Structure of glass capillary sodium ion selective electrode Direct Measurement of Na+ Ion Concentration in Live Plants Using Miniaturized Ion-selective Electrode (ISE) Md. Abunasar Miah, Masatoshi Yokokawa, Edwin T. Carlen, and Hiroaki Suzuki Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan A miniaturized glass capillary sodium ion selective electrode (ISE) was used to measure [Na+] in live plants. The ISE was fabricated by forming of Na+ ion specific ionophore membrane at the end of a glass capillary. Another glass capillary end was filled with 2% agarose gel that act as a reference electrode. The performance of the ISE was evaluated by measuring the [Na+] in standard NaCl solutions. As a preliminary experiments, ISE was used to measure the diffusion of Na+ ion in a 1% agarose gel. Finally, the Na+ ion concentration was measured in both normal (purchased from supermarket) and salt exposed Welsh onions. This measured [Na+] is directly correlated to the salt tolerance of plant. Abstract Salt affected areas World wide about 400 – 950 million hectors (m. ha.) Bangladesh, 2.8 m. ha. (about 53% coastal areas) Problem of salinity Plant can not grow No production of food Solving the problem of salinity Drainage and chemical treatment in the field but costly. So, finding salt tolerant varieties is so important. Now, plants are finding by using conventional method like phenotypic screening but require almost 1 year We developed a micro-fabricated glass capillary ISE for measuring Na+ ion level in plant within a few minutes that is related to salt tolerance of the plant. Background Structure of glass capillary sodium ion selective electrode POTENTIOSTAT ISE Ionophore 1 M KCl Liquid junction Ag wire sample B Ag/AgCl AgCl 1 mm A Glass capillary ISE End of glass capillary A microfabricated glass capillary sodium ion selective electrode. (A) 1 mm internal diameter shape of a glass capillary ion selective electrode, and (B) measurement setup of sodium ion selective electrode in the sample solutions. Measuring the diffusion of sodium in in 1 % agarose gel by sodium ISE ISE used to measure [Na+] in the 1 % agarose gel (A) sensor inserted at different locations of gel (B) fitting of experimental curve with theoretical curve. Time ( ×103 s) 20 40 60 80 110 90 70 50 30 10 Concentration (mM) 1 2 3 4 Distance (cm) Agaroge gel area Ag/AgCl Sample area (A) ISE (cm) Potential (mV) 0.2 0.1 -0.2 -0.1 20 40 60 Time (s) 100 mM KCl 1 mM NaCl 10 mM 1000 mM Concentration (mM) 200 150 -150 -50 50 10 100 1000 1 y = 24.56ln(x) - 59.2 R2 = 0.999 The performance of ISE was checked in the standard NaCl solutions. (A) Response and (B) calibration curve of ISE was obtained from various concentration of salt. Checking the performance of sodiun ion selective electrode A B ISE inserted in the Welsh onion Measuring the local sodium ion level in live Welsh onions 300 mM NaCl / 2 days 300 mM NaCl / 1 day 50 mM NaCl / 2 days 50 mM NaCl / 1 day Normal welsh onion A miniaturized glass capillary ISE was fabricated to measure local Na+ ion concentrations in live Welsh onion. The changes of [Na+] was measured in welsh onions which is correlated with the salt tolerance of plant. This technique could be beneficial for finding of salt tolerant plant within a few minutes. Conclusion E-mail: nasorbtc@gmail.com 6th Anniversary, Interdisciplinary Workshop on Science and Patents (IWP) 2016. September 2, 2016, University of Tsukuba, Tsukuba, Ibaraki, Japan