New sample treatment for determination of linear alkylbenzene sulfonate (LAS) in agricultural soils by liquid chromatography with fluorescence detection

• Published in: Analytical and bioanalytical chemistry 2007-03, Vol.387 (6), p.2175-2184
• Main Authors: Nimer, M, Ballesteros, O, Navalón, A, Crovetto, G, Verge, C, López, I, Berna, J L, Vílchez, J L
• Format: Article
• Language: English
• Subjects: Agriculture; Alkanesulfonic Acids - analysis; Chromatography, Liquid - methods; Soil - analysis; Solid Phase Extraction; Spectrometry, Fluorescence - methods; Ultrasonics
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-006-1069-y

A new sample-treatment procedure has been developed for determination of total linear alkylbenzene sulfonate (LAS), i.e. homologues and isomers, in agricultural soil. The procedure involves two steps, ultrasound-assisted extraction of LAS from the samples with methanol then clean-up of the methanolic extracts and preconcentration of the LAS by solid-phase extraction on two adsorbent cartridges (SAX and C18). The ultrasound-assisted procedure reduces extraction time (10 min in contrast with 6-12 h for conventional Soxhlet extraction) and requires only small volumes of organic solvent. The effect of different variables interacting in the ultrasound-assisted extraction process was studied. Finally, separation and quantification of the homologues and isomers of LAS was performed by liquid chromatography with fluorescence detection (LC-FD). 2-Octylbenzenesulfonic acid sodium salt (Na-2ØC8-LAS) was used as internal standard. The proposed method was satisfactorily used for determination of LAS in agricultural soil samples from the fertile plain of Granada (Spain).