A Novel Method for Determination of the Natural Toxin Ptaquiloside in Ground and Drinking Water

Natasa Skrbic,Ann-Katrin Pedersen,Hans Christian Bruun Hansen,Lars Holm Rasmussen,Sarah C B Christensen

doi:10.3390/w12102852

Natasa Skrbic, Ann-Katrin Pedersen + Show 3 more

Open Access

https://doi.org/10.3390/w12102852

Copy DOI

Journal: Water	Publication Date: Oct 13, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: University of Copenhagen, University College Copenhagen

Abstract

Ptaquiloside (PTA) is a carcinogenic compound naturally occurring in bracken ferns (Pteridium aquilinum). It is highly water soluble and prone to leaching from topsoil to surface and groundwaters. Due to possible human exposure via drinking water, PTA is considered as an emerging contaminant. We present a sensitive and robust method for analysis of PTA and its degradation product pterosin B (PtB) in groundwater. The method comprises two steps: sample preservation at the field site followed by sample pre-concentration in the laboratory. The preservation step was developed by applying a Plackett–Burman experimental design testing the following variables: water type, pH, filtering, bottle type, storage temperature, transportation conditions and test time. The best sample preservation was obtained by using amber glass bottles, unfiltered solutions buffered at pH 6, transported without ice, stored at 4 °C and analysed within 48 h. The recovery was 94% to 100%. The sample purification step had a pre-concentration factor of 250, and the recovery percentages of the entire method were 85 ± 2 (PTA) and 91 ± 3 (PtB). The limits of detection (LOD) of the full method were 0.001 µg L−1 and 0.0001 µg L−1 for PTA and PtB, respectively. The method enables sensitive monitoring of PTA and PtB in groundwater. Carcinogenic PTA was detected in one groundwater well (0.35 µg L−1).

Highlights

Bracken fern Pteridium aquilinum (L.) Kuhn is a cosmopolitan plant species found on all continents except Antarctica
The final groundwater preservation protocol is as follows: 50 mL water sample collected in amber glass bottles, pH 6 obtained by addition of 0.5% ammonium acetate buffer in the field, no filtration, transportation without ice, stored at 4 ◦ C if analysed within two weeks
The presented method was successful in preservation and pre-concentration of the bracken toxin PTA and its degradation product pterosin B (PtB) in various groundwater samples

Summary

Introduction

Bracken fern Pteridium aquilinum (L.) Kuhn is a cosmopolitan plant species found on all continents except Antarctica. It is considered one of the most abundant plants in the world [1]. This plant species exhibits opportunistic and invasive character, often proliferating into abandoned, newly cut or burned areas. It is mostly found in forests/forest margins, recently deforested areas and regressing farmland [2,3]. The land area covered by bracken is rising on a global scale [4]. In the United Kingdom alone, Pteridium aquilinum (L.) Kuhn covers 7.3% of the total country territory [5,6]

Objectives

Methods

Results

Conclusion