Graphitized carbon black cartridges for monitoring polar pesticides in large volumes of surface water

A method was developed to analyse 20 polar pesticides-9 organophosphorus, 9 organonitrogens and 2 degradation products of atrazine-simazine and propazine-in large volumes of surface water (1-20 L). During a recent study in our laboratory, the majority of these chemicals (2 < Log K-oc < 4) were found in the dissolved phase. This paper presents a new extraction method for pesticides in the dissolved phase, using a fibre glass filter with 0.7 mu m porosity. Samples of filtered surface water (1-20 L) were extracted by means of a solid-phase technique, using cartridges filled with 500 mg of Carbopack B (60/80 mesh) graphitized carbon black as adsorbent. The pesticides were monitored by gas chromatography on two DB-5 and DB-210 capillary columns with a nitrogen-phosphorus detector (GC-NPD). With the exception of metribuzin, phosmet and anilazine, percent recoveries were high (70-100 %) for all pesticides in a volume of 17.85 L of Milli-Q water compared to percent recoveries in the same volume of filtered surface water (51-93%). Detection limits ranged from 0.1-4 ng/L.