A permit must be obtained for the system when it is installed. At that point, the city has a record of the sprinkler system. Computers were interfaced with spectrometers, making it possible to repeat a measurement schedule on a steady basis and record the data acquired.
The invention of the Irving Langmuir shortly thereafter, freed mass spectroscopy from the severe limitations of poor vacuum.
Because isotopes differ in mass, their relative abundance can be determined if the masses are separated in a mass spectrometer see below Use of mass spectrometers.
But the city's water department sees it as a potentially high-level hazard, requiring a permit and annual inspections that can be a big surprise, especially to homeowners who are inheriting an irrigation system along with a new house.
Most elements exist in different atomic forms that are identical in their chemical properties but differ in the number of neutral particles— i.
For a single element, these atoms are called isotopes.