Evaluation of a Gas-Phase Selective Electrode for the Quantitation of Ammonia in Liquid Piggery Wastes

We evaluated a commercially available gas-sensing electrode for measuring the ammonia content of liquid piggery wastes (LPW). Samples previously acidified were analysed directly without purification or separation steps. The influence of metal ions, urea, volatile amines and suspended solids on electrode response was verified at concentration ranges generally encountered in LPW samples but no effects were observed. Reproducibility of measurements over the range 12.4–89.0 mM as ammonia was satisfactory (cv = ±5%) and recovered ammonia varied between 92% and 104%. Comparison of the electrode method to the standard distillation-titrimetric method yielded a close relationship as reflected by linear regression analysis on results (m = 1.01±0.08; r = 0.997). With adequate arrangements, one analyst could perform up to 200 samples per day.