Nitrates are present in nature as a result of decomposition of organic microorganisms or due to their use as fertilizers. Nitrates reduce to nitrites, which in turn easily combine to form substances dangerous to man.A maximum level of 45 mg/L is established as a worldwide guideline for nitrate concentration in water. In Europe, the maximum consented level of nitrates in potable water is 50.0 mg/L, while in the USA the EPA has established a guideline for the maximum level of nitrate nitrogen of 10 mg/L (NO-³-N), which corresponds to 45.0 mg/L of nitrates.The HANNA® solutions are HI 93728 and HI 93828, hand held meters suited for field measurement. Reading procedures have been made as simple as possible to allow everyone to perform accurate nitrate measurements.The kit provides you with all you need for field measurement: photometer, reagents and apparatus perfectly fitted in a rugged carrying case HI96728 reads nitrogen nitrate from 0 to 30 mg/L (NO-³-N); multiply the readout by a factor of 4.43 and you can read up to 133 mg/L of nitrate (NO-³). HI96728 reads nitrate directly in mg/L of NO-³, from 0 to 100 mg/L.With a normal 9V battery you will be able to get more than 300 measurements. The auto shut-off feature (after 10 minutes of non-use) guarantees a long battery life.