The HACH DR3900 is an example of a single-analysis spectrometer. It is also a single-beam, fixed-wavelength spectrophotometer. It is primarily used for water quality analysis. The spectrometer comes preprogrammed for specific field kits sold by HACH. The user simply follows the instructions on the field kit, inputs the name of the analysis being conducted, places the sample into the spectrometer, and the desired data is displayed. The system is designed to be very user friendly and requires a minimum of technical training to operate. The HACH DR3900 can be used to measure turbidity, pH, salinity, dissolved oxygen, total nitrogen, total phosphorus, and more.