Jump to main content
Jump to site search

Issue 8, 2015
Previous Article Next Article

A step towards mobile arsenic measurement for surface waters

Author affiliations

Abstract

Surface modified quantum dots (QDs) are studied using a bio-inspired cysteine rich ligand (glutathione, GSH) and their quenching response and selectivity to arsenic examined. As predicted from As3+ binding with highly crosslinked phytochelatin-(PCn)-like molecules, better arsenic selectivity is obtained for a thicker more 3-dimensional GSH surface layer, with exposed sulfhydryl groups. A detection limit of at least 10 μM can be achieved using CdSe/ZnS core–shell QDs capped with this GSH structure. The system is also demonstrated using a mobile phone camera to record the measurement, producing a detection limit of 5 μM. However, copper remains the main interferent of concern. Water-soluble CdTe QDs show little sensitivity to As3+ even with a GSH surface, but they remain sensitive to Cu2+, allowing a copper baseline to be established from the CdTe measurement. Despite anticipating that spectrally non overlapping fluorescence would be required from the two types of QDs to achieve this, a method is demonstrated using RGB channels from a mobile phone and processing the raw data for CdTe QDs, with an emission wavelength of 600 nm, and CdSe/ZnS QDs, with emission maximum of 630 nm. It is shown that As3+ measurement remains feasible at the WHO guideline value of 10 μg L−1 up to a copper concentration of around 0.3 μM Cu2+, which corresponds to the highest recorded level in a selection of large rivers world-wide.

Graphical abstract: A step towards mobile arsenic measurement for surface waters

Back to tab navigation

Publication details

The article was received on 23 Dec 2014, accepted on 18 Feb 2015 and first published on 25 Feb 2015


Article type: Paper
DOI: 10.1039/C4AN02368D
Citation: Analyst, 2015,140, 2644-2655
  •   Request permissions

    A step towards mobile arsenic measurement for surface waters

    C. A. de Villiers, M. C. Lapsley and E. A. H. Hall, Analyst, 2015, 140, 2644
    DOI: 10.1039/C4AN02368D

Search articles by author

Spotlight

Advertisements