{"product_id":"horiba-ionic-strength-adjustors-isa-tisab","title":"Horiba Ionic Strength Adjustors - ISA \u0026 TISAB","description":"\u003cp\u003eIonic strength adjustors for HORIBA ion-selective electrode measurements. An ISA — or TISAB in the case of fluoride — is added in a fixed proportion to both your standards and your samples so that every solution the electrode sees has the same background ionic strength.\u003c\/p\u003e\n\n\u003ch3\u003eWhy this reagent is not optional\u003c\/h3\u003e\n\u003cp\u003eAn ion-selective electrode does not respond to concentration. It responds to ion \u003cem\u003eactivity\u003c\/em\u003e, which is concentration multiplied by an activity coefficient that falls as the total dissolved salt content of the solution rises. Calibrate in clean standards and then measure a sample containing other dissolved salts, and the same concentration of your target ion will produce a different reading.\u003c\/p\u003e\n\n\u003cp\u003eAdding ISA swamps that variability. Because both standards and samples are dominated by the same high, known ionic strength, activity coefficients become effectively identical and the electrode's response tracks concentration directly. Omitting the adjustor is the single most common reason ISE results come back consistently low while looking entirely plausible.\u003c\/p\u003e\n\n\u003ch3\u003eTISAB does more than adjust ionic strength\u003c\/h3\u003e\n\u003cp\u003eFor fluoride, use \u003cstrong\u003e500-F-TISAB\u003c\/strong\u003e. Total Ionic Strength Adjustment Buffer performs three jobs at once: it fixes ionic strength, it buffers pH into the window where fluoride exists as free F⁻ rather than as HF or interfering hydroxide, and it complexes aluminum and iron, which otherwise bind fluoride and hide it from the electrode. Fluoride measurements made without TISAB are unreliable — particularly in drinking water compliance work.\u003c\/p\u003e\n\n\u003ch3\u003eAvailable adjustors\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-NH3-ISA\u003c\/strong\u003e — ammonia\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-NH4-ISA\u003c\/strong\u003e — ammonium\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-CA-ISA\u003c\/strong\u003e — calcium\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-CL-ISA\u003c\/strong\u003e — chloride\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-F-TISAB\u003c\/strong\u003e — fluoride (total ionic strength adjustment buffer)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-NO3-ISA\u003c\/strong\u003e — nitrate\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-K-ISA\u003c\/strong\u003e — potassium\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-NA-ISA\u003c\/strong\u003e — sodium\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eEach bottle is 500 mL. Use the adjustor matched to the ion you are measuring.\u003c\/p\u003e\n\n\u003ch3\u003eGood practice\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eAdd the same ratio of adjustor to every standard and every sample without exception\u003c\/li\u003e\n\u003cli\u003eAdd the adjustor before measuring, and allow the reading to stabilize\u003c\/li\u003e\n\u003cli\u003eDo not carry over adjustor between solutions — rinse the electrode between measurements\u003c\/li\u003e\n\u003cli\u003ePrepare only what you will use; do not store adjusted samples for later re-measurement\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated items\u003c\/h3\u003e\n\u003cp\u003eIon standard solutions, ion-selective electrode kits, replacement ISE cartridges and membranes and ISE filling solutions are all stocked — see the \u003ca href=\"https:\/\/envirotechonline.com\/collections\/horiba-parts-accessories\"\u003eHoriba Parts \u0026amp; Accessories\u003c\/a\u003e collection.\u003c\/p\u003e\n\n\u003cp\u003eBrowse all \u003ca href=\"https:\/\/envirotechonline.com\/collections\/horiba\"\u003eHORIBA instruments\u003c\/a\u003e.\u003c\/p\u003e","brand":"Horiba","offers":[{"title":"500-NH3-ISA - Ammonia Ionic Strength Adjustor, 500 mL - 3200697174","offer_id":48226477211838,"sku":"3200697174","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-NH4-ISA - Ammonium Ionic Strength Adjustor, 500 mL - 3200987466","offer_id":48226477244606,"sku":"3200987466","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-CA-ISA - Calcium Ionic Strength Adjustor, 500 mL - 3200697178","offer_id":48226477277374,"sku":"3200697178","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-CL-ISA - Chloride Ionic Strength Adjustor, 500 mL - 3200697170","offer_id":48226477310142,"sku":"3200697170","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-F-TISAB - Fluoride Total Ionic Strength Adjustment Buffer, 500 mL - 3200697166","offer_id":48226477342910,"sku":"3200697166","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-NO3-ISA - Nitrate Ionic Strength Adjustor, 500 mL - 3200697182","offer_id":48226477375678,"sku":"3200697182","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-K-ISA - Potassium Ionic Strength Adjustor, 500 mL - 3200697186","offer_id":48226477408446,"sku":"3200697186","price":92.0,"currency_code":"USD","in_stock":true},{"title":"500-NA-ISA - Sodium Ionic Strength Adjustor, 500 mL - 3200987465","offer_id":48226477441214,"sku":"3200987465","price":92.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0592\/9926\/6750\/files\/csm_500-NA-ISA_01_5fba8f3a56.png?v=1785337211","url":"https:\/\/envirotechonline.com\/products\/horiba-ionic-strength-adjustors-isa-tisab","provider":"EnviroTech Services","version":"1.0","type":"link"}