Fast miniaturised sample preparation for the screening and comprehensive two-dimensional gas chromatographic determination of polychlorinated biphenyls in sludge

Abstract

Polychlorinated biphenyls (PCBs) in sludge are usually extracted by a technique such as Soxhlet with subsequent fractionation prior to long GC runs using GC-ECD or GC-HRMS. In this study, the extraction of selected chlorinated biphenyls (CBs) from a spiked sludge sample by three rapid techniques, i.e. ultrasonic (USE), pressurised-liquid (PLE), and microwave-assisted (MAE) extraction using a domestic microwave, was studied, with subsequent direct GC-ECD, GC-MS, or GC x GC-microECD analysis of the extracts. The main goal was to select an appropriate, and miniaturised, extraction method after only a brief optimisation and demonstrate the power of GC x GC analysis of dirty extracts. For PLE similar CB recoveries were found when extracting with either n-hexane or n-hexane/acetone (1/1). For USE and MAE, n-hexane/acetone (1/1) was the preferred extraction solvent. USE gave the best recoveries (80-95%; except 130% for CB 105). The only clean-up needed prior to GC-MS or GC x GC-gECD analysis was the removal of sulphur-containing compounds. GC-ECD was not suitable for these dirty extracts. The lowest LODs for the CBs (20 fg or 0.1 ng/g sludge) were found when combining USE and GC x GC-microECD, because of the powerful extraction, high separation power and excellent detectability provided by this technique.

The penetration of green sample-preparation techniques in comprehensive two-dimensional gas chromatography

“…A comparison between MAE, PLE and UAE was made by Kristenson et al for the GC×GC-μECD analysis of polychlorinated biphenyls (PCBs) in sludge [46]. The UAE process was carried out in a water bath for 45 min, by adding 2 mL of n-hexane/acetone (1:1 v/v) to 0.5 g of sludge contained in a vial.…”

Analysis of polybrominated diphenyl ethers in sewage sludge by matrix solid‐phase dispersion and isotope dilution GC–MS

“…A 5-mL glass column (5 cm610 mm id), with a Teflon frit (1 cm diameter and 20 lm pore size, Supelco, Madrid, Spain) was filled with 2 g of C 18 and preconditioned by passage of 3 mL of acetonitrile and 5 mL of distilled water. The sample extract (2 mL) was transferred to the column and the graduated tube was washed with 3 mL of acetonitrile, which was also transferred to the column.…”

“…In recent years, several fast extraction techniques have been developed to overcome the limitations of conventional methods. Ultrasonic-assisted extraction [16], pressurized liquid extraction (PLE) also named accelerated solvent extraction (ASE) [17], and microwave assisted extraction [18] have been used, being more rapid and consuming much less solvent and time than Soxhlet extraction. Matrix solid-phase dispersion (MSPD), a sample preparation procedure that is increasingly used for extracting/purifying contaminants from a variety of solid and semi-solid foodstuffs [19], can also be used as an alternative technique and offers advantages over classical extraction methods, such as the simplification of the analytical procedure and reduction in solvent consumption, without requiring special expensive instrumentation.…”

“…Numerous methods for the determination of PBDEs have been reported using GC with different detectors, such as electron capture [18] or mass spectrometry with either negative chemical ionisation [23] or electron impact [24,25]. Analysis of decabromodiphenyl ether can pose problems because this compound is both light sensitive and unstable at the high temperatures required for gas chromatography [10,26].…”

Global and selective detection of organohalogens in environmental samples by comprehensive two-dimensional gas chromatography–tandem mass spectrometry and high-resolution time-of-flight mass spectrometry

“…In recent years, comprehensive two-dimensional gas chromatography (GC × GC), which is a high performance technique for the separation of chemical compounds, has been used to characterize hundreds or perhaps thousands of petroleum chemicals [1][2][3] as well as food components and flavors [4][5][6]. GC × GC technology has also been used to analyze environmental contaminants with many congeners such as polychlorinated biphenyls (PCBs) [7][8][9][10][11][12], polybrominated diphenyl ethers (PBDEs) [9,12,13], toxaphene [14], polyaromatic hydrocarbons (PAHs) [7,15,16], and other halogenated compounds [9,10] as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) [17][18][19]. In our recent studies, we quantified dioxins in extracts of fly ash and flue gas samples [20] without employing any cleanup process by using a GC × GC connected to a high resolution time-of-flight mass spectrometer (HRTofMS).…”