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A droplet microfluidic-based sensor for simultaneous in situ monitoring of nitrate and nitrite in natural waters

A droplet microfluidic-based sensor for simultaneous in situ monitoring of nitrate and nitrite in natural waters
A droplet microfluidic-based sensor for simultaneous in situ monitoring of nitrate and nitrite in natural waters
Microfluidic-based chemical sensors take laboratory analytical protocols and miniaturize them into field-deployable systems for in situ monitoring of water chemistry. Here, we present a prototype nitrate/nitrite sensor based on droplet microfluidics that in contrast to standard (continuous phase) microfluidic sensors, treats water samples as discrete droplets contained within a flow of oil. The new sensor device can quantify the concentrations of nitrate and nitrite within each droplet and provides high measurement frequency and low fluid consumption. Reagent consumption is at a rate of 2.8 mL/day when measuring every ten seconds, orders of magnitude more efficient than those of the current state-of-the-art sensors. The sensor’s capabilities were demonstrated during a three-week deployment in a tidal river. The accurate and high frequency data (6% error relative to spot samples, measuring at 0.1 Hz) elucidated the influence of tidal variation, rain events, diurnal effects, and anthropogenic input on concentrations at the deployment site. This droplet microfluidic-based sensor is suitable for a wide range of applications such as monitoring of rivers, lakes, coastal waters, and industrial effluents.
0013-936X
9677-9685
Nightingale, Adrian
4b51311d-c6c3-40d5-a13f-ab8917031ab3
Hassan, Sammer-Ul
8a5ae3f1-3451-4093-879e-85f40953da8b
Warren, Brett
e385df8c-3284-449a-9d84-80e48c591cf9
Makris, Kyriacos
e86a7750-ce44-4256-9fc7-e9fd4035fbbf
Evans, Gareth W.H.
235f863f-e661-464e-ba15-79faa28c6d77
Papadopoulou, Evanthia
089fbae5-0658-42d4-8d6e-ceb83c728d64
Coleman, Sharon
2653c332-2105-46b7-98ca-450d88a3aa9f
Niu, Xize
f3d964fb-23b4-45db-92fe-02426e4e76fa
Nightingale, Adrian
4b51311d-c6c3-40d5-a13f-ab8917031ab3
Hassan, Sammer-Ul
8a5ae3f1-3451-4093-879e-85f40953da8b
Warren, Brett
e385df8c-3284-449a-9d84-80e48c591cf9
Makris, Kyriacos
e86a7750-ce44-4256-9fc7-e9fd4035fbbf
Evans, Gareth W.H.
235f863f-e661-464e-ba15-79faa28c6d77
Papadopoulou, Evanthia
089fbae5-0658-42d4-8d6e-ceb83c728d64
Coleman, Sharon
2653c332-2105-46b7-98ca-450d88a3aa9f
Niu, Xize
f3d964fb-23b4-45db-92fe-02426e4e76fa

Nightingale, Adrian, Hassan, Sammer-Ul, Warren, Brett, Makris, Kyriacos, Evans, Gareth W.H., Papadopoulou, Evanthia, Coleman, Sharon and Niu, Xize (2019) A droplet microfluidic-based sensor for simultaneous in situ monitoring of nitrate and nitrite in natural waters. Environmental Science & Technology, 53 (16), 9677-9685. (doi:10.1021/acs.est.9b01032).

Record type: Article

Abstract

Microfluidic-based chemical sensors take laboratory analytical protocols and miniaturize them into field-deployable systems for in situ monitoring of water chemistry. Here, we present a prototype nitrate/nitrite sensor based on droplet microfluidics that in contrast to standard (continuous phase) microfluidic sensors, treats water samples as discrete droplets contained within a flow of oil. The new sensor device can quantify the concentrations of nitrate and nitrite within each droplet and provides high measurement frequency and low fluid consumption. Reagent consumption is at a rate of 2.8 mL/day when measuring every ten seconds, orders of magnitude more efficient than those of the current state-of-the-art sensors. The sensor’s capabilities were demonstrated during a three-week deployment in a tidal river. The accurate and high frequency data (6% error relative to spot samples, measuring at 0.1 Hz) elucidated the influence of tidal variation, rain events, diurnal effects, and anthropogenic input on concentrations at the deployment site. This droplet microfluidic-based sensor is suitable for a wide range of applications such as monitoring of rivers, lakes, coastal waters, and industrial effluents.

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NitrateNitritePaper_main_postreview_clean - Accepted Manuscript
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More information

Accepted/In Press date: 28 July 2019
e-pub ahead of print date: 29 July 2019

Identifiers

Local EPrints ID: 433163
URI: http://eprints.soton.ac.uk/id/eprint/433163
ISSN: 0013-936X
PURE UUID: aa7b7974-fe38-46c3-b558-fae6a748d220
ORCID for Sammer-Ul Hassan: ORCID iD orcid.org/0000-0002-0319-5814

Catalogue record

Date deposited: 09 Aug 2019 16:30
Last modified: 26 Nov 2021 07:13

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Contributors

Author: Brett Warren
Author: Kyriacos Makris
Author: Gareth W.H. Evans
Author: Evanthia Papadopoulou
Author: Sharon Coleman
Author: Xize Niu

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