Absorbance based light emitting diode optical sensors and sensing devices

The ever increasing demand for in situ monitoring of health, environment and security has created a need for reliable, miniaturised sensing devices. To achieve this, appropriate analytical devices are required that possess operating characteristics of reliability, low power consumption, low cost, autonomous operation capability and compatibility with wireless communications systems. The use of light emitting diodes (LEDs) as light sources is one strategy, which has been successfully applied in chemical sensing. This paper summarises the development and advancement of LED based chemical sensors and sensing devices in terms of their configuration and application, with the focus on transmittance and reflectance absorptiometric measurements

Emerging organic contaminants in groundwater

Emerging organic contaminants (ECs) are compounds now being found in groundwater from agricultural, urban sources that were previously not detectable, or thought to be significant. ECs include pesticides and degradates, pharmaceuticals, industrial compounds, personal care products, fragrances, water treatment by-products, flame retardants and surfactants, as well as ‘life-style’ compounds such as caffeine and nicotine. ECs may have adverse effects on aquatic ecosystems and human health. Frequently detected ECs include the anti-epileptic drug carbamazepine, the antibiotic sulfamethoxazole, the anti-inflammatories ibuprofen and diclofenac, and caffeine, as well as pesticide degradates. This means there will be challenges in the future in order to address these ECs and to minimise their impact on drinking water and ecosystems. In the coming decades, more ECs are likely to have environmental standards defined, and therefore a better understanding of environmental behaviour remains a priority