An automatic and sensitive method for simultaneous determination of sixteen polycyclic aromatic hydrocarbons and four derivatives by online solid-phase extraction coupled with ultra-high performance liquid chromatography with online solvent filtration

An automatic and sensitive method for simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) and 4 derivatives by online solid-phase extraction (SPE) coupled with ultra-high performance liquid chromatography (UHPLC) with online solvent filtration in groundwater samples was developed. Groundwater samples were injected directly after filtration and automatic preconcentration into a C18 online SPE column. After the valve switching, the analytes were eluted in the forward-flush mode and then separated on a UHPLC column. Chromatographic parameters, cleanup conditions, elution time, sample loading flow rate and selection of online SPE columns were compared and optimized in detail. An online precolumn for solvent filtration was effective in reducing background interference. The separation resolution and peak shape were sharply improved by adding 1‰ formic acid in the elution mobile phase. Complete separation was obtained for all the analytes. An aliquot of 2.4 mL groundwater samples was sufficient for sensitive analysis with fluorescent detectors (FLDs). The method recoveries ranged from 60.0% to 126.0% and the interday and intraday relative standard deviations (RSDs) ranged from 1.1% to 7.5%. The limits of detection (LODs) were between 0.1 and 35.0 ng L−1. The total analysis time including the pretreatment procedure was only 21.0 min. The developed method was successfully applied to the analysis of groundwater samples for routine surveys. The proposed method provides an alternative way to automatic and simultaneous determination of 16 PAHs and 4 derivatives in groundwater, especially for routine monitoring of batch groundwater samples.