**3.3 Analysis of pesticides**

EPA method 525.5 (EPA Methods 525.2) is used in order to determine the presence of pesticides in samples. This method is based on gas chromatography and mass spectrometry with a previous solid-liquid extraction.

An Autotrace Workstation (Zymark) automatic extractor was used for the extraction. The chromatographic conditions and equipment used are shown in table 2 and the results of the methodology validation in table 3. The results were obtained using the Xcalibur POLARIS 1.2 version program (ThermoQuest).


Table 2. Conditions of pesticides analysis

The sampling of WWTPs effluents, waters under study in this work, was carried out in May 2009 in the outlet of each WWTP. Samples were conserved refrigerated until their

The characterization of samples was carried out by the analysis of physical-chemical

Suspended solids concentration Standard Method 2540 D Eaton et al., 2005 Chemical Oxygen Demand EPA Method 410.4 EPA Method 410.4 Biological Oxygen Demand 5-days Standard Method 5210 B Eaton et al., 2005

EPA method 525.5 (EPA Methods 525.2) is used in order to determine the presence of pesticides in samples. This method is based on gas chromatography and mass spectrometry

An Autotrace Workstation (Zymark) automatic extractor was used for the extraction. The chromatographic conditions and equipment used are shown in table 2 and the results of the methodology validation in table 3. The results were obtained using the Xcalibur POLARIS

**Gas chromatographer TRACE GC 2000 (TermoFinnigan)**  Column DB5-MS (J&W, 30 m, 0.25 mm, 0.25 μm) Program of temperatures 90 ºC (1 min) – 20 ºC min-1 – 180 ºC (1 min) – 2 ºC min-1 –

**Mass spectrometer POLARIS (ThermoFinnigan)** 

Injector temperature 250 ºC

Ionization energy 70 eV Acquisition mode Full scan Mass interval 50-450 amu Screen speed 1 scan s-1 Acquisition time 32.5 min

Injection volume 1 μL, splitless 0.8 min Carrier gas He (N55), 1mL min-1

Conductivity Norm UNE-EN ISO

**Parameter Analytic methodology Reference**  pH Standard Method 4500-H+ B Eaton et al., 2005

Turbidity Norm ISO 7027:1999 ISO 7027:1999

7888:1985 ISO 7888:1985

240 ºC (1 min) – 20 ºC min-1 – 310 ºC (10 min)

**3. Materials and methods** 

**3.2 Characterization of samples and methodology** 

parameters and the methodology shown in the table 1.

Table 1. Characterization of effluents of WWTPs

**3.3 Analysis of pesticides** 

with a previous solid-liquid extraction.

1.2 version program (ThermoQuest).

Table 2. Conditions of pesticides analysis

**3.1 Samples** 

analysis.


Table 3. Results of the methodology validation of pesticides analysis.

Study of the Presence of Pesticides in Treated Urban Wastewaters 461

Fig. 6. Chemical structures of detected pesticides in effluents of studied WWTPs

In the first place, organic-phosphorous pesticides such as chlorfenvinfos, chlopyrifos and dimethoate are detected. These pesticides are mainly used as insecticides. Chlorpyrifos and dimethoate are very toxic and chlorfenvinfos is extremely toxic. The main effects in the health caused by these pesticides are irritation of eyes and skin and if the exposition to these pesticides is long-term they can affect to nervous, respiratory and immunological systems. Pesticides derived of urea such as isoproturon and diuron are detected too. These pesticides are mainly used as herbicides and they are moderately toxic compounds. They can cause irritation of skin, eyes and respiratory system, in addition to blood alterations in the case of

Some of detected pesticides belong to triazines group; they are terbutryn, terbuthylazine and simazine. These pesticides are mainly used as herbicides and they are moderately toxic substances. With respect to effects on health, the can cause irritation in eyes and skin and moreover, affections in liver, kidney, nervous and circulatory systems in the case of long-

Finally, the rest of detected pesticides are metholachlor and 3,4-dichloroaniline. Metholachlor belongs to anilide group, it is a moderately toxic substance and used as herbicide. It can cause irritation in eyes and in the case of long-term exposition it can provoke liver and blood conditions. 3.4-dichloroaniline is used as herbicide and it is a moderately toxic pesticide. It can cause dermatitis and damages in liver and kidney after

Some of the pesticides detected in the studied effluents, such as chlorpyrifos, chlorfenvinfos, isoproturon and simazine were detected in other effluents of WWTPs such as it is shown in

Detected pesticides belong to different groups.

extend expositions.

long-term expositions.

term contact.
