Refill the low-range ISO COD method with the right chemistry.

Keep a validated ISO 15705:2002 low-range COD workflow supplied with HI93754F-25. Its 25 pre-dosed reagent vials cover 0–150 mg/L as O2 when used with the documented photometer procedure and separate heated digestion. Choose it by method family as well as range: this ISO formulation contains mercury and is neither the mercury-free refill nor a universally approved EPA replacement.

Choose chemistry and range together

HI93754F-25 is the orderable pack; HI93754F-0 is the component code identified in the instrument method and US Safety Data Sheet. The ISO family attribution is 15705:2002. A low-range label alone does not make this equivalent to the mercury-free or EPA formulations.

Match the exact instrument procedure

Use HI93754F-0 reagent in the exact-model COD LR procedure: HI97106 selects COD LR; HI83314 and HI83399 select COD LR (16). The verified range is 0–150 mg/L as O2. Follow the instrument’s specified vial adapter and insertion instructions for both zero and read. Official sources conflict on physical vial diameter, so this listing does not assert the diameter of supplied vials or universal adapter fit.

Prepare the blank as deliberately as the sample

Prepare one vial with 2 mL sample and a separate same-lot blank vial with 2 mL deionized water. Follow the full manual’s mixing precautions, then digest at 150 °C for 120 minutes in a separate heater. Cool exactly as directed: allow the initial cooling interval, invert while still warm when instructed, then rack until room temperature without shaking or inverting during final cooling. Never place a hot vial in the photometer adapter. Zero on the blank before reading the sample.

Count vials, not promised results

The pack contains 25 actual pre-dosed vials. A reagent blank consumes one of those vials, leaving 24 sample vials when one blank is prepared for a batch. This explains the benchtop manuals’ 24-test ordering count versus the retail 25-test label. Same-lot blanks and samples are required; follow the manual’s blank-reuse rules and run a blank for each measurement set for improved accuracy. Additional blanks, QC checks, repeats or failed preparations consume more vials. There is no guarantee of 25 reportable results.

Check the matrix before interpreting COD

ISO instructions require chloride below 2000 mg/L. Dilute higher-chloride samples as directed, account for the dilution and keep the result within the method range. This condition belongs to the ISO formulation; it is not a permission to use mercury-free reagents in chloride-containing samples.

Have the complete digestion station ready

Provide a compatible photometer and its specified adapter, a separate digestion reactor capable of 150 °C for 120 minutes, deionized water, accurate 2 mL pipetting/measuring tools and separate clean tips, a cooling rack, and the prescribed safety equipment. The photometer does not heat the vials. A safety shield is strongly recommended by the instrument manuals and required by the ISO reagent instructions; those instructions specify class A glass pipettes.

Confirm reporting acceptance before use

ISO 15705:2002 identifies this formulation’s method family. It is different from the EPA reagent family and cannot be treated as an automatically interchangeable EPA substitute. A common instrument-manual EPA-adaptation heading does not establish universal EPA/ISO approval. Confirm the laboratory’s SOP, matrix validation and local reporting acceptance before regulatory use.

Handle and ship as hazardous chemistry

This ISO formulation contains mercury(II) sulfate as well as sulfuric acid and chromium-containing chemistry. It is not mercury-free. Treat fresh reagent and reacted vials as hazardous chemical materials; use the current US component SDS, suitable PPE, ventilation and a compliant waste service. Do not put spent vials in ordinary trash or pour them down the drain. Hanna classifies this product as Dangerous Goods, with ground-only shipping. An SDS air-transport classification is not permission to ship by air. No dispatch date or freight quote is promised.

Manage received stock by its own markings

Keep unused vials in their original packaging in a cool, dark place, subject to the current SDS storage precautions. Check the lot and expiry on received stock; a reference photo does not establish your lot, expiry or available shelf life. No numeric storage temperature or shipping weight is asserted here.