Presence of carbamate pesticides in environmental waters from the northwest of Mexico: determination by liquid chromatography.

A study on the presence of carbamate pesticides, namely aldicarb, aldicarb sulfoxide, baygon, benthiocarb, carbofuran, 3-hydroxycarbofuran, carbaryl, desmedipham, methiocarb, methomyl, thiodicarb, oxamyl, and propham was made in ground and surface waters from an agricultural zone of the Yaqui Valley located in northwest Mexico. Trace determinations were made by liquid chromatography (LC) with post-column fluorescence detection (EPA method 531.1) or LC-diode array UV detection coupled on-line to a solid-phase extraction (SPE) system and using a 13 x 4.6 mm i.d. precolumn and a 150 x 4.6 mm i.d. analytical column, both packed with a C18 silica. Results indicated that the level of contamination with methiocarb was 5.4 micrograms/L in a groundwater sample and that for 3-hydroxycarbofuran was 18 micrograms/L in a surface water sample. This study provides the basis for a future monitoring program.