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Ocean Observation: From Microfluidics to Global Scale
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Development of an integrated Syringe-pump-based Environmental-water Analyzer (iSEA)
Tuesday 8th @ 1530-1550, Conference Room 7
Jian Ma* , Xiamen University
Presenter Email: jma@xmu.edu.cn |
| Since the publication of the first flow-based techniques, various types of flow analysis techniques have been developed over the past several decades. Due to its simplicity, robustness and excellent analytical figures of merit, analytical flow techniques present an elegant way to apply wet-chemistry procedures in environmental monitoring applications. Among the unsegmented flow techniques, flow injection analysis (FIA) and sequential injection analysis (SIA) might be the most widely used methods for environmental analysis. However, FIA has the disadvantage of high reagent consumption, laborious optimization via manual manipulation of the manifold and flow rate drift, and both FIA and SIA are based on flow-through detection at non-equilibrium conditions, which result in decreased sensitivity compared to similar manual methods. Flow batch analysis (FBA) was developed in 1999, it combines the characteristics of both flow (continuous) and batch (discrete) systems through the use of programmed multi-commutation. FBA has the favorable advantages of both flow analysis (e.g. low sample and reagent consumption and high sampling rate) and batch analysis (e.g. high sensitivity and wide application range), which is suitable for field analysis. Herein, we describe a new automated system based on FBA, and our system is termed iSEA (integrated Syringe-pump-based Environmental-water Analyzer). The compact and portable system consisted a mini-syringe pump equipped with a selection valve and laboratory-programmed software written by LabVIEW. Based on spectrophotometric detection, the analyzer has been applied in the field determination of nutrients (More details can be found at Ma et al., Anal. Chem., 2018, 90, 6431-6435). When combined with a 2.5 m liquid waveguide capillary cell (LWCC), the iSEA is also a powerful tool for measuring trace analytes such as nanomolar level phosphate and Cr (VI). For the research of ocean acidification, the iSEA has an elegant performance in the measurement of carbonate system parameters (e.g. pH, carbonate ion and total alkalinity) when all components are thermostatted at 25° inside an air bath using a Peltier device and a PID controller. The iSEA has been successfully applied in several occasions: 1) continuous real-time monitoring of ammonium and carbonate ion variations for 14 days and 5 days respectively; 2) high resolution shipboard underway monitoring of macro nutrients and carbonate ion in seawater (including estuarine, coastal and open ocean waters); 3) the detection of Cr (VI) in industrial waste and mineral water. The successful applications in real samples demonstrated the robustness and reliability of iSEA for autonomous environmental monitoring under harsh conditions. |
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