COMPARISON OF SORBENTS FOR THE SOLID-PHASE EXTRACTION OF THE HIGHLY POLAR DEGRADATION PRODUCTS OF ATRAZINE (INCLUDING AMMELINE, AMMELIDE AND CYANURIC ACID)

Three different types of non-polar sorbents, i.e., C-18 silica, apolar styrene-divinylbenzene copolymer (PRP-1) and porous graphitic carbon (PGC), were compared for the solid-phase extraction of atrazine, simazine and nine degradation products obtained by dealkylation, dehalogenation, hydroxylation or deamination mechanisms. The C-18 silica was shown to be effective only for the first degradation products (deethyl-, deisopropyl- and hydroxyatrazine), the others being too polar. Despite a higher retention provided by PRP-1, the retention of the hydroxy-dealkylated derivatives is too low to allow the handling of a sufficiently large volume for determinations below the mu g/l level. The more polar derivatives, i.e., ammeline, ammelide and cyanuric acid, are not retained by either C-18 silica or PRP-1, whereas the capacity factor measured on a PGC column eluted with water was above 100. The conditions of extraction and elution using a cartridge packed with 500 mg of PGC are described for all the series of compounds and recoveries above 90% were obtained from 500-ml samples. The analytical separation was carried out using a C-18 silica column and confirmation was obtained using a PGC column. Determinations of the degradation products in real samples are presented with detection limits below the 0.1 mu g/l level.