1. science
2. chemistry

Application Bulletin 280/1 e
Automated Karl Fischer water determination
with the 774 Oven Sample Processor
Of interest to:
General analytical laboratories; Pharmaceutical industry; Petrochemistry; Plastics, photographic industry; Food analysis
F 1, 4, 5, 6, 7
Summary
Instruments and accessories
In principle the 774 Oven Sample Processor can be
used with all samples that release their water when
heat is applied. However, the KF oven method is essential whenever direct volumetric or coulometric Karl
Fischer titration is impossible because the sample
contains interfering components or, due to its consistency, is difficult to place in the titration vessel.
The combination of the 774 Oven Sample Processor
with coulometric Karl Fischer titration (756 or 831 KFCoulometer) is ideal for samples with a low water content. Foodstuff, pharmaceutical products, plastics or
mineral oil products can be analyzed fully automaed
and extremely accurately. On the other hand, a volumetric Karl Fischer titration using a KF Titrino is to be
preferred for sample with a very high water content
(>50%).
In accordance with the gas extraction principle the
water is driven out of the heated sample by a stream of
dry carrier gas and transferred to the titration vessel,
where the water is determined by a KF titration.
For temperature-sensitive samples, e.g. foodstuff, the
water can be released gently at lower temperatures by
simultaneous extraction with methanol. In this way it is
possible to prevent any water released by decomposition.
This Application Bulletin uses examples from the food,
pharmaceutical, plastics and petrochemical industries
to describe automatic Karl Fischer water determination
using the 774 Oven Sample Processor and a KF Coulometer. Information applying to the combination of the
Oven Sample Processor with a volumetric KF titrator is
given in brackets.
774/Coulometer System
2.774.0010 Oven Sample Processor
6.2419.000 Sample vessels for 774
6.1448.050 Septum with sealing
6.1808.040 Adapter for needle
6.1808.090 Adapter for needle
2.756.0110 KF Coulometer with diaphragm-less
generator cell or
2.831.0110 KF Coulometer with diaphragm-less
generator cell
2.728.0010 Magnetic Stirrer
6.2125.110 Cable 774–PC
6.2134.040 Cable 756–PC
6.2141.020 Remote cable 774–756
6.6012.140 Metrodata TiNet 2.4
6.6008.200 Metrodata VESUV 3.0
6.5618.000 Test tool for oven temperature
2.767.0010 Calibrated Reference
774/Titrino System
2.774.0010 Oven Sample Processor
6.2419.000 Sample vessels for 774
6.1448.050 Septum with sealing
6.1808.040 Adapter for needle
6.1808.090 Adapter for needle
2.758.0010 KFD Titrino or
2.758.0020 KFD Titrino or
2.784.0010 KFP Titrino or
2.795.0010 KFT Titrino
2.728.0010 Magnetic Stirrer
6.3014.213 10 mL Exchange Unit
6.2125.110 Cable 774–PC
6.2134.040 Cable 758/784–PC
6.2141.020 Remote cable 774–758/784
6.6012.140 Metrodata TiNet 2.4
6.6008.200 Metrodata VESUV 3.0
6.5618.000 Test tool for oven temperature
2.767.0010 Calibrated Reference
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 2/11
•
HYDRANAL Coulomat AG Oven, Riedel-de Haën
no. 34739 (for coulometric KF titration)
•
HYDRANAL Methanol Dry, Riedel-de Haën no.
34741 (as additional extraction agent or for volumetric KF titration)
•
HYDRANAL Composite 5, Riedel-de Haën no.
34805 (for volumetric KF titration)
•
HYDRANAL Standard Sodium tartrate dihydrate,
Riedel-de Haën no. 34803
•
HYDRANAL Water Standard KF Oven (potassium
citrate monohydrate), Riedel-de Haën no. 34748
or
•
Apura CombiCoulomat fritless, Merck no. 1.09257
(for coulometric KF titration)
instruments themselves and, if necessary, modified to
suit the samples to be analyzed.
The flow rate of the carrier gas (air or N2) should lie
between 40...60 mL/min. For solid samples 40 mL/min
is normally used, for liquid samples 60 mL/min is set.
The gas flow must be large enough to transfer the
released moisture as quickly as possible to the titration vessel, and small enough to guarantee the complete absorption of the water in the titration solution.
The vessels for conditioning, system preparation,
determination of the blank value (see under «Titration
sequence») and the sample vessels are placed on the
rack of the 774 Oven Sample Processor. For coulometric KF titration the titration vessel is filled with
150 mL HYDRANAL Coulomat AG Oven (for volumetric KF titration with approx. 30 ... 40 mL HYDRANAL
Methanol Dry) and then conditioned.
•
Apura CombiTitrant 5, Merck no. 1.88005 (for volumetric KF titration)
Temperature ramps
•
Apura CombiSolvent, Merck no. 1.88008
•
Apura Sodium tartrate dihydrate, Merck no.
1.06664
•
Molecular sieve, pore size 0.3 nm, Metrohm no.
6.2811.000
•
Carrier gas (air or N2)
Reagents
For samples whose temperature behavior is unknown
a so-called temperature ramp is run (available temperature range 50 ... 250 °C). The heating rate should
be selected so that it can be guaranteed that the
temperature can actually be achieved inside the sample. Figure 1 shows a temperature ramp in which the
sample is heated from 50 °C to 250 °C in 100 min, i.e.
the heating rate is 2 °C/min.
Sample preparation
The sample is thoroughly mixed under conditions
which are as dry as possible. The sample weight depends on the water content. Sample weights that are
too low have a negative effect on the measuring accuracy (weighing error); the maximum sample weight is
limited by the reagent capacity (1000 mg H2O per
100 mL reagent for HYDRANAL Coulomat AG Oven).
The absolute amount of water transferred to the titration vessel for analysis should be in the range 300 ...
1000 µg. We also recommend that the KF reagent is
changed once per week under «normal» operation,
more often if necessary.
The appropriate amount of sample are weighed into
the sample vessels, which should previously have
been conditioned for at least 24 h in the surrounding
air. The vessels are then sealed with PTFE-coated
septa which have also been conditioned. When working gloves should be worn to avoid contamination of
the samples and prevent contact with skin moisture.
Table 2, page 6 makes the relationship between the
amount of sample used in the analysis and its water
content clear.
Instrument preparation
On the 774 Oven Sample Processor the lift positions
for the conditioning vessel (rinsing position) and the
sample vessels (working position in the oven) as well
as the maximum lift path are configured. The previously programmed methods for the Oven Sample
Processor and the KF Coulometer (or the KF Titrino)
are called up by the TiNet software or directly on the
Fig. 1:
Diagram showing a possible temperature ramp.
While a temperature ramp is being recorded it is possible to record both the amount of water released and
the drift as a function of time (see Fig. 5 and 6 in the
annex). By using the heating rate and the elapsed
time it is possible to calculate the associated temperature curve (see Fig. 2). This allows statements about
the kinetics of the water release as a function of the
temperature. In addition, with thermally unstable samples any decomposition reactions in which water is
released can be recognized.
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 3/11
2500
2000
15000
1500
10000
1000
5000
500
0
50
100
Drift [ug/min]
Wasser [ug]
20000
T [°C]
Wasser [ug]
Analytical procedure
Each analysis consists of the following steps:
•
•
•
•
•
0
200
150
tract all the water it contains. Any transfer of the water
of decomposition formed in the titration vessel at
higher temperatures (from approx. 180 °C) must be
avoided.
Drift [ug/min]
Conditioning the titration vessel
Extracting the water from the sample
Transporting the water to the titration vessel
Karl Fischer titration
Calculation of the result
Conditioning
Fig. 2:
Temperature curve of sodium tartrate dihydrate:
amount of released water and the associated drift
as a function of the temperature.
10000
600
Water extraction
8000
500
Carrier gas dried by molecular sieve is passed
through or over the heated sample and drives out the
water it contains (see Fig. 4). The temperature of the
oven can be varied according to the thermal stability
of the sample.
400
6000
300
4000
200
2000
Drift [ug/min]
Wasser [ug]
In the temperature curve of the tartrate sample (see
Fig. 2) it can be seen that it releases its surface water
uniformly up to a temperature of approx. 110 °C. In
parallel the drift sinks from approx. 500 µg/min to
100 µg/min. Between 110 °C and 125 °C the water of
crystallization contained in the sodium tartrate dihydrate is released; this can also be very clearly recognized by the occurrence of a «drift peak». When all
the water has been driven out of the sample the drift
sinks to its basic value of approx. 10 µg/min.
The temperature curve is used to determine the optimum oven temperature for driving out the water of the
sample. This temperature should be high enough for
the water to be extracted completely without any decomposition of the sample occurring; the reaction time
should also be kept as short as possible. For sodium
tartrate dihydrate 160 °C are recommended as analysis temperature. The analytical procedure when recording a temperature ramp is the same as for a determination at a given, fixed temperature (see below).
Figure 3 shows the temperature curve of a sample of
food which, after releasing all its water, starts to decompose at approx. 180 °C.
100
0
50
100
150
200
0
250
T [°C]
Wasser [ug]
Fig. 3:
Conditioning, i.e. titrating the titration vessel to dryness is carried with the 774 Oven Sample Processor
in the so-called conditioning position. This conditioning step must be carried out before every determination. The oven is heated up to the selected analysis
temperature. Then the needle moves to the sample
position. Only now is the water driven out of the sample by a combination of a dry stream of carrier gas
and the increased temperature of the oven and transferred to the KF titration vessel, where the determination by a Karl Fischer titration takes place. This titration may be coulometric (with the 756 or 831 KF Coulometer) or – for samples with a high water content
(>50%) – volumetric (with a Karl Fischer Titrino). The
latter method should be used if very small sample
weights and the associated large measuring inaccuracies are to be avoided.
The double hollow needle of the Oven Sample Processor can be lowered almost to the base of the sample vessel and in this way the carrier gas can be
passed though the heated sample. With liquid samples this achieves an additional extraction effect. For
the analysis of solid samples a shortened needle is
normally used [this requires the use of special adapters (Ordering no. 6.1808.040 and 6.1808.090. In this
way turbulent mixing of the sample and contamination
of the following samples or the conditioning vessel by
substances adhering to the needle tip can be avoided.
Drift [ug/min]
Temperature curve of a food sample that starts to
decompose at 180 °C.
This temperature curve is used to select an analysis
temperature of 120 °C for the sample in order to ex-
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 4/11
dry carrier gas
to the titration vessel
oven
septum
double hollow needle
sample
Fig. 4:
Sample vessel with double hollow needle.
Thermosensitive samples can be gently analyzed at
lower temperatures by using HYDRANAL Methanol
Dry as the extraction agent. This is placed in the sample vessel together with the sample. Methanol supports
the release of water, particularly during the boiling
process in the oven. It is transferred to the titration
vessel together with the water but does not interfere
with the titration as the KF reagent also contains
methanol.
It is generally advisable to set an extraction time. This
ensures that the driven off water is completely transferred to the titration vessel. We recommend a time of
180 seconds. If methanol is used as an additional
extraction agent then it is important that a sufficiently
long extraction time is selected in order to prevent a
premature termination of the determination. In this
case we recommend at least 15 min.
Karl Fischer titration
For a coulometric Karl Fischer titration a modified KF
reagent is used which contains iodide. During the
determination the iodide is oxidized anodically (generator electrode) to iodine which then reacts with the water. As this is an absolute method no titer adjustment is
necessary.
In volumetric Karl Fischer titration the titer of the titrant
must first be determined by using a certified water
standard. In combination with the 774 Oven Sample
Processor this is done by driving the water out of the
«KF Oven Standards» sodium tartrate dihydrate at
160 °C or potassium citrate monohydrate at 220 °C.
Titration sequence
The water content determined by the gas extraction
with subsequent KF titration is made up as follows:
Water contentabsolute
= water contentsample + blank value + drift
In conditioning, during which the needle is located in
the conditioning vessel, any moisture contained in the
system is removed until a constant low drift in the
range 10 ... 20 µg/min is achieved. The conditioning
step must be carried out before each new analysis,
and also before system preparation and the determination of the blank value. In combination with TiNet
the start of the sample series takes place via the
<COND> button; this starts conditioning both the
Oven Sample Processor and also the KF Coulometer
or KF Titrino. If the TiNet software is not used the
analysis is started with the <START> key of the 774
Oven Sample Processor. At this point the KF Coulometer or the KF Titrino must be in the STOP mode.
With automatic drift correction the drift value measured immediately before the determination will be
used for determining the water content of the sample
(subtracted).
System preparation means that the whole system will
be adjusted to the selected conditions. An empty
sample vessel will be treated in exactly the same way
as the following samples, but the value obtained will
not be taken into account. We recommend that this
step – which at the same time is used for checking
that the analysis system is working properly – is carried out before each new sample series.
Apart from the water in the sample, the sample vessel
also contains atmospheric humidity; this makes a
blank value determination necessary. If methanol is
used as an additional extraction agent then its water
content must also be determined, i.e. included in the
blank value. A three-fold determination of the blank
value is normally sufficient. The mean value is stored
as a Common Variable and taken into account in the
calculation of the water content (subtracted).
The system preparation and the blank value determinations must be carried out under exactly the same
conditions as the analysis of the samples. In order to
do this an empty system preparation vessel and three
empty (or filled with solvent) blank value vessels are
placed on the rack of the 774 Oven Sample Processors and processed before the samples.
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 5/11
Instrument settings
Validation of the analysis system
Tab. 1:
GLP (Good Laboratory Practice) requires among
other things, that the correctness and precision of
analytical instruments are checked at regular intervals
by using SOPs (Standard Operating Procedures). We
recommend to validate the analytical system as a
whole by carrying out a series of determinations with
certified standards (see Metrohm Application Bulletins
No. 255, 273 and 281).
The validation of the 774/Coulometer and 774/Karl
Fischer Titrino Systems is carried out by using sodium
tartrate dihydrate or potassium citrate monohydrate
(methods in Annex). These KF standards are supplied
with analysis certificates in which their exact water
content is given. A 10-fold determination is carried out
with different sample weights. The relative standard
deviation should be less than ≤2.0%.
In addition to the start-up check routines of the instruments, the use of the built-in diagnosis programs
and regular service we also recommend to check the
electronic components of the instruments (Coulometer
or Karl Fischer titrino) by using the 767 Calibrated
Reference.
A measuring insert for the heating block with a built-in
temperature sensor (6.5618.000) is used in combination with a calibrated temperature measuring instrument as an oven temperature test tool for the 774
Oven Sample Processor. The measuring setup is
inserted into the oven block in the same way as a
sample vessel and fixed in position. When the set
temperature has been reached the inner temperature
measured by the test tool is compared with the display of the Oven Sample Processor. If the measured
temperature varies greatly from the oven temperature
displayed (more than ±4 °C) please contact Metrohm
Service.
In order to check the gas flow of the Oven Sample
Processor a calibrated flowmeter is included in the
gas flow of the system and the flow rate measured by
the test tool is compared with the set value. The permissible tolerance of the flowmeter (with micro-bridge
air flow sensor) built into the 774 Oven Sample Processor is ±20%. The external flowmeter cannot be
purchased from Metrohm AG.
Control and titration parameters.
Parameter
Control parameters
coulometry:
Setting
EP at U
50 mV
dynamics
70 mV
max.rate
max. µg/min
min.rate
15 µg/min
stop crit.
rel.drift
rel.drift
10 µg/min
Titration parameters
coulometry:
start drift
10 µg/min
I(pol)
10 µA
Preselections
coulometry:
generator I
400 mA
Control parameters
volumetry:
EP at U
250 mV
dynamics
100 mV
max.rate
max. mL/min
min.volume incr.
min. µL
stop crit.
drift
stop drift
20 µL/min
Titration parameters
volumetry:
titr.direction
–
I(pol)
50 µA
Oven settings:
initial temp.
depending on
sample,
normally 50 °C
Gas flow:
flow rate
40...60 mL/min
gas type
air or N2
gas flow factor
1.0 (for air or N2)
Troubleshooting
Procedure in case of poor precision (reproducibility):
•
Optimize the titration and control parameters.
•
Check whether the sample vials are tightly sealed.
•
Drift too high: check titration cell, septum and/or
seals leaks, molecular sieve used up, poorly conditioned, ensure thorough mixing.
•
Clean electrodes: indicator electrode mechanically
with moist polishing powder (aluminum oxide or
toothpaste), rinse and dry; treat with conc. HNO3 or
change the electrode; align Pt-pins parallel. Clean
generator electrode with conc. HNO3.
•
KF reagent contaminated/used up: change the
solution; use a different batch number if necessary.
•
Check electrical contacts.
•
Check oven temperature.
•
Balance: too inexact, drafts, temperature influences, temperature equilibrium not reached, sample weight not optimal/too low.
•
Possibly carry out a validation of the analysis system.
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 6/11
Examples of applications
Sample
The following table provides an overview of samples
analyzed by the 774 Oven Sample Processor. In each
case the Karl Fischer water determination was carried
out in combination with the 756 KF Coulometer using
N2 as the carrier gas (flow rate 40 mL/min). As well as
the determined water content the sample weights and
analysis temperatures are given.
Tab. 2:
Water content of samples from various branches
together with their analysis parameters.
Sample
Aromas
1
Sample wt. Water content
[g]
[ppm]
Pharmaceutical products:
Collagens
160
0.07...0.4
106000...919000
Denture cleaner,
Effervescent ta6
bletts
70
0.2...1.5
38000
Drugs
140
0.04
67000
Lyophilizate
150
0.01
50000
Vitamin C
80...90
0.1
30000
T
[°C]
Sample wt. Water content
[g]
[ppm]
Others:
Sodium tartrate
dihydrate
160
0.02...0.08
155000
120
0.06
Potassium citrate
monohydrate
220
0.03
55500
Methanol
110
0.5
230
220
0.03...0.3
10000...850000
Foodstuff:
Lyophilizate
T
[°C]
14000
100
0.03...0.08
25000...54000
(Malto-)Dextrin
100
0.03...0.08
47000...88000
Lactose monohydrate
155
0.06
52000
Polyammonium
compounds
0.06
44000
Emulsified fat com- 220
pound
0.03...0.08
850000
Whole milk powder 90
0.06
39000
Formamidosulfonic 220
acid
0.2...0.3
<10000
Sweet whey pow2
der
90
0.06
49000
Pigment
100
0.03...0.3
79000
Glucose monohy2
drate
90
0.06
89000
Polyolether
150
0.6...1.3
Dibutene
100...140 0.03
Maltose monohy3
drate
120
0.06
59000
Roast coffee,
ground
145
0.06
48200
Garlic powder
110
0.2
35000
Mineral mixtures
110
0.3
60000...70000
Skimmed milk pow- 90
2
der
2
Plastics:
Polypropylene
Polyethylene
4
170
3.0
1500
250
Inorganic salt
100
0.01...0.03
580
Lithium cobaltite
100
0.45...1.0
64
Surface water
50...60
0.3
6000
Bound water
85...140
0.3
10000
Building rubble
1
With the 774 Oven Sample Processor the dissolution of the sample
in KF reagent, which is required in a direct Karl Fischer titration and
which frequently cannot be carried out completely, is no longer
necessary.
2
With the addition of 4 mL methanol as extraction reagent. Regular
checks of the gas flow are necessary as there is a risk that the
needle may be blocked.
380
115
3.0
40
Olefins
180
3.0
100
Polyamide
180
0.3
7800
3
Polyoxymethylene
(POM)
170
0.3
1400
With the addition of 4 mL 1,5-pentandiol, extraction time 600 s.
4
20 ppm water could be determined as the detection limit.
5
With self-expanding plastics only the surface water can be determined with the 774/756 System. The plastics also contain trapped
water. This can only be calculated as the difference between the
total water and surface water; the total water is determined by
completely dissolving the sample in p-xylene under heating and
subsequent volumetric Karl Fischer titration.
6
Above 70 °C the contained carbonate decomposes.
5
120
0.05...0.2
200...500
Transformer oil
150
3.0
80
Mineral oil
120
1...3
10...100
Insulating oil
140
3
5
Crude oil
140
2
500...1200
Additive
120
0.01...0.03
44000
3.0
700
Polystyrene
Refinery products:
Antimony dialkyldi- 50...130
thiocarbamate in
crude oil
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 7/11
Literature
•
Instructions for use of 758 KFD Titrino.
•
•
Instructions for use of 795 KFP Titrino.
•
Instructions for use of 767 Calibrated Reference.
•
Metrohm leaflet 8.110.1663
6.5618.000 measuring set for checking the temperature of the 774 Oven Sample Processor.
Metrohm Application Bulletin No. 137
Karl Fischer water determination with the KF coulometer.
•
Metrohm Application Bulletin No. 255
Validation of Metrohm KF titrators and KF ovens
according to GLP/ISO 9001.
•
•
Metrohm Application Bulletin No. 273
Validation of Metrohm KF Coulometers using Standard Operating Procedures.
Metrohm leaflet 8.110.1643
Checking the gas flow of the 774 Oven Sample
Processor.
•
•
Instructions for use of 774 Oven Sample Processor.
HYDRANAL Manual
Eugen Scholz reagents for Karl Fischer Titrations,
2006.
•
Instructions for use of 756/ 831 KF Coulometer.
Schematic diagram of the 774 Oven Sample Processor and 756 KF Coulometer analysis system
Water
TiNet
2.4
756 KF
LPT 1
stirrer 728
COM 1
Oven Sample
Processor 774
COM 2
6.2134.040
6.2125.060
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 8/11
Appendix
Parameter report for a temperature ramp (created with Metrodata TiNet 2.4)
'pf
Date 01.03.2001 Time 15:10:11
Method: temperature gradient
Stored 01.03.01
>Start
Common variables
Name Blankvalue
Value 89.4
Comment
Method variables
Name SmplSize
Assign &SmplSize
Comment SmplSize
>Start sequence, Startsequenz
Instrument 774_1
Sample variable reset
>Calculations, Shiftrate
Formulas
Transfer
From TiNet to devices
To device 774_1
To path &m.ch.sh"15"
Comment
>Sequence, Sequence
Instrument 774_1
Sequence used as ... RMove
>Oven settings, OvenSetting
Sample temp. 50 °C
Oven heat.time OFF min
Conditioning ON
>Wait Oven temp., WaitOvenTemp
Timeout 0 min
Error message OFF
>Feed sample, Probe zuführen
Instrument 774_1
Next sample
Feed sample to...
Station 1
Sample heating
Sample temp. 50
Conditioning ON
>Sequence, Sequenz
Instrument 774_1
Sequence used as ... RMove
>Oven settings, Ofen Einstellung
Sample temp. 140 °C
Oven heat.time 45 min
Conditioning OFF
>KFC, KFC
Instrument 756_1
Parameters
Control parameters
EP U 50 mV
Dynamics 70 mV
Max.rate max. ug/min
Min.rate 15 ug/min
Titration parameters
Extr. time 2700 s
I(pol) 10 uA
Electrode test ON
Temperature 25.0 °C
Cell type no diaph.
I generator 400 mA
Start conditions
Pause 0 s
Start drift 10 ug/min
Time cond.ok 60 s
Activate pulse OFF
Stop parameters
Rel. drift 5 ug/min
Max. titr. time OFF s
Drift correction
Auto drift correction
Save data
Curve ON
Interval for meas. 5 s
Save changes only OFF
EP ON
C4# from Coulometer OFF
>Calculations, Berechnungen
Formulas
RS
Content
('KFC.EP1'-'Blankvalue')/'SmplSize';ppm;1;0;
Content%
('KFC.EP1''Blankvalue')/10000/'SmplSize';%;4;0;
>Report, Report
Database
Select data
Curve ON
Result report ON
Parameter report ON
Save in water
Print layout
Print options
Font width 12
Report per determination
Print immediately OFF
Multipage printout
page numbers OFF
Header on each page OFF
Footer on each page OFF
Print in reverse order OFF
Layout
Text
Print result report line(s)...
Report ident. ON
Date ON
Method ON
EP variables ON
C4X variables OFF
Other variables OFF
Common variables ON
Results ON
Satistics OFF
Report blocks
Results
>Remove sample, Probe wegfahren
Instrument 774_1
Remove sample from ...
Station 1
>End sequence, Endsequenz
Instrument 774_1
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 9/11
Parameter report for a KF water determination with selectable analysis temperature T = ‘ID1’
(created with Metrodata TiNet 2.4)
'pf
Date 16.08.2001 Time 17:14:51
Method: samplevartemp
Stored 14.03.01
>Start
Common variables
Name Blankvalue
Value 112.9
Comment
Method variables
Name SmplSize
Assign &SmplSize
Comment SmplSize
Name Id1
Assign &Id1
Comment Identifikation
>Start sequence, Start sequence
Instrument 774_1
Sample variable reset
>Calculations, Shiftrate
Formulas
Transfer
From TiNet to devices
To device 774_1
To path &m.ch.sh"15"
Comment
>Sequence, Sequence
Instrument 774_1
Sequence used as ... RMove
>Oven settings, OvenSetting
Sample temp. ='Id1' °C
Oven heat.time OFF min
Conditioning ON
>Wait Oven temp., WaitOvenTemp
Timeout 0 min
Error message OFF
>Feed sample, Feed smpl
Instrument 774_1
Next sample
Feed sample to...
Station 1
Sample heating
Sample temp. ='Id1'
Conditioning ON
>KFC, KFC
Instrument 756_1
Parameters
Control parameters
EP U 50 mV
Dynamics 70 mV
Max.rate max. ug/min
Min.rate 15 ug/min
Titration parameters
Extr. time 1000 s
I(pol) 10 uA
Electrode test ON
Temperature 25.0 °C
Cell type no diaph.
I generator 400 mA
Start conditions
Pause 0 s
Start drift 10 ug/min
Time cond.ok 60 s
Activate pulse OFF
Stop parameters
Rel. drift 10 ug/min
Max. titr. time OFF s
Drift correction
Auto drift correction
Save data
Curve ON
Interval for meas. 20 s
Save changes only ON
EP ON
C4# from Coulometer ON
>Calculations, Calculations
Formulas
RS
Content
('KFC.EP1'-'Blankvalue')/'SmplSize';ppm;1;0;
%Content
('KFC.EP1''Blankvalue')/10000/'SmplSize';%;4;0;
>Report, Report
Database
Select data
Curve ON
Result report ON
Parameter report ON
Save in water
Print layout
Print options
Font width 12
Report per determination
Print immediately OFF
Multipage printout
page numbers OFF
Header on each page OFF
Footer on each page OFF
Print in reverse order OFF
Layout
Text
Print result report line(s)...
Report ident. ON
Date ON
Method ON
EP variables ON
C4X variables OFF
Other variables OFF
Common variables ON
Results ON
Satistics OFF
Report blocks
Results
Curve
From proc. KFC
x axis
Quantity t/s
Scaling Auto
y axis
Quantity ug H2O
Scaling Auto
Color
Curve 1 Auto
Curve 2 Auto
Layout
Grid ON
Curve
From proc. KFC
x axis
Quantity t/s
Scaling Auto
y axis
Quantity Meas
Scaling Auto
Color
Curve 1 Auto
Curve 2 Auto
Layout
Grid ON
>Remove sample, Remove smpl
Instrument 774_1
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 10/11
Remove sample from ...
Station 1
>Sequence, Endsequence
Instrument 774_1
Sequence used as ... CMove
>Shift, Shift
Next sample
Beaker shift to...
Station 1
>RinsePosition, RinsePosition
Station 1
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 11/11
Method for validating the 774/756 system using sodium tartrate dihydrate
(created with 756 KF Coulometer)
'fr
756 KF Coulometer
date 1999-12-14
time
KFC-B
774-D j3
smpl size
0.01466
smpl heat.time
756
sample temp.
160.0
lowest temp.
158.7
highest temp.
160.6
gas flow
38.5
drift auto
3.5
titr.time
775
H2O
2346.9
blank
51.5
content
156575.7
Water
15.658
============
5.756.0010
16:26
6
g
s
°C
°C
°C
mL/min
µg/min
s
µg
µg
ppm
%
1500
Wasser
[µg]
2000
1250
1000
1500
750
Drift [µg/min]
'fm
756 KF Coulometer
5.756.0010
date 1999-12-14
time 16:27
6
KFC-B
774-D j3
>calculations
blank=C39;1;µg
content=(H2O-C39)*C01/C00/C02;1;ppm
Water=(H2O-C39)*C03/C00/C04/C05;3;%
C00=
0.01466
C01=
1.0
C02=
1.0
C03=
100
C04=
1000
C05=
1000
C39=
51.5
============
2500
Wasser [µg]
'pa
756 KF Coulometer
5.756.0010
date 1999-12-14
time 16:27
6
KFC-B
774-D j3
parameters
>control parameters
EP at U
..50 mV
dynamics
70 mV
max.rate
max. µg/min
min.rate
15 µg/min
stop crit:
rel.drift
rel.drift
5 µg/min
>titration parameters
pause
0 s
extr.time
180 s
start drift
10 µg/min
temperature
25.0 °C
time interval
2 s
max.titr.time
OFF s
>statistics
status:
OFF
>preselections
drift corr:
auto
req.ident:
OFF
req.smpl size:
OFF
smpl unit:
g
limit smpl size:
OFF
text id1
id1 or C21
text id2
id2 or C22
text id3
id3 or C23
oven:
COM1
activate pulse:
OFF
============
1000
500
Drift
[µg/min]
500
250
0
0
0
Fig. 5:
100
200
300
400
t [s]
500
600
700
800
Titration curves for the determination of the water
content of sodium tartrate dihydrate: released
amount of water and drift as a function of time
(conditions: T = 160 °C, 40 mL/min N2, headspace
technique).
The determinations were carried out in 150 mL HYDRANAL Coulomat AG Oven. The theoretical water
content of the standard substance (Apura sodium
tartrate dihydrate from Merck) was 15.65% according
to the analysis certificate. Within this validation context
the content was determined as being 15.680 ±
0.032 % water (srel = 0.21%); this corresponds to a
recovery rate of 100.2%.
Application Bulletin 280/1 e
Automatic KF water determination with the 774 Oven Sample Processor
Page 12/11
Method for validating the 774/756 system using potassium citrate monohydrate
(created with 756 KF Coulometer)
'fm
756 KF Coulometer
5.756.0010
date 1999-10-28
time 16:31
11
KFC-B
774-D j2
>calculations
blank=C39;1;µg
content=(H2O-C39)*C01/C00/C02;1;ppm
Water=(H2O-C39)*C03/C00/C04/C05;3;%
C00=
0.02588
C01=
1.0
C02=
1.0
C03=
100
C04=
1000
C05=
1000
C39=
74.4
============
'fr
756 KF Coulometer
date 1999-10-28
time
KFC-B
774-D j2
smpl size
0.02588
smpl heat.time
592
sample temp.
220.0
lowest temp.
218.1
highest temp.
220.3
gas flow
39.2
drift auto
4.6
titr.time
613
H2O
1520.9
blank
74.4
content
55892.6
Water
5.589
============
5.756.0010
16:30
11
g
s
°C
°C
°C
mL/min
µg/min
s
µg
µg
ppm
%
1100
1500
1000
Wasser
[µg]
900
1250
800
700
Wasser [µg]
1000
600
750
500
Drift [µg/min]
'pa
756 KF Coulometer
5.756.0010
date 1999-10-28
time 16:31
11
KFC-B
774-D j2
parameters
>control parameters
EP at U………………………………………..50 mV
dynamics
70 mV
max.rate
max. µg/min
min.rate
15 µg/min
stop crit:
rel.drift
rel.drift
5 µg/min
>titration parameters
pause
0 s
extr.time
180 s
start drift
10 µg/min
temperature
25.0 °C
time interval
2 s
max.titr.time
OFF s
>statistics
status:
OFF
>preselections
drift corr:
auto
req.ident:
OFF
req.smpl size:
OFF
smpl unit:
g
limit smpl size:
OFF
text id1
id1 or C21
text id2
id2 or C22
text id3
id3 or C23
oven:
COM1
activate pulse:
OFF
============
400
500
300
Drift
[µg/min]
250
200
100
0
0
0
Fig. 6:
100
200
300
t [s]
400
500
600
Titration curves for the determination of the water
content of potassium citrate monohydrate: released
amount of water and drift as a function of time
(conditions: T = 220 °C, 40 mL/min N2, headspace
technique).
The determinations were carried out in 100 mL HYDRANAL Coulomat AG Oven plus 50 mL methanol.
The theoretical water content of the standard substance (HYDRANAL Water Standard KF Oven from
Riedel-de Haën) was 5.59% according to the analysis
certificate. Within this validation context the content
was determined as being 5.589 ± 0.049 % water (srel =
0.88%); this corresponds to a recovery rate of 100.0%.