Field Determination of Phosphate in Environmental Water by Using a Hand-Powered Paper Centrifuge for Preconcentration and Digital Image Colorimetric Sensing

Figure 1

(a) Photo of taped six empty tubes on the paperfuge; (b) image of the paperfuge after preconcentrating phosphate; (c) spinning paperfuge; (d) materials required for field analysis by the PMB-SPE method; (e) capturing photo by a mobile phone equipped with a microlens; and (f) photo of six tube tips with preconcentrated PMB; cycles indicate the selected areas for analyzing color intensity.