Keep rapid chlorine dioxide checks on the matched DPD method.
Bring a shorter, clearly defined color-development sequence to chlorine dioxide monitoring in drinking, tap and treated water. HI96779 combines its specified glycine masking reagent A with DPD reagent B for the rapid photometer method. Choose a nominal 100- or 300-test refill while keeping sample handling, reagent order and reporting as ClO₂ consistent.
Official Hanna HI96779 reagent packaging reference. Photo is illustrative, not a bottle/packet inventory for either pack; printed lot, expiry and any container markings do not specify supplied stock.
Match the refill to the complete method
Match the Chlorine Dioxide, Rapid Method program—not a conventional chlorine dioxide or chlorine program. The documented range is 0.00–2.00 mg/L as ClO₂ on HI83300, HI83305, HI83326 and HI83399. Mandatory HI96779A-0 masking reduces free-chlorine response, but does not remove every oxidant interference.
Two components with distinct jobs
Chlorine dioxide reacts with DPD to produce the measured pink tint. HI96779A-0 is the glycine masking reagent: it inhibits free-chlorine response without replacing the DPD indicator in HI96779B-0. The specified method requires reagent A in the sequence; it is not an optional helper added only when chlorine has been detected.
Collect cleanly and analyze immediately
Use a clean glass collection bottle and analyze without delay. Chlorine dioxide is a strong oxidizer and is unstable in water; delayed testing can change the sample before the photometer measures it. The documented applications are drinking water, tap water and treated water. The method does not establish universal suitability for every industrial, colored or oxidant-rich matrix.
Keep the masking step before zeroing
Fill a clean cuvette with 10 mL sample, add 5 drops of HI96779A-0, replace stopper and cap, and shake gently for 30 seconds. Wait another 30 seconds, then zero. Add one packet of HI96779B-0 to that cuvette, cap and shake gently for 20 seconds, then wait 1 minute and read. Follow the exact model manual; the one-minute development time is not the total sampling-to-result time.
Account for oxidants and matrix effects
The manual flags acidity, alkalinity, flocculating agents, hardness, inorganic and organic chloramines, manganese, metals, monochloramine, oxidized chromium/manganese, ozone and peroxides. Chlorine above 5 mg/L, bromine above 0.1 mg/L, high buffering and extreme sample pH are also interference conditions. Glycine masking does not make the method selective against all oxidants; assess the actual matrix and reporting need.
Do not transfer another chlorine dioxide workflow
HI93738 uses the conventional four-liquid chlorophenol-red method and is not the same reagent system. HI93703-52 ozone-method glycine powder is not the specified HI96779A-0 masking reagent; exact official code equivalence has not been established. Neither a shared chemical name nor nearby accessory placement supports substitution or an extra helper addition.
Plan the refill and keep its safety record
The nominal 100- and 300-test labels identify analytical refill capacity, not independently verified bottle counts, fill volumes or packet inventory. Provide the compatible meter, clean cuvette/cap/stopper and clean glass collection bottle separately. Follow both actual US component SDS and current labels for PPE, storage and waste handling, and retain lot/expiry identification. No fixed shelf life, dispatch promise or air-transport permission is inferred.
Frequently Asked Questions
What changes between the 100- and 300-test options?
HI96779-01 is labeled for 100 tests and HI96779-03 for 300 tests. Both use the same rapid DPD method with HI96779A-0 followed by HI96779B-0. These are nominal test counts, not a claim about physical bottle/packet counts, fill volumes or guaranteed reportable samples after QC and repeats.
Is reagent A optional if I expect no free chlorine?
No. The documented procedure always adds 5 drops of HI96779A-0 before shaking, waiting and zeroing. Its glycine masks the response of free chlorine. Do not skip that step or move it after zeroing based on an assumption about the sample.
Which instruments have the exact rapid method?
HI83300, HI83305, HI83326 and HI83399 manuals document the HI96779 A/B rapid chlorine dioxide procedure. Select that exact program and follow the model-specific operating instructions. Compatibility is not inferred from generic cuvette fit or an accessory located near a reagent listing.
How quickly can the sample be read?
Collect in clean glass and analyze immediately. For 10 mL sample: add 5 drops A, shake gently 30 seconds, wait 30 seconds and zero; then add one packet B, shake gently 20 seconds, wait 1 minute and read. The one-minute final wait excludes collection, masking, zeroing and handling time.
What does the result represent?
The range is 0.00–2.00 mg/L as chlorine dioxide, ClO₂, with 0.01 mg/L resolution. It is not a result as chlorine Cl₂, free chlorine, ozone or total oxidants. The method is a DPD adaptation of Standard Methods 18th edition, 4500 ClO₂ D; record the analyte and reporting basis explicitly.
Can I substitute HI93738 or HI93703-52?
No substitution is established. HI93738 is the conventional four-liquid chlorophenol-red chemistry, not this rapid DPD system. HI93703-52 is an ozone-method glycine powder, not the method-specified HI96779A-0. Exact official code equivalence has not been established, so neither replacement nor an extra cross-sold helper is recommended.
Does glycine eliminate all oxidant interference?
No. The method still flags other oxidants and matrix conditions, including ozone, peroxides, chloramines, oxidized metals, acidity/alkalinity, high buffering and extreme pH. Chlorine above 5 mg/L and bromine above 0.1 mg/L are specified interference conditions. Assess sample suitability under the full method, not just the masking step.
Where are handling, storage and expiry instructions?
Use the actual HI96779A-0 and HI96779B-0 US SDS in the document tab together with the current supplied labels. The instrument manuals are procedure references, not standalone consumable manuals. Follow their PPE, handling, storage and waste directions, retain lot/expiry identification and do not use the illustrative photo to infer supplied expiry or a fixed remaining shelf life.
