Environmental Engineering Reference
In-Depth Information
and Chlorothalonil (Fig. 1 shows the chemical structures). Current extrac-
tion and mass spectrometric techniques as well as future prospects are
outlined.
2
Sample Preparation
2.1
Marine Waters
Given that antifouling booster biocides are usually detected at trace levels in
marine water samples, pre-concentration techniques have been applied previ-
ously to the analytical determination. Extraction of biocide residues has been
carried out with different techniques. Tables 1 and 2 show the recovery results
obtained with different extraction methods. LLE is a traditional technique
that, in spite of its known disadvantages, is still applied [2, 10, 13, 14, 16, 33].
As an example, this technique has been used for the extraction of Irgarol 1051,
Chlorothalonil and Dichlofluanid [2, 14, 16]. Organic solvents with apolar to
medium polarity such as
n
-hexane, dichloromethane (DCM), acetone and
methylene chloride have been used, obtaining recoveries higher than 75%in
particular for Irgarol 1051. Information concerning recoveries for the other
two compounds has not been reported.
SPE has become a common and effective technique to extract and en-
rich the analytes from environmental samples. SPE has been applied in the
majority of reported studies [9, 19, 20, 27, 28, 37, 47, 51]. Characteristics that
make suitable its use, are the low quantities of solvent needed, or that the
procedures can be readily automated. Automatic off-line SPE is generally
performed by passing a water sample volume of 0.1-1 Lthroughcartridges
or disks [27, 28]. C18-bonded silicas [9, 30, 31, 37, 42, 44, 48, 51], polymeric
material [19, 20, 27, 28, 32, 34, 47, 51] and graphitized carbon black [47] have
been selected as sorbents. Another approach is on-line SPE for the auto-
mated preparation of samples prior to the analysis [20]. Advantages of on-line
systems include minimized adsorptive losses that can occur with off-line
sample transfers and sample-handling procedures. The contamination pro-
cess from external sources can be more difficult than in off-line SPE pro-
cedures. Limitations can be related to the reduced sample through-put and
stability problems for the sample caused by extended storage times in the
auto-sampler. The efficiency with which biocides are extracted from ma-
rine water by SPE procedures is satisfactory. Recoveries higher than 80%
are generally obtained in the experiments performed to extract Irgarol 1051,
TCMTB and Diuron [19, 30-32, 44, 47, 51]. Good efficiency in the extrac-
tion method was also observed for Chlorothalonil (approx. 78%) [19, 27, 28].
Lower recoveries have been reported for the results obtained for Dichloflu-
