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STANDARDIZATION OF METHODOLOGY FOR MEASUREMENT OF CERTAIN HAZARDOUS ORGANIC COMPOUNDS (PCB'S)
Polychlorinated biphenyls (PCB's) are the group of highly toxic, synthetic, chlorinated organics compounds with chlorine substitution around biphenyl as basic structural unit and constitute large number of individual organic species. Several of these species are non-biodegradable, stable with high toxicity and having tendency of bioaccumulation. PCB's have potential industrial applications, where non-flammability and heat resistant properties are desired and these compounds are most commonly used in heat transfer systems, hydraulics/lubricants, transformers, and capacitors, as plasticizer and as petroleum additives. The analysis of PCB's is quite complex involving several pre-treatment, concentration, clean up and instrumental optimisation steps.
Photo 27
GC-MS System for measurement of Hazardous Organic Compounds at CPCB Laboratories
There are about 209 individual chlorinated biphenyls often referred as Congeners, resulting from 10 different levels of chlorination of biphenyl nucleus. There is fragmentary knowledge at the laboratories of Central/State Pollution Control Boards about measurements of residual PCB's in environmental matrices viz. waste water, industrial effluents, sludge and soil. With this in view, the project on "Standardization of methodology for selective PCB compounds in environmental samples" has been undertaken. The main objectives of the research project are:
- To develop facilities and standardization of analysis of PCB's in water, soil and sediment.
- To standardize the procedure for extraction, concentration and sample clean up.
- To standardize the gas chromatograph's optimum conditions (oven temperature, detector, injector flow etc.) to achieve resolved peaks of individual PCB species.
- To undertake spiking and recovery studies in field samples i.e. water, wastewater, soil and sediments.
- Intra-laboratory (within laboratory) Analytical Quality Control for each PCB's.
The analysis of PCB is complicated as several of the congeners are available in form of complex commercial mixture e.g., Aroclors each having upto 60 or more individual compounds or congeners. The large number of congeners are common among two or three Aroclor mixtures, which provides overlapping peaks during Gas Chromatographic analysis, complicating the identification and quantification of Aroclors. Moreover other organics like Pesticides also interferes with the measurement of individual PCB congeners.
During the study, the qualitative segregation of individual Polychlorinated Biphenyl congeners have been achieved from standard Aroclor mixture. The Aroclor mixture could only provide crude approximation of total PCB's concentration in the environmental samples. Therefore, Congener Specific analysis in environmental samples are presently being undertaken.
Publication:
• Polychlorinated Biphenyl - Persistent
Pollutants, CPCB Newsletter, 2002.
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DETERMINATION OF PCB IN WATER AND SEDIMENTS OF RIVER YAMUNA AND DRAINS IN DELHI
To assess the present situation about the PCB levels in water and sediments of river Yamuna, Central Pollution Control Board has undertaken studies in Delhi stretch of River Yamuna and five major drains joining river Yamuna. The water and sediment samples from river Yamuna and drains of Delhi were pre-treated at CPCB Laboratory and samples were forwarded to National Institute of Oceanography (NIO), Goa for analysis of PCB's. The findings of the study are:
- Minimum and maximum levels of PCB's in water samples were found at old Yamuna Bridge and at Okhla i.e. 0.190 ng/l and 1.926 ng/l respectively, whereas in sediment samples minimum and maximum levels of PCB's were observed at Palwal (0.616 ng/g) and at Palla (8.927 ng/g) respectively.
- Among the major drains, the total PCB's in the drain water was recorded in the range 0.288 ng/l to 6.545 ng/l, whereas in sediments PCB's were in the range 0.282 ng/g to 281.397 ng/g. The highest concentration of PCB's in water and in sediment were detected in Power House drain and Civil Mill drain respectively.
- The results indicate that after mixing of Civil Mill drain and Power House drain with river Yamuna, the PCB's levels in river water increased from 0.190 ng/l (at Old Yamuna bridge) to 1.926 ng/l (Okhla) indicating that PCB's are contributed by the drains along with the wastewater. The level of PCB's again decreased to 0.501 ng/l down stream to Okhla, may be due to dilution or PCB's removal through bio-accumulation.
Publication:
• Polychlorinated Biphenyl - Persistent
Pollutants, CPCB Newsletter, 2002.
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STUDY ON ENVIRONMENTAL CONTAMINATION WITH POLYCHLORINATED DIOXINS (TCDDs)
Polychlorinated dibenzo-p-dioxins (PCDDs) and poly-chlorinated dibenzofurans (PCDFs) are created inadvertently by a host of industrial activities in which chlorine based compounds are exposed to a high heat in the presence of organic material. These are highly stable and present in a variety of synthetic chemicals, the important environmental contamination for these compounds includes incineration of municipal, hazardous and hospital wastes, automobiles operation, fossil fuel combustion and contaminated commercial chemical products. Many effluents have been listed for the presence of dioxins, some of which are black liquor from pulp & paper industry, wood, plastics, pesticides, antiseptics, lubricating fluids and bleach. The exposure to these contaminants results in adverse health effects in human and experimental animals like liver necrosis, neurobehavioral changes, skin lesions, reproductive and endocrine dysfunction.
There are 75 positional PCDDs and 135 PCDFs. The most toxic isomer is 2,3,7,8 - tetrachlorodibenzo-p-dioxins (2,3,7,8 TCDD). These chemicals accumulates in the body and results in increased risk of cancer, reproductive and nervous system disorders over the time. It is imperative to study such sources and work places where there is a potential of environmental contamination with PCDDs and PCDFs. The emission of dioxin-like compounds can be reduced by source identification and analysis of the life cycle of chlorinated compounds. More detailed studies of recorded depositions input from accidents and favouring process with lower dioxin outputs would help to focus strategies for further reducing dioxin emissions.
The main objective of the study is to standardize the analytical techniques
for the determination of residue levels of PCDDs and PCDFs in water, wastewater
and soil samples and to estimate the levels of TCDDs in water, wastewater and
soil samples of the contaminated sites, e.g., waste disposal sites, fly ash
of incinerators, water resources and soil around pesticides, pulp & paper,
wood and antiseptic industries and of commercial chemical products and evolution
of techniques for reducing the emissions of 2,3,7,8 - TCDD in the polluted areas
e.g., water resources, waste disposal site and municipal incinerators.
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