Development of a baseline-temperature correction methodology for electrochemical sensors and its implications for long-term stability
Development of a baseline-temperature correction methodology for electrochemical sensors and its implications for long-term stability
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DOI：
10.1016/j.atmosenv.2016.10.024
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发表时间：
2016-12-01
影响因子：
5
通讯作者：
Jones, Roderic L.
中科院分区：
文献类型：
--
作者：
Popoola, Olalekan A. M.;Stewart, Gregor B.;Jones, Roderic L.
最近的研究表明，（三电极）电化学传感器可用于空气质量监测和暴露评估。然而，这些传感器的长期性能往往受到环境气象参数对传感器基线的影响的限制，特别是温度。如果要采用电化学（EC）传感器进行长时间（数月）的空气质量测量，则必须考虑到这种影响。最近使用EC传感器对CO、NO和NO2进行的长期环境测量显示，温度（和相对湿度（RH））对基线有影响，在NO传感器的确定系数R-2为0.9的情况下，与R-2 < 0.2的CO和NO2相比，温度（和相对湿度）对基线的影响更为明显。在本文中，我们提出了一种校正方法来量化这种效应（这里称为拟合基线），并在EC测量上实施这些校正。我们发现，用本文方法校正的EC传感器与传统的参考仪器相比，具有很好的一致性。基线温度校正后NO的决定系数R-2为0.7 ~ 0.8，梯度为0.9，而基线温度校正前的R-2 = 0.02。此外，通过比较从一组新型四电极电化学传感器的第四电极获得的温度基线和代理温度补偿测量值，验证了校正方法。在温度拟合基线和第四电极（也称为非传感/辅助电极）的输出之间观察到良好的一致性（R-2 = 0.9，梯度为0.7-1.08的NO和0.5 < R-2 < 0.73的CO）。同时，通过比较传感器增益与温度、相对湿度、风速和风向等气象参数的变化，评价温度校正数据的长期稳定性（标定信号输出）。结果显示，经过温度校正的电化学传感器对这些参数的灵敏度（双侧t检验，p = 0.34）在几个月内没有统计学意义上的显著变化。这项工作表明，使用本文中描述的基线温度校正方法，电化学传感器可以用于长期（数月），定量测量城市环境中典型环境条件下十亿分之一体积（ppb）混合比水平的空气质量气体。(C) 2016年作者。Elsevier Ltd.出版。
Recent studies have shown that (three-electrode) electrochemical sensors can be utilised for air quality monitoring and exposure assessment. The long-term performance of these sensors is however, often limited by the effects of ambient meteorological parameters on the sensor baseline, in particular temperature. If electrochemical (EC) sensors are to be adopted for air quality measurement over extended periods (months), this effect must be accounted for. Recent long-term, ambient measurements of CO, NO and NO2 using EC sensors have revealed that temperature (and relative humidity (RH)) had an effect on the baseline which was more pronounced in the case of NO sensors with coefficient of determination, R-2 of 0.9 when compared to CO and NO2 with R-2 < 0.2. In this paper we present a correction methodology that quantifies this effect (referred to here as fitted baseline), implementing these correction on the EC measurements. We found that EC sensors corrected for baseline-temperature effect using the method describe in this paper show good agreement when compared with traditional reference instrument. The coefficient of determination R-2 of 0.7-0.8 and gradient of 0.9 was observed for baseline-temperature corrected NO compared to R-2 = 0.02 prior to baseline-temperature correction. Furthermore, the correction methodology was validated by comparing the temperature-baseline with proxy temperature compensating measurements obtained from the fourth electrode of a set of novel four-electrode electrochemical sensors. A good agreement (R-2 = 0.9, with gradients = 0.7-1.08 for NO and 0.5 < R-2 < 0.73 for CO) was observed between temperature fitted baselines and outputs from the fourth electrodes (also known non-sensing/auxiliary electrode). Meanwhile, the long-term stability (calibrated signal output) of temperature-corrected data was evaluated by comparing the change in sensor gain to meteorological parameters including temperature, relative humidity, wind speed and wind direction. The results showed that there was no statistically significant change in sensitivity (two-sided t-test, p = 0.34) of the temperature-corrected electrochemical sensor with respect to these parameters (over several months). This work demonstrates that using the baseline-temperature correction methodology described in this paper, electrochemical sensors can be used for long-term (months), quantitative measurements of air quality gases at the parts per billion volume (ppb) mixing ratio level typical of ambient conditions in the urban environment. (C) 2016 The Authors. Published by Elsevier Ltd.