Hach AutoCAT 9000 - Sulfite, Amperometric Back Titration

Total Chlorine
Total Ch lo rine
50081_Chlorine_Total_Forward.fm Page 109
Method Performance
Estimated Detection Limit
Based on the USEPA procedure of estimating the method detection limit (40 CFR 136,
App. B, 7-1-95), the estimated detection limit, using the procedure as written, is 1.2 µg/L
(0.0012 mg/L) chlorine.
Table 1 Recommended Volume Increment Settings for Total Chlorine
Estimated Chlorine Conc. (mg/L) Suggested Volume Increment (mL)
< 0.010 0.0003
0.010–0.050 0.0010
0.050–0.200 0.0030
0.200–0.400 0.0070
0.400–0.600 0.0110
0.600–0.800 0.0150
0.800–1.000 0.0200
> 1.000 0.0500
Note: These recommendations apply to Total Chlorine forward titrations, correspond to data
collection times typically under 5 minutes, and provide adequate data points on both sides of
the titration end point for proper analysis. Adjusting the volume increment will proportionately
adjust the data collection times and number of data points collected. For example, doubling the
volume increment will cut the data collection time, and the number of points collected, in half.
Table 2 Precision Statements
At Concentration 95% Confidence Limits
0.0090 mg/L Cl
2
0.0084–0.0096 mg/L Cl
2
0.423 mg/L Cl
2
0.413–0.433 mg/L Cl
2
4.241 mg/L Cl
2
4.165–4.317 mg/L Cl
2
Table 3 Accuracy Assessments
Sample Spike Addition Average % Recovery
% Range of
Recovery
Drinking Water
Free Cl
2
at 0.196 mg/L 101.2 (n=4) 100.3–101.9
Free Cl
2
at 0.391 mg/L 99.8 (n=4) 99.0–100.4
NH
2
Cl at 0.196 mg/L 93.4 (n=4) 93.0–93.9
NH
2
Cl at 0.391mg/L 93.4 (n=3) 93.0–94.0
Denitrified
Wastewater
Effluent
(Source #1)
NH
2
Cl at 0.489 mg/L
87.3 (n=6) 82.2–90.7NH
2
Cl at 0.975 mg/L
NH
2
Cl at 1.459 mg/L
Denitrified
Wastewater
Effluent
(Source #2)
NH
2
Cl at 0.489 mg/L
93.6 (n=6) 88.8–95.8NH
2
Cl at 0.975 mg/L
NH
2
Cl at 1.465mg/L