Hach DR/850 - Page 152

152
CHLORINE DIOXIDE, continued
Method Performance
Precision
For more information on determining precision data and method
detection limits, see Section 1 of the DR/800 Procedures Manual.
Estimated Detection Limit (EDL)
For more information on derivation and use of Hach’s estimated
detection limit, see Section 1 of the DR/800 Procedures Manual.
Interferences
A substance interferes if it changes the final reading by 0.1 mg/L
ClO
2
or more.
Program Standard 95% Confidence Limits
112 0.24 mg/L 0.22–0.26 mg/L ClO
2
112 4.79 mg/L 4.67–4.91 mg/L ClO
2
113 0.26 mg/L 0.21–0.27 mg/L ClO
2
113 4.83 mg/L 4.71–4.97 mg/L ClO
2
Program EDL
112 0.04 mg/L ClO
2
113 0.04 mg/L ClO
2
Interfering Substance Interference Levels and Treatments
Acidity Greater than 150 mg/L CaCO
3
. May not develop full color or color may fade
instantly. Neutralize to pH 6–7 with 1 N sodium hydroxide. Determine amount to be
added on separate sample aliquot, then add the same amount to the sample being tested.
Correct for volume addition (see Section 1, Correction For Volume Additions, in the
DR/800 Procedures Manual).
Alkalinity Greater than 250 mg/L CaCO
3
. May not develop full color or color may fade
instantly. Neutralize to pH 6–7 with 1 N sulfuric acid. Determine amount to be added
on separate sample aliquot, then add the same amount to the sample being tested. Correct
for volume addition (see Section 1, Correction For Volume Additions, in the DR/800
Procedures Manual).
Bromine, Br
2
Interferes at all levels.
Chlorine, Cl
2
May interfere at levels greater than 6 mg/L. Additional glycine may be able to
compensate for this interference.
Chloramines, organic May interfere.
Flocculating agents High levels of most flocculating agents can be tolerated. This tolerance is decreased
if chlorine is present. See the information about metals in this table. In the presence
of 0.6 mg/L Cl
2
, Al(SO
4
)
3
(< 500 mg/L) and FeCl
2
(<200 mg/L) may be tolerated.
Hardness No effect at less than 1,000 mg/L as CaCO
3
.