Performance of an Infrared Photoacoustic Single Gas Analyzer in Measuring Ammonia from Poultry Houses

A single-gas photoacoustic analyzer, Chillgard RT, was evaluated for its performance of measuring ammonia (NH3) concentrations in poultry production under laboratory and field conditions, using a multi-gas photoacoustic analyzer, INNOVA 1412, as a reference method. Calibration gases were used to evaluate the cross-interferences of carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), and water vapor on NH3 measurements by Chillgard RT. The response times of Chillgard RT and INNOVA were measured in the laboratory using four vessels containing broiler litter. Side-by-side field comparisons between the Chillgard RT and INNOVA were conducted on a laying-hen farm and a broiler farm over two five-month periods. A strong linear relationship existed between the Chillgard RT and INNOVA NH3 readings. The NH3 measurement by the Chillgard RT showed no effect by CO2, N2O, CH4, or water vapor under typical operational conditions in poultry operations. The Chillgard RT demonstrated a faster response to NH3 than the INNOVA. Following 120-s measurements, the Chillgard RT and INNOVA achieved 99.6% and 96.7% of the expected values, respectively, when the INNOVA was configured at a 30-s sampling interval. The INNOVA response time was positively affected by water vapor level in the air samples. The Chillgard RT overestimated NH3 concentrations by 3.24%, 10%, and 22.9% for laying-hen houses, stored boiler litter, and broiler houses, respectively, as compared to the INNOVA. Thus, performance of the Chillgard RT should be carefully validated before used in field NH3 measurements.