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

SIANO, GABRIEL; CARRIQUE, JUAN; GOMEZ, GABRIEL; VERA CANDIOTTI, LUCIANA; KLER, PABLO A.; GIOVANINI, LEONARDO

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

The production of food and the rational use of water, in relation to the speed of growth of the worldpopulation, represent very great challenges in recent years. In this sense, hydroponics is presentedas an efficient alternative (it uses between 10 and 20 % of the water for crops on land), capable ofaccelerating and homogenizing food production, with the potential to be automated in severalaspects. Salts/nutrient replenishment is usually based on measurement of the total conductivityof the system solution. In other words, there is no specific information on which nutrients areconsumed 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 involvingwet, photometric, reagent-dependent reactions, etc. are proposed13 . This implies several differentexperimental setups, rarely compatible with classic hydroponic ventures.The present work shows results related to a prototype designed to quantify, in a single capillaryelectrophoresis instrument with C4D detector, several nutrients simultaneously. Additionally, thesystem was built from a commercial High Voltage source, but with various 3D designs and controlachieved through accessible and cheap 3D printing circuitry. The detector design is based on apreviously reported open source one14.The objective is to evaluate the potential of an EC-C4D, with the possibility of automating washingtasks, and achieving not only electrokinetic injection, but also low pressure one. For this, a pressuregeneration and stabilization system is proposed using Luer standards (medicine/nursing) andpneumatic standards, cheap and easy to obtain, together with a printed valve for injection, andprinted syringe pumps.As a case of study, the monitoring of the consumption of macro and micro nutrients in hydroponiccampaigns is presented.