Metrohm 794 Basic Titrino - Manual (Page 173)

6.3 User methods
794 Basic Titrino
169
6.3.5 "TAN-TBN"
Determination of the acid number according to ASTM D 5664-95 resp. of the base number accord-
ing to ASTM D 2896-88.
Electrodes: 6.0102.102 pH glass electrode at measuring input 1 ("Ind I")
6.0729.100 Ag/AgCl reference electrode (outer elektrolyte solution LiCl in sat. etha-
nol) at measuring input 2 (Ind II")
6.0301.100 Pt-Electrode at measuring input "Ref"
Differential input
Optional a Solvotrode can be used, in this case select meas.input: 1 in the method.
TAN 6.0229.100 Solvotrode at measuring input 1 ("Ind I")
6.2320.000 elektrolyte c(TEA-Br) = 0.4 mol/L in ethylene glycol
TBN 6.0229.100 Solvotrode at measuring input 1 ("Ind I")
6.2312.000 elektrolyte diluted 1:1 with ethanol ( ca. 2 mol/L LiCl in ethanol)
TAN titrant: c(KOH) = 0.1 mol/L in isopropanol/methanol (e.g. Merck No. 105544).
TBN titrant: c(HClO
4
) = 0.1 mol/L in acetic acid.
TAN solvent: toluene/isopropanol/H
2
O 500:495:5
TBN solvent: acetic acid/toluene 1:1
Sample: 0.1 – 10 g sample in 50 – 125 mL solvent.
Remarks:
- Store glass electrode in dist. water over
night. Before titrating, brecondition it in
solvent during 10…30 min.
- ASTM requires an equilibration time of 100
s between volume increments. In most
cases it is possible to titrata with shorter
equilibration times.
- If fix end points are evaluated, the voltage
value to be set has to be determined with
buffers.
Reference:
METROHM Application Bulletin Nr. 80:
Differential potentiometry, see page 155.
Makes sure that the sum value is evaluated.
– Result in mg KOH per g sample
– Sample size in g
– Consumption of blank sample in mL
– Normality of the titrant (0.1*titer)
– Molar mass of KOH
'pa
794 Titrino 01102 794.0010
date 2002-01-03 time 09:42 0
MET U TAN-TBN
parameters
>titration parameters
V step 0.10 ml
titr.rate max. ml/min
signal drift OFF mV/min
equilibr.time 50 s
start V: OFF
pause 100 s
meas.input: diff.
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 20 mV
EP recognition: last
fix EP1 at U OFF mV
pK/HNP: OFF
>preselections
req.ident: OFF
req.smpl size: value
activate pulse: OFF
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'fm
794 Titrino 01102 794.0010
date 2002-01-03 time 09:42 0
MET U TAN-TBN
>calculations
TAN-TBN=(EP1-C01)*C02*C03/C00;2;mg/g
C00= 1.0
C01= 0
C02= 0.1
C03= 56.106
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