Snap happy: Digital camera to oust atomic spectrometer?

Skip to Navigation


  • Published: Aug 15, 2011
  • Author: David Bradley
  • Channels: Atomic
thumbnail image: Snap happy: Digital camera to oust atomic spectrometer?

Aqueous photography

Researchers in Spain are hoping that a standard digital camera is the perfect alternative to expensive and sophisticated laboratory instrumentation for some analytical applications. They have demonstrated how it can be used to determined potassium and magnesium concentrations and water hardness and validated the results against conventional AAS measurements.

Alejandro Lapresta-Fernández and Luis Fermín Capitán-Vallvey of the ECsens group, at the University of Granada, Campus Fuentenueva, in Granada, Spain, explain how ongoing technological developments in the world of digital cameras has allowed researchers to use them as increasingly powerful tools in a wide range of fields beyond the normal notion of point-and-shoot photography, such as in engineering remote sensing, astronomical observation, food technology, medical surgery and archiving. The researchers have now exploited the digital camera in multi-analyte sensing for range of water and beverage samples all without the need for any expensive modifications, additional devices or extended optics systems.

Previously, the team has studied the colour information available to observation of the sensing zone of multi-analyte one-shot sensors. They point out that typical supports for such a system is usually different types of paper, powdered silica gel and polymeric materials, including polyurethane foams. Such supports are normally opaque and so diffuse reflectance spectroscopy has been the measurement technology of choice, usually carried out at one or two wavelengths.

Getting a sensor feasibility

The researchers hoped to determine the feasibility and performance of a novel approach to such one-shot optical sensors for testing for water hardness and the potassium and magnesium content of a sample. As such, they used a conventional 6 megapixel colour digital photographic camera as the detection system for simultaneous multi-analyte detection. By using a multi-analyte one-shot sensors based on ionophore-chromoionophore chemistry, the team could capture the colour information using the camera focused on a defined region of interest on the sensing membrane and through computation use this to quantify potassium, magnesium and hardness simultaneously from the image.

"One of the colour channels in the camera's red, green, blue (RGB) colour space is used to build the analytical parameter, the effective degree of protonation, in good agreement with the theoretical model," the team explains. "The linearization of the sigmoidal response function increases the limit of detection (LOD) and analytical range in all cases studied. They could distinguish between a potassium concentration 2.7 × 10-7 to 1 × 10-1 molar and from 2.0 × 10-6 to 1.5 molar for magnesium. Calcium carbonate representing "hardness" of the sample could be determined from 2.0 x 10-2 to 200,000 milligrams per litre.

The team adds that the precision of their method is high, but it is the fact that all three characteristics of water and beverage samples could be quickly and easily determined at the same time that is perhaps most important. The results were statistically validated against atomic absorption spectrometry as the reference procedure, the team says. "This [research] is an attempt to demonstrate the possibility of using a conventional digital camera as an analytical device to measure this type of one-shot sensor based on ionophore-chromoionophore chemistry instead of using conventional lab instrumentation," the team asserts. As such, it could find widespread utility in water and beverage quality control and quality analysis across the water supply and food and beverage industries where ion concentrations and hardness are important factors in terms of product quality as well as economically.



Examples of calibration points for Mg(II), K(I) and hardness. The written concentrations in the figure correspond to the molar concentration of each analyte used to equilibrate the one-shot sensor. This image capture goes from B: buffer, to OH−: basic form. Showing two one-shot sensors per analyte with three sensing zones each. (Credit: Royal Society of Chemistry)
Examples of calibration points for magnesium and potassium ions and hardness, showing two one-shot sensors per analyte with three sensing zones each. Credit: RSC

Social Links

Share This Links

Bookmark and Share


Suppliers Selection
Societies Selection

Banner Ad

Click here to see
all job opportunities

Copyright Information

Interested in separation science? Visit our sister site

Copyright © 2018 John Wiley & Sons, Inc. All Rights Reserved