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Polycyclic aromatic hydrocarbons (PAHs) are significant pollutants in the environment. They are chiefly generated due to incomplete combustion of organic materials. The particle or gas partitioning of PAHs has a strong impact in eliminating them from the atmosphere through wet and dry deposition techniques.
A major source for PAHs in soil is atmospheric deposition . This can be ascertained through a number of extraction and purification methods, and then detected with the help of (gas chromatography-mass spectrometry) GC/MS using the UNI EN 15527 reference technique.
The main aim of this article is to show that the removal of high organic component from the environmental matrix through the gel permeation chromatography purification (AZURA GPC Cleanup, FS conditioned resins CHEX/DCM) method, as against solid phase extraction (SPE) purification, enables well-defined separation time of the analytes. It can also allow narrow bands without physical or chemical interaction of the analytes with the column, thereby reducing the chances of loss of analytes . This is different from other separation methods which are reliant on physical or chemical interactions for the separation of analytes .
As shown in Figure 1a, evaluation of the baseline can be performed by comparing the analytical chromatograms obtained from GC-MS. The obtained overlay results evidently validate that the signal-to-noise ratio (S/N) and even the matrix effect of the sample are largely reduced, compared to SPE purification, when the gel permeation chromatography (GPC) purification is performed (see Figure 1b).
As illustrated in Figure 2, the GPC purification method also improves the process of identification of the third mass.
Figure 1. (a) Overlay of chromatograms obtained from GC-MS; blue—SPE, red—GPC. (b) Selected ion 166,1 (Fluorene).
Figure 2. Identification of the third mass.
Materials and Methods
A mud sludge sample (20 g) of civil waste was used for the purification process. The analysis was performed based on UNI EN 15527: 2008 (Determination of polycyclic aromatic hydrocarbons (PAH) in waste by gas chromatography with mass spectrometric detection (GC/MS)). Following is the information related to the extraction method: Soxhlet extraction (BUCHI B-811 system:100 extraction cycles with Acetone/Hexane = 1/1 v/v).
The cleanup information is as follows: AZURA GPC Cleanup system; GPC column = 450 mm x 10 mm; Phase: Biobeads SX3 = 10 g; Mobile Phase: CEX/DCM = 70/30 (v/v); flow rate = 1 mL/minute; injected volume: 1 mL (concentrated sample corresponding to 4 g of sample). Following cleanup, the sample volume reduces to 1 mL through evaporation. The extract, which is concentrated to a minimum volume, is diluted to 5 mL with GPC mobile phase. A GC-MS single quadrupole 5975C (Agilent) was used for the analysis by injecting a volume of 1 µL.
Using the GPC cleanup process for analyzing mud sludge samples for the presence of PAHs with the help of the GC/MS method is a better alternative to SPE purification. Evident benefits of this technique are optimal S/N ratios and identification of the third mass.
Automation of the GPC Cleanup with the help of the AZURA GPC Cleanup system increases the efficiency of the application.
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 Hussein I. Abdel-Shafy, Mona S.M. Mansour. Egyptian Journal of Petroleum (2015)
 A. Bertin, S.Iacobellis, T.Bonato, Laboratorio di ricerca S.E.S.A., S.Guidotti, Labservice Analytica S.R.L
 Skoog, D.A. Principles of Instrumental Analysis, 6° ed.; Thompson Brooks/Cole: Belmont, California, 2006, Chapter 28.
This information has been sourced, reviewed and adapted from materials provided by KNAUER Wissenschaftliche Geräte GmbH.
For more information on this source, please visit KNAUER Wissenschaftliche Geräte GmbH.