A restricted access medium column for the trace determination of triadimefon and tetraconazole in water with large-volume injection coupled-column RPLC with UV detection

Coupled-column liquid chromatography (LC-LC) with ultraviolet detection was used for the trace level determination of triadimefon and tetraconazole in groundwater samples. A sample volume of 5.0 ml was directly injected into the chromatographic system, using a restricted access medium (RAM) 5 mu m G FF-II (ISRP, Pinkerton) analytical column (50 x 4.6 mm id) as a first colum n coupled to a 5 mu m reversed-phase Hypersil C-18 analytical column (50 x 4.6 mm id). In comparison with an analytical C-18 column, the RAM column su bstantially improved the separation between analytes and humic acid interfe rent. Detection limits < 0.1 mu g l(-1) were reached without a preconcentra tion step. Average recoveries were between 92 and 112% (n = 6) with RSD bet ween 0.6 and 8%. The overall procedure allowed a sample throughput of up to 45 samples per day. Groundwater samples from El Ejido (Almeria, Spain) wer e analyzed by means of the proposed LC-LC procedure.