Metrohm 794 Basic Titrino - Manual (Page 175)

6.3 User methods
794 Basic Titrino
171
6.3.7 "Br-Index"
Determination of the bromine index in petro-
leum hydrocarbons according to ASTM D
2710-72.
The bromine index is defined as the quantity
of mg bromine which reacts with 100g sam-
ple.
Electrode:
6.0308.100 double Pt-electrode, at measuring
input "Pol".
Titrant:
Solution of bromide/bromate,
c(BrO
3
– /Br – ) = 0.05 mol/L
Dilute 5.1 g KBr and 1.4 g KBrO
3
separately
and make up to 1 L.
Solvent:
714 mL glacial acetic acid,
134 mL 1,1,1-trochloroethane,
134 mL Methanol,
18 mL w(H
2
SO
4
) = 0.2 (20%)
Sample:
app. 3 g sample in 20 – 100 mL solvent. Ti-
trate blank sample the same way.
Remarks:
The bromine index can be determined easily
by endpoint titration (SET).
Reference:
Metrohm Application Bulletin Nr. 177
– Result in mg bromine/100 g sample
– Sample size in g
– Consumption of blank sample in mL
– Normality of the titrant (0.05*titer)
– Calculation factor (includes molar mass of the
bromine)
'pa
794 Titrino 01102 794.0010
date 2002-01-03 time 09:44 0
MET Ipol Br-Index
parameters
>titration parameters
V step 0.05 ml
titr.rate max. ml/min
signal drift OFF mV/min
equilibr.time 20 s
start V: OFF
pause 0 s
I(pol) 1 µA
electrode test: OFF
temperature 25.0 °C
>stop conditions
stop V: abs.
stop V 10 ml
stop U 5 mV
stop EP 9
filling rate max. ml/min
>statistics
status: OFF
>evaluation
EPC 30 mV
EP recognition: greatest
fix EP1 at U OFF mV
>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 09:44 0
MET Ipol Br-Index
>calculations
Br-Index=(EP1-C01)*C02*C03/C00;1;mg
C00= 1.0
C01= 0
C02= 0.05
C03= 7990
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