Analysis of volatile and semivolatile organic compounds in municipal wastewater using headspace solid-phase microextraction and gas chromatography

[Determination of 2,4-dimethylhydroxybenzene by chromatographic methods in forensic toxicological research of biological material]

OBJECTIVE

Is to develop a method for determining 2.4-dimethylhydroxybenzene (2.4-DMHOB) in biological material. The analytical methods used in the experiments were extraction, column chromatography of normal pressure, TLC, GC-MS and HPLC. To extract the analyte from the bioactive matrix, maceration with the binary insulating agent acetone-ethyl acetate (3:7) was used, observing the 2:1 mass ratio of the «insulating agent-matrix». Optimal conditions of semi-preparative analyte chromatography were achieved in column (150×10 mm) of «Silasbor» S-18 sorbent in elution with a mixture of acetonitrile-water (7:3), which was used in the proposed cleaning scheme, combining extraction and reversed-phase column chromatography. The application of the mobile phase of tetrachloromethane-dioxane (9.5:0.5) has been substantiated for the selective determination of 2.4-DMHOB by TLC («Sorbfil» plates). The expediency of confirming identification of the analyte in the form of 2.4-dimethyltrymethylsilylphenol using GC-MS (DB-5MS EVIDEX column (25.000×0.2 mm), stationary phase (5%-phenyl)-methylpolysiloxane, carrier gas - helium) has been shown. The group of characteristic particles in the mass spectrum of trimethylsilyl analyte derivative was represented by 45; 59; 73; 82; 91; 105; 119; 135; 149; 163; 179; 194 m/z ions. HPLC (Discovery C18 250×4.6 mm column, eluting liquid - acetate buffer solution with pH 5.5 - acetonitrile, 50:50) was used to confirm the identification and quantification of 2.4-DMHOB. A method for determining 2.4-DMHOB by the HPLC method in biological material (liver tissue) is proposed, which corresponds to the criteria of linearity, selectivity, accuracy, precision and stability. The minimum detectable quantity of 2.4-DMHOB in the bioactive matrix is 0.5 µg/g, the minimum determined quantity is 1.2 ug/g.

Health risk of semi-volatile organic pollutants in Wujin river inflow into Taihu Lake

Semi-volatile organic compounds (SVOCs), including polycyclic aromatic hydrocarbons (PAHs), phthalates and pesticides in water of Wujin river inflow into Taihu Lake, were detected for assessment of risk to human health. SVOCs were tested with Method 525.2 established by the US Environmental Protection Agency (EPA) and health risk assessment (HRA) was conducted by the hazard quotient (HQ) approach from US HRA for screening stage. The results for the liquid-solid extraction of water sample measured by gas chromatography/mass spectrometry (GC/MS) showed that three of the tested twenty-three semi-volatile organic contaminants posed potential health risk and the concentrations of 2,4-dinitrotoluene, di-n-butyl phthalate, chrysene and benzo(a)anthracene was 0.736, 15.201, 0.307, and 0.334 μg/l, respectively. SVOCs in the Wujin river water might induce risk to environmental health of Taihu Lake as a source of drinking water.

Qualitative screening for volatile organic compounds in human blood using solid-phase microextraction and gas chromatography-mass spectrometry

A fast and simple screening procedure using solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) in full-scan mode for the determination of volatile organic compounds (VOC) is presented. The development of a fast and simple screening technique for the simultaneous determination of various volatiles is of great importance, because of their widespread use, frequent occurrence in forensic toxicological questions and the fact that there is often no hint on involved substances at the crime scene. To simulate a screening procedure, eight VOC with different chemical characteristics were chosen (isoflurane, halothane, hexane, chloroform, benzene, isooctane, toluene and xylene). To achieve maximum sensitivity, variables that influence the SPME process, such as type of fiber, extraction and desorption temperature and time, agitation and additives were optimized by preliminary studies and by means of a central composite design. The limits of detection and recoveries ranged from 2.9 microg/l (xylene) to 37.1 microg/l (isoflurane) and 7.9% (chloroform) to 61.5% (benzene), respectively. This procedure can be used to answer various forensic and toxicological questions. The short time taken for the whole analytical procedure may make its eventual adoption for routine analysis attractive.