Capillary electrophoresis with capacitively coupled non-contact conductivity detector (EC-C4D) for the quantification of nutrients in hydroponics.

G.G. SIANO; J. E. CARRIQUE; G. A. GÓMEZ; L. VERA CANDIOTI; P. KLER; L. GIOVANINI

Buenos Aires

Congreso; III Brazil-Argentine Microfluidics Congress - VI Congreso de Microfluídica Argentina; 2022

MFARG-CNEA-CONICET-AGENCIA

The production of food and the rational use of water, in relation to the speed of growth of the world population, represent very great challenges in recent years. In this sense, hydroponics is presented as an efficient alternative (it uses between 10 and 20 % of the water for crops on land), capable of accelerating and homogenizing food production, with the potential to be automated in several aspects. Salts/nutrient replenishment is usually based on measurement of the total conductivity of the system solution. In other words, there is no specific information on which nutrients are consumed more or less, nor if this is related to the type of cultivated species, the season of the year, etc. To obtain a specific and automated description of nutrient consumption, solutions involving wet, photometric, reagent-dependent reactions, etc. are proposed. This implies several different experimental setups, rarely compatible with classic hydroponic ventures. The present work shows results related to a prototype designed to quantify, in a single capillary electrophoresis instrument with C4D detector, several nutrients simultaneously. Additionally, the system was built from a commercial High Voltage source, but with various 3D designs and control achieved through accessible and cheap 3D printing circuitry. The detector design is based on a previously reported open source one. The objective is to evaluate the potential of an EC-C4D, with the possibility of automating washing tasks, and achieving not only electrokinetic injection, but also low pressure one. For this, a pressure generation and stabilization system is proposed using Luer standards (medicine/nursing) and pneumatic standards, cheap and easy to obtain, together with a printed valve for injection, and printed syringe pumps. As a case of study, the monitoring of the consumption of macro and micro nutrients in hydroponic campaigns is presented.