DETECÇÃO DE PESTICIDAS NA ATMOSFERA DA PRÉ-AMAZÔNIA MARANHENSE: USO DE BIOSSENSORES ACOPLADOS A DRONES.

Abstract

Organophosphate pesticides (OFs) are able to fight pests in food cultivation, by inhibiting the enzyme acetylcholinestesterase (AChE). The enzyme catalyzes the hydrolysis of acetylcholine (ACh), a neurotransmitter that acts on the autonomic nervous system of insects and mammals. The present work had to monitor the presence of OF's pesticides in the atmosphere, in a vegetable growing region in the Pre-Amazon region of Maranhão. For this, previously tested amperometric biosensors were coupled to a drone. Enzymatic biosensors were prepared using a graphite-based screen printed electrode, with electrochemical mediators such as cobalt phthalocyanine (CoPC), meldola blue combined with Reinecke salt screen-printed with 1 layer (MBRS 1X) and two layers (MBRS2X) incorporated into the working electrode. Electrochemical characterization was performed, with the MBRS 2X mediator being defined with a fixed potential of 0.1V versus Ag / AgCl. The detection limits, based on the inhibition curves and considering 10% relative inhibition were: 2.4 × 10−2 nmol L-1, 3.75 × 10−3 nmol L- 1 , 9.4 × 10−3 nmol L-1 and 1.71 × 10−2 nmol L-1, for chlorpyrifos, fenitrotion, malation and temephos, respectively. The biosensors showed stability and high repeatability in production, through control chart statistics. With biosensors coupled to a drone, OF’s residues were detected at ~50m altitude for a 5 min flyover period, from November/2020 to February/2021 at two points of agricultural production. The determined values of relative inhibition ranged from 6,98±0,98% to 57±0,48%, in relation to the sampling period. The application of biosensors to monitor OFs residues is an innovative strategy. These residues can be transported by atmospheric currents and contribute to the decline of non-target insect populations, including pollinating bees.