Comparison of microwave assisted, ultrasonic assisted and Soxhlet extractions of N-nitrosamines and aromatic amines in sewage sludge, soils and sediments

This paper describes a cost-effective and sensitive method for the gas chromatographic determination of 10 aliphatic and aromatic N-nitrosamines and 14 aromatic amines (including aniline, several chloroanilines and 2-nitroaniline) in various soil matrices, after microwave-assisted extraction (MAE) combined with continuous solid-phase extraction. A systematic comparison of MAE with ultrasonic assisted and Soxhlet extraction alternatives showed that MAE provided the highest extraction efficiency (94–96%) with the shortest extraction time (3 min). The method developed provides a linear response throughout the concentration range 0.1–150 ng g −1 and features low limits of detection (0.03–0.35 ng g −1 ) and good precision. The method was successfully applied to study the occurrence of the analytes in sewage sludge, agricultural soils, and river and pond sediments. Aniline and chloroanilines were the amines most frequently detected (0.4–5.4 ng g −1 ), whereas N-nitrosodimethylamine, N-nitrosodiethylamine and N-nitrosomorpholine were only found in two of the urban sewage sludge samples analyzed (0.4−1.6 ng g −1 ).