Xylem ISE Electrodes User Manual
Instruction manual for the
y
r
SCHOTT
®
Instruments
electrodes for measuring
the Na
+
concentration
®
SI Analytics GmbH
Hattenbergstrasse 10
55122 Mainz
Germany
Telefon +49 (0) 6131/66 5119
Telefax +49 (0) 6131/66 5001
e-mail: support@si-analytics.com
www.si-anal
electrode plug
refilling hole
diaphragm
senso
tics.com
Preparation and general
If there is an irrigation cap over the sensor and diaphragm,
this should be removed. It contains irrigation fluid (sodium
chlorid solution 0.1 mol/l). The electrode is ready to perfor m
a measurement. Electrodes stored dry must be irrigated for
24 hours in irrigation fluid. Lacking electrolyt solution 3 M
potassium chlorid solution (L 3008) should be refilled. The
filling level of the electrode solution should always be at
least 5 cm above the level of the measurement solution.
Attention!
Electrolyte solution and irrigation fluid are different.
The closure of the refilling hole must be opened during
measurement. The membrane and diaphragm must be
immersed in the measurement solution.
Please also note the instruction manual of the measuring
device.
For calibration following standard solutions are needed:
0.1 M NaCl
Dissolve 5.85 g sodium chloride in approximately 800 ml
distilled water and fill it up to 1 l.
0.001 M NaCl
Dilute 10 ml of the 0.1 M NaCl solution up to 1 l with distilled
water.
Calibration
The pNa electrode should be connected to the pH-meter lik e
a pH electrode. Switch the pH-meter in the mV range. For
calibration begin with the lowest concentration and without
rinsing the next solution is measured. The resulting mV
value is noted and a calibration curve printed. The pNa
electrode follows the Nernst equation. The temperature of
the solution must be taken into account.
Example calibration curve
mV
mV1
mV2
Measurement
The measured solution should be slightly alcalic, b ut at least
have a pH of 6. Is this not the case, the pH can be adjusted
with sodium free bases like ammonia water or
triethanolamine.
Attention!
Do not take sodium hydroxide solution for adjusting the pH.
The response of the pNa electrode is slow. For a stable
signal it takes from 10-40 min. A shorter waiting time can be
reached when the electrode is rinsed before measuring with
the new solution or an alcalic buffer solution is added.
Cleaning
Dirt and contamination on the sensor and diaphragm le ad to
measurement inaccuracies. They can be removed with the
following procedure:
• Coatings and deposits can be removed with diluted
mineral acids (e.g. diss. hydrochloric acid)
• Organic contaminations with the aid of suitable solvents
• Grease with tensid solution or alcohol
• Proteins with hydrochloric pepsine solution (cleaning
solution L 510).
During maintenance there is to pay attention to:
• After cleaning, rinse off the electrodes with distilled water,
do not rub dry.
• Platinum diaphragms must not be treated by any
mechanical treatment. Rinsing (e.g. vacuuming) may be
followed by chemical cleaning (e.g. with diluted
hydrochloric acid).
• The glass membrane can be clea ned by r ubbing off with a
fluff-free cloth soaked in ethanol.
log a
P 1
P 2
1
log a2
log a
Storage and maintenance
Electrodes should be stored at a temperature between
0°C and 40°C. Depending on the storage conditions
(temperature and air humidity) the irrigation fluid in the cap
may dry out prematurely. pNa electrodes stored dr y must be
irrigated for minimum 24 hour in sodium chlorid so lution
0.1 mol/l before measurement. Crystals in the electrolyte
area can be dissolved by warming the electrode in a water
bath. The electrolyte solution should then be replaced.
The correct potassium chlorid concentration must be
observed.
Quality
Every electrode must fulfill the strict quality requireme nts of
final testing. The working life depends mainly on the us age
conditions. Extreme measuring conditions as for example
high or frequently fluctuating temperatures, strong acids and
caustic solutions, protein and heavily contaminated
solutions, sulfides, bromides and iodides shorten the
electrode’s working life. Hydrofluoric acid, sodium hydroxide
and hot phosphoric acid attack glass.
Technical details Na 61
pNa range: 0 ... 6
Temperature range: -10 ... +80°C
Length: 170 mm
Sensor: Na sensitive glass
Diaphragm: platinum
Reference systeme: Silamid®
Material: glass, d = 12 mm
Zero point: pNa = 2.0
Electrolyt: 3 M KCl
Irrigation fluid: 0.1 M NaCl
Connection cable: e.g. L 1 A
Temperature sensor: no
Order number
Combination electrode Na 61 285100026
Connection cable L1A 285122456
Electrolyte 3M KCl L 3008 285138505
Cleaning solution L 510 285138538
Further information
Further information can be found in the labratory catalo gue
of SI Analytics GmbH.
Subject to technical amendment.
GA_pNa_us_T814047_090603
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