In the present study, a three-dimensional graphene aerogel (3D-GA), synthesised by chemical reduction of an aqueous solution of graphene oxides (GOs) with ethylenediaminethermal by a simple water bath method followed by freeze-drying treatment, was used for the solid-phase extraction (SPE) of six organophosphorus pesticides (OPPs) (i.e. trichlorfon, dimethoate, ethoprophos, parathion, fenitrothion and fenthion) from water samples. The target analytes were extracted using packed SPE cartridges and then eluted with tetrahydrofuran. The eluate was collected and dried with high-purity nitrogen gas at room temperature. After redissolving in acetone, the residue was analysed using gas chromatography/mass spectrometry (GC/MS). The proposed method demonstrated a good linearity between 0.5 and 500 μg L⁻¹ with the correlation coefficient of 0.9990–0.9998. The limits of detection (LODs) (S/N = 3) and the limits of quantification (LOQs) (S/N = 10) for the six OPPs pesticides were in the range of 0.12–0.58 μg L⁻¹ and 0.41–1.96 μg L⁻¹, respectively. The accuracy of the present method was evaluated by measuring the recovery of the spiked samples, which ranged from 93.8% to 104.2% with relative standard deviations (RSDs) of 1.1–5.6%. The established method was successfully applied to the determination of the target analytes in environmental water samples including tap water, river water, drinking water and lake water, demonstrating its great potential for the determination of OPPs in water.

Based on the interaction of Pb (II) ions with nucleic acid via phosphate groups and nucleic bases of the deoxyribonucleic acid structure, an electrochemical sensor with DNA wrapped metallic single-walled carbon nanotube (SWNT) has been fabricated for sensitive and selective detection of lead ion (Pb²⁺). The sensor shows a rapid differential pulse voltammetry signal response to the content of Pb²⁺, and a quantitative detection of Pb²⁺ has been established with an expanded linear responsive range from 1 × 10⁻⁹ to 1.0 × 10⁻⁸ mol L⁻¹ (R = 0.9979) and a detection limit of 4.1 × 10⁻¹⁰ mol L⁻¹ in buffer solution (pH 5.0). Furthermore, the sensor displayed a negligible differential pulse voltammetry signal response for other metal ions, indicating its high selectivity for Pb2⁺. The investigation of electrochemical impedance spectroscopy and cyclic voltammetry in buffer solution demonstrated that metallic SWNTs played an important role in enlarging current response and increasing sensitivity of the sensor.