Separate ionic iron forms without losing the reporting basis.
Keep ferrous and ferric iron results distinct with the HI96777 two-stage phenanthroline method. The matched A/B reagent system supports sequential readings in one cuvette, helping water-testing teams distinguish Fe²⁺ from Fe³⁺ and review their ionic sum. Choose the nominal 100- or 300-test refill for an established compatible instrument workflow—not a different iron chemistry.
Official Hanna HI96777 reagent packaging reference. Image is illustrative, not a count of the selected pack’s packets or a promise of its lot, expiry or remaining shelf life.
Match the refill to the complete method
Use the exact Iron(II)/(III) program on HI83300, HI83325 or HI83399. The method measures reactive ionic iron over 0.00–6.00 mg/L as Fe. It does not automatically include particulate or otherwise undigested iron. HI96778 is a separate digested-total-iron vial method; HI96776 Fe²⁺-only and HI93746 Iron LR are not equivalent replacements.
One sequence, three useful ionic reporting views
In the first stage, Fe²⁺ reacts with 1,10-phenanthroline to form an orange-red complex. Reagent B then reduces Fe³⁺ to Fe²⁺, so the second chemical measurement represents the ionic sum. The instrument uses the sequential results to display ferric iron; its chemical-form control also exposes Fe²⁺ and Fe²⁺ + Fe³⁺. Record the selected chemical form with every result rather than labeling all readings simply “total iron.”
Keep both three-minute steps under control
Zero with 10 mL of unreacted sample, add one packet of HI96777A-0, cap and shake gently for 30 seconds. Wait 3 minutes and take Read 1 for Fe²⁺. In the same cuvette, add one packet of HI96777B-0, cap and shake gently for 30 seconds, then wait 3 minutes and take Read 2 for Fe³⁺. The manual warns that extending the first reaction beyond 3 minutes can let ferric iron react and falsely elevate the ferrous result. Use the exact model’s timer and logging instructions.
Match the sample matrix to the method
The documented applications are surface water, drinking water, mineral water, groundwater and process control. No digestion is specified in this ionic method. If the reporting question includes precipitated or particulate iron, define the required sample preparation and governing method separately; this refill alone does not establish a digested total-iron result.
Check interference limits before relying on a trend
The manual flags chloride and sulfate above 1000 mg/L; ammonium, calcium, potassium and sodium above 500 mg/L; silver above 100 mg/L; carbonate, chromium(III)/(VI), cobalt, lead, mercury, nitrate and zinc above 50 mg/L; nickel above 25 mg/L; copper above 10 mg/L; and tin above 5 mg/L. Extreme pH and high buffering also interfere: sample pH after reagent addition must be 3.8–5.5. Assess these conditions under your validated method rather than assuming a clear sample is interference-free.
Choose capacity without inventing a packet inventory
HI96777-01 and HI96777-03 are sold as nominal 100- and 300-test reagent sets. The procedure identifies A and B doses; these analytical doses do not independently verify the physical packet inventory shipped in either retail box. The pack labels are not a promise of 100 or 300 paired panels, reportable sample sets or QC-adjusted results. Blanks, checks, repeats and your SOP govern practical yield.
Retain traceability at the bench
Provide a documented compatible photometer and clean 10 mL cuvette, stopper and cap separately. Follow the current label and both component US SDS for handling, storage, protective equipment and waste management. Keep original lot and expiry identification with the working reagents; no fixed remaining shelf life is promised. Component SDS are safety evidence, not proof of bottle sizes, packet counts or permission for air transport.
Frequently Asked Questions
What is the difference between the two pack options?
HI96777-01 is the nominal 100-test reagent set and HI96777-03 is the nominal 300-test set. They use the same documented A/B Iron(II)/(III) method. Select capacity for your workload; the nominal test labels do not establish a physical packet count, a paired-panel count or a guaranteed number of reportable samples after QC and repeats.
Does this measure total iron including particles?
Not automatically. This is a sequential reactive ionic Fe²⁺/Fe³⁺ method, with an available Fe²⁺ + Fe³⁺ ionic sum. The stated procedure does not digest particulate iron. HI96778 is a different digested-total-iron vial method; decide the required sample preparation and report basis before selecting chemistry.
Which instruments have procedure proof?
Exact HI96777 procedures are documented for HI83300, HI83325 and HI83399. Select their Iron(II)/(III) program. HI83305 is deliberately not claimed here: a US retail compatibility statement does not resolve the missing exact procedure proof. Physical cuvette fit or an accessory-list mention alone is not method validation.
What does each reading mean?
After reagent A, Read 1 reports Fe²⁺. Reagent B reduces ferric to ferrous iron, so the second chemical response is Fe²⁺ + Fe³⁺; the instrument derives and displays Fe³⁺ from the sequence. Chem Frm cycles the available Fe²⁺ and ionic-sum views. Record the chemical form and mg/L as Fe with the result, following the exact model manual.
Why is the first three-minute wait critical?
Waiting longer than 3 minutes after reagent A can allow some ferric iron to react and falsely increase the reported Fe²⁺ concentration. Shake gently for 30 seconds and use the prescribed 3-minute timing for each stage. Do not treat longer color development as an improvement or transfer timing from another iron method.
Can I use HI96776 or HI93746 instead?
No interchangeability is established. HI96776 is the separate Fe²⁺-only method; HI93746 is Iron LR with different chemistry. Match the reagent family, instrument program, range and reporting question. Similar analyte names or overlapping concentration ranges do not establish equivalence.
Which samples and limits should I check?
The documented matrix scope is surface, drinking, mineral and groundwater plus process control, over 0.00–6.00 mg/L as Fe. Check the detailed ion thresholds in the specifications and method manual. Extreme pH/high buffering interfere; post-reagent pH must be 3.8–5.5. Evaluate any required preparation and validation for your actual matrix.
What is supplied separately, and where are safety instructions?
This listing is a reagent refill, not an instrument kit. Supply the compatible meter, clean 10 mL cuvette/cap/stopper and method-required bench and safety equipment separately. The document tab links the actual HI96777A-0 and HI96777B-0 US SDS and instrument method manuals. Follow current labels/SDS for storage, PPE, disposal and expiry; no shipping-mode permission is inferred.
