One-step cleanup for PAH residue analysis in plant matrices using size-exclusion chromatography

Abstract

A new one-step cleanup procedure, based on size-exclusion chromatography (SEC), usable for the extracts from accelerated solvent extraction (ASE), Soxhlet extraction, or ultrasonic extraction (USE), is described. The method is suitable for the determination of polycyclic aromatic hydrocarbons (PAHs), especially from very complicated plant matrices (e.g. pine needles, deciduous leaves, mosses). The main improvement compared with previous conventional procedures is that analyte peaks barely overlap with matrix peaks in the chromatograms and that it is a very rapid and simple one-step procedure with clearly improved analytical performance. Essential advantages of this SEC procedure are the sharper GC-MS chromatograms for the PAH fraction at retention times between 9.2 and 12.0 min, distinctly separated substance peaks resulting in better analysis, shorter running times, and lower solvent consumption.

Microwave-assisted headspace solid-phase microextraction to quantify polycyclic aromatic hydrocarbons in pine trees

“…The method LODs varied from 21 to 915 pg g −1 (dw) for needles and from 10 to 421 pg g −1 (dw) for bark. For pine needles, the LOD values are similar to those found in literature for PAHs extraction from pine needles by USE [30,33], PLE [36] or HF-LPME [37]. Regarding pine bark, the results are slightly better than those previously reported for USE and simple MAE [33], although again with higher repeatabilities.…”

“…However, the analytical methodologies employed to extract such pollutants involve solvent-consuming and sometimes timeconsuming techniques like Soxhlet [29,30], ultrasonic extraction (USE) [30][31][32], microwave-assisted extraction (MAE) [30,33] or pressurised liquid extraction (PLE) [30,31,34], followed by intricate clean-up of the numerous unwanted matrix extracts employing different solid-phase extraction (SPE) commercial or laboratory-made silicabased columns [31,32,35] or size-exclusion chromatography [36]. A first approach to the application of a solventreduced clean-up-free methodology, namely involving hollow-fiber liquid-phase microextraction (HF-LPME), was successfully reported by Ratola et al [37] in the extraction of PAHs from pine needles.…”

An analytical multi-residue approach for the determination of semi-volatile organic pollutants in pine needles

“…Thus, cleanup with acidimpregnated silica columns was abandoned but nevertheless GPC were tested alone. Hubert et al [28] obtained good recoveries and chromatographic performance using this approach for PAHs in pine needles extracts. For this, the same columns containing 6 g of Bio-Beads  S-X3 and solvents mentioned above were used, but the extracts were passed through glass columns containing approximately 0.5 g Na2SO4 beforehand, in order to remove water.…”

“…As mentioned previously, a thorough cleanup of matrices containing several coextractives such as chlorophylls, lipids, waxes and sugars is essential to obtain a good chromatographic performance. Different cleanup approaches and setups were found in literature and, among them, the ones by Thomas et al [31] and by Hubert et al [28] were chosen as the most promising ones for adaptation. Thomas et al [31] used a two-step cleanup procedure employing silica gel/acid silica followed by GPC to quantify PCBs in vegetation extracts (grass and silage).…”

“…Solid-phase extraction (SPE) using cartridges or glass columns are broadly employed for pine needle extracts, with silica [24,25], Florisil  [21,26] and alumina [24,26] as the main sorbents. Gel permeation chromatography (GPC), a separation technique based on molecular size [27], is also used, individually [28] or combined with SPE [29]. Our workgroup has previous experience in the development and validation of analytical methodologies to evaluate the levels of PAHs, OCPs and PBDEs in pine needles [13,26,30].…”