An On-line Admicellar SPE-HPLC System Using CTAB-Modified Zeolite NaY as Sorbent for Determination of Carbamate Pesticides in Water

Zeolite NaY modified with cetyltrimethylammonium bromide (CTAB) was considered for extraction/preconcentration of carbamate pesticides using an on-line SPE-HPLC system. The simultaneous determination of carbamate pesticides, including aldicarb, carbofuran, carbaryl, isoprocarb, methiocarb and promecarb, was performed by HPLC-UV using a LichroCART RP-18 column with gradient elution of methanol and 0.1 % acetic acid. The sorbent presented admicelles of CTAB on its surfaces and exhibited a sorption capacity of 180-18,600 mg kg(-1) sorbent, which could be re-modified for at least five extraction cycles. The quantitative retention of target pesticides on the admicellar sorbent involved hydrophobic and pi-cation interaction, while pesticides were eluted from the admicellar SPE column using only 750 mu L of methanol. LODs and LOQs of the proposed method were 0.005-140 and 0.02-600 mu g L-1, respectively. The analytes were effectively concentrated with the enrichment factors between 5 and 551. The developed on-line admicellar SPE-HPLC system was successfully applied to the determination of carbamate pesticides in ten environmental water samples from different sources. Recoveries of spiked samples at a concentration of 0.1-5 mg L-1 ranged from 77 to 111 %.