Determination of the NaCl in Broth with Potentiometric end-point Indication

Determination of the NaCl in Broth with Potentiometric end-point Indication

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

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

Sample
20 mL sample solution
5 mL c(HNO3) = 2 mol/L
30 mL dist. Water

Remarks
· Calculations:

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

NaCl = content of NaCl in broth in %
C00 = sample size (10 g / 100 = 0.1 g)
C01 = molecular mass of NaCl (58.44 g/mol)
C02 = concentration of titrating agent (0.1 mol/L)
C03 = factor for conversion mL Þ L and for % (0.001*100 = 0.1)

. Answer

NaCl = 8.070 x 58.44 x 0.1 x 0.1 / 0.1 = 47.16 %

EP1 = 8.070 mL
C00 = 0.1 g

· Sample preparation:
Dissolve 10 g (1 cube) conc. broth in 800 mL boiling dist. water. Rinse
this solution in a 2000 mL measuring flask. Allow to cool down and fill
up to the mark. Filter with a folded filter. Take 20 mL aliquots.

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

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U… NaCl
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:… all
activate pulse: …OFF
------------
'fm
751 GPD Titrino 15215 751.0010
DET U… NaCl
>calculations

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

C00= 0.1000
C01= 58.44
C02= 0.1
C03= 0.1
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 208 mV DET U... NaCl
smpl size 0.1000 g id#1 Chicken
id#2 Broth
EP1 …8.070 ml…. 46 mV
NaCl …47.16 %
stop #EP reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U NaCl
1.0 ml/div dU=50.0 mV/div

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