibr.time …10 s
start V: ….OFF
pause ….30 s
dos.element:…. internal D0
meas.input: ….1
temperature ….25.0 °C
>stop conditions
stop V: ….abs.
stop V ….20 ml
stop U… OFF mV
stop EP ….9
filling rate max….. ml/min
>statistics
status: ….OFF
>evaluation
EPC ….5
EP recognition:… greatest
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 Tens.An
>calculations
Anionic=EP1*C01/C00;4;meq/g
C00= 0.2128
C01= 0.004
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 103 mV DET U Tens.An
smpl size 0.2128 g
EP1 12.638 ml 271 mV
Anionic 0.2376 meq/g
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Tens.An

Potentiometric Determination of the Cationic Surfactants in Fabric softener

Potentiometric Determination of the Cationic Surfactants in Fabric Softener


Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0507.120 Ionic surfactant electrode; input 1
6.0733.100 Ag/AgCl reference electrode (c(KCl) = 3 mol/L)

Reagents
c(DOS) = 0.01 mol/L; D0
Dioctylsodium sulfosuccinat M(DOS) = 444.57 g/mol, Fluka No. 86139

Sample
app. 1 g sample (fabric softener)
5 mL Methanol puriss p.a.
5 mL Buffer solution pH = 3, citrate/HCl, e.g. Merck Titrisol No. 9883
1 mL c(HCl) = 2 mol/L
60 mL dist. water

Remarks
Calculations:

Cationic=EP1*C01/C00;4;meq/g

Cationic = concentration of cationic surfactants in meq/g
C01 = concentration of titrating agent (0.01 mol/L)

Answer

Cationic = 12.631 x 0.01 / 1.0631 = 0.1188 meq/g

EP1 = 12.631 mL
C00 = 1.0631 g

Electrode preparation, maintenance and storage:
Store the Ionic Surfactant electrode dry. They are conditioned by two to three titrations. Rinse the electrode after several titrations with methanol or wipe it with a cloth moistend woth methanol and rinse with dist. water. If you use the electrode frequently, it may also be stored in a solution of 1% polyethyleneglycol 1000. In this case, the electrode is always ready to use.

Sample preparation:
Adjust the sample size in order to have a titrating agent consumption of at least 10 mL.
The pH of buffer solution, the amount of added methanol or the titrating agent may change according to the type of surfactant. See also Application Bulletin No. 233.

Literature
Metrohm Application Bulletin No. 233: Titrimetric / potentiometric determination of anionic and cationic detergents with the high-sense
surfactant electrode.

Method documentation
'pa
751 GPD Titrino 15215 751.0010
DET U Tens.Cat
parameters
>titration parameters
meas.pt.density 3
min.incr. ...10.0 ml
dos.rate max…. ml/min
signal drift …OFF mV/min
equilibr.time ….10 s
start V: ….OFF
pause ….30 s
dos.element:… internal D0
meas.input: …1
temperature …25.0 °C
>stop conditions
stop V: …abs.
stop V …20 ml
stop U …OFF mV
stop EP …9
filling rate max…. ml/min
>statistics
status: ….OFF
>evaluation
EPC …5
EP recognition: greatest
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 Tens.Cat
>calculations
Cationic=EP1*C01/C00;4;meq/g
C00= 1.0631
C01= 0.01
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 300 mV DET U Tens.Cat
smpl size 1.0631 g
EP1 12.631 ml 157 mV
Cationic 0.1188 meq/g
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Tens.Cat

Potentiometric Determination of Non-Ionic Surfactans with the NIO Electrode

Potentiometric Determination of Non-ionic Surfactants with the NIO Electrode

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0507.010 NIO surfactant electrode; input 1
6.0726.100 Ag/AgCl double junction reference electrode
(inner electrolyte c(KCl) = 3 mol/L, outer electrolyte
c(NaCl) = 1 mol/L)

Reagents
c(STPB) = 0.01 mol/L; D0
STPB = sodium tetraphenylborate

Sample
5 mL sample solution
3 mL c(BaCl2) = 0.1 mol/L
60 mL dist. water

Remarks
Titrating agent:

Dissolve 3.4223 g sodium tetraphenylborate in 300 mL dist. water. Dissolve separately 10 g polyvinyl alcohol in 300 mL dist. water and heat it slightly. Allow to cool and rinse both solutions in a 1000 mL flask. Add 10 mL buffer pH = 10 and fill up to 1 liter.

BaCl2 solution:
Dissolve 21 g BaCl2 or 25 g BaCl2*2H2O in dist. water, add 1 mL
conc. HCl and fill up to 1 liter.

Buffer pH = 10:
Dissolve 1.24 g H3BO4 in dist. water, add 10 mL c(NaOH) = 1 mol/L and fill up to 100 mL.

Sample preparation:

Dissolve app. 0.5 ... 1 g detergent (Renex 650 ICI; polyoxyethylene-(30)-nonylphenol, molecular mass 1541 g/mol) in 100 mL dist. water.

Calculations:

Nonionic=EP1*C01*C02/C00;4;meq/g

Nonionic = concentration of nonionic Tensides in meq/g
C01 = concentration of titrating agent (0.01 mol/L)
C02 = dilution factor for the sample solution, aliquot (20)

Nonionic = 8.795 x 0.01 x 20 / 0.5145 = 3.4189 meq/g

EP1 = 8.795 mL
C00 = 0.5145 g

Literature
Metrohm Application Bulletin No. 230: Titrimetric/potentiometric determination of non-ionic tensides (oxyethylates) with the NIO electrode

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U Tenside
parameters
>titration parameters
meas.pt.density… 4
min.incr. ….100 ml
dos.rate ….5 ml/min
signal drift… 5 mV/min
equilibr.time …60 s
start V: ….OFF
pause ….60 s
dos.element:…. internal D0
meas.input: ….1
temperature… 25.0 °C
>stop conditions
stop V: ….abs.
stop V ….12 ml
stop U…. OFF mV
stop EP …9
filling rate max….. ml/min
>statistics
status:… OFF
>evaluation
EPC …10
EP recognition:…. all
fix EP1 at U …OFF mV
pK/HNP: ….OFF
>preselections
req.ident: ….OFF
req.smpl size:…. OFF
activate pulse:… OFF
------------
'fm
751 GPD Titrino 15215 751.0010
DET U Tenside
>calculations

Nonionic=EP1*C01*C02/C00;4;meq/g

C00= 0.5145
C01= 0.01
C02= 20
------------

Potentiometric Determination of EDTA/NTA in Detergents

Potentiometric Determination of EDTA/NTA in Detergents

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(Cu²⁺) = 0.01 mol/L; D0

Sample
10 mL sample solution
10 mL buffer pH = 9.6 [c(NH₃/NH₄NO₃) = 1 mol/L]
2 mL c(Na₂EDTA) = 0.01 mol/L
30 mL dist. Water

Remarks
Calculations:

EDTA=(EP1-C01)*C02*C03/C00;2;%
NTA=(EP1-C01)*C02*C04/C00;2;%

EDTA = content of EDTA in %
NTA = content of NTA in %
C01 = amount of EDTA/NTA added (2 mL)
C02 = factor for % (100)
C03 = 1 mL c(Cu²⁺) = 0.01 mol/L = 2.9225 mg EDTA
C04 = 1 mL c(Cu²⁺) = 0.01 mol/L = 1.9114 mg NTA

Answer

EDTA = (3.004-2.00) x 100 x 2.9225 / 82.63 = 3.55 %
NTA = (3.004-2.00) x 100 x 1.9114 / 82.63 = 2.32 %

EP1 = 3.004 mL
C00 = 82.63 mg

Sample preparation:

Dissolve 0.5 ... 1 g detergent in 50 mL dist. water at 40 °C. Allow solution to cool and add up to 100 mL. Select the appropriate formula. The other may be deleted. Na2EDTA is added to get a greater break. Treat the amount of Na2EDTA added like a blank value.

Literature
Metrohm Application Bulletin No. 143: Potentiometric determination of nitrilotriacetic acid (NTA) and/or ethylenediaminetetracetic acid (EDTA) in detergents.

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U…... EDTA-NTA
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 ….10 ml
stop U ….OFF mV
stop EP ….9
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:…. all
activate pulse: ….OFF
------------
'fm
751 GPD Titrino 15215 751.0010
DET U…. EDTA-NTA
>calculations

EDTA=(EP1-C01)*C02*C03/C00;2;%
NTA=(EP1-C01)*C02*C04/C00;2;%

C00= 82.63
C01= 2
C02= 100
C03= 2.9225
C04= 1.9114
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) -26 mV DET U.... EDTA-NTA
smpl size ….82.63 mg id#1 Total
id#2 Futura id#3 MIFA
EP1 ….3.004 ml 6 mV
NTA …..2.32 %
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U EDTA-NTA
1.0 ml/div dU=20.0 mV/div
============

Potentiometric Determination of the 2-Aminophenol

Potentiometric Determination of the
2-Aminophenol

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

Reagents
c(NaNO₂) = 0.2 mol/L; D0

Sample
app. 0.3 ... 0.35 g sample (2-aminophenol)
10 mL w(HBr) = 0.20 (20%)
30 mL dist. Water

Remarks
Determination reaction:

H+

R-NH₂ + HNO₂ + HBr →[R-NN+]Br- + 2 H₂O

Calculations:

Content=EP1*C01*C02*C03/C00;2;%

Content = content of 2-aminophenol in %
C01 = molecular mass of 2-aminophenol (109.13 g/mol)
C02 = factor for conversion mL to L, and for % (0.001*100=0.1)
C03 = concentration of titrating agent (0.2 mol/L)
Enter the appropriate molecular mass for other amines (C01).
Instead of the Pt Titrode the 6.0420.100 combined Pt electrode can be used.

. Answer

Content = 14.396 x 109.13 x 0.1 x 0.2 / 0.3188 = 98.56 %

EP1 = 14.396 mL
C00 = 0.3188 g

Literature

Metrohm Application Bulletin No. 228: Diazotisation titrations

Method documentation

'pa
751 GPD Titrino 15215 751.0010
MET U …Diazo
parameters
>titration parameters
V step …0.10 ml
dos.rate max…. ml/min
signal drift… OFF mV/min
equilibr.time…. 15 s
start V: ….OFF
pause ….30 s
dos.element:… internal D0
meas.input: …1
temperature… 25.0 °C
>stop conditions
stop V: …abs.
stop V …17 ml
stop U …OFF mV
stop EP …9
filling rate max…. ml/min
>statistics
status: …OFF
>evaluation
EPC …30 mV
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
MET U Diazo
>calculations

Content=EP1*C01*C02*C03/C00;2;%

C00= 0.3188
C01= 109.13
C02= 0.1
C03= 0.2
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 125 mV MET U Diazo
smpl size 0.3188 g id#1 09120
EP1 14.396 ml -203 mV
Content 98.56 %
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 10.000 ml MET U Diazo
2.0 ml/div dU=100.0 mV/div
============

Determination of the Lipase with Potentiometric Method

Determination of the Lipase with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0233.100 combined pH glass electrode; input 1
6.1110.100 T sensor

Reagents
c(NaOH) = 0.1 mol/L; D0

Sample
29.5 mL substrate emulsion
0.5 mL enzyme solution

Remarks
Pancreas lipase is determined using a TIP method: The pH is adjusted to 9.20 with a pretitration (LipPre), then the sample is addedand the pH kept at 9 during 5 minutes (LipDeter). The determination is carried out in a thermostated titration vessel (e.g. 6.1418.220) at 37 °C.

Calculations:

FIP=C70*C31/C00;1;U/mg

LipStd
Factor = calculation factor
FIP = activity of the reference standard in FIP units/mg.
C01 = declared activity of FIP standard (36.2)
C02 = 1000*concentration of titrating agent (100)
C70 = mean rate from LipDeter
LipSmpl1)
FIP = activity of the sample in FIP units/mg.
C30 = calculation factor from LipStd
C70 = mean rate from LipDeter
LipSmpSC2)
FIP = Aativity of the sample in FIP units/mg.
C31 = calculation factor from silo calculation of LipStd
C70 = mean rate from LipDeter
1): Delete the following assignments in method „LipStd“:
. in key , >silo calculations, C24=RS1 and C25=RS2
. in key , >common variables, C31=C26
2): Delete the following assignment in method „LipStd“:
. in key , >common variables, C30=MN1

Solution of Arabic gum:
Dissolve 100 g Arabic gum in 1000 mL dist. water. Centrifuge until the solution is clear (app. 10 minutes with 4000 r/min). This solution can be kept several weeks if frozen in portions.

Substrate standard solution:
Add 165 mL Arabic gum solution, 20 mL olive oil (BP 73) and 15 mLdist. water and cool it in ice to 5 °C. Homogenize with an electric mixer during 30 minutes. The temperature of the solution should never rise above 30 °C. This solution can be kept up to 14 days in a refrigerator. Always homogenize the emulsion before use.

Substrate emulsion:

Stir 100 mL substrate standard solution, 80 mL TRIS buffer solution, 20 mL sodium taurocholate and 95 mL dist. water. This solution must be prepared daily.

TRIS buffer solution:
Dissolve 60.6 mg Tris(hydroxymethyl)-amino methane (C4H11NO3) and 234.0 mg sodium chloride in dist. water and fill up to 100 mL. This solution can be kept up to 3 days in a refrigerator.

Sodium taurocholate solution:
Dissolve 4.0 g sodium taurocholate (F.I.P. controlled) in dist. Water and fill up to 50 mL.

Enzyme solvent

Dissolve 10.0 g sodium chloride, 6.06 g Tris(hydroxymethyl)-amino methane and maleic acid anhydride (C4H2O3) in 900 mL dist. water. Adjust pH to 7.0 with 4N NaOH (app. 13 mL) and fill up to 1000 mL. This solution can be kept up to 3 days in a refrigerator.

Sample preparation:
Dissolve the enzyme in the enzyme solvent. The solution should contain between 8 and 16 FIP Units per mL.

Comments to parameters:

LipDeter Time windows for rate evaluation. Monitoring of rate and temperature is ON: the rate should be kept in the range of 0.08...0.16 mL/min, the temperature in 0.1°C. LipStd, LipSmpl, LipSmpSC T may be measured with .

Literature

B. Stellmach, Bestimmungsmethoden Enzyme, Steinkopff Verlag Darmstadt, 1988, p. 263

Method documentation

Results

'fr

751 GPD Titrino 15215 751.0010

date 97-02-26 time 15:53 10

pHc(init) 9.20 STAT pH LipDeter

smpl size 0.3475 mg id#1 Sample 2

C81 rate 0.1125 +/- 0.00033 ml/min

C82 rate 0.1064 +/- 0.00036 ml/min

C83 rate 0.1020 +/- 0.00029 ml/min

C84 rate 0.0980 +/- 0.00027 ml/min

C80 m.rate 0.1047 +/- 0.00017 ml/min

stop time reached

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

'cu
751 GPD Titrino 15215 751.0010
date 97-02-26 time 15:53 10
start time 60 s STAT pH LipDeter
50.0 s/div dV=0.1 ml/div
============
'fr
751 GPD Titrino 15215 751.0010
date 97-02-26 time 15:54 10
TIP LipSmpSC
smpl size 0.3475 mg id#1 Sample 2
C70…. 0.1047
FIP 35.0 U/mg
mean( 2) +/-s s/%
FIP 35.1 0.14 U/mg 0.40
TIP terminated
============
'fm
751 GPD Titrino 15215 751.0010

date 97-02-26 time 15:59 10
TIP LipSmpSC
>calculations

FIP=C70*C31/C00;1;U/mg

C00= 1.0
C31= 11.29
C70= 0.1047

Determination of the Trypsin with Potentiometric Method

Determination of the Trypsin with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0234.100 combined micro pH glass electrode; input 1
6.1110.100 T sensor

Reagents

c(NaOH) = 0.1 mol/L in a 1 mL exchange unit; D0

Sample
10 mL borate buffer solution pH = 8.0
1 mL substrate solution
0.05 mL enzyme solution

Remarks

Trypsin is an enzyme which is determined using a TIP method: The pH is adjusted to 8.00 with a pretitration (TrypsPre), then the sample is added and the pH kept at 8 during 8 minutes (TrypsDet). The determination is carried out in a thermostated titration vessel (e.g.6.9914.023 with 6.2036.000 holding ring) at 25 °C.

Calculations:

FIP = calculation using the final volume, according to FIP. Result in FIP units/mg.
FIP(reg) = calculation using the mean rate. Result in FIP units/mg. *)
C01 = (factor for mLL) * (concentration of reagent)(100)
C02 = determination time = 8 minutes
C70 = final volume from TrypsDet
C71 = mean rate from TrypsDet

*) The calculation using the mean rate is fundamentally different form the FIP method (final volume / time). The mean rate is calculated by linear regression over all measuring points of the list. If you wish to use only the linear part of the curve for the regression, use a start time of app. 30 s in the method “TrypsDet“. If one of the formulas is not used, you may delete it.

Sample preparation:

Dissolve the enzyme in c(HCl) = 0.001 mol/L. The solution should not contain more than 50 FIP Units per mL.

Substrate solution:

Dissolve 171.3 mg N-Benzoyl-L-arginine ethylester hydrochloride in dist. water and fill up to 25 mL.

Borate buffer solution pH = 8.00:
Dissolve 286.0 mg Disodiumtetraborate-decahydrate and 1.47 g Calciumchloride-dihydrate in 400 mL dist. water, set the pH with c(HCl) = 1 mol/L to 8.00 and fill up with dist. water to 500 mL.

Comments to parameters:

TrypsDetMonitoring of pH and temperature is ON: pH should be kept in the range of 0.1, the temperature in 0.1°C. Trypsin T may be measured with .

Literature
B. Stellmach, Bestimmungsmethoden Enzyme, Steinkopff Verlag Darmstadt, 1988, p. 263

Method documentation

'pa
751 GPD Titrino 15215 751.0010
TIP Trypsin
parameters
>sequence
1.stirrer:… ON
2.method: …TrypsPre
3.info Add smpl & start
4.method: …TrypsDet
>statistics
status: …OFF
>preselections
req.ident:…. OFF
req.smpl size:… OFF
meas.mode: ….T
temperature ….25.0 °C
------------
'fm
751 GPD Titrino 15215 751.0010
TIP Trypsin
>calculations

FIP=C70*C01/C02/C00;1;U/mg
FIP(reg)=C71*C01/C00;1;U/mg

C00= 0.0507
C01= 100
C02= 8
C70= 0.1920
C71= 0.0238
------------
'fr
751 GPD Titrino 15215 751.0010
TIP Trypsin
smpl size 0.0507 g
C70 0.1920
C71 0.0238
FIP 47.3 U/mg
FIP(reg) 46.9 U/mg
TIP terminated
============

Determination of the Trypsin with Potentiometric Method

Determination of the Trypsin with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0234.100 combined micro pH glass electrode; input 1
6.1110.100 T sensor

Reagents
c(NaOH) = 0.1 mol/L in a 1 mL exchange unit; D0

Sample
10 mL borate buffer solution pH = 8.0
1 mL substrate solution
0.05 mL enzyme solution

Remarks
Trypsin is an enzyme which is determined using a TIP method: The pH is adjusted to 8.00 with a pretitration (TrypsPre), then the sample is added and the pH kept at 8 during 8 minutes (TrypsDet). The determination is carried out in a thermostated titration vessel (e.g.6.9914.023 with 6.2036.000 holding ring) at 25 °C.

Calculations:
FIP = calculation using the final volume, according to FIP. Result in FIP units/mg.
FIP(reg) = calculation using the mean rate. Result in FIP units/mg. *)
C01 = (factor for mLL) * (concentration of reagent)(100)
C02 = determination time = 8 minutes
C70 = final volume from TrypsDet
C71 = mean rate from TrypsDet

*) The calculation using the mean rate is fundamentally different form the FIP method (final volume / time). The mean rate is calculated by linear regression over all measuring points of the list. If you wish to use only the linear part of the curve for the regression, use a start time of app. 30 s in the method “TrypsDet“. If one of the formulas is not used, you may delete it.

Sample preparation:
Dissolve the enzyme in c(HCl) = 0.001 mol/L. The solution should not contain more than 50 FIP Units per mL.

Substrate solution:
Dissolve 171.3 mg N-Benzoyl-L-arginine ethylester hydrochloride in dist. water and fill up to 25 mL.

Borate buffer solution pH = 8.00:
Dissolve 286.0 mg Disodiumtetraborate-decahydrate and 1.47 g
Calciumchloride-dihydrate in 400 mL dist. water, set the pH with
c(HCl) = 1 mol/L to 8.00 and fill up with dist. water to 500 mL.

Comments to parameters:
Tryps Det Monitoring of pH and temperature is ON: pH should be kept in the range of 0.1, the temperature in 0.1°C. Trypsin T may be measured with .

Literature
B. Stellmach, Bestimmungsmethoden Enzyme, Steinkopff Verlag

Darmstadt, 1988, p. 263

Method documentation

'pa

751 GPD Titrino 15215 751.0010

TIP Trypsin

parameters

>sequence

1.stirrer:… ON

2.method: …TrypsPre

3.info Add smpl & start

4.method: …TrypsDet

>statistics

status: …OFF

>preselections

req.ident:…. OFF

req.smpl size:… OFF

meas.mode: ….T

temperature ….25.0 °C

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

'fm

751 GPD Titrino 15215 751.0010

TIP Trypsin

>calculations

FIP=C70*C01/C02/C00;1;U/mg

FIP(reg)=C71*C01/C00;1;U/mg

C00= 0.0507

C01= 100

C02= 8

C70= 0.1920

C71= 0.0238

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

'fr

751 GPD Titrino 15215 751.0010

TIP Trypsin

smpl size 0.0507 g

C70 0.1920

C71 0.0238

FIP 47.3 U/mg

FIP(reg) 46.9 U/mg

TIP terminated

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

Potentiometric Determination of the Antacid in the Tablets

Potentiometric Determination of the Antacid in the Tablets

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0233.100 combined pH glass electrode; input 1
6.1110.100 T sensor

Reagents
c(HCl) = 1.0 mol/L; D0

Sample
25 mL dist. water
1 drop c(NaOH) = 0.1 mol/L
0.268 g Antacid Trigastril (or 0.2-0.4 g)

Remarks
Method to determine the efficiency of tablets against an excess of acid in the stomach. Use a TIP method for the determination: The pH is adjusted to 3 with a pretitration (AntacPre), then the sample is added and the pH kept at 3 during 30 minutes (AntacDet). The determination is carried out in a thermostated titration vessel (e.g.6.1418.220) at 37 °C. You may have to adjust the control parameters of the submethod “AntacDet“ according to your sample. The given parameters are optimized for products which release their base slowly (rate app. 100 L/min).

Calculations:

Acid cap=C70*C01/C00;3;mmol/g

acid cap = acid capacity in mmol/g
C01 = concentration of titrating agent (1 mol/L)

Answer

Acid cap = 3.218 x 1 /0.268 = 12.008 mmol/g

C00= 0.268
C01= 1
C70= 3.218

Sample preparation:
Pulverize the tablet and weigh it exactly. Rinse the powder with 20 mL of pretitrated solution (pH=3) into the titration vessel during the request “Add smpl & start“ and titrate immediately.

Literature
N.J. Kerkhoff et al., Journal of Pharmaceutical Sciences, 66, 1528-1535 (1977)

Method documentation

'pa
751 GPD Titrino 15215 751.0010
TIP… Antacid
parameters
>sequence
1.stirrer:… ON
2.method: …AntacPre
3.info Add… smpl & start
4.method:…. AntacDet
>statistic
status: …OFF
>preselections
req.ident:… OFF
req.smpl size:… OFF
meas.mode: …T
temperature …25.0 °C
------------
'fm
751 GPD Titrino 15215 751.0010
TIP Antacid
>calculations
acid cap=C70*C01/C00;3;mmol/g
C00= 0.268
C01= 1
C70= 3.218
------------
'fr
751 GPD Titrino 15215 751.0010
TIP…. Antacid
smpl size… 0.268 g id#1 Trigast.
C70 ….3.218
acid cap….. 12.008 mmol/g
TIP terminated

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

Potentiometric Determination of the Na+ / Cl - in Isotonic Solution

Potentiometric Determination of the Na+ / Cl- in Isotonic Solution

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0430.100 Ag Titrode; input 1

Reagents
c(AgNO3) = 0.1 mol/L; D0

Sample
5 mL sample solution (153 mmol/L Na+ / Cl-)
2 mL c(HNO3) = 2 mol/L
30 mL dist. water

Remarks
· Calculations:

Na+Cl-=EP1*C01*C02/C00;2;mmol/l

Na+Cl- = concentration of Na+ / Cl- in isotonic solution in mmol/L
C01 = concentration of titrating agent (0.1 mol/L)
C02 = factor for conversion mol/L Þ mmol/L (1000)

. Answer

Na+Cl- = 7.652 x 0.1 x 1000 / 5.00 = 153.04 mmol/L

EP1 = 7.652 ml
C00 = 5 mL

Literature
· Metrohm Application Bulletin No. 130: Chloride titrations with
potentiometric end-point indication.

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U Na+Clparameters
>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 …10 ml
stop U …OFF mV
stop EP …9
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:… OFF
activate pulse: …OFF
------------
'fm

751 GPD Titrino 15215 751.0010
DET U Na+Cl-
>calculations

Na+Cl-=EP1*C01*C02/C00;2;mmol/l

C00= 5.0
C01= 0.1
C02= 1000
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 224 mV DET U Na+Clsmpl
size 5.0 ml
EP1 7.652 ml 49 mV
Na+Cl- 153.04 mmol/l
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Na+Cl-
2.0 ml/div dU=100.0 mV/div
========

Potentiometric Determination of Vitamin C

Potentiometric Determination of Vitamin C

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0309.100 double Pt sheet electrode; input Pol
polarized Ipol = 1 mA
Voltametric indication

Reagents
c(DPIP) = 0.001 mol/L; D0
2,6-Dichlorophenol indophenol

Sample
5 mL sample solution
Dissolve 1 effervescent vitamin C tablet in 1 L dist. water
15 mL oxalic acid solution 1 g/L
1 mL w(sodium acetate) = 0.10 (10%)
10 mL dist. Water

Remarks
· Calculations:

Vit.C=EP1*C01*C02*C03;0;mg/pc
Vit.C=EP1*C01*C02/C00;4;g/l

Vit.C = content of Vitamin C in mg/pc (tablet)
Vit.C = content of Vitamin C in g/L
C01 = mg Vitamin C / 1 mL titrating agent (0.088)
C02 = factor of titrating agent (1.00)
C03 = dilution factor (200)

. Answer

Vit.C = 15.291 x 0.088 x 1.00 x 200 = 269 mg/pc
Vit.C = 15.291 x 0.088 x 1.00 / 5.00 = 0.2691 g/L

EP1 = 15.291 mL
C00 = 5.00 mL

· Titrating agent:
Dissolve 295 mg 2,6-Dichlorophenol indophenol with vigorous agitation in 1 L dist. water, then filter and mix with 100 mg sodium bicarbonate.
This solution can be stored in the refrigerator for about 1 month, the factor should be checked daily with standard ascorbic acid. (As a titrating agent, the more readily soluble sodium salt may be used instead.)

· Standard solution:
r (Vitamin C) = 500 mg/L
Dissolve 50 mg ascorbic acid in oxalic acid solution (1 g/L) and make up to 100 mL. This solution should be freshly prepared daily.

· Sample preparation:
Place dist. water, oxalic acid solution and sodium acetate buffer in the titration vessel and deaerate by passing a stream of nitrogen for 3...5 min. Then add a quantity of sample or standard solution containing about 0.05...0.5 mg vitamin C. Now titrate under nitrogen with titrating agent.
· Store electrode in acidified Na2S2O3 solution.
· Select the appropriate formula. The other may be deleted.
· The 6.0431.100 Pt Titrode may be used together with mode MET U.

Literature
· Metrohm Application Bulletin No. 98: Determination of ascorbic acid
(Vitamin C) and its compounds.

Method documentation

'pa
751 GPD Titrino 15215 751.0010
MET Ipol… Vit.C
parameters
>titration parameters
V step …0.10 ml
dos.rate max…. ml/min
signal drift …OFF mV/min
equilibr.time …15 s
start V: …OFF
pause …30 s
dos.element:… internal D0
I(pol) …1 mA
electrode test:… OFF
temperature …25.0 °C
>stop conditions
stop V: …abs.
stop V …20 ml
stop U… OFF mV
stop EP …9
filling rate max…. ml/min
>statistics
status: …OFF
>evaluation
EPC …30 mV
EP recognition: all
fix EP1 at U …OFF mV
>preselections
req.ident: …OFF
req.smpl size: …OFF
activate pulse: …OFF
------------
'fm
751 GPD Titrino 15215 751.0010
MET Ipol Vit.C
>calculations

Vit.C=EP1*C01*C02*C03;0;mg/pc
Vit.C=EP1*C01*C02/C00;4;g/l

C00= 5.0
C01= 0.008
C02= 1.00
C03= 200
------------
'fr

751 GPD Titrino 15215 751.0010
U(init) 121 mV MET Ipol Vit.Csmpl size 5.0 ml

EP1 …15.291 ml…. 122 mV
Vit.C… 269 mg/pc
Vit.C ….0.2691 g/l
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 12.000 ml MET Ipol Vit.C
1.0 ml/div dU=50.0 mV/div

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

Potentiometric Determination of the Iodine Number

Potentiometric Determination of the Iodine Number

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

Reagents
c(Na2S2O3) = 0.1 mol/L; D0

Sample
app. 0.5 g sunflower oil
15 mL CCl4
25 mL c(ICl) = 0.1 mol/L (according to Wijs in glacial acetic acid / CCl4,
e.g. Merck No. 9163)
10 mL w(Hg acetate) = 0.025 (2.5%) in glacial acetic acid
15 mL w(KI) = 0.10 (10%)
30-50 mL dist. water

Remarks
· Calculations:

Iod.No=(C01-EP1)*C02/C00;2;g/100g

Iod.No = iodine number in g iodine / 100 g sample
C01 = consumption of blank sample (0 mL)
C02 = molecular mass of I * concentration titrating agent * 100g
sample / factor mL -> L (126.9 * 0.1 *100/1000 = 1.269)

. Answer

Iod.No = (0 – 6.149) x 1.269 / 0.5204 = 104.61 g/100g

EP1 = 6.149 mL
C00 = 0.5204 g

· Sample preparation:
According to the expected iodine number, weigh out 0.10 ... 1.00 g of the sample in an Erlenmeyer flask and add 15 mL CCl4.
Add 25 mLiodine monochloride solution and add 10 mL mercuric acetate solution, mix and allow to stand for 5 min. in a dark place.
Then add 15 mL KI solution, rinse into a beaker with dist. water and back-titrate the excess iodine with sodium thiosulphate.
A blank control sample should be prepared and treated in the same way. Enter the blank value as C01.
· You may add a solution of w(Mg-acetate) = 0.03 (3%) instead of the Hg-acetate solution.
· 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
DET U… Iod.No
parameters
>titration parameters
meas.pt.density… 4
min.incr…. 10.0 ml
dos.rate max…. ml/min
signal drift …20.0 mV/min
equilibr.time …38 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 ….20 ml
stop U ….OFF mV
stop EP ….9
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 Iod.No
>calculations

Iod.No=(C01-EP1)*C02/C00;2;g/100g

C00= 0.5204
C01= 0
C02= 1.269
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) -16 mV DET... U Iod.No
smpl size ....0.5204 g
EP1… 6.149 ml …92 mV
Iod.No ….104.61 g/100g
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Iod.No
2.0 ml/div dU=50.0 mV/div
============

Determination of Acid Number with Potentiometric Method

Determination of Acid Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0133.100 pH glass electrode; input 1
6.0726.100 Ag/AgCl double junction reference electrode
(LiCl sat. in ethanol)

Reagents
c(NaOH) = 0.1 mol/L; D0

Sample
app. 5-10 g sunflower oil
50 mL ethanol / diethylether (1 : 1), neutralized

Remarks
· Calculations:

Acid.No=EP1*C01/C00;2;mg/g
FFA=RS1*C02/C03;2;

Acid.No = acid number in mg KOH per g of sample
FFA = free fatty acid
C01 = mg KOH / 1 mL titrating agent (5.61)
C02 = relative molecular mass (282 for oleic acid)
C03 = factor (561)

. Answer

Acid.No = 0.150 x 5.61 / 10.3223 = 0.08 mg/g
FFA = 0.08 x 282 / 561 = 0.04

RS1 = 0.08
EP1 = 0.150 mL
C00 = 10.3223 g

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

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U… Acid.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 …3 ml
stop U …OFF mV
stop EP …9
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 Acid.No
>calculations

Acid.No=EP1*C01/C00;2;mg/g
FFA=RS1*C02/C03;2;

C00= 10.3223
C01= 5.61
C02= 282
C03= 561
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 35 mV DET U... Acid.No
smpl size ....10.3223 g
EP1 ....0.150 ml.... -201 mV
Acid.No .....0.08 mg/g
FFA 0.04
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Acid.No
1.0 ml/div dU=100.0 mV/div
============

Determination of Acid Number with Potentiometric Method

Determination of Acid Number with Potentiometric Method

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0133.100 pH glass electrode; input 1
6.0726.100 Ag/AgCl double junction reference electrode
(LiCl sat. in ethanol)

Reagents
c(NaOH) = 0.1 mol/L; D0

Sample
app. 5-10 g sunflower oil
50 mL ethanol / diethylether (1 : 1), neutralized

Remarks
· Calculations:

Acid.No=EP1*C01/C00;2;mg/g

FFA=RS1*C02/C03;2;

Acid.No = acid number in mg KOH per g of sample

FFA = free fatty acid

C01 = mg KOH / 1 mL titrating agent (5.61)

C02 = relative molecular mass (282 for oleic acid)

C03 = factor (561)

. Answer

Acid.No = 0.150 x 5.61 / 10.3223 = 0.08 mg/g

FFA = 0.08 x 282 / 561 = 0.04

RS1 = 0.08

EP1 = 0.150 mL

C00 = 10.3223 g

Literature

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

Method documentation

'pa

751 GPD Titrino 15215 751.0010

DET U… Acid.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 …3 ml

stop U …OFF mV

stop EP …9

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 Acid.No

>calculations

Acid.No=EP1*C01/C00;2;mg/g

FFA=RS1*C02/C03;2;

C00= 10.3223

C01= 5.61

C02= 282

C03= 561

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

'fr

751 GPD Titrino 15215 751.0010

U(init) 35 mV DET U... Acid.No

smpl size ....10.3223 g

EP1 ....0.150 ml.... -201 mV

Acid.No .....0.08 mg/g

FFA 0.04

stop V reached

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

'cu

751 GPD Titrino 15215 751.0010

start V 0.000 ml DET U Acid.No

1.0 ml/div dU=100.0 mV/div

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