Preparation and evaluation of various banana-based biochars together with ultra-high performance liquid chromatography-tandem mass spectrometry for determination of diverse pesticides in fruiting vegetables.

Biomass, originates from plant- or animal-based materials with a huge potential to be reused. Here we report a simple, rapid and inexpensive method for preparation of modified biochars derived from the banana peel followed by their applications in pipette-tip micro solid-phase extraction (PT-µSPE). Due to the contribution of various effective parameters on modification of banana peel biochars (BPBs), Taguchi design was used to optimize activation temperature, activation repetition, treatment material and impregnation ratio. Efficiency of the prepared BPBs were studied by extraction of twelve various pesticides, as model analytes with an extended range of log P values (1.4-5.7), followed by their determination using ultra-high performance liquid chromatography-tandem mass spectrometry. After finding the most suitable BPB, the affecting parameters on the PT-µSPE performance were optimized. Accordingly, the LOD values of 0.03-10 µg L-1, linear dynamic range of 0.1-200 µg L-1 and a range of RSD values of 5.3-19% were obtained. Eventually, five fruiting vegetables were analyzed and screened for their possible contaminations. Among the tested pesticides, chlorpyrifos, diazinon, malathion, phosalone, propargite and thiophanate-methyl were detected in eggplant, sweet pepper, zucchini and tomato.