Abstract
This paper describes the evaluation of the properties of a portable ion analyzer (Culturyzer-mini) for measuring the concentrations of ions used in hydroponic nutrient solutions. This analyzer uniquely includes a disposable sensor card that contains electrodes, a calibration solution, a heater and a drain reservoir. The analyzer is compact and requires minimal maintenance and user interaction, and is able to give results with only 200 μL of solution within 3 min. Together with pH and EC, the following ions can be measured using two kinds of sensor cards: K+, Ca2+, Mg2+, H2PO4-, NO3-, NH4+. The sensor signal revealed a linear output over the wide range of specific standard solutions. Correlation coefficients between the Culturyzer-mini readouts and conventional methods, such as ion chromatography, a pH meter and a conductivity meter, were over r=0.9 and the coefficient of the variables for day by day use were within 10% CV for all items. This analyzer is able to reduce environmental pollution, since it allows more effective nutrient management and thereby reduces the amount of fertilizer waste in hydroponic systems. The utility and the problems of the analyzer are also described.
