On-line Trace Level Determination of Polar Organic Microcontaminants in Water Using Various Pre-column–Analytical Column Liquid Chromatographic Techniques With Ultraviolet Absorbance and Mass Spectrometric Detection

Abstract

The on-line combination of solid-phase extraction (SPE) and liquid chromatography (LC) with diode-array UV/particle beam mass spectrometric (MS) detection was used to determine a range of organic micropollutants with different polarities, e.g., neutral pesticides, phenolic compounds and acidic herbicides in a single run, down to sub-µg l^–1 levels. A method was developed which included an on-line dual pre-column based trace enrichment approach. Parameters such as sample pH, LC column oven temperature and elution conditions, and type of LC column used, were studied. The selection of the LC column was found to be the most important parameter. A Zorbax C₁₈ 150 × 4.6 mm id column was selected, but good results were also obtained with Chromspher B and LiChrospher B columns. The optimized procedure was used to distinguish bentazone and several dichlorobenzoic acids from each other in real-world samples by means of SPE–LC–diode-array UV and SPE–LC–particle beam MS techniques. Using a dual pre-column approach and UV detection at 195 nm, it was possible to determine phenol down to 0.1 µg l^–1 in 10 ml of river water.