科研之友
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摘要
We explore in this work a novel analytical concept consisting on the combined use of chemically modified commercial screen-printed electrodes as passive samplers and voltammetric detectors for monitoring of ozone levels in ambient air, a highly relevant pollutant for air quality assessment. The proposed approach is based on the modification of commercial carbon screen-printed electrodes by surface deposition of a known amount of indigotrisulfonate (ITS). The screen-printed platforms are then inserted in passive sampler diffusive bodies and exposed to ambient air for a relatively short period (5 h), allowing the reaction of ITS with tropospheric ozone to proceed. After the sampling stage, the remaining ITS onto the electrode surface is solubilized in 0.1 M perchloric acid and quantified by square wave voltammetry using a portable potentiostat. The optimization of the experimental conditions allows to measure 5-h average ambient air ozone levels in the range 20-120 mu g/m(3) (detection limit 1.6 mu g/m(3)), covering the usual ozone range in most urban and rural environments. The relative standard deviation of the combined passive sampling- voltammetric detection system varied from 9.5 to 17.6%. The proposed methodology was tested in field conditions against a reference UV absorption equipment with acceptable results showing a significant correlation at the 95% confidence level, with slope and intercepts not statistically different from expected values. The uncertainty of the proposed method was estimated to be in the range 25.6-26.2 according to ISO 13,752. The combination of cheap and simple sampling and detection based on chemically modified screen-printed electrodes opens new analytical options in ambient air monitoring, with promising applicability for decentralized testing by simple and affordable air pollution sensors.
- 出版日期2018-11-10
