| A friendly ocean environment could benefit our society greatly.However,ocean pollution is becoming worse with the developrment of industy,which cause a series of problems.A regular monitor in ocean environment is important and necessary.The toxins in shellfish,a kind of mainly economic sea product,may exceed the safe limit,which can cause food poisoning and economic loss:okadaic acid is one of most harmful and widespread marine toxins in China.Nonetheless,standard detection methods for okadaic acid take long time and should be operated by specialists.What's more,the laboratories are far from the coastline,and the shellfish samples could be analyzed after long distance transportation.In this case,if the portable detection for shellfish toxin could be performed under on-site condition,it will make ocean environment monitor more convenient and it is meaningful for many aspects of our society.In this study,we designed and implemented a portable analytical system for a kind of main shellfish toxin,okadaic acid,which is widespreading in China coast line.The portable analytical system contains pretreatment system and detection system.In this dissertation,the status quo about ocean environment problem in China and the knowledge about shellfish toxins and detection methods are introduced firstly;next,the demands for system design are analyzed and the relative design are determined;finally,the performance of analytical system is determined by addition testing and shellfish sample.As a result,the portable analytical system is suitable for on-site detection,and providing a new method for shellfish detection,which can make the monitor for ocean environment more regularly.The main contents and innovations of this dissertation are listed as follows:1.Design and implement a portable pretreatment system for okadaic acid on-site detection.In order to reduce the error brought by different operators and enhance the on-site pretreatment efficiency,we designed and implemented a portable pretreatment system to solve these problems.The procedures of pretreatment were decided according to the Chinese Industry Standard about ELISA and combine with the requirements for on-site condition.Based on this point,different modules were designed for different functions.All of the modules are controlled by MCU and corresponding relay circuits.For easier operation to users,user interface was designed on upper computer,which can control the work of system and monitor the working condition.At last,the performance of portable pretreatment system was tested.It showed a high consistency with the pretreatment by hand and when the addition OA concentration was 80?g/kg,the recovery rate was 90.8 percent.2.Design and implement a portable smartphone-based detection system for OA ELISA kit.The portable detection system,which based on colorimetric analysis,has a small size and provides a complete environment for on-site detection of ELISA kit,including suitable structure,the narrow-band plane light source by optical filter and thermostatic chamber for incubation.The consistency between portable detection system and microtiter plate reader was verified and the performance of detection system was tested and calculated.The detection limit of detection system is 0.196?g/L;the error rate of system is no great than 10%and the precision of system is 5%.3.Design and implement an imaging processing algorithm and data communication based on smartphone for ELISA kit imagesWhen the ELISA reaction was finished,the shade difference in color can be detected by algorithm in smarphone.Taking photos by smartphone in detection software and choosing suitable RGB channel,the segmentation of photos would be performed by software.According to the concentration of standard OA solution and corresponding RGB value,the calibration curve could be set up.The unknown sample could be calculated according to the calibration curve and the detection results also could be saved in smartphone storage.All of the photos and detection results could be sent by email for further processing and archiving.4.Detect the OA addition and practical samples by portable analytical systemThe OA addition and practical samples were detected by portable analytical system under on-site condition,the procedures including the operation of pretreatment system and detection system.Firstly,OA addition recovery test was performed by pretreatment system,the OA addition concentration was 20?g/kg,40?g/kg,80?g/kg,160 pg/kg and 200?g/kg,respectively.The impact of shellfish flesh to recovery rate could be known from this test.Next,20 samples got from the coastline were tested by detection system and microtiter plate reader.The detection results showed a good consistency between two methods,and the portable analytical system can achieve a convenient detection under on-site condition.The portable analytical system for OA provides a new method for shellfish toxins and ocean environment monitor. |
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