At a Glance
Researchers at Colorado State University have developed ion selective electrodes that utilize a potentiometric method for simultaneous and point-of-care detection of various ions including K+, Na+, Ca2+. It can be also adapted to any cations and anions. The miniaturized and low-cost thermoplastic carbon ion-selective electrode material includes a polymeric membrane mixture. This technique allows for in-situ sampling in real time, with direct quantification of ions in water, soil and biological fluids.
Ion detection can play a critical role in many fields. Environmental monitoring, diagnosis of certain diseases, agricultural analysis, and others rely on accurate ion detection and quantification. The current methods for ion detection are inductively coupled plasma mass spectrometry (ICP-MS) or colorimetry, of which both have significant limitations. These methods are time-consuming, require expensive stationary instrumentation, sample pretreatment, and specialists to operate testing. Moreover, these techniques do not allow in-situ or real-time sample analysis. Point of care or field monitoring of these electrolytes and ions is especially valuable, bringing critical insight and decision-making out of the lab and into the field.
Fabrication of such electrodes can be customized for user specifications. The electrodes can be single-use and disposable, and quantify ions in aqueous samples for real time measurements. The electrodes can be adjusted for specific ions based on need, and may be multiplexed in a single assay, as shown above.
Figure 1 (below) illustrates the proposed device, using the thermoplastic electrodes to detect ions and showing the data wirelessly on a mobile phone device.
Figure 1. An example of the thermoplastic electrodes sensing multiple ions in a sample, and the result being transmitted wirelessly to a phone for sample results.
Figure 2 (below) illustrates an example calibration curve of the potassium and sodium selective electrodes.
Figure 2. A K+-selective TPEs fabricated by (a) Nano19 and (b) 3805 as carbon sources for varying potassium activity in water, B Na+-selective TPEs fabricated by (a) Nano19 and (b) 3805 as carbon sources for varying sodium activity in water (n = 4)
- In-situ sampling of ion content, including Fe 2+, Fe3+, K+, Na+, Ca2+
- Low cost
- Miniaturized electrodes allow for portability
- Fast response and sample analysis
- The reference electrode may be a customized electrode array for simultaneous ion detection in a small volume of samples
- Monitoring of other ion contents , such as calcium and potassium in Food and Dietary Supplements
- Monitoring soil nutrients for agricultural purposes
- Simultaneous ion analysis in aqueous solutions
- A portable potentiometer could be employed with this sensing platform for point-of-care clinical diagnostics using blood, serum, sweat, urine, interstitial fluids; and in environmental, pharmaceutical, and food applications
- Monitoring of iron content
- Wastewater facilities
- Healthcare facilities
- Produced water facilities
- Drinking water
- Acid mine damages,
- Soil analysis
- water supplies used for commercial beverage production
- iron contamination in the oil industry
- corrosion of pipes
- iron speciation analysis in iron-fortified food products
- Monitoring of heavy metals in environmental samples