The gold film sensor is inherently stable and selective to mercury, eliminating interferences common to ultraviolet analysers, such as water vapour and hydro-carbons. When the sample cycle is activated, the internal pump in the 431-XE draws a precise volume of air over the sensor. Mercury in the sample is adsorbed and integrated by the sensor, registering it as proportional change in electrical resistance. The instrument computes the concentration of mercury in milligrams per cubic meter or nanograms, and displays the final result in the LCD readout. An improved film regeneration circuit in the 431-XE makes the sensor last even longer than earlier models.

Additional accessories are available to customise the Jerome 431-XE to meet individual application needs. An optional communications configuration allows data logging and computer interface capabilities. For data acquisition during portable surveys, a Jerome data logger plugs into the 431-XE. Using the Jerome Communications (JCS) software, the analyser and data logger download recorded data to the computer for analysis, printout, and permanent record storage. The JCS software can also program the instrument for stand-alone monitoring. If the sensor becomes saturated while the 431-XE is attached to the data logger or computer, the analyser automatically regenerates the sensor and then resumes sampling. They can also be used as collection devices for applications such as gas stream analysis. An internal option board allows auto-zeroing, DC power operation, timed regeneration, and timed sampling during prolonged unattended sampling periods. The option board also allows external fresh air solenoid support and 4-20 mA or 0-2 V analogue output. A moulded hard carrying case or soft field case give added versatility and organised storage for the instrument and its accessories.