YSI pHotoFlex Series - Manual (Page 18)

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Note: Before using the test with your photometer for the first time, determine the reagent blank
value. To determine the reagent blank value it is not necessary to measure the pH and temper-
ature.
Step 1: pH and temperature measurement
Step 2: photometric measurement
YSI model no.: NH4-2 TC (LR)
Category: KT (reaction cell test)
Cell: 16 mm
Measuring range: Corresponding to 0.03 - 3.20 mg/l NH
4
or 0.02 - 2.50 mg/l NH
4
-N
Measuring ranges for NH
3
or NH
3
-N depending on pH value and temperature,
Example: 0.005 - 0.447 mg/l NH
3
at pH 8.5 and 25 °C.
Measuring mode, pH &
ORP:
Measure pH value and
temperature immediately
after sampling. Store measured values
with <STO>. If neces-
sary, assign an ID for
easier retrieving. Switch to the Photometry
measuring mode and
select program no. 339. When the prompt Assign
pH und temp.
appears,
select and accept the
stored values from the
pH and temperature
measurement.
The meter is ready for
the photometric mea-
surement (step 2).
The measuring range is
shown on the display.
Check the pH value of
the sample.
Desired value: approx.
pH 7.
Correct with diluted
sodium hydroxide
solution or hydrochloric
acid as necessary. Pipette 2.0 ml of sample
into a reaction cell. Add the contents of a
VARIO AMMONIA
Salicylate F5 powder
pack. Add the contents of a
VARIO AMMONIA
Cyanurate F5 powder
pack and close the cell
with the screw cap. Shake the cell vigorously
to dissolve solids.
Allow to react for 20
minutes. Insert the cell in the
photometer cell shaft
and start measurement.
approx.
pH 7
20:00
Notes:
• We recommend to determine a new reagent blank value (deionized water
instead of sample) for each test package started.
• If NH
4
-N is present in the sample, the solution becomes green after VARIO
AMMONIA Cyanurate F5 was added.
• If chlorine is present, sodium thiosulfate has to be added to the sample
immediately after sampling. Add 1 drop of a 0.1 mol/l sodium thiosulfate solution
per 0.3 mg/l chlorine to 1 liter sample.
• Iron disturbs the measurement and can be eliminated as follows: Determine the
total iron concentration and prepare an iron standard solution with the deter-
mined concentration. Use this solution instead of distilled water to determine the
reagent blank value for ammonium measurement.
Ammonia
Program no.
339
*RN339*