A paper-based device for measurement of reactive phosphate in water

• Published in: Talanta (Oxford) 2012-10, Vol.100, p.454-460
• Main Authors: Jayawardane, B.Manori, McKelvie, Ian D., Kolev, Spas D.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Applied sciences; Chemistry; Chemistry Techniques, Analytical - instrumentation; Color; Determination of reactive phosphate; Exact sciences and technology; Global environmental pollution; Hydrogen-Ion Concentration; Indicators and Reagents - chemistry; Inkjet printing; Molybdenum - chemistry; Molybdenum blue reaction; Paper-based device; Phosphates - analysis; Phosphates - chemistry; Pollution; Soil - chemistry; Time Factors; Water - chemistry
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2012.08.021

The preparation and evaluation of a simple paper-based device for the determination of reactive phosphate in natural and soil waters based on the formation of phosphomolybdenum blue is reported. Hydrophilic reagent zones were defined by printing filter paper with a hydrophobic paper-sizing agent using an inkjet printer. The molybdate/potassium antimony(III)-tartrate reagent and ascorbic acid reductant merged together from adjacent hydrophilic zones after spotting the liquid sample onto the paper. The colour intensity of the phosphoantimonylmolybdenum blue complex produced was measured using a flat bed scanner. Under optimal conditions, the paper-based device is characterised by a working range of 0.2–10mgL−1 P, limits of detection and quantitation of 0.05 and 0.16mgL−1 P, respectively, and repeatability of less than 2% RSD at 1 and 5mgL−1 P (n=10 and 8). There was no significant difference between the results obtained using the paper-based device and reference methods (t=0.0135, P (T≤t) two-tail=0.9892, df=38). In its optimum form, the paper-based device was stable for up to 15 day under ambient conditions, and up to 122day when stored at ≤−20°C. The small dimensions, minimal reagent consumption, low cost (a few cents), ease of operation and favourable analytical performance make the proposed paper-based device attractive for on-site environmental monitoring and analysis. ► A paper-based microfluidic device for reactive phosphate measurement is proposed. ► The detection is based on the molybdenum blue reaction. ► The working range is 0.2–10mgL−1 P and the detection limit is 0.05mgL−1 P. ► The device was successfully applied to natural water and soil water samples.