Abstract: Multidimensional solid phase extraction (SPE) coupled with liquid chromatography (LC) is a powerful technique for the quantitative analysis of micro or trace-levels compounds in complex samples. Fully automated online tandem SPE instruments have been developed in other countries, enabling fully automated online coupling of multidimensional SPE with LC and significantly improving analytical efficiency. Domestic research in this area remains limited. Most fully automated online SPE instruments used are imported at high cost, which restricts application-oriented research in related fields in China. This paper presents the development of a fully automated online tandem SPE instrument. It employs a tray-based system to transport extraction cartridges, replacing a robotic arm system used in similar foreign products. Through the design of three pairs of double-sealed high-pressure heads and the corresponding workflow, the instrument enables fully automated tandem SPE and its online integration with a high performance liquid chromatography (HPLC) system. The pressure resistance and lifetime of the SPE cartridges were systematically evaluated. Results showed that the prepared cartridges exhibited a pressure resistance of ≥30 MPa and a service life of ≥10 cycles. The instrument was applied to detect carbamate pesticide residues in corn by online tandem SPE-HPLC method. Sample preparation time was only 15 min per sample, significantly improving analytical efficiency. The instrument integrates multidimensional SPE, online elution, chromatographic injection, separation and detection. Its flexible operational mode allows for the free combination of different extraction cartridges and the integration of on-column derivatization. It is adaptable to various application scenarios and demonstrates great application potential.

Key words: online tandem solid phase extraction, sample pretreatment, high performance liquid chromatography(HPLC), pesticide residues