Running the chlorine standard – Hach-Lange CL17 Instruction sheet User Manual
Page 7
CL17 Free and Total Chlorine Calibration/Verification
Page 7
5449089Cal Kit.fm
CL17 Free and Total Chlorine Calibration/Verification
Note: Take care when
preparing the standard.
An incorrectly prepared
standard can skew the
calibration curve and may
result in a calibration failure.
6.
Using the concentration of the ampule printed on the box, calculate the expected
standard concentration using the following equation:
7.
Write the calculated concentration on the bottle.
Running the Chlorine Standard
1.
Perform steps
15
of “
” using the prepared chlorine
standard in place of the Zero Standard (Organic-free Water) and in step
, use the
exception below:
New Style Analyzer:
a.
After the four measurements are complete, press the
MENU
key.
b. Record each reading if the analyzer is not connected to a computer.
c.
Using the up and down arrow keys, scroll to SETUP and press
ENTER
.
d. Scroll to CAL STD and press
ENTER
.
e.
Using the up and down arrow keys, enter the calculated concentration and
press
ENTER
.
f.
Press
ENTER
again to set the slope to its new value.
g. Exit to main display.
Old Style Analyzer:
a.
After the four measurements are complete, use the numeric keypad to enter the
calculated concentration.
b. Press the
STD
key.
c.
Exit to main display.
Calculating Average Concentration, %RSD and %Difference
1.
Calculate the average concentration of the standard (omit the first replicate) by either
manually calculating it or by using a spreadsheet program.
where a, b and c are the actual concentrations for the 2nd, 3rd and 4th readings of the standard.
2.
Calculate the standard deviation (SD) and the % relative standard deviation (%RSD).
The %RSD value should be less than 3%.
Important Note: If %RSD value is greater than 3%, rerun the test with fresh standard reagents.
Concentration of Ampule
(
)
0.020 L
(
)
×
0.52 L
------------------------------------------------------------------------------------------------------
Standard Concentration
=
Avg
a
b
c
+
+
3
----------------------
=
S D
a
avg
–
(
)
2
b
avg
–
(
)
2
c
avg
–
(
)
2
+
+
(
)
1/2
3
------------------------------------------------------------------------------------------------------------
=
%RSD
SD
100
×
avg
------------------------
=