Abstract
For the first time, dispersive solid phase extraction combined with headspace sampling was introduced and applied to separation and pre-concentration of polycyclic aromatic hydrocarbons (PAHs) as representative of volatile and semi-volatile compounds, from aqueous solutions and sediments using multiwall carbon nanotubes (MWCNTs). After adsorption, PAHs were desorbed thermally from the surface of MWCNTs using a gas chromatography mass spectrometry (GC-MS) CombiPAL headspace device or a homemade thermal desorption system. Pre-concentration was maximized through optimization of solution pH, sorbent amount, and extraction time as well as desorption time and temperature of PAHs. The calibration curves were linear in the range 0.005-30 ng mL-1 for 13 PAHs at optimum conditions, with the coefficients of determination (R2) above 0.992, and detection limit in the range of 0.0021 to 0.0045 ng mL-1. Reproducibility for all PAHs was between 1.6 and 4.2%. Method recoveries were in the range of 94.0-102% for threeReferences spiked levels (1, 10, 20 ng mL-1). The methodology is even better if the selective or specific magnetic sorbent is used.
Highlights
Sample preparation is the bottleneck of all instrumental analysis
Amount of multiwall carbon nanotubes (MWCNTs) The sorbents capacity towards an analyte is limited and determines the amount of sorbents used in each separation and pre-concentration procedure
It means that MWCNTs approximately reached the highest capacity toward a tested amount of polycyclic aromatic hydrocarbons (PAHs) at this point
Summary
Sample preparation is the bottleneck of all instrumental analysis. Depending on the analyte and the instrumental technique, different sample preparation protocols had been introduced and developed.[1,2,3,4,5,6,7,8,9] Solid phase extraction (SPE), with advantages of using a lower volume of the sample solution and organic solvents, became a good replacement for tedious classical liquid-liquid extraction (LLE).[9] SPE is a multistep sample preparation technique, and the volume of solvents used is still considerable, and a final solvent exchange or volume reduction is required.
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