Analytical procedure for the concomitant analysis of 242 polar and non-polar organic compounds of different functional groups in fog water

Abstract

Fog droplets consist of a mixture of organic and inorganic compounds resulting from scavenging hygroscopic particles and water-soluble trace gases. Organic matters found in fog water are able to accumulate non-volatile, semi-volatile and volatile compounds of different chemical structures and properties (different functional groups and chemical properties). However, their extraction and analysis are still very limited and infrequent. The paper presents a new analytical procedure based on the combination of liquid–liquid extraction (LLE) on a solid support (XTR Chromabond cartridge). It is developed, optimized and validated for the simultaneous analysis of 38 organic acids, 64 phenols, 55 semi-volatile pesticides, 27 non-volatile pesticides, 16 polycyclic aromatic hydrocarbons (PAHs), 20 organochlorine pesticides (OCPs) and 22 polychlorinated biphenyls (PCBs) residues in fog water. The obtained extract is concentrated, derivatized and then analyzed with different chromatographic techniques. Phenols and acids are injected into gas chromatography-mass spectrometry (GC-MS) preceded by a derivatization reaction with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MtBSTFA). Semi-volatile pesticides, PAHs, PCBs and OCPs are injected into gas chromatography-tandem mass spectrometry (GC-MS/MS), while non-volatile pesticides are injected into liquid chromatography-tandem mass spectrometry (LC-MS/MS). The new protocol is validated for its linearity (r2), recovery (R), precisions (inter and intra-day), limit of detection (LOD) and limit of quantification (LOQ). It shows good linearity (r2 > 0.99) in the concentration ranging from 0.05 to 150 ng/L. The repeatability and reproducibility of measurements expressed as relative standard deviation (% RSD) is found to be satisfactory (% RSD < 20 %). Furthermore, the detection limits obtained are in the low order of ng/L. Then the developed procedure is tested successfully for its efficiency on real fog samples collected from Erstein (Bas-Rhin, Alsace) and Fnaideq (Akkar, North-Lebanon).