The Ultrapen PT6 is a nitrate and temperature test pen. It is designed to be accurate and simple to use in diverse water quality applications. The ISE sensor measures the electric potential of a solution as it is affected by nitrate activity and is compatible with U.S. EPA Method 92010A. It can display the results as nitrate (NO3), nitrate as nitrogen (NO3— -N), and directly as millivolts (mV).