User manual HANNA INSTRUMENTS HI 38035

[. . . ] Rinse the plastic vessel with the water sample, fill to the 25 mL 25 mL mark and replace the cap. · Add 5 drops of Buffer Solution through the cap port and mix carefully swirling the vessel in tight circles. · Continue adding the EDTA Solution until the solution in the vessel becomes purple. Then mix for 15 seconds after each additional drop until the solution in the vessel turns blue. [. . . ] The ionic species in water causing the precipitation were later found to be primarily calcium and magnesium. At the present time, water hardness is a quantitative measure of these ions in the water sample. Now it is also known that certain other ion species, such as iron, zinc and manganese, contribute to the overall hardness of water. The measure and subsequent control of water hardness is essential to prevent scaling and clogging in water pipes. Calcium concentration in water depends on the source and on water treatment. Calcium contributes to the total hardness of water. The Hanna total hardness and calcium test kit makes monitoring easy and quick. The compact size provides the versatility to use the kit anywhere and the design makes the kit easy to handle. Note: 1 gpg (grains per gallon) CaCO3 is equivalent to 17 ppm CaCO3 (where ppm - parts per million - is equivalent to mg/L). · Add 2 drops of HI 38035A-0 Calcium Reagent through the cap port and mix carefully by swirling the vessel in tight circles. x5 · Add 1 drop of Calmagite Indicator through the cap port and mix as described above. The solution becomes a redviolet color. x2 x1 · Add 1 drop of HI 38035B-0 Calcium Reagent through the cap port and mix as described above. CHEMICAL REACTION The total hardness level is determined by an EDTA (ethylenediamine-tetraacetic acid) titration. The solution is first adjusted to a pH of 10 using a buffer solution. The indicator chelates with metal ions such as magnesium or calcium to form a red colored complex. As EDTA is added, metal ions complex with it. After all the free metal ions have been complexed, an excess EDTA removes the metal ions complexed with the indicator to form a blue colored solution. [. . . ] Read the relevant Health and Safety Data Sheets before performing the test. · Continue adding HI 38035D-0 reagent until the solution in the vessel turns orange. Wait for 30 seconds and if the solution in the vessel becomes violet, add another drop of HI 38035D-0 reagent to turn it orange. · Read off the milliliters of titration solution used from the syringe and multiply by 20 to obtain the calcium concentration as gpg CaCO3. [. . . ]