Ramaswamy
Babu Rajendran
Department
of Eco-Biotechnology, School of Environmental Sciences
Bharathidasan
University
Widespread
contamination of biosphere by number of anthropogenic chemicals resulted in
some impact on wildlife and humans. Most of the synthetic organic pollutants
are environmentally persistent, non-biodegradable, bioaccumulative and endocrine
disrupting in behaviour. Endocrine disrupting persistent toxic substances
such as organochlorines, organotins and organobromines have been reported
from all over the globe for the past few decades. There are several approaches
to measure the chemical contaminants in environment. Combinations of bio/chemical
analytical tools will help to solve problems associated with the detection
of persistent pollutants of endocrine disrupting in nature. It is unlikely
that the biochemical screening methods will ever replace chemical instrumental
analysis or in vivo toxicological studies, but could compliment these two.
Environmental monitoring of contaminants by coupled instruments like GC/MS
and GC/ICPMS, etc has enabled to measure a wide range of pollutants both quantitatively
and qualitatively, and with high selectivity and sensitivity even up to femtogram
level.
The
analysis of organic compounds from aqueous sample matrices can be performed by
a combination of various extraction and analytical methods. The extraction
methods employed with liquid samples include liquid-liquid extraction, solid
phase extraction (SPE), and headspace and purge-and-trap techniques. A new
extraction technique known as solid-phase microextraction (SPME) is being used
for the past several years. SPME combined with GC and LC is widely in use.
Apart from SPME, sorptive techniques for sample enrichment have been performed
since the 1980s. More rapid and less solvent-dependent techniques have been
developed for extraction of analytes including accelerated solvent extraction
(ASE) for solids (soil, sediment, biota, food commodities etc.). ASE at
elevated pressure and temperature is an efficient and automated alternative to
soxhlet extraction of nonpolar contaminants such as organochlorine
insecticides, etc. The related technique of microwave assisted solvent
extraction also gave high recoveries of these contaminants. Programmed
temperature vaporizer (PTV) system helps to quantify ultra trace levels by
injecting large volume of sample extracts. The use of isotope-labelled internal
standards and surrogates greatly increases the precision and accuracy.
Quantification
of organotins in open ocean water by PTV-GC/ICPMS, and brominated flame
retardants (PBDEs) in marine and riverine sediments by GC/ICPMS, and the efficiency
of two different extraction (soxhlet and microwave) techniques will be
discussed.