{"product_id":"hanna-hi781-25-marine-nitrate-low-range-reagents-25-tests","title":"Hanna HI781-25 Marine Nitrate Low Range Reagents — 25 Tests","description":"\u003cdiv id=\"bts-hi781-25-description\" style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;max-width:1400px;margin:0 auto;padding:20px 12px;color:#26332C;background:#fff;\"\u003e\n\u003cdiv style=\"display:flex;flex-wrap:wrap;align-items:center;gap:20px;padding-bottom:20px;margin-bottom:24px;border-bottom:1px solid #e0e0e0;\"\u003e\n\u003cdiv style=\"flex:1 1 360px;min-width:0;box-sizing:border-box;\"\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003eResolve low marine nitrate without switching to a high-range refill\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eChoose HI781-25 to keep low-level seawater nitrate monitoring supplied with 25 tests of the matched three-reagent formulation. It suits an existing HI781 Checker or HI83399 Marine Nitrate Low Range setup when you want low-range readings and can include the required filtration stage.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cfigure style=\"flex:0 1 310px;min-width:0;margin:0;text-align:center;box-sizing:border-box;\"\u003e\n\u003cimg alt=\"Hanna HI781-25 manufacturer reagent photograph\" height=\"1200\" loading=\"lazy\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0896\/1579\/4474\/files\/HI781-25_holder__49657.1600954069.jpg?v=1793900744\" style=\"width:100%;max-width:300px;height:auto;object-fit:contain;\" width=\"1200\"\u003e\n\u003cfigcaption style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-size:0.9rem;margin-top:8px;\"\u003eManufacturer component illustration; use the supplied lot label, not photographed dates or volumes.\u003c\/figcaption\u003e\u003c\/figure\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background:#F1F7F3;border-left:3px solid #245B45;padding:20px;box-sizing:border-box;margin:0 0 24px;\"\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003eMatch the matrix, method and reporting basis\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003e0.00–5.00 ppm as NO3− direct; samples above 5 up to 50 ppm use the exact approved 1:10 dilution\u003c\/p\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eMatch this refill to the HI781 Checker or HI83399 Marine Nitrate Low Range method. It is not HI782-25 high-range chemistry or a freshwater nitrate substitute. The direct range is as nitrate (NO3−), not nitrogen; HI83399’s chemical-form display conversion does not change that reporting distinction.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003eWhat one refill supplies\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eOne HI781-25 refill provides reagent capacity for 25 tests using liquid HI781A-0 and powders HI781B-0 and HI781C-0. It is not an instrument starter kit. Do not assume filters, holder, syringes or other method tools are included; check and replenish your existing setup separately.\u003c\/p\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003eHave the complete testing workflow ready\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eFiltration is mandatory, so have the HI740271 filter holder, dry HI740228 filter discs, HI740270 10 mL Luer-lock syringe, HI740226 5 mL syringe\/tip, mixing vial, HI740272 blunt needle and model-appropriate cuvette\/cap available. Keep scissors and a lint-free wipe ready. Approved dilution also needs an accurate 1 mL syringe and nitrate\/nitrite-free artificial seawater.\u003c\/p\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003ePlan for the method, not just the reagents\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eAllow time for the complete reduction, filtration and timed color-development stages—not just a quick reagent addition. Follow all preparation, mixing, filtration and timing conditions in the \u003ca href=\"https:\/\/www.documentation.hannainst.com\/manuals\/download\/6703\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eHI781 Checker manual\u003c\/a\u003e or the \u003ca href=\"https:\/\/pages.hannainst.com\/hubfs\/product-manuals\/MAN83399_07_26.pdf\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eHI83399 Marine Nitrate LR method\u003c\/a\u003e, as appropriate. Shared reagent chemistry does not make the two instruments’ operating instructions interchangeable.\u003c\/p\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003eAbove 5 ppm? Check the approved dilution limits\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eFor 5–50 ppm nitrate samples only, the approved 1:10 dilution can extend testing beyond the direct 0.00–5.00 ppm range. It requires nitrate\/nitrite-free artificial seawater, the full model-specific preparation and timed method, and a ×10 result correction. Dilution reduces accuracy; it is not an unrestricted 0–50 ppm range. Follow the linked model manual for every dilution and measurement condition.\u003c\/p\u003e\n\u003ch4 style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;font-weight:400;line-height:1.35;margin:0 0 16px;color:#245B45;\"\u003eHandling and shipment checks\u003c\/h4\u003e\n\u003cp style=\"font-family:'Open Sans',sans-serif;font-weight:300;font-size:1rem;line-height:1.65;box-sizing:border-box;margin:0 0 16px;\"\u003eNitrite and copper interfere. Review all three component SDS and the supplied labels for PPE, storage and waste handling. Confirm destination and carrier eligibility before ordering: component transport provisions do not establish a whole-refill shipping exemption, and Hanna specifies ground-only shipping for Dangerous Goods.\u003c\/p\u003e\n\u003cdiv class=\"faq_block\" style=\"border-top:1px solid #e0e0e0;margin-top:24px;\"\u003e\u003cdiv itemscope=\"\" itemtype=\"https:\/\/schema.org\/FAQPage\" style=\"width: 100%; padding: 20px 0; font-family: 'Open Sans', sans-serif; font-weight: 300; color: #333;line-height:1.15;\"\u003e\n\u003ch3 style=\"font-size:1.1rem;font-weight:400;margin:0 0 16px;color:#245B45;\"\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eWhen should I choose HI781-25 rather than HI782-25?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eChoose HI781-25 for the documented marine low-range method, 0.00–5.00 ppm as nitrate. HI782-25 is high-range chemistry and is not a substitute in an HI781 method. Match the reagent code to the exact program, not just the word nitrate.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eIs the range reported as nitrate or nitrate-nitrogen?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eThe direct 0.00–5.00 ppm range is as NO3−, not as N. HI83399 can display nitrate-nitrogen through its chemical-form function. Numerically equal NO3− and NO3−–N results mean different concentrations; do not relabel a nitrate reading as nitrogen.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eWhich instruments have a verified method?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eThe current HI83399 manual lists HI781-25 for Marine Nitrate Low Range. The HI781 Checker manual also specifies this refill. Other benchtop models are not added merely because they measure nitrate, and this page does not create or imply a separate Checker instrument listing.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eWhat do the three reagent components do?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eThe procedure adds HI781A-0 and HI781B-0 before filtration, then zeroes the filtered preparation and adds HI781C-0 for final color development. The prescribed per-test doses are 4 mL A and one packet each of B and C. These method quantities do not establish the supplied bottle fill or full physical pack contents.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eAre the filters, holder and syringes in the refill?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eThey are required for the procedure but are not established as included with HI781-25. The HI781 instrument starter-kit contents are not the reagent refill packing list. Check your reusable holder, 10 mL Luer-lock syringe, 5 mL syringe\/tip, mixing vial, blunt needle and cuvette; replenish the dry filter discs separately as needed.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eWhy must the sample be filtered?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eFiltration is a prescribed stage after adding reagents A and B and before zeroing. Use a dry filter disc and holder, apply constant light pressure and allow about 30 seconds. Excess pressure can tear the filter; a wet assembly or omitted filtration is not the documented method.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eCan I measure samples above 5 ppm?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eOnly with the approved 1:10 preparation for 5–50 ppm samples: dilute 1 mL sample to 10 mL with nitrate\/nitrite-free artificial seawater, mix, use 7 mL of that preparation and complete the normal method. Multiply by 10. The HI781 manual specifies degraded diluted accuracy of ±2.5 ppm ±5% of calculated reading; measure volumes carefully.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\u003cdetails itemprop=\"mainEntity\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Question\" style=\"border: 1px solid #e0e0e0; border-radius: 8px; margin: 0 0 10px 0; background: #fff;\"\u003e\u003csummary itemprop=\"name\" style=\"cursor: pointer; padding: 14px 16px; font-size: 1rem; font-weight: 400; list-style-position: inside;\"\u003eWhich timing, interferences and safety checks matter?\u003c\/summary\u003e\u003cdiv itemprop=\"acceptedAnswer\" itemscope=\"\" itemtype=\"https:\/\/schema.org\/Answer\" style=\"padding: 0 16px 14px 16px;\"\u003e\u003cp itemprop=\"text\" style=\"font-size: 0.97rem; line-height: 1.6; margin: 0;\"\u003eOn HI781, shake the A\/B preparation for one minute, filter, zero, add C and shake for two minutes, then allow the eight-minute color-development time. Nitrite and copper interfere. Consult all three component SDS and the full method; the transport status of one component is not a whole-kit shipping guarantee.\u003c\/p\u003e\u003c\/div\u003e\u003c\/details\u003e\n\u003c\/div\u003e\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Hanna Instruments","offers":[{"title":"Default Title","offer_id":53468052455722,"sku":"BTS-HI781-25","price":27.49,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0896\/1579\/4474\/files\/HI781-25_holder__49657.1600954069.jpg?v=1793900744","url":"https:\/\/bluetigerscientific.com\/products\/hanna-hi781-25-marine-nitrate-low-range-reagents-25-tests","provider":"Blue Tiger Scientific","version":"1.0","type":"link"}