An easy-to-use colorimetric enzymatic test-system for organophosphorus insecticides detection in olive oil

International audienceImmobilization of a low amount of electric eel acetylcholinesterase on microtiter plates by bioencapsulation in a sol-gel composite led to the preparation of a simple colorimetric enzymatic-assay for pesticides detection in olive oil. This bioassay has been used to carry out inhibition studies with three pesticides mainly used in the treatment of olive trees: Malaoxon, Methidathion-oxon and Omethoate, and tested using standard solutions and real samples of olive oil. The developed bio-tools showed a good reproducibility and stability as well as good analytical performances with limits of detection at least 10 times less than the maximum residue limit tolerated by international regulations. The obtained LODs were as low as 10-9 M for the widely used pesticide Malaoxon, 10-8 M for Methidathion oxon and 10-7 M for Omethoate. The developed test was designed for fast detection of the three target insecticides in such a complex matrix as olive oil without a laborious pre-treatment and after a simple liquid-liquid extraction, which demonstrate the potentiality of this technique to be used for commercial purpose

Enzymatic biosensor associated with Molecularly Imprinted Polymers for sensitive and selective detection of organophosphorus insecticides in olive oil

International audience5 different bio-tools have been developed for sensitive detection of three organophosphorus insecticides mainly used for the treatment of olive trees: Malaoxon, Omethoate and Methidathion-oxon. The systems are based on the immobilization of electric eel acetylcholinesterase on screen-printed electrode (SPE) and microtiter plates by 3 different methods of immobilization. These developed systems were optimized with laboratory samples and then tested on natural samples of olive oil after a simple liquid-liquid extraction. Among these five systems designed, the amperometric biosensor based on acetylcholinesterase immobilized by bioencapsulation in a sol-gel matrix presented the best performance in terms of operational stability, storage stability, reproducibility, and it proved to be best suited for the determination of insecticides in real samples of olive oil. This biosensor has been associated with a highly selective extraction method based on the use of Molecularly Imprinted Polymers (MIPs) to improve selectivity. The results showed that the association MIPs-biosensor can selectively detect and quantify the three organophosphorus insecticides in such a complex matrix as olive oil, with limits of detection much lower than the maximum residue limit tolerated by international regulations

Study of the Hydroponic Barley Effect on the Performance of Feedlot of Calves in the Region Souss Massa (Southern Morocco)

The objective of this research is to investigate the effect of the introduction of hydroponic barley; produced as feed supplement in the ration, on the performance of feedlot calves. This study was performed in the Taroudant region (South of Morocco), during a trial period between July and October 2017). A total of 100 calves were used in a feeding trial, which were divided into two groups. The calves of the first group received a total mixed ration (control), while the calves of the second group received a similar ration with the addition of hydroponic barley.Similar growth performance is observed for the two groups, which is easily explained by the equivalent rationing. In the finishing phase, however, a higher average daily gain is observed for the group fed with an enriched diet in hydroponic green fodder. In fact, the average daily gain for this group amounts to 1.48 Kg/Day compared to 1.42 Kg/Day for the control group.The slaughter results confirm those noted in terms of growth performance, with a relatively similar carcass yield for the two groups.However, since hydroponic fodder reveals a positive impact especially at the level of the finishing phase, it seems judicious to introduce it in the key phases of fattening and finishing in order to perfect the weight gain of the species benefiting from this contribution.The test results suggest that hydroponic barley based rationing is to deepen, and that it would be desirable to repeat the experiment by testing different levels of hydroponic barley intake, adjusting both the type and the level of complementation, with a more accurate monitoring of feeding. Keywords: Feedlot calves; Growth, Hydroponic barley, Performance, DOI: 10.7176/JBAH/11-14-05 Publication date:July 31st 202

Acetylcholinesterase Immobilized on Magnetic Beads for Pesticides Detection: Application to Olive Oil Analysis

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