Detection of silver nanoparticles in seawater at ppb levels using UV–visible spectrophotometry with long path cells

Pablo Lodeiro,Eric P Achterberg,Mohammad S El-Shahawi

doi:10.1016/j.talanta.2016.11.055

Pablo Lodeiro, Eric P Achterberg + Show 1 more

Open Access

https://doi.org/10.1016/j.talanta.2016.11.055

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Abstract

Silver nanoparticles (AgNPs) are emerging contaminants that are difficult to detect in natural waters. UV–visible spectrophotometry is a simple technique that allows detection of AgNPs through analysis of their characteristic surface plasmon resonance band. The detection limit for nanoparticles using up to 10cm path length cuvettes with UV–visible spectrophotometry is in the 0.1–10ppm range. This detection limit is insufficiently low to observe AgNPs in natural environments. Here we show how the use of capillary cells with an optical path length up to 200cm, forms an excellent technique for rapid detection and quantification of non-aggregated AgNPs at ppb concentrations in complex natural matrices such as seawater.

Highlights

The increasing use of silver nanoparticles (AgNPs) in consumer products is raising concerns about their behaviour, fate and toxicological effects following discharge into natural waters [1]
We report the use of long path cells (100 to 200 cm) in UV-Visible spectrophotometry to enhance the precision and accuracy, and decrease the detection limit for metallic NPs by at least one order of magnitude
The molar attenuation coefficient was determined from the slope of the calibration graph using a 100 cm optical path length cell

Summary

Introduction

The increasing use of silver nanoparticles (AgNPs) in consumer products is raising concerns about their behaviour, fate and toxicological effects following discharge into natural waters [1]. The transformations of AgNPs through aggregation and oxidation processes, and their interactions in the environment, make their detection and quantification challenging. Their low environmental concentrations, typically in the ppt range, forms a major analytical detection problem for the most commonly used analytical techniques, which include Light Scattering and UV-Visible spectrophotometry. Applications have been hampered due to the relatively high detection limit (sub-ppm) for NPs, with the use of 1 or 10 cm path length cuvettes. We report the use of long path cells (100 to 200 cm) in UV-Visible spectrophotometry to enhance the precision and accuracy, and decrease the detection limit for metallic NPs by at least one order of magnitude. The obtained molar attenuation coefficient was later used to quantify the presence of non-aggregated AgNPs, previously spiked in two different natural seawaters

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