Brazilian Journal of Analytical Chemistry - BRJAC - Brazilian Journal ...

Br J Anal Chem 2011, 03, 169–174
dE t E r m i n a t i o n o f C h l o ro P h E n o l s in E n v i ro n mE n t a l
samPlEs By fiBEr i n t ro d uC t i o n m a s s sPECtromEtry u s i n g
a n o v E l s o l-g E l fiBEr
ro g é r i o C. l. silva a,C , an d r E f. P. Bi a J o l i B , fa B i o au g u s t o B , ma rC o s n. EBErlin C *
A) Chemistry Laboratory, State University of Mato Grosso do Sul – UEMS, 79950-000, Naviraí, MS, Brazil
B) Gas Chromatography Laboratory, Institute of Chemistry, University of Campinas - UNICAMP, 13084-971, Campinas, SP, Brazil
C) ThoMSon Mass Spectrometry Laboratory, Institute of Chemistry, University of Campinas - UNICAMP, 13084-971, Campinas, SP, Brazil
*Corresponding author:
Marcos N.Eberlin
eberlin@iqm.unicamp.br
Phone: + 55 19 3521 3073
www.brjac.com.br
aBstraCt
A new sol-gel solid phase microextraction fiber, based on aminopropyltrimethoxysilane
(APTMS) and polydimethylsiloxane (PDMS), is applied for the extraction of chlorophenols
from environmental samples followed by fiber introduction mass spectrometry
(FIMS) determination. Sensitive, selective, simple and simultaneous quantitation of several
chlorophenols is achieved with no derivatization or pre-separation by monitoring
diagnostic fragment ions. Extraction efficiencies were maximized by sample acidification
to pH = 1 and by allowing an equilibrium time of ca. 8 min. Analytical curves ranging
from 25 to 400 µg L -1 were obtained, with correlations higher than 0.93. Limits of
detection (LOD) and quantification (LOQ) were in the range of a few µg L -1 with recoveries
from creek water samples spiked with 100 µg L -1 of chlorophenols ranging from
55 to 107%. The APTMS/PDMS sol-gel fiber presented good chemical and mechanical
resistance to the extreme desorption conditions of FIMS, with no substantial carry over
effects, and could be utilized in more than 200 extraction/desorption cycles.
1. in t ro d u C t i o n
Chlorophenols (CP) have been extensively utilized as
disinfectants, herbicides, insecticides, fungicides and
for wood conservation. These compounds tend to accumulate
in fat tissues of animals, where they may
act as endocrine-disrupting agents [1][2]. CP may also
give rise to dioxins in milk and beef when cows are
fed with CP-contaminated vegetable matter, in a clear
risk to human health [3]. Other sources of CP environmental
contamination is chlorination of phenolic compounds
in waste waters treated with chlorine [4]. Due
to their toxicity, CP were considered priority pollutants
by both the US Environmental Protection Agency [5]
and the European Community [6].
To achieve the necessary detectivity for contaminants
in environmental samples, matrix clean-up and analyte
pre-concentration are often required. For example,
Bagheri et al. [7] developed a solid phase extraction
(SPE) device based on a polypyrrol conductive polymer,
achieving limits of detection (LOD) of ca. 0.15 μg
L -1 in river water analyses. A major drawback of traditional
extraction techniques such as SPE is, however,
the need for great amounts of toxic and expensive
solvents; hence alternative extraction techniques have
been developed. Solid phase microextraction (SPME),
developed in the early 1990s [8], offers a much simplified
procedure and in a single step combines sampling,
clean-up, extraction and pre-concentration. SMPE is
relatively inexpensive, fast, and highly sensitive, and
its operational principle is the sorption of analytes by
a sorbent coating deposited onto a piece of fused silica
fiber. After extraction, the fiber is removed from
the sample vial and inserted into the injector of a gas
chromatograph or a liquid chromatograph for further
separation and quantitation. Chlorophenols, for instance,
have been determinated by SPME-GC in honey
[9], wine [10] and water [11] whereas SPME coupled
to high-performance liquid chromatography was used
to determine CP in water [12].
The commercial SPME fibers applied to chlorophenol
determination suffer, however, from low thermal
stability and bleeding when exposed to organic
solvents. There is a need therefore to develop new
sorbent coatings to overcome these drawbacks. Solgel
chemistry is a mild and easy way to obtain glassy
materials and has been applied in the preparation of
SPME sorbent coatings since 1997 [13]. A wide variety
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