| In this work,a simple and efficient chip-based FIA system without the need of mechanical pump and valve was developed.The present system supplied a simple operation approach for sample injection in microchip under gated injection mode by changing the vertical position of the waste reservoir.A liquid-core waveguide absorbance detection system was integrated to the microchip to achieve high sensitive detection.The performance of the system was tested in the determination of sodium nitrite based on Saltzman reaction under optimized conditions.A precision of 0.3% (RSD,n=17) was achieved using 10 mg/L[NO2]2- solution.The sample injection volume for each cycle was 1.57 nL with a sampling time of 1 s.The analysis throughput was 113/h.A linear range of 0.1-20 mg/L for detection of[NO2]2- was obtained with a limit of detection of 0.19 mg/L(3σ).The present system has the advantages of simple structure,ease of operation and application,high integration and low cost.World-to-chip interfacing is considered as a major challenge,particularly in high-throughput applications requiring frequent sample change.Based on the previous work,we developed a chip basedμ-FIA system with two on-chip probes coupled with slotted-vial array systems in order to perform simultaneous sample/reagent change.Carmine was used as a model sample to test the performance of the system.A reproducibility of 2.5%(RSD,n=9) was obtained.The preliminary results proved the feasibility of the system in changing the sample and reagent simultaneously,which implied the possibility of the system to be applied in clinical assay with multiple samples and multiple analytes. |
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