Hach DR/850, Procedures Manual, Page: 122 / 460

122
beaker.
e) Analyze the spiked and unspiked sample as described in
the procedure.
f) Calculate the concentration of mg/L chlorine added to the
sample:
g) The spiked sample result should reflect the analyzed
sample result + the calculated mg/L Cl
2
added (step f).
h) If this increase does not occur, see Standard Additions in
Section 1 for more information.
Method Performance
Precision
In a single laboratory using a standard solution of 1.00 mg/L
chlorine and two representative lots of reagents with the
instrument, a single operator obtained a standard deviation of
±0.01 mg/L chlorine.
In a single laboratory using a standard solution of 1.00 mg/L
chlorine and two representative lots of AccuVac Ampuls with the
instrument, a single operator obtained a standard deviation of
±0.01 mg/L chlorine.
Estimated Detection Limit (EDL)
The estimated detection limit for programs 9 and 11 is 0.02 mg/L
Cl
2
. For more information on derivation and use of Hach’s
estimated detection limit, see Section 1 .
Pollution Prevention and Waste Management
Samples treated with sodium arsenite for manganese or
chromium interferences will be hazardous wastes as regulated by
Federal RCRA for arsenic (D004). See
Section 3 for more
information on proper disposal of these materials.
mg/L Chlorine added
0.2 vol. standard added
( )
Label value (mg/L Cl
2
) ×
25.2 sample
(
standard volume
)
+
----------------------------------------------------------------------------------------------------------------------------- =
CHLORINE, FREE
continued