Abstract
A sensing platform for the in situ, real-time analysis of phosphate in natural waters has been realised using a combination of microfluidics, colorimetric reagent chemistries, low-cost LED-based optical detection and wireless communications. Prior to field deployment, the platform was tested over a period of 55 days in the laboratory during which a total of 2682 autonomous measurements were performed (854 each of sample, high standard and baseline, and 40 × 3 spiked solution measurements). The platform was subsequently field-deployed in a freshwater stream at Lough Rea, Co., Galway, Ireland, to track changes in phosphate over a five day period. During this deployment, 165 autonomous measurements (55 each of sample, high standard, and baseline) were performed and transmitted via general packet radio service (GPRS) to a web interface for remote access. Increases in phosphate levels at the sampling location coincident with rainfall events (min 1.45 µM to max 10.24 µM) were detected during the deployment. The response was found to be linear up to 50 µM PO43−, with a lower limit of detection (LOD) of 0.09 µM. Laboratory and field data suggest that despite the complexity of reagent-based analysers, they are reasonably reliable in remote operation, and offer the best opportunity to provide enhanced in situ chemical sensing capabilities. Modifications that could further improve the reliability and scalability of these platforms while simultaneously reducing the unit cost are discussed.
Highlights
Excessive nutrient loading in both fresh and marine ecosystems can have adverse effects on aquatic ecosystems [1]
We describe the development of an autonomous sensing platform for the detection of phosphate in natural waters with significantly improved operational performance and potentially much reduced cost of ownership
These demonstrate that both the benchtop microfluidic detection and the UV-Vis spectrometer measurements have excellent linearity, with the microfluidic chip exhibiting enhanced sensitivity compared to the UV-Vis, due to the longer 2.0 cm fluidic chip detector path length compared to the standard 1 cm cuvette used with the spectrometer
Summary
Excessive nutrient loading in both fresh and marine ecosystems can have adverse effects on aquatic ecosystems [1]. Phosphate levels in natural water are taken by manual collection and subsequent laboratory analysis [4] This process is labour intensive and costly, but provides limited regarding the spatial and temporal variation of the nutrient within the waterbody. Real-time monitoring provides reliable in situ measurements, which can provide spatial data that can enhance our understanding of the processes that drive increases in nutrient levels [5]. These data can be used to strengthen the development of projection models for mitigation measures to reduce economic and environmental impacts caused by nutrient stresses [6]. Advances in rapid prototyping related to 3D printing and fabrication technologies have dramatically improved the efficiency of producing in situ reagent-based analysers for monitoring key environmental parameters, Chemosensors 2018, 6, 57; doi:10.3390/chemosensors6040057 www.mdpi.com/journal/chemosensors
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
