Determination of residues of sulfonylurea herbicides in soil by using microwave-assisted extraction and high performance liquid chromatographic method/ODREDIVANJE OSTATAKA SULFONILUREA HERBICIDA U ZEMLJISTU PRIMENOM MIKROTALASNE EKSTRAKCIJE I TECNE HROMATOGRAFIJE VISOKIH PERFORMANSI

A modified method for the analysis of nicosulfuron, rimsulfuron and prosulfuron was developed and validated by using microwave-assisted extraction (MAE) and ultra-performance liquid chromatography with diode array detection in the ultraviolet region (HPLC-UV-DAD). The most important experimental parameters of extraction procedure and HPLC-UV-DAD technique were optimised in respect to those sulfonylurea herbicides. High recoveries of the microwave-assisted extraction were obtained by using a dichloromethane-acetonitrile mixture (2:1 volume ratio) acidified with acetic acid (0.8 vol.%) with the addition of urea. The mean recoveries at three spiking levels ranged from 97.47 to 98.76% for nicosulfuron, 97.88 to 99.17% for rimsulfuron and from 97.91 to 99.83% for prosulfuron. The limits of detection of nicosulfuron, rimsulfuron and prosulfuron were 0.95, 0.91 and 0.89 [micro]g [kg.sup.-1], respectively. The accuracy of the developed method was confirmed by HPLC coupled with tandem mass spectrometry parallel analyses. The developed method was used to investigate the dissipation dynamics of sulfonylurea herbicides in the real field trials in Vojvodina Province, Serbia. The obtained half-lives were 0.05, 0.23 and 0.15 days for recommended dose application of nicosulfuron, rimsulfuron and prosulfuron, respectively. Low residues and short half-life in soil suggested that the risk to sensitive rotational crops after application of those sulfonylurea herbicides is low when they are used in the appropriate dosages. Keywords: sulfonylurea herbicide, microwave-assisted extraction, HPLC-UV-DAD, soil, dissipation. IZVOD (Naucni rad) Modifikovana metoda za analizu nikosulfurona, rimsulfurona i prosulfurona razvijena je i validovana uz pomoc mikrotalasne ekstrakcije (MAE) i tecne hromatografije visokih performansi sa ultravioletnim detektorom sa nizom dioda (HPLC-UV-DAD). Najvazniji eksperimentalni parametri ekstrakcione procedure i HPLC-UV-DAD tehnike su optimizirani za ispitivane sulfonilurea herbicide. Visoki prinosi mikrotalasne ekstrakcije dobijeni su primenom mesavine dihlormetan-acetonitril (zapreminski odnos 2:1) zakiseljene sa sircetnom kiselinom (0,8 zapr.%) uz dodatak uree. Prosecan prinos na tri spajkovana nivoa se kretao u opsegu od 97,47 do 98,76% za nikosulfuron, 97,88 do 99,17% za rimsulfuron i od 97,91 do 99,83% za prosulfuron. Granice odredivanja za nikosulfuron, rimsulfuron i prosulfuron su bile 0,95, 0,91 i 0,89 [micro]g [kg.sup.-1], redom. Tacnost razvij