Hach AutoCAT 9000 - Total Chlorine, Amperometric Forward Titration

Total Chlorine
Total Ch lo rine
50081_Chlorine_Total_Back.fm Page 103
Note: These recommendations apply to Total Chlorine back 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 reduce 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.
Method Performance
Estimated Detection Limit
Based on the USEPA procedure of estimating the method detection limit
(40 CFR Pt.136, App. B, 7-1-95), the estimated detection limit, using the procedure as
written, is 5.1 µg/L (0.0051 mg/L) chlorine.
Safety
Use good safety practices and laboratory techniques throughout the procedure. Consult
the Material Safety Data Sheet (MSDS) for specific reagent(s) information.
Table 1 Recommended Volume Increment Settings for Total Chlorine (Back)
Estimated Chlorine Conc. (mg/L) Suggested Volume Increment (mL)
<0.10 0.0010*
0.10–0.90 0.0030
0.90–1.00 0.0010
* with pre-dose
Table 2 Precision Statements
At Concentration 95% Confidence Limits
0.023 mg/L Cl
2
0.020–0.026 mg/L Cl
2
0.398 mg/L Cl
2
0.370–0.426 mg/L Cl
2
1.313 mg/L Cl
2
1.287–1.339 mg/L Cl
2
4.751 mg/L Cl
2
4.689–4.813 mg/L Cl
2
Table 3 Accuracy Assessments
Sample Spike Addition Average % Recovery
% Range of
Recovery
Drinking Water Free Cl
2
at 0.465 mg/L 97.3 (n=4) 95.8–99.1
Denitrified
Wastewater
Effluent
(Source #1)
NH
2
Cl at 0.423 mg/L 87.23 (n=3) 73.5–94.8
NH
2
Cl at 0.844 mg/L 93.07 (n=3) 91.8–93.8
NH
2
Cl at 1.262 mg/L 88.56 (n=3) 85.3–91.9
Denitrified
Wastewater
Effluent
(Source #2)
NH
2
Cl at 0.423 mg/L 92.59 (n=3) 88.9–97.2
NH
2
Cl at 0.844 mg/L 98.06 (n=3) 96.8–98.8
NH
2
Cl at 1.262 mg/L 95.01 (n=3) 89.9–98.0