A prototype industrial sensing system for phosphorus based on micro system technology

Abstract

Progress in the development of a miniaturised microfluidic instrument for monitoring phosphorus in natural waters and wastewater is presented. The yellow colorimetric method for phosphate analysis has been transferred to a microfluidic chip configuration This simple method employs one reagent mixed in a 1:1 ratio with a sample to produce a yellow colour absorbing strongly below 400 nm. A stopped flow approach is used which, together with the very rapid kinetics and simple reagent stream, enables a very uncomplicated microfluidic manifold design to be adopted. The working wavelength is 380 nm to coincide with the peak output of a recently developed UV-LED narrow bandwidth light source. The limit of detection for the yellow method is 0.2 ppm with a dynamic linear range from 0-50 ppm possible. The reaction time at room temperature is less than 3 min, which means that up to 20 samples per hour can be analysed.

Hydrochemical processes in lowland rivers: insights from in situ, high-resolution monitoring

“…Over the last few years, microfluidic devices have been shown to be capable of making analytical measurements to acceptable levels of accuracy and precision in a number of laboratory-based environmental applications (Marle and Greenway, 2005;Chen et al, 2006a;Richardson and Ternes, 2011;Jokerst et al, 2012). Integrated chips with separation and detection have been developed (and even used in the field) to measure streamwater P concentrations (Kang et al, 2001;Bowden et al, 2002a;Chen et al, 2006b). Most of the work on developing environmental methods for field applications has involved sensors or microfluidic devices for single analytes, or new miniature in situ water samplers, where the sample is recovered and analysed using conventional laboratory instrumentation (Bowden et al, 2002b;Datta and Banerjee, 2007;Gkritzalis-Papdopoulos et al, 2012;Jokerst et al, 2012).…”

Development and Deployment of a Microfluidic Platform for Water Quality Monitoring

“…Salicylate was also used as a replacement for phenol, and was found to yield broadly similar analytical performance in terms of the sensitivity, and kinetics, while having the major advantages of being highly stable and non-toxic. Diamond and co-workers [29,30] evaluated the yellow vanadomolybdophosphoric acid method as an analytical method for the determination of phosphate in water within a microfluidic device with the aim of producing an automated device with a field-deployable lifetime of one year. In this method ammonium molybdate, (NH 4 ) 6 3 .…”

A Simple, Low-Cost Double Beam Spectrophotometer for Colorimetric Detection of Nitrite in Seawater

“…Highly specific colorimetric methods based on absorption have been developed for a number of analytes [15]- [17]. In each case, the absorbance at the peak absorbance wavelength is directly proportional to the concentration of the sample as described by the Beer Lambert law (2) where is the absorbance, is the path length in centimeters, is the sample concentration (molarity), and is a wavelength-dependant molar absorptivity with unit of .…”