Chlorine Dioxide, Amperometric Forward Titration - Hach AutoCAT 9000 Instruction Manual

Titration Workstation
Scope and Application:
* Higher ranges can be determined through sample dilution. See Section 5.2.3.3 Dilution on page 46.
**Procedure equivalent to Standard Methods 4500-ClO
Sample Tips and Techniques
• Soak all glassware in a strong chlorine dioxide (ClO
Rinse thoroughly with deionized water. Use the glassware for this method only.
• Chlorine dioxide and its by-products are volatile and can be easily lost from aqueous solution. Minimize air contact by attaching a
flexible hose to a tap and placing the end at the bottom of a 1-L amber glass bottle. Turn on the tap and allow several volumes to
overflow, then slowly remove the sample line and cap the container with minimum headspace.
• Minimize agitation when measuring sample volumes. Remove sample portions with a volumetric pipet. Always place the tip at the
bottom of the sample container. If using 200-mL sample increments, use a 100-mL pipet to withdraw two portions of sample.
• Always use organic-free water for sample dilution (Cat. No. 26415-49).
• Rinse the electrode, temperature probe, and anti-diffusion tip with deionized water before every titration.
.
Reagent Tips and Techniques
• Download the "Certificate of Analysis" (COA) to obtain the exact concentration of any unopened bottle of Hach titrant or standard
solution. See Obtaining the Certificate of Analysis for Hach Reagents on page 41.
• Hach buffer reagents for chlorine titrations are highly recommended for this analysis.
• Never substitute buffers designed for calibrating pH meters. They may contain dyes that interfere with amperometric titration.
• Never use buffers contaminated with mold or bacteria.
Instrument Tips and Techniques
• Adjust the contrast of the display by accessing the Methods menu and pressing 7 to lighten or 0 to darken.
• A distinction is drawn between running a new test and a new sample. Each test is a replicate run of the current or previous
sample analysis. The AutoCAT 9000 automatically tracks the results of a series of tests, and automatically calculates the mean
and standard deviation for all the results. Each test is given a different number, all of which are listed under the same Sample ID.
When starting a new sample, a new ID is assigned.
• The AutoCAT 9000 can accommodate any sample size. Standard Methods recommends a default volume of 200 mL. The
volume can be adjusted to expand the test range.
• The AutoCAT 9000 calculates concentration based on the sample volume. Make sure that the sample volume is correct.
• Press STOP any time to interrupt instrument operation; the user can resume, restart, or quit completely.
• Press the CHECK MARK any time during data acquisition to halt data collection.
• Press DEL during any timer period (except Start Timer) to immediately exit the timer and proceed to the next step.
• Press ESC during any titration/calibration data collection period or timer to access Edition mode. See Edition Mode on page 30.
• Flush the burette each day before the first sample test or calibration is performed. See Daily Start-up on page 26.
• Flush the burette when changing titrants. See Changing Titrants on page 25.
50081_Chlorine_ChlorineDioxide.fm
Chlorine Dioxide
Chlorite
Free Chlorine
For water and wastewater**
E.
2
) solution (300–500 mg/L) for at least 1 hour.
2
Chlorine Dioxide
w/ Chlorite and Free Chlorine
Amperometric Forward Titration
0.10–5.00 mg/L as Cl0
0.10–5.00 mg/L as Cl0
0.10–2.00 mg/L as Cl
Chlorine Dioxide
*
2
–
2
2
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