High-throughput miniaturized purge-and-trap device integrating semiconductor refrigeration storage for on-site extraction and long-term preservation of VOCs in water

To accomplish on-site separation, preconcentration and cold storage of highly volatile organic compounds (VOCs) from water samples as well as their rapid transportation to laboratory, a high-throughput miniaturized purge-and-trap (μP&T) device integrating semiconductor refrigeration storage was developed in this work. Water samples were poured into the purge vessels and purged with purified air generated by an air pump. The VOCs in water samples were then separated and preconcentrated with sorbent tubes. After their complete separation and preconcentration, the tubes were subsequently preserved in the semiconductor refrigeration unit of the μP&T device. Notably, the high integration, small size, light weight, and low power consumption of the device makes it easy to be hand-carried to the field and transport by drone from remote locations, significantly enhancing the flexibility of field sampling. The performances of the device were evaluated by comparing analytical figures of merit for the detection of four cyclic volatile methylsiloxanes (cVMSs) in water. Compared to conventional collection and preservation methods, our proposed device preserved the VOCs more consistently in the sorbent tubes, with less than 5 % loss of all analytes, and maintained stability for at least 20 days at 4 °C. As a proof-of-concept, 10 municipal wastewater samples were pretreated using this device with recoveries ranging from 82.5 % to 99.9 % for the target VOCs.