®
Oxygen Gas Sensor
sensor amplifier
sampling
bottle
connecting cable
sensing
element
rubber stopper
Included Equipment Part Number
Sensor Amplifier
PS-2126A (with
sensing element)
Oxygen Sensing Element (with deflector)
PS-6524
Rubber Stopper
Connecting Cable (3.5 millimeter)
Sampling Bottle
Required Equipment
PASPORT Interface and Software
See PASCO catalog
or www.pasco.com
PS-2126A
Oxygen Sensing Element Life:
Galvanic fuel cells have a limited lifetime which is determined
by their age and their exposure to oxygen. This is similar to
the life of a battery in a flashlight. If the flashlight frequently
used, the battery life will not be as long as it would have been
with limited usage. Similarly, the fuel cell’s useful life is
determined by its exposure to oxygen gas.
The fuel cell included with the PS-2126A has a useful life of
900,000 oxygen percent (O
An example: If the sensor is used in a 100% oxygen atmosphere, the life of the sensor may be calculated as
900,000 O
9,000 hours. This is about 1 year.
% hours divided by 100% oxygen which is
2
Instruction Sheet
%) hours.
2
012-11736C
Introduction
The PS-2126A Oxygen Gas Sensor measures oxygen gas concentration in percent (%) and parts per million (ppm) oxygen.
It can be used to study plant, animal, or cellular respiration; air
quality; and the rate of oxygen (O
reactions (see the experiment on page 2 for one example).
How it works:
The Oxygen Sensing Element is a galvanic fuel cell with a gas
permeable membrane at one end. It is very similar to a battery.
The fuel cell contains an electrolyte, anode and cathode. When
oxygen enters the fuel cell through the membrane, a chemical
reaction between the metallic cathode and anode and the electrolyte occurs. This chemical reaction produces a voltage and
current that is present at the output jack at the other end of the
Oxygen Sensing Element. The current produced is proportional to the concentration of oxygen present.
) production in chemical
2
The life of the sensor in normal air (20.9% oxygen) is
900,000 O
% hours divided by 20.9% oxygen which is
2
43,062 hours. This is about 4.9 years.
The sensor is guaranteed for a minimum of 2 years from the
date of manufacture. This is the absolute guarantee. If it is
used in a 100% oxygen atmosphere its life will be shortened.
If it is used in normal air, its life will be 4 to 5 years. There is
reported evidence of this particular sensing element being in
use for almost 10 years. In the end, the useful life of the sensing element is dependent on the manner in which it is used.
Setup
Connect the Oxygen Gas Sensor to your PASPORT interface.
To prepare the Oxygen Sensing Element for use:
1. Remove the Oxygen Sensing Element and deflector from
the packaging.
2. Remove the pink tape from the Oxygen Sensing Element.
3. Carefully thread the deflector onto the Oxygen Sensing
Element.
4. Slide the rubber stopper over the deflector.
®
Model No. PS-2126A Collecting O2 Samples
5. Plug one end of the connecting cable into the Oxygen
Sensing Element.
6. Plug the other end of the connecting cable into the Sensor
Amplifier.
7. Connect the Sensor Amplifier to the PASCO interface.
8. Refer to the documentation that came with the PASCO
interface and software for further instructions for data
collection.
Collecting O2 Samples
To collect an atmospheric sample, hold the bottle upright and
open to the air. Insert the end of the sensing element into the
bottle. Press the rubber stopper into the neck to seal the bottle.
To collect expired air or other gas samples, place the sensing
element inside a plastic bag.
Press any atmospheric air
out of the bag. Use a tube to
fill the bag with the gas sample. Hold, tie, or clamp the
bag closed round the tube
and sensing element cable to
contain the gas sample and
exclude atmospheric air.
Calibration
The sensor is factory calibrated. However, for greater accuracy, you can follow these steps to calibrate the sensor:
1. With the sensor connected to a powered PASPORT interface, place the sensing element in the empty sampling
bottle. Outside air has an O
concentration 20.9%.
2
2. Press the CAL (20.9%) button on the sensor and hold it
for 3 seconds. The green light will flash on and off for 4
seconds, indicating that calibration is in progress.
3. After 4 seconds, the reading will stabilize at 20.9%. When
calibration is complete, the light will stop flashing.
Note: If the green light flashes rapidly after calibration, the sensing element may be expired and it may need replacement.
Experiment: Oxygen
Production from Liver Catalase
Equipment required: Oxygen Gas Sensor with sampling bottle, beef
or chicken liver, hydrogen peroxide, pipette, mortar and pestle, ice
bath, boiling water, and safety goggles.
Safety: Always wear safety goggles when performing this experiment.
Do not allow excessive pressure to develop in the sampling bottle.
When doing an experiment
that requires a faster than usual response time, the response
time of the sensor may be increased by removing the white
deflector and stopper from the Oxygen Sensing Element. This
shortens the path to the sensor's membrane allowing it to be
populated more rapidly with the sample.
The purpose of the white deflector is to deflect air from an air
stream into the sensing element and provide protection for the
gas permeable membrane. It also holds the rubber stopper.
While the white deflector is removed from the sensing element, be careful not to place sharp objects near the membrane
as puncturing the membrane could lead to damage to the sensing element and electrolyte leaking from the membrane.
Removal of the deflector is not required or recommended
during typical operating conditions.
Warning: Do not allow the sensing element to contact liquids.
1. Place the liver in an open container and allow it to warm
to room temperature.
2. (Optional) Calibrate the Oxygen Gas Sensor (see above).
3. Grind the liver to a mushy consistency.
4. Place 10 mL of hydrogen peroxide into the clean, dry
sampling bottle.
Note: Perform step 5 through 7 carefully and quickly.
5. With a pipette, extract 1 mL of blood/homogenate from
the ground liver and release it into the sampling bottle.
6. Insert the end of the sensing element into the bottle. Press
the rubber stopper into the neck of the bottle just enough
to close the bottle, but not too tightly
7. Start data collection on the computer or interface.
8. After about 300 seconds, stop data collection.
9. Clean and dry the sampling bottle. Repeat steps 4 through
8 with cold liver homogenate that has been chilled in an
ice bath. Repeat again with liver homogenate that has
been boiled in water.
10. Compare your results from the three runs.
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®
Model No. PS-2126A
Specifications
Range 0 to 100% O2 concentration
0 to 1000000 parts per million (ppm)
Resolution 0.025% oxygen
Sensing Element Maintenance
Storage:
The Oxygen Sensing Element may be stored in its package
until its first use.
It is recommended that the sensing element be stored with the
threaded nose piece in the downward position. This insures
that the electrolyte remains in contact with the membrane for
extended periods of storage. Sensor life may be extended by
storing the sensing element in a refrigerator at 40ºF to 50ºF
(4°C to 10°C). Do not freeze the sensor or sensing element.
Replacement:
Order Model Number PS-6524 Oxygen Sensing Element
Replacement.
Repeatability
Accuracy
Operating temperature
Relative humidity range 0 to 100%, non-condensing
Sensing element
useful life
Sensing element
warranty period
±0.5% oxygen
±1% O
at constant temperature and
2
±5% O
pressure;
temperature range
0 to 40
°C
4+ years
24 months
over operating
2
Technical Support
For assistance with any PASCO product, contact PASCO at:
Address: PASCO scientific
10101 Foothills Blvd.
Roseville, CA 95747-7100
Phone: 1 916 462 8384 (worldwide)
877-373-0300 (U.S.)
Web: www.pasco.com
Email: support@pasco.com
Limited Warranty: For a description of the product warranty, see the
PASCO catalog.
Copyright: The PASCO scientific 012-11736C Oxygen Gas Sensor Instruc-
tion 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.
Trademarks: PASCO and PASCO scientific are trademarks or registered
trademarks of PASCO scientific, in the United States and/or in other countries. For more information visit www.pasco.com/legal.
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Model No. PS-2126A Technical Support
MSDS : 974-11983
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