Graphene Nanocomposite For The Detection Of Pesticides In Food

Post by Liam Critchly for AzoNano

Pesticides, in particular organophosphorus (OP) pesticides, are widely used across the agricultural sector to protect crops and increase the yield of food production. However, many pesticides have raised concerns regarding safety and public health, with some chemicals even becoming banned.

Now, an international team of scientists have a developed a nanocomposite composed of silver and nanoribbons (GNRs) to detect methyl parathion residues (the most common type of OP pesticide) in various fruits and vegetables.

More than 70% of all pesticides used around the world are of the organophosphorus (OP) variety. Out of these, methyl parathion (MP) is the most widely used on agricultural crops to increase the food productivity.

However, it has arisen that lethal amounts of MP residues have been found in various foodstuffs and has raised a serious concern regarding food safety standards.

Due to the concerns of methyl parathion, new methods have been required for the quick and easy detection in food samples. Gas chromatography (GC), high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) have all been used in the past but are limited in their run times and availability.

Other attempts have included biological detection methods using immunoassays and acetylcholine esterase, enzymatic sensing approaches, various using both organic and inorganic materials and electroanalytical , all of which have not quite reached sensitivities and detection limits that would enable them to be used commercially.

The team have now developed a nanocomposite composed of graphene nanoribbons (GNRs) and silver nanoparticles through simple wet-chemical techniques and modified it with a screen-printed electrode. GNRs are strips of graphene nanosheets with a confined width of less than 50 nm. The result was a sensor that can detect in MP in fruit and vegetable samples, namely in cabbage, green beans, strawberries and nectarines.

The researchers produced the nanocomposites by acidifying and reducing the GNRs, whilst simultaneously decorating the sheets with the silver nanoparticles. The researchers used scanning electron microscopy (SEM, Hitachi S-3000 H), transmission electron microscopy (TEM, Hitachi H-7600), dispersive X-ray spectroscopy (EDX, Horiba Emax x-act), X-ray diffraction (XRD, PANalytical B.V. XPERT-PRO), Raman spectroscopy, UV-visible spectroscopy and electrochemical impedance spectroscopy (EIS, Zahner EIM6ex) to characterise the nanocomposite and a CH Instruments (CHI 1205A) electrochemical work station was used to produce all of the electrochemical results.
Source: Liam Critchley, AzoNano