Analyses for detection of some organic pollutants from environment

Transcription

1 Analyses for detection of some organic pollutants from environment ECATERINA MATEI, CRISTIAN PREDESCU, ANDRA STOICA, ANDREI PREDESCU, MIRELA SOHACIU, ANDREI BERBECARU Center for Research and Eco-Metallurgical Expertise Politehnica University of Bucharest Splaiul Independentei, 313, Bucharest ROMANIA Abstract: - The paper presents the main analyses methods for different persistent organic pollutants from environment that are resulted from antropic activities. The methods are correlated with Environmental Acquis, being applied in order to increase the analytical performance and ability for integration and assessment of environment issues according to European Union requirements. Key-Words: - POP, environment, chromatography, pollution, water samples, analyses 1 Generalities For the international scientific community it is generally acknowledged that due to human activities certain chemical compounds are distributed and found as residues in several abiotic and biotic materials. Due to their already known or at least assumed (eco)toxicological impact they should be monitored by trace analytical means in order to gain an overview regarding their factual qualitative and quantitative distribution. Only on the basis of such monitoring system with evaluated and comparable data it is possible that endeavors undertaken by individual countries of European Union lead to appropriate legal principles as to limiting and eliminating spreads of these undesired chemicals into the environment [1]. In this context, this paper it will be dealt only with a special group of semivolatile chlorinated organic compounds, classified as POPs ( persistent organic pollutants ). This means that any other organic chemicals (e.g., volatile organic chemicals = VOCs) and all inorganic chemicals, such as certain heavy metals (e.g., Pb, Cd, Hg, Cu) and metalloids (e.g,,as, Se, Sb) and others (e.g., CO2, NOx, Br2, N2O) are not considered here, notwithstanding their (eco)toxicological importance and the need of their analytical surveillance. 2 Definition and characterization of POP according to Environmental Acquis As to POPs it has to be differentiated between those compounds which have been and/or still are introduced into the environment with purpose as they were/are needed as biocides or/and agrochemicals (pesticides): DDT, dieldrin, endrin, HCB, heptachlor, toxaphene, or as industrial chemicals (PCB). The third sub-group comprises of the polychlorinated dibenzodioxins/furans (PCDD/PCDF) which are generated by combustion processes and are released into the environment without intention (according to Stockholm Convention on POPs) [2]. For agrochemicals (pesticides, biocides) it means the development of rules and regulations as to their registration, trade, distribution and application [e.g., establishment of rules for good agricultural practice (GAP) and establishment of toxicologically approved maximum residue limits (MRL) for food, which must not be exceeded when reaching the trade/consumer level]. Further it includes the proper disposal of obsolete pesticides. PCB and to a certain extent also HCB have been used worldwide as industrial chemicals for a multitude of technical applications for several decades. Due to their slowly degradation to environmentally harmless products and their bioaccumulation potential they pose a significant ecotoxicologic risk. Therefore, it is necessary to obtain sound knowledge as to the various emission sources and their extent (inventories) and to monitor their concentrations in selected materials. Polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) comprise of highly toxic by-products of industrial processes involving chlorine. Sources of dioxins include paper and pulp mills, hazardous waste ISSN: ISBN:

2 incineration, sludge from waste facilities; cement kilns that burn chemical waste, and the manufacturing of PVC plastics and some pesticides. As, up to now, their emission is obviously inevitable, a powerful legal framework must be elaborated on a national basis by which the effective and long term protection of man and the environment can be secured. This implies the fixation of some emission limits (TEQ for PCDD/PCDF in air, e.g., stack emissions), the improvement of technical processes for the reduction of emissions (Best Available Technology = BAT), the establishment of monitoring programs and highly qualified and well-equipped laboratories for the unambiguous detection and determination of the different dioxin/furan congeners in environmental samples [3]. The POPs comprise with respect to the Stockholm Convention (2001) twelve defined organic chemicals that are known for their widespread (transboundary) distribution via various transport means (air, water, biota, atmosphere) and/or long term (eco)toxicological relevance irrespective of their intended use. The risk of these chemicals has lead to an agreement Guidance for a Global Monitoring Programme for POPs, by UNEP (United Nations Environment Programme). 3. Experimental Research Researches have been made in order to analyze different water samples for identifying some organochlorine insecticides, polychlorinated biphenyls (PCB) and chlorobenzens. The specific methods for waste waters, potable and surface waters consist of chromatography analysis, especially for samples with suspended solids up to 0,05 g/l. The standard is SR EN ISO 6468:2000 Water quality. The determination of certain organochlorine insecticides, polychlorinated biphenyls and chlorobenzenes. Gaz chromatographic method after liquid-liquid extraction. Organic suspended materials or colloidal dissolved substances lead to interferences and to the increase of the detection limit. The detection limits for different compounds are presented in table 1. Steps for analysis by help of gas-chromatography are specific and the sample extraction is realized with a specific solvent. Also, if it is necessary, the concentration of compounds with low volatility and the purification may be realized with an electron capture detector. Any substance capable by a response to the electron capture detector having the same retention time as the analyzed compounds will have interferences. Table 1:Detection limits for organochlorine insecticides, polychlorinated biphenyls (PCB) Component Detection limit Retention time (min) (µg/l) 1 st Column 2 nd Column 1,3 dichlorobenzene 1,19 4,5 6,8 Hexachloretane 0,03 4,9 8,3 1,4 dichlorobenzene 1,34 5,2 7,6 1,2 dichlorobenzene 1,14 6,6 9,3 Hexachlorobutadiene 0,34 7,7 20,0 1,2,4 trichlorobenzen (TrCB) 0,05 15,5 22,3 Hexachlorocychlopentadiene 0,40 nd 16,5 ** 2- chloronaphtalene 0,94 2,7 * 3,6 *** Hexachlorbenzene (HCB) 0,05 5,6 * 10,1 *** Organochlorine insecticide (HCH): 1,2,3,4,5,6 hexachlorcyclohexane, 5 stereoisomers: α,β,γ,δ (lindan),ε - HCH Aldrin Diendrin Metoxychlorine Heptachlorine Heptachlorine-epoxyde Endosulphane de la 1 ng/l până la 10 ng/l, funcńie de compus Polychlorurates bifenyls: PCB 28: 2,4,4 trichlorobifenyl PCB 52: 2,2`,5,5` tetrachlorobifenyl PCB 101: 2,2`,4,5,5` pentachlorobifenyl ISSN: ISBN:

3 PCB 138: 2,2`,3,4,4`,5 hexaclorobifenyl PCB 153: 2,2`,4,4`,5,5` hexaclorobifenyl PCB 180: 2,2`,3,4,4`,5,5` heptaclorobifenyl PCB 194: 2,2`,3,3`,4,4`,5,5` hoxachlorobifenyl Note: 1st column conditions: carrier gas 5% mehtane / 95% argon at 25 ml/min debit, column temperature (isotherm conditions): 65 C. 2st column conditions: carrier gas 5% mehtane / 95% argon at 25 ml/min debit, column temperature (isotherm conditions): 75 C. nd not determined * - column temperature: 150 C ** column temperature: 100 C *** column temperature: 165 C. Electron capture detector (ECD) is specific for PCB and it is suitable for using of some glass or melted silica capillary columns (inner diameter = 0,4 mm, length m), covered with stationary phases capable for separation of compounds. The injection system is on-column or vaporization chamber. The oven runs in isotherm regime or with temperature gradient. Some of working characteristics for the main components of GC are presented in table 2. Table 2: Working conditions for GC Open tubular column Carrier gas Atomizer Detector Stationary phase Column material Column performance 1) DB 1 Silice topită 2313 m C 2) DB Melted silice 1475 m C Length Width Thickness Film 30 m 0,25 mm 0,25 µm 30 m 0,25 mm 0,25 µm He 1 bar pressure at column s end 25 cm/s gas debit /linear flow speed Temperature Model Split ratio Exit debit a) split b) purjing 280 C Split 10:1 a) 50 ml/min b) 5 ml/min Type Action way Temp. ECD, Ni- 63 Pulsat 350 C Adittion gas Gas ratio Gas debit Ar / CH 4 95:5 (V/V) 40 ml/min Work program m Temp. for oven 80 C (8 min) 6 C 250 C Isotherm: 20 min. The identification of the compounds is realized is: by comparing the retention times of peaks from registered chromatograms with the ones of the standards. If the response of the peak is higher than working domain of the system, the extract is diluted and reanalyzed. 4. Results The sample concentration of the analyzed sample ( A ) ( V ) t Concentration (µg/l) = ( V ) ( V ) i s (1) where: A quantity of the injected material (ng) V i injected extract volume (µl) V t total extarct volume (µl) V s extracted water volume (ml) Below, are presented the results obtained for different water samples. ISSN: ISBN:

4 Fig. 1: Used Water composition Fig. 2: Waste Water composition ISSN: ISBN:

5 Fig 3: Used Water composition 5. Conclusions The POPs, including PCBs, are considered hazardous products, due to their persistence in the environment and their bio-accumulation process, nondegradable properties and due to their adverse effects on human body. For their analysis, the detection limit is defined as the minimum substance concentration measured and reported in a confidence interval by 99%, the value being over zero value. The detection limit varies with equipment sensitivity and matrix effect. The risk to produce erroneous results/data is associated with technical, material and methodological reasons: Lowering of limit of detection (LOD)/Limit of quantification (LOQ) of analyte to detect/determine - Recalcitrance of the analyte/matrix - Complexity of the matrix - Increasing number of analytes in the same matrix - Malfunctioning of analytical instruments. References [1] Ecaterina Matei, Andra Stoica, ş.a Caracterizarea poluanńilor metalurgici, Ed. Printech, Bucureşti, 2007, ISBN [2] ConvenŃia privind poluanńii organici persistenńi, adoptată la Stockholm la 22 mai 200 [3] Polychlorinated Biphenyls (PCBs), Hazardous Substances Series, OSPAR Commission 2001 (2004 Update) [4] SR EN ISO 6468:2000 Calitatea apei. Determinarea unor insecticide organoclorurate, bifenili policlorurańi şi clorobenzeni. Metoda prin cromatografie în fază gazoasă după extracńie lichidlichid. [5] Ecaterina Matei, C. Predescu, Mirela Sohaciu, A. Berbecaru Method for assessment of potentially pollution of slag from iron and steel industry Proceedings of the 3rd WSEAS International Conference on Energy, Environment, Ecosystems and Sustainable Development, Greece, 2007 [6] C. Predescu, Ecaterina Matei, Mirela Sohaciu, Andra Stoica, A. Predescu, Avram Nicolae Environmental science applied to the engineering educational system Proceedings of the WSEAS Conference Computational Engineering in systems applications, Greece, 2007 ISSN: ISBN: