N-compounds speciation analysis in environmental samples using ultrasound-assisted solid-liquid extraction and...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Spectrometry

Background:

• Accurate speciation of nitrogen compounds (nitrite, nitrate, p-nitrophenol) is crucial for environmental assessment, particularly in disaster-affected areas.
• Traditional methods for N-compound analysis can be time-consuming and complex, necessitating faster and more efficient alternatives.

Purpose of the Study:

• To develop and validate a fast, efficient, and non-chromatographic method for the extraction and speciation of nitrite, nitrate, and p-nitrophenol in environmental samples.
• To enable accurate quantification of these N-compounds in water, soil, and sediment matrices.

Main Methods:

• Ultrasound-assisted solid-liquid extraction (USLE) was employed for the efficient extraction of target analytes from diverse environmental matrices.
• Selective conversion of analytes to nitric oxide gas (NO(g)) via UV photolysis (nitrate), H2O2/UV photocatalysis (p-nitrophenol), and direct conversion (nitrite).
• High-resolution continuum source molecular absorption spectrometry (HR-CS MAS) was utilized for the determination of NO(g) after phase separation.

Main Results:

• The developed method achieved low limits of detection (LODs): 0.097 µg L⁻¹ (nitrite), 0.119 µg L⁻¹ (nitrate), and 0.090 µg L⁻¹ (p-nitrophenol).
• Analysis of environmental samples yielded concentrations up to 0.99 mg L⁻¹ (nitrite), 49.80 mg L⁻¹ (nitrate), and 0.10 mg L⁻¹ (p-nitrophenol).
• Spike/recovery studies demonstrated high accuracy, with recoveries of 101±2% (nitrite), 100±1% (nitrate), and 96±5% (p-nitrophenol) in real samples.

Conclusions:

• The proposed ultrasound-assisted, non-chromatographic method offers a rapid and efficient approach for N-compound speciation in environmental samples.
• The technique is suitable for analyzing water, soil, and sediment, providing accurate and reliable results for environmental monitoring.