Development and application of a simple formate-buffered extraction method for the analysis of 104 organic pollutants in river suspended particulate matter by HPLC-ESI-MS/MS

Abstract

Globally, rivers are contaminated by a diverse range of organic micropollutants originating from waste water effluents or surface runoff in urban and agricultural areas. In rivers, suspended particulate matter (SPM), which can be constituted by a high proportion of organic material and fine mineral particles, sorbs many of these organic micropollutants and thus influences their distribution and residence times. Furthermore, benthic organisms, which live and feed in freshly deposited sediments, may be at increased risk of exposure to SPM-associated organic micropollutants. Efficient methods for the analysis of organic micropollutants in river SPM are therefore required for studying the distribution of these pollutants in space and time as well as the potential exposure of benthic organisms. In recent years, the "quick, easy, cheap, effective, rugged and safe" (QuEChERS) sample preparation methodology has gained increasing popularity for the analysis of organic micropollutants in environmental samples, including soils and sediments. In this study, we compared four extraction methods based on the QuEChERS methodology for their performance when combined with high-performance liquid chromatography tandem mass spectrometry analysis. As a result, a simple formate-buffered extraction method for the analysis of 104 selected organic pollutants, including pesticides and pharmaceuticals, in river SPM was developed and validated. The validated method was sensitive, with a median method limit of quantification of 1.0 ng/g. The method was applied to investigate the spatial and temporal distribution of the selected pollutants in SPM samples collected in the French-German border river, Lauter, which is an important regional refuge for biodiversity.

Keywords: Freshly deposited sediment; Method development and validation; Organic micropollutant monitoring; QuEChERS; Relative matrix effects; Suspended particulate matter.

Fig. 1

Average (n = 4) percentage recoveries (%RECs, A) and percentage relative standard deviations (%RSDs, B) of 104 analytes when extracted from fortified reference SPM sample material (25.0 ng/g, dw) after ageing (1 h) of fortified samples using an acidified acetonitrile extraction (AA), formate-buffered (FB) extraction or modified versions of the official citrate (Q-CB)- and acetate (Q-AB)-buffered official QuEChERS methods

Fig. 2

Percentage matrix effects (%ME) determined for 104 targeted analytes in extracts of six reference samples (A–F) which were prepared using a formate-buffered (FB) extraction method. The samples were collected at two reference sites (reference site R1 and R2 in red and blue, respectively) and contained increasing organic matter contents (%OM) between samples from the same site

Fig. 3

Total number of analytes detected (out of 104) in monthly (April–October 2023) SPM samples collected at eight study sites (S1–S8) and two reference headwater tributaries (R1 and R2) in the Lauter river catchment

Fig. 4

Sum concentrations of pesticides (A) and concentration of the tire-rubber-related pollutant 6PPD-quinone (B) measured above their respective MLOQs in SPM collected at 2 reference headwater tributaries and 8 study sites along the river Lauter