Calibration of ceramic passive samplers for the analysis of chlorophenoxy pesticides and their metabolites in landfill leachate water

Ceramic passive samplers (CPS) are a novel tool for up-concentrating pollutants from water. They are diffusion-controlled samplers consisting of ceramic cylinder filled with a sorbent of choice. We wanted to test these CPS for analysis of chlorophenoxy compounds (pesticides and metabolites) from groundwater contaminated by a landfill. To enable this, CPS have to be validated to determine the uptake of contaminants, the diffusivity and sampling rates. As expected, the calibration experiments yielded compound-specific diffusivity rates, which ranged from 0.48 to 4.2 × 10^-6 cm²/s and the sampling rates from 1.17 to 2.47 mL/day. This method showed strong linearity (deployment time vs concentration) with R² ranging from 0.92 to 0.98 at an accumulation period of 19 days resulting in a considerable up-concentration. Thus, the limits of quantification decreased from 0.030 μg/L to 3.0 μg/L (50 μL direct injection with liquid-chromatography coupled to mass spectrometry) to 0.001 μg/L to 0.113 μg/L for the CPS based method. However, an industry standard method with a newer HPLC-MS/MS instrument provided LOQs of 0.00025-0.006 μg/L based on direct injections. A comparative field study was conducted at a water treatment facility and demonstrated comparable performance between CPS and conventional grab sampling. Cost assessment of direct injection and CPS show economic advantages and disadvantages of each procedure.