Introduction
Organochlorine pesticides (OCPs) have been widely used
in agriculture. They have been effective in the control of pests
and diseases and due to their low biodegradability and persistence
they have become an important group of contaminants
in the environment. Moreover, these chemicals are very toxic,
and they are known to induce cancer and be endocrine disrupters
in several organisms, so they result to be a significant
risk to natural ecosystems and human health [1]. Although
the use of most organochlorine pesticides have been banned
or restricted in industrialized countries, they are still detected
in the environment [2,3] because of their former use and spill
out, high persistence and low biodegradability.
Contaminant levels in vegetation samples can be used as
indicators of environmental pollution as plants can suffer
adhesion and absorption of compounds from soil and deposition
and absorption of volatile compounds from atmosphere. Previous studies have shown that different organs
of the plant present different accumulation pattern of pesticides,
showing the following sequence of contamination
levels: leaves > stalks > roots [4]. This can be attributed to
the lipid content of the tissue and to atmospheric deposition
[5]; furthermore as pesticides are semivolatile compounds,
they volatilize from soil increasing their concentration in the
atmosphere close to the plant [6]. Therefore, leaves can be
used to biomonitor atmospheric contamination being possible
studies overlong periods of time on global, regional or
local levels [7].
In last years, new analytical procedures for the determination
of pesticides are in use [8]. These new techniques have
advantages over conventional methods with respect to solvent
consumption, time of analysis, sample amount requirements
and automation feasibilities. The analytical methods
used to monitor pesticide residues require the extraction and
isolation of pesticides from the studied matrix and a final determination
with chromatographic procedures [9]. In the case
of complex matrices, such as plant materials, the presence of
interferences may obscure the analytical signal of the studied compounds. Therefore, most sample pretreatments need
clean-up steps to reduce the detection limits of the methods
and to avoid inaccurate results in chromatographic determinations
[10].
不需要用翻译软件翻译的，谢谢~