YSI 400365 Operating Manual

Required Equipment

• Ion meter (preferred) or pH/mV meter.

• Wash bottle with distilled or deionized water.

• Several clean beakers (glass, 15 0 m L preferred).

• Pipette for measuring 10 mL or less.

• Graduated cylinder (100 mL)

• Fill Solution YSI #400367*

• 1000 mg/L (ppm) Ammonia Standard YSI #400370*

• 100 mg/L (ppm) Ammonia Standard YSI #400369

• Ionic Strength Adjustor (ISA) YSI #400368*

• Replacement Membrane Modules (pk/4) YSI #400366**

*Small bottles included with ammonia ISE kit (YSI #400365)
**Two Membrane modules included with ammonia ISE kit.

Overview

The YSI 400365 Ammonia Ion Selective Electrode is a gas­sensing electrode for measuring ammonia (NH
samples. It must be used with an ISA that buffers the sample
>pH 11 to cause the ammonia in the sample to become
gaseous. The Ammonia ISE is a pH Electrode behind an
ammonia gas permeable membrane – the ammonia gas
causes a pH shift in the Fill Solution that is correlated to
ammonia concentration based on the results of calibration.

• Technology: Gas sensing technology

• Size and material:

Membrane Body (ABS)—12 mm OD x 158 mm L
Cap (ABS) —16 mm OD x 37 mm L
Cable (Coax type) – 100cm; BNC Connector

• Reference: The pH electrode inside has a single-
junction, Ag/AgCl, annular ceramic junction.

• Features: Replaceable, pre -formed membrane module.
The ISA has a pH indicator that indicates the pH is in
range (>11) by the presence of a blue coloration.

• Range: 0.02-17,000 mg/L

• Reproducibility: ±2%

• Slope: 54 to 59 mv/decade @ 25°C typical

• pH range: >11

• Operating Temperature: 0 to 50°C

• Interferences: Volatile amines

• Applications/Notes: Popular for wastewater,

aquaculture, agriculture, and industrial appli cations.

) in aqueous

3

Electrode Preparation

1. The glass pH sensor and reference junction of the pH

electrode should be kept conditioned during transit and
storage. Unscrew the cap of the storage solution bottle
(Soaker Bottle) and remove the pH electrode.

2. Fill a Membrane Module with Fill Solution
a) Add 15-20 drops of Fill Solution to the Membrane Module
b) Tap the Membrane Module to ensure no bubbles are

present in the fill solution.

c) Thread the Membrane Module slowly into the Electrode

Cap. If the Module was overfilled, the excess Fill Solution
will le ak o ut. Av oid rupturing the Membrane Module with
too much Fill Solution.

3. Preferably, allow the pH electrode to condition within the

filled Membrane Module for 2 hours prior to use. The

Membrane Module can be conditioned by placing in a low
to mid-range standard for at least 15 min utes pri or to us e.

Calibration

1. Connect the assembled ammonia electrode to a meter with

BNC inp ut. Meters with an ISE mode can direc tly dis play i on
concentration (e.g. display in mg/L). Ensure the meter is
setup for ammonia and be sure to follow the calibration
procedure in the meter user manual.

Alternatively, a meter with a mV mode can be used, although
the instrument will not display the result of calibration (i.e.
calibration curve will need to be created by the user).

2. For highest accuracy, use a meter with automatic
temperat ur e c om pe nsat i on (A TC ) an d c on nec t a t em per at ur e
sensor.

3. Prepare Standards:

At least 2 standards that bracket the expected sample

a)

range must be used. As an example, prepare 1 mg/L and
10 mg/L standards if the expect ed sample is ~5 mg/L.
Some meters allow up to a 7 point calibration.

b) There must be at least one order of magnitude

difference between high and low standards (e.g. 10
mg/L and 100 mg/L).

c) If standards span more than one order of magnitude

(e.g. 1 mg/L and 100 mg/L), it is best t o prepare at least
one mid-range standard (e.g. 10 mg/L).

d) Each standard should have a volume of 100 mL and

should be placed in a 150 mL glass beaker.

e) Standards should be fresh and carefully prepared. It is

best to use a pipette when measuring small volumes
(10 mL or less) of a more concentrated standard.

f) Use the equation C1*V1=C2*V2 when preparing diluted

standards from a more concentrated standard solution.
As an example, if using the YSI 100 mg/L standard as a

stock solution (YSI #400369) to m ake 100 mL of a 10

mg/L standard: C1=100 mg/L, V1=?, C2=10 m g/L, and
V2=100 mL. V1=(C2*V2)/C1 =10 mL.

Therefore, 10 mL of the 100 mg/L stock standard should
be added to 90 mL of DI water (i.e. solution should be 100
mL) to make a 10 mg/L standard.

Note: It is not recommended to use a very concentrated
standard (e.g. 1000 mg/L) to make a very dilute standard
(e.g. 0.1 mg/L).

4. Place the electrode in the lowest concentration standard and
stir at a co nstant rate usi ng a sti r bar an d stir plat e, alt hough
the stirring speed should be limited to minimize loss of
ammonia gas. Use the same stirring rate throughout
calibration.

If you do not have a stir plate, it is best to swirl the s olution
or use a stir rod once ISA is added.

5. Add 2 mL of ammonia ISA to the first standard:

a) Using a pipette is recommended. The standard solution

should have a pale blue color that persists after ISA is
added.

b) Allow the solution to stir for 1 minute and begin

calibration. Calibration is time sensitive, as ammonia
diffuses from the sample ~4 minutes after ISA is added.
Therefore, ensure calibration with the standard is
complete 1 to 4 minutes after ISA is added. This timing
is critical! If calibration using the standard is
unsuccessful within this time limit, a fresh standard will
need to be prepared.

6. After calibrating with the first point, finish calibrating using
steps #4 and #5 for the remaining calibration points.
Calibrate in order of increasing concentration.

7. Evaluate electrode slope:

a) View the calibration record on the ISE meter, or create

a curve if using a meter with only a mV mode.

b) For highest accuracy, the ammonia electrode slope

should be between -52 mV/decade and -60 mV/decade.

8. Recalibrate often:

a) The ammonia electrode should be calibrated at the

beginning of each day.

b) For best accuracy, it is best to calibrate the ammonia

electrode every 10 samples. If this calibration interval is
too frequent, at least verify your c alibration result every
2 hours by preparing a fresh lo w t o mid-range standard,
adding ISA, and verifying the reading. If t he mV reading
has changed ~3 mV compared to the reading in that
standard during calibration, you will need to rec alibrate
the electrode.

Measurement

Samples must be prepared like standards. Follow steps #3-5
of the calibration procedure when preparing samples and
taking a measurement.

In summary, 100 mL of sample should be collec ted and 2 mL
of ISA added. The sample should be fresh and the same
stirring rate using during calibration should be utilized. A
measurement can be taken 1 to 4 minutes after ISA is added.

The temperature of measurement solutions should be as
close as possible to solution temperatures during calibration.

Troubleshooting & Maintenance

If the electrode slope is not between -52 mV/decade and

-60 mV/decade, or the electrode mV reading drifts, the
electrode Fill Solution may need refreshing. Hold the
electrode body with one hand, and then gently pull the
cable. Release the cable. Fresh Fill Solution will now
occupy the space between the inner glass electrode and
the membrane.

If refreshing the internal fill solution does not work, remove
the pH electrode from the membrane module and use the
following procedure to verify the pH electrode slope:

1. Remove the internal glass pH electrode from the
Membrane Module

2. Connect the internal glass electrode to a pH/mV
meter. Switch to mV mode.

3. Put the internal glass electrode in pH 7.00 buffer. The
annular ceramic junction should be immersed in the buffer.
Record the stable reading in mV, which should be 0±25
mV.

4. Remove the internal glass electrode from the pH 7.00
buffer. Rinse with Dl water, blot dry.

5. Put the internal glass electrode in pH 4.01 buffer.
Record the stable reading in mV.

6. The millivolt difference in the two readings should be
between 1 60 and 180 mV.

The Membrane Module will likely need to be changed if the pH
electrode passes the test above. Replacement of the
Membrane Module is needed more often in dirty sampl es lik e
wastewater. The membrane will eventually develop pinholes or
tears, get stretched, or the membrane will become fouled
(surface coating).

You may attempt to clean a Membrane Module that has
surface contamination by soaking it in DI water for 1 hour or
more, then soak in a low or mid-range standard for at least 15
minutes prior to use.

The pH sensor can be cleaned like other pH el ectrodes. A voi d
rubbing or scratching the glass pH sensor. Placing the pH
electrode in pH 4 buffer with some KCl add ed i s recom me nded
after any pH electrode cleaning procedure, but ensure the
reference junction (i.e. the white layer where the glass
changes in dim ens ion ) is compl et ely immers e d. S oakin g in pH
4 buffer with KCl overni ght can also restore the electrode.

Contact YSI Technical Support if electrode slope and/or
response continue to be poor.

Electrode Storage

Short Term (overnight or the weekend):

Between measurements, the ammonia ISE should be stored in
a low concentration stand ard with ISA added. For over ni gh t or
weekend storage, place the assembled electrode in 1000 mg/L
standard and do not add an y ISA. Avoid removing the
Membrane Module and reinstalling – this could stretch the
membrane causing it to be less responsive.

Long Term: It is important to keep the pH sensor conditioned through long

term storage situations. Completely disassemble the electrode.
Rinse the internal glass electrode and Membrane Module

with Dl water. Dry all of the parts. Ensure the internal glass
electrode is stored inside the included soaker bottle with some
storage solution (pH 4 buffer with KCl added).

Use a new Membrane Module, or make sure the old one is not
damaged or overly stretched. Follow procedures in "Electrode
Preparation" and "Calibration" before using the electrode again.

Warranty Statement

The YSI TruLine Ammonia ISE is warranted for twelve (12)
month from date of purchase by the end user against defects in
materials and workmanship. Within the warranty period, YSI
will repair or replace, at its s ole discretion, free of charge, any
product that YSI determines to be covered by this warranty.

To exercise this warranty, call your local YSI representative, or
contact YSI Customer Service in Yellow Springs, Ohio at +1
937 767-7241, 800-897-4151, [e-mail] or visit ysi.com
(Support tab). Send the product and proof of purchase,
transportation prepaid, to the Authorized Service Center
selected by YSI. Repair or replacement will be m ade and the
product returned, transportation prepaid. Repai red or replaced
products are warranted for the balance of the original warranty
period, or at least 90 days from date of repair or replacement.

Limitation of Warranty

This Warranty does not apply to any YSI product damage or

1) Failure to install, operate or use the product in accordance
with YSI's written instructions;

2) Abuse or misuse of the product;

3) Failure to maintain the product in accordance with YSI's
written instructions or standard industry procedure;

4) Any improper repairs to the product;

5) Use by you of defective or improper components or parts in
servicing or repairing the product;

6) Modification of the product in any way not expressly
authorized by YSI.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESSED OR IMPLIED, INCLUDING ANY WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PART ICULAR
PURPOSE. YSI's LIABILITY UNDER THIS WARRANTY IS
LIMITED TO REPAIR OR REPLACEMENT OF THE
PRODUCT, AND THIS SHALL BE YOUR SOLE AND
EXCLUSIVE REMEDY FOR ANY DEFECTIVE PRODUCT
COVERED BY THIS WARRANTY. IN NO EVENT SHALL YSI
BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL DAMAGES RESULTING FROM ANY
DEFECTIVE PRODUCT COVERED BY THIS WARRANTY.

DOCUMENT ID: 400365MAN DEC2015

failure caused by:

YSI

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