Sensitive, accurate and rapid detection of trace aliphatic amines in environmental samples with ultrasonic-assisted derivatization microextraction using a new fluorescent reagent for high performance liquid chromatography

• A new fluorescent reagent designed for selective labeling of trace aliphatic amines.
• Rapid, simple and convenient pretreatment of micro complex sample.
• Much low detection limits and more accurate analysis.
• Improved extraction recoveries and matrix interferences for environmental samples.

A new fluorescent reagent, 1-(1H-imidazol-1-yl)-2-(2-phenyl-1H-phenanthro[9,10-d]imidazol-1-yl)ethanone (IPPIE), is synthesized, and a simple pretreatment based on ultrasonic-assisted derivatization microextraction (UDME) with IPPIE is proposed for the selective derivatization of 12 aliphatic amines (C1: methylamine–C12: dodecylamine) in complex matrix samples (irrigation water, river water, waste water, cultivated soil, riverbank soil and riverbed soil). Under the optimal experimental conditions (solvent: ACN–HCl, catalyst: none, molar ratio: 4.3, time: 8 min and temperature: 80 °C), micro amount of sample (40 μL; 5 mg) can be pretreated in only 10 min, with no preconcentration, evaporation or other additional manual operations required. The interfering substances (aromatic amines, aliphatic alcohols and phenols) get the derivatization yields of <5%, causing insignificant matrix effects (<4%). IPPIE–analyte derivatives are separated by high performance liquid chromatography (HPLC) and quantified by fluorescence detection (FD). The very low instrumental detection limits (IDL: 0.66–4.02 ng/L) and method detection limits (MDL: 0.04–0.33 ng/g; 5.96–45.61 ng/L) are achieved. Analytes are further identified from adjacent peaks by on-line ion trap mass spectrometry (MS), thereby avoiding additional operations for impurities. With this UDME–HPLC–FD–MS method, the accuracy (−0.73–2.12%), precision (intra-day: 0.87–3.39%; inter-day: 0.16–4.12%), recovery (97.01–104.10%) and sensitivity were significantly improved. Successful applications in environmental samples demonstrate the superiority of this method in the sensitive, accurate and rapid determination of trace aliphatic amines in micro amount of complex samples.