A sensitive and fast method for simultaneous determination of gaseous ammonia (NH₃) and particulate ammonium (NH₄⁺) in ambient air is presented. NH₃ is sampled in a cylindrical wet effluent diffusion denuder (CWEDD) and analyzed online by a continuous flow system with a fluorescence detector (FLD), while NH₄⁺ bound to aerosol particles is sampled in parallel by a condensation growth unit—the aerosol counterflow two-jet unit (CGU-ACTJU) sampler—and analyzed online with another FLD. The sensitive fluorescence detection of ammonium in concentrates of the CWEDD and the ACTJU is based on its reaction with ortho-phthaldialdehyde and sulfite to form isoindol-1-sulfonate. The calibration curve of ammonium is linear in the concentration range of 5 × 10^–9 to 2 × 10^–6 M. The limit of detection (LOD = 3 s/n) values of NH₃ and NH₄⁺ are 3.52 ng m^–3 (5.05 ppt) and 1.04 ng m^–3, respectively. The developed method enables online measuring of distribution of NH₃/NH₄⁺ in ambient air with a time resolution of 1 s. The optimized method was used for the determination of NH₃/NH₄⁺ in urban air in Brno in two campaigns during the winter and summer of 2018. The results obtained by the developed method were compared with a reference method based on the sampling on filters and “dry” diffusion denuders coated by phosphoric acid.

中文翻译：

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圆柱湿式湿式扩散消散仪和连续气溶胶采样器同时测定环境空气中的气态氨和颗粒铵

提出了一种灵敏而快速的方法，用于同时测定环境空气中的气态氨（NH ₃）和颗粒铵（NH ₄ ⁺）。NH ₃在圆柱形湿式废水扩散式剥蚀仪（CWEDD）中进行采样，并通过带有荧光检测器（FLD）的连续流系统进行在线分析，而与气溶胶颗粒结合的NH ₄ ⁺通过冷凝生长单元（气溶胶）进行并行采样逆流两喷嘴单元（CGU-ACTJU）采样器-并与另一个FLD在线分析。CWEDD和ACTJU精矿中铵的灵敏荧光检测基于与邻苯二甲酸-邻苯二醛和亚硫酸盐形成异吲哚-1-磺酸盐。铵的校准曲线在5×10 ^–9到2×10 – ⁶ M的浓度范围内是线性的。NH ₃和NH ₄ ⁺的检出限（LOD = 3 s / n）为3.52 ng m ^{– 3}（5.05 ppt）和1.04 ng m ^–3。所开发的方法可以在线测量NH ₃ / NH ₄ ⁺在环境空气中的分布，时间分辨率为1 s。优化后的方法用于测定NH ₃ / NH ₄ ⁺ 在2018年冬季和夏季进行了两次运动，在布尔诺的城市空气中进行了研究。将通过发达方法获得的结果与参考方法进行了比较，该参考方法基于在过滤器和涂有磷酸涂层的“干燥”扩散裸露器上采样的参考方法。