Accelerated equilibrium sampling of hydrophobic organic chemicals in solid matrices

A proof of concept on how to reach equilibrium for PCBs within 1 day

Chiara Maria Vitale*, Karina Knudsmark Sjøholm, Antonio Di Guardo, Philipp Mayer

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Equilibrium sampling of hydrophobic organic chemicals (HOCs) is increasingly used to measure freely dissolved concentrations and chemical activities in sediments and soils. However, for the most hydrophobic chemicals (Log Kow > 6) such equilibrium sampling requires often very long sampling times in the order of weeks to months. The aim of the present study was to explore two strategies for markedly increasing the HOC mass transfer from matrix to sampler with the overall goal to shorten equilibration times down to a few hours. Two Solid Phase Microextraction (SPME) approaches were thus developed and tested in sediment and soil contaminated by polychlorinated biphenyls (PCBs). In the first method, the SPME fiber was immersed directly in the aqueous suspension of the sample under vigorous agitation. In the second method equilibration took place via the headspace and was accelerated by elevating the temperature. Headspace-SPME at 80 °C provided fast equilibration within approximately 2 h without contacting the sample and thus avoiding fiber fouling. Both SPME methods were calibrated by passive dosing from preloaded silicone rods and yielded similar results, supporting the validity of HS-SPME at elevated temperatures on a proof of principle level. Finally, by using 13C labelled PCB standards, total concentrations were simultaneously measured, which in turn allowed calculation of matrix–water distribution coefficients.

Original languageEnglish
Article number124537
JournalChemosphere
Volume237
Number of pages10
ISSN0045-6535
DOIs
Publication statusPublished - 2019

Keywords

  • Direct immersion
  • Headspace
  • K determination
  • Mass transfer enhancement
  • Partitioning
  • Passive sampling

Cite this

@article{316d0c9e152e4dd3b7c74d129ffc89ad,
title = "Accelerated equilibrium sampling of hydrophobic organic chemicals in solid matrices: A proof of concept on how to reach equilibrium for PCBs within 1 day",
abstract = "Equilibrium sampling of hydrophobic organic chemicals (HOCs) is increasingly used to measure freely dissolved concentrations and chemical activities in sediments and soils. However, for the most hydrophobic chemicals (Log Kow > 6) such equilibrium sampling requires often very long sampling times in the order of weeks to months. The aim of the present study was to explore two strategies for markedly increasing the HOC mass transfer from matrix to sampler with the overall goal to shorten equilibration times down to a few hours. Two Solid Phase Microextraction (SPME) approaches were thus developed and tested in sediment and soil contaminated by polychlorinated biphenyls (PCBs). In the first method, the SPME fiber was immersed directly in the aqueous suspension of the sample under vigorous agitation. In the second method equilibration took place via the headspace and was accelerated by elevating the temperature. Headspace-SPME at 80 °C provided fast equilibration within approximately 2 h without contacting the sample and thus avoiding fiber fouling. Both SPME methods were calibrated by passive dosing from preloaded silicone rods and yielded similar results, supporting the validity of HS-SPME at elevated temperatures on a proof of principle level. Finally, by using 13C labelled PCB standards, total concentrations were simultaneously measured, which in turn allowed calculation of matrix–water distribution coefficients.",
keywords = "Direct immersion, Headspace, K determination, Mass transfer enhancement, Partitioning, Passive sampling",
author = "Vitale, {Chiara Maria} and {Knudsmark Sj{\o}holm}, Karina and {Di Guardo}, Antonio and Philipp Mayer",
year = "2019",
doi = "10.1016/j.chemosphere.2019.124537",
language = "English",
volume = "237",
journal = "Chemosphere",
issn = "0045-6535",
publisher = "Pergamon Press",

}

Accelerated equilibrium sampling of hydrophobic organic chemicals in solid matrices : A proof of concept on how to reach equilibrium for PCBs within 1 day. / Vitale, Chiara Maria; Knudsmark Sjøholm, Karina; Di Guardo, Antonio; Mayer, Philipp.

In: Chemosphere, Vol. 237, 124537, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Accelerated equilibrium sampling of hydrophobic organic chemicals in solid matrices

T2 - A proof of concept on how to reach equilibrium for PCBs within 1 day

AU - Vitale, Chiara Maria

AU - Knudsmark Sjøholm, Karina

AU - Di Guardo, Antonio

AU - Mayer, Philipp

PY - 2019

Y1 - 2019

N2 - Equilibrium sampling of hydrophobic organic chemicals (HOCs) is increasingly used to measure freely dissolved concentrations and chemical activities in sediments and soils. However, for the most hydrophobic chemicals (Log Kow > 6) such equilibrium sampling requires often very long sampling times in the order of weeks to months. The aim of the present study was to explore two strategies for markedly increasing the HOC mass transfer from matrix to sampler with the overall goal to shorten equilibration times down to a few hours. Two Solid Phase Microextraction (SPME) approaches were thus developed and tested in sediment and soil contaminated by polychlorinated biphenyls (PCBs). In the first method, the SPME fiber was immersed directly in the aqueous suspension of the sample under vigorous agitation. In the second method equilibration took place via the headspace and was accelerated by elevating the temperature. Headspace-SPME at 80 °C provided fast equilibration within approximately 2 h without contacting the sample and thus avoiding fiber fouling. Both SPME methods were calibrated by passive dosing from preloaded silicone rods and yielded similar results, supporting the validity of HS-SPME at elevated temperatures on a proof of principle level. Finally, by using 13C labelled PCB standards, total concentrations were simultaneously measured, which in turn allowed calculation of matrix–water distribution coefficients.

AB - Equilibrium sampling of hydrophobic organic chemicals (HOCs) is increasingly used to measure freely dissolved concentrations and chemical activities in sediments and soils. However, for the most hydrophobic chemicals (Log Kow > 6) such equilibrium sampling requires often very long sampling times in the order of weeks to months. The aim of the present study was to explore two strategies for markedly increasing the HOC mass transfer from matrix to sampler with the overall goal to shorten equilibration times down to a few hours. Two Solid Phase Microextraction (SPME) approaches were thus developed and tested in sediment and soil contaminated by polychlorinated biphenyls (PCBs). In the first method, the SPME fiber was immersed directly in the aqueous suspension of the sample under vigorous agitation. In the second method equilibration took place via the headspace and was accelerated by elevating the temperature. Headspace-SPME at 80 °C provided fast equilibration within approximately 2 h without contacting the sample and thus avoiding fiber fouling. Both SPME methods were calibrated by passive dosing from preloaded silicone rods and yielded similar results, supporting the validity of HS-SPME at elevated temperatures on a proof of principle level. Finally, by using 13C labelled PCB standards, total concentrations were simultaneously measured, which in turn allowed calculation of matrix–water distribution coefficients.

KW - Direct immersion

KW - Headspace

KW - K determination

KW - Mass transfer enhancement

KW - Partitioning

KW - Passive sampling

U2 - 10.1016/j.chemosphere.2019.124537

DO - 10.1016/j.chemosphere.2019.124537

M3 - Journal article

VL - 237

JO - Chemosphere

JF - Chemosphere

SN - 0045-6535

M1 - 124537

ER -