Development of a solventless method for the pesticides analysis

•A novel, simple, inexpensive and easily attainable green analysis method was developed for the determination of Chlorpyrifos as a case study in aqueous matrix.•Pencil graphite was electrothermaly conditioned before the sampling step.•This method does not require any time-consuming sample preparation steps.•Electrothermal conditioning increases the adsorption performance of pencil graphite.•The method can be applied for the determination of other volatile pollutants in aqueous matrix.