Detection System for Concentration Measurement of Heavy Metal and Escherichia Coli in Water

• Main Authors: Cheng-Yu Tsai, 蔡政裕
• Other Authors: Chih-Wei Wu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/29381777020657572904

碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 100 === Due to global climate change and environmental pollution, access to safe drinking water has drawn increasing concern. Among which, E. coli and heavy metal concentrations (such as inorganic arsenic and hexavalent chromium) are important indicators for detecting water contamination. Although common E.coli test and analysis approaches can be adopted to derive at accurate testing results, these approaches are often time-consuming and require more test samples, making the tests difficult to conduct and costly. Although real-time measurement technology is available for inorganic arsenic and hexavalent chromium tests, complex piping and equipment are mandatory, thus the increased number of test samples and reagents needed. In addition, the test pipes that are reused are prone to measurement errors, so the research objective in this paper is to develop a set of E. coli and heavy metal concentration real-time testing system, combined with small disposable test chips that feature lightweight, low sample requirements, high sensitivity, and high detection limit characteristics. In this study, the Lab-on-a-chip technology has been adopted to create a chip for E. coli and heavy metal detection. With an optical detection device, the micro total analysis system is produced to detect E. coli and heavy metal concentrations in water. The chip measures 65.8 mm × 51 mm in overall size, which only requires a total of 140 μL of samples and reagents to simultaneously measure the concentrations of E. coli and heavy metal in water. The test samples combined with fluorescent antibodies are injected into the chip. First, the E. coli concentration can be increased through the microfilter. Then, the florescent signals of the E. coli fluorescent antibodies are extracted and converted into voltage signals. The E. coli concentration calibration curve is then used to calculate the concentrations. After the mixing and coloration of the sample water and heavy metal reagent, the sample’s light absorption is determined through the attenuation of light intensity, from which the heavy metal concentrations can be determined based on the Beer-Lambert Law. Finally, the objective of the detection of the E. coli and heavy metal concentrations can be simultaneously achieved. In this study, the E. coli and heavy metal calibration curve has been successfully developed, which has been used to measure the concentrations of both. The concentration calibration curve has also been produced. The experimental results show that the effectiveness of the microfilter used to filter E. coli has reached 99% and the detection limit is 2.83×105 cells/mL. In addition, the standard calibration curve of the heavy metals is greater than the R2 value of the generation test specification of 0.995, indicating that the sensitivity, linearity, and accuracy have reached the standard of spectrophotometers commercially available in the market. It has therefore been proven that the product has great potential for product development.