Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements
Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements
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DOI：
10.1016/j.aca.2013.05.008
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发表时间：
2013-07-05
影响因子：
6.2
通讯作者：
Achterberg, Eric P.
中科院分区：
文献类型：
--
作者：
Rerolle, Victorie M. C.;Floquet, Cedric F. A.;Achterberg, Eric P.
为了充分了解海洋碳酸盐岩体系的动力学，需要进行高质量的碳酸盐岩化学测量。具有良好时空覆盖范围的海水pH值数据对于理解海洋酸化现象及其后果尤为重要。在远程平台上测量pH值的自动原位仪器的需求越来越大。我们的目标是开发一种准确、精确的自动原位pH传感器，用于远程平台的长期部署。广泛使用的分光光度法pH值技术能够实现所需的高质量测量。我们报告了迈向小型化比色pH传感器的关键一步，成功实现了低试剂消耗的简单微流体设计。该系统特别适用于船载部署：在欧洲西北部大陆架水域的船载部署期间，在一个多月的时间内获得了高质量的数据，消耗的指示剂不到30毫升。该系统的短期精度为0.001 pH (n = 20)，准确度在经过认证的Tris缓冲液（0.004 pH）的范围内。使用各种方法检查了pH系统测量的质量：测量经认证的Tris缓冲液，测量经认证的海水中的DIC和TA，将测量的pH值与在欧洲西北部大陆架水域巡航期间从pCO(2)、DIC和TA计算的pH值进行比较。所有这些都表明我们的测量是高质量的。测量是在接近原位温度（+0.2摄氏度）的采样室中进行的，该采样室有持续流动的船舶正在进行的海水供应。由于使用了USB微型光谱仪、定制的聚合物流动池和LED光源，光学装置坚固且相对较小。使用三波长LED进行检测，集成了整个LED输出光谱的功率，表明可以使用低波长分辨率检测器代替当前的USB迷你分光光度计。由于多色光源和吸收池中的不均匀性造成的伪影对数据质量的影响可以忽略不计。传感器小型化的下一步将是采用光电二极管作为检测器来取代分光光度计。爱思唯尔B.V.版权所有
High quality carbonate chemistry measurements are required in order to fully understand the dynamics of the oceanic carbonate system. Seawater pH data with good spatial and temporal coverage are particularly critical to apprehend ocean acidification phenomena and their consequences. There is a growing need for autonomous in situ instruments that measure pH on remote platforms. Our aim is to develop an accurate and precise autonomous in situ pH sensor for long term deployment on remote platforms. The widely used spectrophotometric pH technique is capable of the required high-quality measurements. We report a key step towards the miniaturization of a colorimetric pH sensor with the successful implementation of a simple microfluidic design with low reagent consumption. The system is particularly adapted to shipboard deployment: high quality data was obtained over a period of more than a month during a shipboard deployment in northwest European shelf waters, and less than 30 mL of indicator was consumed. The system featured a short term precision of 0.001 pH (n = 20) and an accuracy within the range of a certified Tris buffer (0.004 pH). The quality of the pH system measurements have been checked using various approaches: measurements of certified Tris buffer, measurement of certified seawater for DIC and TA, comparison of measured pH against calculated pH from pCO(2), DIC and TA during the cruise in northwest European shelf waters. All showed that our measurements were of high quality. The measurements were made close to in situ temperature (+0.2 degrees C) in a sampling chamber which had a continuous flow of the ship's underway seawater supply. The optical set up was robust and relatively small due to the use of an USB mini-spectrometer, a custom made polymeric flow cell and an LED light source. The use of a three wavelength LED with detection that integrated power across the whole of each LED output spectrum indicated that low wavelength resolution detectors can be used instead of the current USB mini spectrophotometer. Artefacts due to the polychromatic light source and inhomogeneity in the absorption cell are shown to have a negligible impact on the data quality. The next step in the miniaturization of the sensor will be the incorporation of a photodiode as detector to replace the spectrophotometer. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.