Assessment of Airborne Ammonia in a Swine Farming Environment by the Fluorimetric Enzyme Method

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Abstract
Airborne ammonia in swine confinement facilities and in the exterior vicinity of confinement facilities was sampled in the breathing zone of farm workers and analyzed by the fluorimetric enzyme method. The results were compared against inter-laboratory results generated using an automated 'alkali-phenate to indophenol' method. Ammonia concentration in solution is reported in μg.L−1 and in air is reported in ppbv.: Inter-method comparison by linear regression analysis yielded a correlation coefficient (R2) of 0.99998, slope (a) of 0.9509 and intercept (b) at -34.12 μg.L−1. The t-values for the slope and intercept were 724.35 (ta), and -0.7372 (tb), with the critical values 4.673 × 10−16 (pa) and 0.4888 (p) respectively for the 95% confidence level. The standard error for the slope and intercept were 0.0013 (σ.a−1) and 46.2858 (σ.b−1). The limit of detection for the fluorimeiric enzyme method was 110 μg.L−1 (3 σ) using field samples. The cumulative limit of detection for the airborne ammonia in the swine farming environment was 4 ppbv (300 L air). Ammonia concentration within the swine confinement facilities was in the range 1.000 to 10,000 ppbv and greater than the ambient atmospheric ammonia concentrations (1 to 5 ppbv). Ammonia levels outside of the swine confinement facilities was in the range 60 to 330 ppbv.