Ammonia detection can be done using gas sensors. Examples of different application areas of ammonia gas detection are: environmental monitoring, medical diagnostics, chemical laboratories and detection of ammonia in drinking water and wastewater (Timmer et al., 2005). High ammonia concentrations are easy to detect, while for very low concentrations we need different gas sensors operating according to different detection principles. Ammonia gas sensors operate at different temperatures, each with a specific detection limit range and response time to quickly measure ppm and sub-ppm concentrations. Commercial ammonia sensors use different techniques for ammonia detection and can be classified into metal oxide sensors, conductive polymer detectors, catalytic ammonia sensors, and optical sensors. Ammonia gas sensors should be considered based on cost, maintenance, installation, and most importantly, the sensors specific to the appropriate application. Metal oxide ammonia gas sensors are the most widely used and are usually made of tin sensors, i.e. SnO2 (Zakrzewska, 2001). These sensors are inexpensive and are based on the principle of conductance change that occurs due to chemical adsorption of gaseous ammonia molecules on a sensing layer. The selectivity and sensitivity of these sensors towards ammonia gas can be improved by using additives which will control the adsorption of the gas molecules. Using additives such as Au and MoO3 ammonia sensors can achieve the detection limit of 1 ppm. Metal oxide sensors have a detection limit of 1 to 1000 ppm and operate at temperatures above 400°C. In applications such as environmental monitoring and flue gas detection, these sensors are very useful. Sensors made of polymer...... middle of paper ...... ysis are required. Using non-selective detectors with gas samplers is also a good selective technique for measuring ammonia accurately. Table 1 (Timmer et al., 2005) summarizes all the parameters of the different types of sensors used for ammonia detection. In the methodology section, a design of experiments using sensors to detect ammonia in water will be presented. However, there are two methods outlined by the EPA for detecting ammonia in bodies of water. The first method (Method 350.1) is the distillation method in which the sample is first buffered and then distilled to boric acid. The ammonia concentration is directly proportional to the indophenol blue formed (SEMI, 1993). In the second EPA method (Method 350.2), the sample is distilled into boric acid and the ammonia concentration is determined either by titrimetry or colorimetry (SEMI, 1993) .