PASCO Potassium PS-3520 User manual

Instruction Sheet
012-15722A
Potassium ISE Probe
PS-3520
3
2
1
4
567
Reference
Chamber
Cotton
*DO NOT
let the BNC
connector
at the top of
the unit get
wet.
Included Equipment Item Included Equipment Item
Potassium ISE Replacement Module 1 Potassium Standard Solution 1000 ppm 5
Potassium ISE (Cl-) Probe 2 Potassium Reference Fill Solution 6
Storage Bottle 3 Potassium Ionic Strength Adjuster (ISA) 7
BNC Male-to-Female Cable 4

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Potassium ISE Probe Introduction
2012-15722A
Introduction
This Potassium Ion Selective Electrode (ISE) Probe is a
combination electrode that includes both reference and
sensing half cells in one body housing. It is used for
measuring potassium ion (K+) activity in aqueous sam-
ples.
Technology: Replaceable Polymer/PVC Membrane
(Potassium ISE Replacement Module PS-3551)
Overview
Required Equipment
• PASCO Wireless pH/ISE/ORP Sensor (PS-3204)
or
• PASPORT High Precision pH/Temperature with
ISE/ORP Amplifier (PS-2107) with a PASCO
interface (see www.pasco.com for information)
or
• Ion meter or pH/mV meter
• PASCO data collection software (see
www.pasco.com)
• Wash bottle filled with distilled or de-ionized water
• Lab wipes
• Pipettes: 1 mL, 10 mL and 100 mL
• Clean beakers*
*SE-7287 100 ml Beakers (12 pack) or SE-7288 1000 ml
Beakers (6 pack)
Included Required Solutions*
• Reference Fill Solution
• 1000 ppm Potassium Standard Solution
• Ionic Strength Adjuster (ISE)
(*SC-3535 Potassium ISE Solutions)
Electrode Preparation
Replace the Module Blank
This electrode performs better when the reference
junction is kept wetted during transit and storage.
However, the sensor module is best stored and
transported dry. Therefore, the electrode is shipped with
a plastic Module Blank inside that must be removed prior
to use.
1. Unscrew the cap of the storage solution bottle (also
known as “Soaker Bottle”) and remove the
electrode. Unscrew the plastic Module Blank from
the end of the electrode. Replace the blank with the
included Potassium ISE Replacement Module.
• The Module Blank can be retained for long term
storage.
• Caution: Do not touch the PVC sensor membrane
on the end of the Potassium ISE Replacement Mod-
ule with your fingers.
2. Thoroughly rinse the electrode with distilled water.
Wipe carefully with a clean lab wipe.
3. Return the electrode to the storage bottle when it is
not in use.
Fill the Electrode with Electrolyte
The reference (outer) chamber must be filled with
Reference Fill Solution and remain open during testing:
Size and Material Body (Epoxy): 12 mm OD x 155
mm Length
Cap (ABS): 16 mm OD x 57 mm
Length
Reference Double-junction Ag/AgCl, ceramic
pin junction, refillable, sodium
chloride electrolyte
Features Replaceable Sensor Module
Range 0.04 to 39,000 mg/L
Reproducibility ±4%
Slope 54 to 59 mV/decade @ 25°C
typical
pH Range 2 to 12
Operating Temperature 0 to 40°C
Interferences Cs+, NH4
+, Tl+, H+, Ag+, Tris+,
Na+, Li+, others
Application/Notes Very popular for environmental,
industrial, agriculture,
food/beverage

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PS-3520 Introduction
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012-15722A
1. Slide the sleeve of
the electrode FastFil
cap down to uncover
the fill hole. (see fig.
1)
2. Shake the electrode
downward like a
thermometer to
remove any air
bubbles trapped
inside.
• The surface of the
Reference Fill
Solution in the
reference chamber
must be above the
inner junction. This is
approximately 3"
from the electrode tip.
3. Rinse the electrode with Dl water, blot dry. Do not
rub dry.
4. Soak the electrode in Dl water for 10 minutes, then
in a diluted Potassium Standard Solution for two
hours prior to calibration or use.
Software Help
See the SPARKvue Help or PASCO Capstone Help for
information about collecting, displaying, and analyzing
data.
• In SPARKvue, select the HELP button in any screen
including the Home Screen.
• In PASCO Capstone, select PASCO Capstone Help
from the Help menu, or press F1.
Checking Electrode Operation (Slope)
1. Connect your electrode to the input connector on the
Wireless pH /ISE/ORP Sensor (or other measuring
device). Place 100 mL of DI water into a 150 mL
beaker. Add 2 ml Potassium ISA to the DI water and
stir throughly.
2. Rinse the electrode with DI water, blot dry, and
place in the beaker with the prepared solution.
3. Pipet 1 mL of 1000 ppm Potassium Standard Solu-
tion into the beaker. Stir thoroughly, then record the
potential (E1) in mV when a stable reading is dis-
played.
4. Pipet 10 mL of the same standard solution into the
beaker. Stir thoroughly. When a stable reading is
displayed, record the potential (E2) in mV.
5. The difference between the first and second poten-
tial readings, (E2-E1), is defined as the electrode
slope. The normal range for the slope is 56±4 mV at
25°C.
Troubleshooting
If the electrode slope is not within the normal range, the
following procedure may restore the electrode.
1. Soak the electrode in a diluted standard solution for
2 hours before use.
2. Repeat "Checking Electrode Operation" procedure
again. Note: All standard solutions should be
prepared fresh. For best performance use ISA in all
solutions.
Periodically check the Reference Fill Solution level in the
reference chamber of the electrode. The solution level
must be higher than the inner junction which is visible as
a white ceramic pin on the inner body.
If the electrode slope is still outside the normal range
after this procedure, you must replace the sensing
module.
Reading a Sample with the Electrode
Various procedures may be used to determine the
concentration of a sample. The most common is the
Direct Calibration method, which is described below.
Contact PASCO's Technical Support department for
details of other methods.
In Direct Calibration a series of standard solutions of
differing concentrations is used to calibrate the
electrode. Then each sample requires only a single
measurement device reading, which is compared with
the calibration readings to obtain the sample
concentration. ISA is added to all solutions to ensure the
samples and the standards have the same ionic
strength.
Set up:
1. Prepare the electrode as described in "Electrode
Preparation" and "Checking Electrode Operation".
Connect the electrode to the sensor or measuring
device.
2. Prepare two standard solutions that differ in
concentration by a factor of ten and bracket the
Fill Hole
FastFil Cap sleeve
Minimum fill level for the
Reference Filling Solution
Minimum immersion depth
Reference Junction
Figure 1

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Potassium ISE Probe Replacement Items
4012-15722A
expected sample concentration range. For example,
if your expected sample concentration is 50 mg/L
Potassium, you should use a 10 mg/L low Standard
Potassium and a 100 mg/L high Standard Solution.
• NOTE: Temperature compensation is not typical of
ISE measurements - for best performance, try to
ensure that the standards are within 5 to 10°C of the
sample.
Measurement:
If using a measuring device with direct concentration
reading capability see the software on-line help or the
measuring device’s instruction manual for specific
information:
1. Place 100 mL of the low standard into a 150 mL
beaker. Add 2 mL of ISA. Stir thoroughly.
2. Rinse electrode with Dl water, blot dry and place in
the beaker. Wait for a stable reading, and then
adjust the measuring device to display the value of
the standard. Refer to the software on-line help or
the measuring device’s instruction manual for the
adjustment procedure.
3. Measure 100 mL of the high standard into a second
150 mL beaker. Add 2 mL of ISA and stir.
4. Rinse electrode with Dl water, blot dry and place in
the second beaker. Wait for a stable reading, and
then adjust the measuring device to display the
value of the second standard.
5. Pipette 100 mL of sample into a 150 mL beaker. Add
2 mL of ISA. Stir thoroughly.
6. Rinse electrode with Dl water, blot dry and place in
the sample beaker. Wait for a stable reading and the
sample concentration will be displayed on the mea-
suring device.
7. Determine the sample concentration using the data
analysis tools in the software.
Electrode Storage
Short Term (over night or the weekend):
Rinse the electrode thoroughly with Dl water and place
the tip in a diluted standard solution between
measurements. Slide the FastFil sleeve upward to close
the fill hole.
Refill the reference before putting the electrode back into
service
Long Term
Refill the electrode with Reference Filling Solution and
close the fill hole. Remove the sensing element and
store in the glass vial or replace the cap to protect the
sensing element.
Follow procedures in "Electrode Preparation" and
"Checking Electrode Operation" before using the
electrode again.
Electrode Cleaning
Cleaning should only be attempted if troubleshooting
methods fail. The PVC membrane is a delicate sensor
and should not be brushed or otherwise contacted. It
can be rinsed vigorously under warm water to remove
debris. Soaking for 10-15 minutes in DI water might be
useful in extracting other contaminants.
Recondition the electrode by soaking in a low standard
solution immediately after any cleaning method.
Replacement Items
• SC-3526 Potassium ISE Solutions: 60 mL Standard
Solution, 30 mL Reference Fill Solution, 30 mL ISA
Solution
• PS-3551 Potassium ISE Replacement Module
Technical Support
For assistance with any PASCO product, contact
PASCO at:
Limited Warranty
For a description of the product warranty, see the PASCO catalog.
Copyright
This PASCO scientific instruction sheet is copyrighted with all rights
reserved. Permission is granted to non-profit educational institutions for
reproduction of any part of this manual, providing the reproductions are
used only in their laboratories and classrooms, and are not sold for profit.
Reproduction under any other circumstances, without the written consent
of PASCO scientific, is prohibited. Rev: 10/17
Trademarks
PASCO, PASCO scientific, PASCO Capstone, PASPORT and
SPARKvue are trademarks or registered trademarks of PASCO scientific,
in the United States and/or in other countries. All other brands, products,
Address: PASCO scientific
10101 Foothills Blvd.
Roseville, CA 95747-7100
Phone: [phone] (worldwide)
800-772-8700 (U.S)
Email: [email protected]

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PS-3520 Technical Support
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012-15722A
or service names are or may be trademarks or service marks of, and are
used to identify, products or services of, their respective owners. For more
information visit www.pasco.com/legal.
Product End of Life Disposal Instructions:
This electronic product is subject to disposal and recycling regulations that
vary by country and region. It is your responsibility to recycle your
electronic equipment per your local environmental laws and regulations to
ensure that it will be recycled in a manner that protects human health and
the environment. To find out where you can drop off your waste equipment
for recycling, please contact your local waste recycle/disposal service, or
the place where you purchased the product.
The European Union WEEE (Waste Electronic and
Electrical Equipment) symbol (to the right) and on the
product or its packaging indicates that this product
must not be disposed of in a standard waste
container.