Sulfite
50081_Sulfite_Back.fm Page 111
Sulfite
• To avoid loss of sulfite, be careful not to agitate the sample when measuring or pouring.
• Always use organic-free reagent water for sample dilution (Cat. No. 26415-49).
• Rinse the electrode, temperature probe, and anti-diffusion tip with deionized water before every titration.
• 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 are highly recommended for this analysis.
• Never substitute buffers designed for calibrating pH meters. They contain dyes that interfere with amperometric titration.
• Never use buffers contaminated with mold or bacteria.
• Adjust the contrast of the display by accessing the Methods menu and pressing 7 to lighten, and 0
to darken.
• A distinction is drawn between running a new test and a new sample on the AutoCAT 9000. 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 a new sample starts, 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 the chlorine concentration based on the sample volume. Ensure that the sample volume is correct.
• The analysis data may be analyzed as many times as needed from the Zoom Range Determination window, in manual (MEPD)
and/or automatic (AEPD) modes. The results are not stored until accepted by the user.
• Press the STOP key at any time to interrupt instrument operation. The user will be given the option to resume, restart, or quit.
• Press CHECK MARK at any time during data acquisition to halt data collection.
• Press DEL during any timer period (except the Start Timer) to immediately exit the timer and proceed to the next step in the
procedure.
• The Predose feature allows the adjustment of titrant addition prior to starting the titration. Ensure that predose does not overshoot
the end point by completely titrating the sample.
• 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.
Amperometric Back Titration
Titration Workstation
0.00–20.00 mg/L as SO
3
2–
*
Scope and Application: For treated wastewater
* Higher ranges can be determined through sample dilution. See Section 5.2.3.3 Dilution on page 46.
Sample Tips and Techniques
Reagent Tips and Techniques
Instrument Tips and Techniques
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