Development of a hydrophilic interaction liquid chromatography–mass spectrometry method for detection and quantification of urea thermal decomposition by-products in emission from diesel engine employing selective catalytic reduction technology

摘要: The use of urea based selective catalytic reduction (SCR) technology for the NOx from exhaust diesel-powered vehicles has potential to emit at least six thermal decomposition by-products, ammonia, and unreacted tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline melamine. In present study, a simple, sensitive reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed identification determination by-products in diesel exhaust. Gradient separation performed on SeQuant ZIC-HILIC column with highly polar zwitterionic stationary phase, using mobile phase consisting acetonitrile (eluent A) 15 mM ammonium formate (pH 6; eluent B). Detection quantification were quadrupole ESI/MS operated simultaneously negative positive mode. With 10 μL injection volume, LODs all target analytes range 0.2-3 μg/L. showed good inter-day precision retention time (RSD<0.5%) peak area (RSD<3%). Satisfactory extraction recoveries spiked blanks ranged between 96 98%. Analyses samples collected during transient chassis dynamometer tests bus engine equipped particulate filter (DPF) SCR presence five acid ammelide most abundant