About Us | Help Videos | Contact Us | Subscriptions



This article in JEQ

  1. Vol. 43 No. 3, p. 1081-1085
    Received: Aug 25, 2013
    Published: June 24, 2014

    * Corresponding author(s): ian.mckelvie@gmx.com
Request Permissions


Evaluation and Application of a Paper-Based Device for the Determination of Reactive Phosphate in Soil Solution

  1. B. Manori Jayawardanea,
  2. W. Wongwilaib,
  3. K. Grudpanb,
  4. S. D. Koleva,
  5. M. W. Heavenc,
  6. D. M. Nashc and
  7. I. D. McKelvie *ad
  1. a School of Chemistry, The Univ. of Melbourne, Victoria 3010, Australia
    b Dep. of Chemistry and Center for Innovation in Chemistry, Faculty of Science, Chiang Mai Univ., Chiang Mai, 50200, Thailand
    c Farming Systems Research Division, Department of Environment and Primary Industries, 1301 Hazeldean Road, Ellinbank, VIC 3821, Australia
    d School of Geography, Earth and Environmental Sciences, Univ. of Plymouth, Plymouth PL4 8AA, UK. Assigned to Associate Editor Barbara Cade-Menun


The evaluation and validation of a new low-cost microfluidic paper-based analytical device (μPAD) for the determination of reactive phosphate in soil solution is described. This device allows up to 15 replicate measurements of reactive phosphate on one credit card–sized device and requires only a desktop or hand scanner for signal detection and quantification. The proposed method showed a linear response between 0.1 and 1.0 mg L−1 and between 1.0 and 10.0 mg L−1 P with a limit of detection of 0.05 mg L−1 P. When applied to the analysis of soil solution, there was excellent agreement between results obtained using the μPAD and those obtained by a reference spectrophotometric method, as indicated by the following regression equation: [P]μPAD = (0.997 ± 0.005)[P]Reference Method – (0.020 ± 0.008) (R2 = 0.997; n = 110). It was found that the ambient temperature storage stability of the μPAD could be extended to 15 d by incorporating a removable polymeric interleaving sheet between the adjacent paper layers of the device. The observed sensitivity of the μPADs to sunlight, which was manifested by photoreduction of the chromogenic molybdate reagent used in the assay, was overcome by preparing the μPADs with an ultraviolet-filtering laminating material. The proposed method is rapid, with a reaction time of only 10 min, is easy to perform, and is suitable for application in the field.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © 2014. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.