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The review describes the use of solid-phase extraction (SPE) techniques for monitoring priority pesticides in ground and surface waters. The focus is on triazine herbicides and their degradation products. Data concerning the fate, occurrence, properties and extraction of triazines and their degradation products using different SPE techniques are tabulated and discussed.

The stability of nine organophosphorus insecticides (azinphos-ethyl, azinphos-methyl, diazinon, EPN, ethion, fonofos, malathion, phosmet and parathion-methyl) 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 and drying 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 a 2-month period, all the chemicals stored on cartridges and kept at -20 degrees C remained stable, with recoveries ranging from 70 to 134%. By contrast, phosmet and EPN could no longer be recovered from the bottled surface water. Cartridges kept at -20 degrees C fared better than did those stored at 4 degrees C and 20 degrees C. The type of matrix water selected appears to have kept the target pesticides stored on cartridges from degrading, compared to the Milli-Q water, in which malathion and phosmet were unstable. The effect of the cartridges being either wet or dry made no difference in terms of improving the recovery of chemicals. After immediate surface water extraction, the most practical storage condition for the target insecticides was found to be storage on cartridges in the dark at -20 degrees C, with no drying or solvent washing of the Carbopack B material.

Liquid chromatography with photodiode array detection (LC-DAD) and liquid chromatography with mass spectrometry (LC-MS) are two techniques that have been widely used in monitoring pesticides and their degradation products in the environment. However, the application of liquid chromatography with tandem mass spectrometry (LC-MS-MS) for such purposes, once considered too costly, is now gaining considerable ground. In this study, we compare these methods for the multi-residue analysis of pesticides in surface waters collected from the central and southeastern regions of France, and from the St. Lawrence River in Canada. Forty-eight pesticides belonging to eight different classes (triazine, amide, phenylurea, triazole, triazinone, benzimidazole, morpholine, phenoxyalkanoic), along with some of their degradation products, were monitored on a regular basis in the surface waters. For LC-MS, we used the electrospray ionization (ESI) interface in the negative ionization mode on acidic pesticides (phenoxyalkanoic, sulfonylurea), and the atmospheric pressure chemical ionization (APCI) interface in the positive ionization mode on the remaining chemicals. Different extraction techniques were employed, including liquid-liquid extraction with dichloromethane, and solid-phase extraction using C18-bonded silica and graphitized carbon black cartridges. Eleven of the target chemicals (desethylatrazine, desisopropylatrazine, atrazine, simazine, terbuthylazine, metolachlor, carbendazime, bentazone, penconazole, diuron and isoproturon) were detected by LC-MS at concentrations ranging from 20 to 900 ng/l in the surface waters from France, and six pesticides (atrazine, desethylatrazine, desisopropylatrazine, cyanazine, simazine and metolachlor) were detected by LC-MS and LC-MS-MS at concentrations ranging from 3 to 52 ng/l in the samples drawn from the St. Lawrence River. There was good correlation between the LC-DAD and LC-MS techniques for 60 samples. The slope of the curves expressing the relationship between the results obtained with LC-DAD versus those obtained by LC-MS was near 1, with a correlation coefficient (r) of over 0.93. The identification potential of the LC-MS technique, however, was greater than that of the LC-DAD; its mass spectra, mainly reflecting the pseudomolecular ion resulting from a protonation or a deprotonation of the molecule, was rich in information. The LC-MS-MS technique with ion trap detectors, tested against the LC-MS on 10 surface water samples, gave results that correlated well with the LC-MS results, albeit generating mass spectra that yielded far more information about the structure of unknown substances. The sensitivity of the LC-MS-MS was equivalent to the selected ion monitoring (SIM) acquisition mode in LC-MS. The detection limits of the target pesticides ranged from 20 to 100 ng/l for the LC-MS technique (under full scan acquisition), and from 2 to 6 ng/l for LC-MS-MS. These limits were improved by a factor of almost 10 by increasing the sample volume to 10 l.

During a recent study to determine the fluxes and fates of contaminants in the St. Lawrence River, the majority of organonitrogen pesticides analysed in samples of surface water were found in the dissolved phase. This paper compares two extraction techniques and two analytical techniques for 10 chemicals (metolachlor, seven triazines and two degradation products of atrazine–cyanazine–propazine and simazine) in the dissolved phase in large volumes of surface water, using a fibre glass filter with 0.7 μm porosity. Samples of filtered surface water (1–20 l) were extracted by means of a liquid–liquid technique using the Goulden large-sample extractor, and by means of a solid-phase extraction technique, using cartridges filled with 500 mg of a large particle-size graphitized carbon black as adsorbent: Carbopack B (500–666 μm). The pesticides were analysed by gas chromatography on two DB-5 and DB-210 capillary columns with nitrogen–phosphorus detection (GC–NPD) and by liquid chromatography coupled with mass spectrometry equipped with an atmospheric pressure chemical ionization interface (LC–APCI-MS). The recoveries were high (67–100%) for the majority of the target pesticides in a volume of 17.85 l of Milli-Q water, compared to recoveries in the same volume of filtered surface water (51–102%). The detection limits ranged from 0.4 to 4 ng/l and from 0.6 to 3 ng/l for GC–NPD and LC–ACPI-MS techniques, respectively.