Microscale solid-liquid extraction: A green alternative for determination of n-alkanes in sediments

In this study, a green microscale solid-liquid extraction method using a miniaturized device combined with cleanup via dispersive micro-solid-phase extraction (MSLE-DµSPE) was developed for the determination by gas chromatography-quadrupole mass spectrometry (GC-MS) of n-alkanes in marine sediments. The main factors affecting the performance of this novel method were optimized using multivariate statistical tools. The MSLE-DµSPE method was validated considering the matrix-matched calibration, recovery, detection and quantification limits, ruggedness and accuracy. Under the optimum conditions, the method detection limits for n-alkanes ranged from 0.0051 to 0.0279 mg kg^-1, and the quantification limits ranged from 0.0171 to 0.0930 mg kg^-1. Correlation coefficients (R²) ≥0.99 were obtained for all compounds within the linear region (0.0025-0.200 mg L^-1). The mean recovery for most n-alkanes ranged from 60.6 to 119%, with intraday and interday relative standard deviation (RSD) <20%. Evaluation of the MSLE-DµSPE method using Analytical Eco-Scale, Green Analytical Procedure (GAPI), and Analytical Greenness (AGREE) assessment metrics demonstrated the green potential of the developed method. Finally, the proposed method was successfully applied to marine sediment samples and the n-alkanes from C₁₂ to C₄₀ were detected with total concentrations in the range of 0.98-7.61 mg kg^-1. This study represents the first application of a green microscale procedure to the analysis of n-alkanes in marine sediments.