YSI Professional Plus User Manual
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CALIBRAtIoN - AMMoNIUM, NItRAtE, CHLoRIDE
the 6051030 ISE/conductivity cable has a specialized calibration container that
resembles a large test tube. this calibration chamber can be used to calibrate
the ISE sensors with the conductivity sensor. A ring-stand should be used to
support this chamber.
The ISE sensors can be calibrated at 1, 2, or 3-points.
A 2-point calibration without chilling a third calibration
solution is extremely accurate and is the preferred method.
Greatest accuracy is achieved if the actual samples to be
measured are within 10 ˚C of the calibration solutions.
CALIBRATION TIP: Exposure to the high ionic content of pH buffers can
cause a significant, but temporary, drift in the ammonium, nitrate, and chloride
ISE sensors. therefore, when calibrating the pH sensor, YSI recommends that
you use one of the following methods to minimize errors in the subsequent
readings:
When calibrating pH, remove ISE sensors from the cable bulkhead and
•
plug the ports. After pH calibration is complete, replace the ISE sensors and
proceed with their calibration with no stabilization delay.
Calibrate pH first, immersing all of the sensors in the pH buffers. After
•
calibrating pH, place the sensors in 100 mg/L nitrate or ammonium standard
or 1000 mg/L chloride standard depending on the sensor in use and monitor
the reading. Usually, the reading starts low and may take awhile to reach
a stable value. When it does, proceed with the calibration. this may take
several hours.
Preparing Chloride Standards
the following recipes are provided for preparation of 10 and 1000 mg/L chloride
reagents. Nitrate and Ammonium standards can be purchased from YSI or other
laboratory supply companies.
It is important to note that some of the chemicals required for these solutions
could be hazardous under some conditions. It is the responsibility of the user
to obtain and study the MSDS for each chemical and to follow the required
instructions with regard to handling and disposal of these chemicals.
You will need: Solid sodium chloride or a certified 1000 mg/L chloride solution
from a supplier, magnesium sulfate, high purity water, a good quality analytical
balance, 1000 mL volumetric flask, an accurate 10 mL measuring devices, and
1000 mL glass or plastic storage vessels.
1000 mg/L Standard: Accurately weigh 1.655 grams of anhydrous sodium
chloride and transfer into a 1000 mL volumetric flask. Add 0.5 grams of
anhydrous magnesium sulfate to the flask. Add 500 mL of water to the flask,
swirl to dissolve all of the reagents , and then dilute to the volumetric mark with
water. Mix well by repeated inversion and then transfer the 1000 mg/L standard
to a storage bottle. Rinse the flask extensively with water prior to its use in the
preparation of the 10 mg/L standard. Alternatively, simply add 0.5 grams of
magnesium sulfate to a liter of a 1000 mg/L chloride standard from a certified
supplier.
10 mg/L Standard: Accurately measure 10 mL of the above 1000 mg/L standard
solution into a 1000 mL volumetric flask. Add 0.5 grams of anhydrous magnesium
sulfate to the flask. Add 500 mL of water, swirl to dissolve the solid reagents, and
then dilute to the volumetric mark with water. Mix well by repeated inversion
and then transfer the 10 mg/L standard to a storage bottle.
AMMoNIUM (NH4+) , NItRAtE (No3-), AND CHLoRIDE CL-
2-PoINt
the calibration procedures for ammonium, nitrate, or chloride are similar to
pH. the only differences are the calibration solutions. Recommended values
for calibration solutions and the order of calibration are as follows:
Sensor
1
st
Point
2
nd
Point
Ammonium-nitrogen (NH4-N)
1 mg/L
100 mg/L
Nitrate-nitrogen (No3-N)
1 mg/L
100 mg/L
Chloride (Cl-)
10 mg/L
1000 mg/L
Place the proper amount of 1 mg/L standard for Ammonium or Nitrate (10
mg/l for Chloride) into a clean, dry or pre-rinsed calibration cup. Carefully
immerse the sensor into the solution. Allow at least 1 minute for temperature
equilibration before proceeding.
Press Cal
. Highlight Probe ID or User ID if you wish to add, select, edit,
or delete an ID. Probe ID must be enabled in the System GLP menu to appear
in the Calibrate menu. User ID will appear automatically. Select ‘None’ if you
do not want a User ID stored with the calibration. When enabled, these IDs are
stored with each calibration record in the GLP file.
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