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

Abstract

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 μm GFF-II (ISRP, Pinkerton) analytical column (50 × 4.6 mm id) as a first column coupled to a 5 μm reversed-phase Hypersil C₁₈ analytical column (50 × 4.6 mm id). In comparison with an analytical C₁₈ column, the RAM column substantially improved the separation between analytes and humic acid interferent. Detection limits <0.1 μg l⁻¹ were reached without a preconcentration step. Average recoveries were between 92 and 112% (n = 6) with RSD between 0.6 and 8%. The overall procedure allowed a sample throughput of up to 45 samples per day. Groundwater samples from El Ejido (Almería, Spain) were analyzed by means of the proposed LC-LC procedure.