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Abstract. The stability of 18 herbicides (ten organonitrogens and eight phenylureas, including four degradation products), selected for the frequency of their detection in the environment, was evaluated under a variety of storage conditions. Large volumes of surface water (4 L) were extracted using large-particle-size graphitized carbon black cartridges (Carbopack B 60-80 mesh). The effects of temperature, matrix type, drying and solvent-washing of cartridges on the recovery of these contaminants, after different storage periods, were studied and compared to the conservation of surface water in bottles. After two months, there was no significant difference between the conserved surface water and the stored cartridges for the selected compounds. Cartridges kept at -20°C were better than those stored at 4°C and 20°C. The type of matrix water selected, in this case St. Lawrence surface water, appears to have a minor effect on the recovery of the target pesticides after cartridge storage. No improvement was observed in the recovery of any of the chemicals when the cartridges were dried or washed and stored in a solvent. After immediate surface-water extraction, the most practical storage condition for the target herbicides was found to be storage on cartridges in the dark at -20°C, with no solvent drying or washing of the Carbopack B material.

Abstract. An analytical method is proposed in order to determine the major nonionic surfactants, octylphenolpolyethoxylates (OPEOs), nonylphenolpolyethoxylates (NPEOs) and aliphatic alcoholpolyethoxylates (AEOs), and their metabolites, nonylphenol and octylphenol in wastewater and sludge samples of sewage treatment plants. This method involved a Soxtec extraction step and a solid phase extraction step for the nonionic surfactant extraction from sludge and wastewater samples, respectively. With both methodologies, all recovery values were higher than 70 %. Quantitation and identification of individual compound were carried out by liquid chromatography-mass spectrometry (LC/MS) using electrospray (ESP) as ionization mode. Reverse phase LC chromatography allowed the elution of all oligomer constituents of each homolog component into a single peak. Gathering all the oligomers into a single peak increased the peak intensity and provided a way to determine low concentration of APEOs and AEOs in different environmental matrices. Information on the oligomers distribution of APEOs and AEOs could be obtained by the extraction of selected m/z ions from the TIC chromatograms. Positive ESP LC/MS analyses of AEOs and APEOs yielded primary pseudo-molecular ions of the [M + Na] + type for each oligomer. The negative ionization mode allowed the determination of the two metabolites, nonylphenol and octylphenol, characterized by the pseudo molecular [M-H] -ion. Limits of detection achieved were 0.1 µg/L in wastewater sample and 10 ng/g in sludge samples. The developed LC-ESP/MS method was applied to the analysis of wastewater and sludge samples of two sewage treatment plants located in Orléans (France).

Abstract. Determinations of pesticides and their degradation products in natural waters, given the great heterogeneity of the substances involved, conventionally demands the use of the following analytical methods:• gas chromatography with different specific detectors such as the electron capture detector, NPD thermo-ionic detector, and mass spectrometry, • high-performance liquid chromatography combined with a diode array ultraviolet detector or a spectrofluorimeter after derivatization, • thin-layer chromatography (TLC) with detection of the isolated substances by UV. With liquid chromatography, the most widely used detector is the diode-array UV detector. This method, recommended in French standard AFNOR T 90 123 (EN ISO 11369) [1], represents a significant advance in the approach to the identification of polar substances detected in unknown samples, compared with the results obtained by UV detection with a single wavelength. However, this method of detection does not guarantee the identification of the detected substances in absolute terms. Confirmation on a second column or by gas chromatography is therefore necessary. The atmospheric interfaces equipped with APCI (Atmospheric Pressure Chemical Ionization) or ESI (Electrospray Ionization) ion sources help to broaden the field of application of the couplings of liquid chromatography with mass spectrometry, and have seen substantial developments in recent years [2][3][4]. They offer performance in agreement with environmental requirements in terms of quantification limits, sensitivity, simplicity of use and reliability [5]. They are accordingly suitable for the identification and quantification of pesticides and their conversion products in waters [6,7]. This article presents a summary of the results obtained on surface waters with the APCI interface in positive ionization mode, after extraction of the pesticides at neutral pH. The analyses were performed as part of a multi-residue approach applied to a priority list of 40 pesticides to be determined in the surface waters of the Centre region of France. In addition to high-performance liquid chromatography combined with the diode array UV detector and coupled with mass spectrometry, gas chromatography coupled with mass spectrometry was used as a technical complement, because of its suitability for apolar substances such as lindane, organochlorinated pesticides, certain organophosphorus pesticides, trifluraline etc. For the other substances investigated, such as triazines and some of their degradation products, phenylureas, triazoles, amides and carbamates, high-performance liquid chromatography coupled in series with a UV detector and a mass spectrometer was employed. The results obtained with the diode array UV detector were compared with those obtained with the mass spectrometer in order to validate the results obtained with the latter detector. Acquisition and quantification methods optimized for HPLC/MS with APCI interface in positive ionization mode are presented in the article. Results on samples of sur...