Highly sensitive poisoning-resistant optical carbon dioxide sensors for environmental monitoring

Fritzsche, Eva; Gruber, Pia; Schutting, Susanne; Fischer, Jan; Štrobl, Martin; Müller, Jens Daniel; Borisov, Sergey M.; Klimant, Ingo

doi:10.1039/c6ay02949c

Cited by 25 publications

(27 citation statements)

References 71 publications

(60 reference statements)

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“…Clarke et al (2015) demonstrated a corresponding positive sigmoidal relationship between R and pH. The optode shows a temperature dependence (Figure 3), which has also been reported for other optical chemical sensors by Clarke et al (2015) and Fritzsche et al (2017). The observed patterns in our study are consistent with the previous work and are in line with thermodynamic considerations dictating temperature influences on the indicator acid dissociation constant, as well as changes to the indicator fluorescence intensity and the permeability of the membrane.…”

Section: Optode Characterization Pco 2 Calibration Of Optodesupporting

confidence: 82%

“…A three dimensional fit to calibration results yielded a first by second degree polynomial (SSE = 0.081, R 2 = 0.99, Equation 3, Table 1), in agreement with previous optical pCO 2 sensor work (Atamanchuk, 2013;Atamanchuk et al, 2014;Fritzsche et al, 2017). Where B, C, D, and E are the slopes, A is the offset (as listed in Table 1), R is the ratio value from Equation (1) and T is the in situ temperature.…”

Section: Optode Characterization Pco 2 Calibration Of Optodesupporting

confidence: 67%

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Characterization of a Time-Domain Dual Lifetime Referencing pCO2 Optode and Deployment as a High-Resolution Underway Sensor across the High Latitude North Atlantic Ocean

et al. 2017

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The ocean is a major sink for anthropogenic carbon dioxide (CO 2 ), with the CO 2 uptake causing changes to ocean chemistry. To monitor these changes and provide a chemical background for biological and biogeochemical studies, high quality partial pressure of CO 2 (pCO 2 ) sensors are required, with suitable accuracy and precision for ocean measurements. Optodes have the potential to measure in situ pCO 2 without the need for wet chemicals or bulky gas equilibration chambers that are typically used in pCO 2 systems. However, optodes are still in an early developmental stage compared to more established equilibrator-based pCO 2 systems. In this study, we performed a laboratory-based characterization of a time-domain dual lifetime referencing pCO 2 optode system. The pCO 2 optode spot was illuminated with low intensity light (0.2 mA, 0.72 mW) to minimize spot photobleaching. The spot was calibrated using an experimental gas calibration rig prior to deployment, with a determined response time (τ 63 ) of 50 s at 25 • C. The pCO 2 optode was deployed as an autonomous shipboard underway system across the high latitude North Atlantic Ocean with a resolution of ca.10 measurements per hour. The optode data was validated with a secondary shipboard equilibrator-based infrared pCO 2 instrument, and pCO 2 calculated from discrete samples of dissolved inorganic carbon and total alkalinity. Further verification of the pCO 2 optode data was achieved using complimentary variables such as nutrients and dissolved oxygen. The shipboard precision of the pCO 2 sensor was 9.5 µatm determined both from repeat measurements of certified reference materials and from the standard deviation of seawater measurements while on station. Finally, the optode deployment data was used to evaluate the physical and biogeochemical controls on pCO 2 .

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Section: Optode Characterization Pco 2 Calibration Of Optodesupporting

confidence: 82%

Section: Optode Characterization Pco 2 Calibration Of Optodesupporting

confidence: 67%

Characterization of a Time-Domain Dual Lifetime Referencing pCO2 Optode and Deployment as a High-Resolution Underway Sensor across the High Latitude North Atlantic Ocean

et al. 2017

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“…One way to avoid the additional complexity of pumping is to use fluorescent lifetime based measurements that have reduced sensitivity to the signal intensity. This technology has been successfully developed for dissolved O 2 sensors (Körtzinger et al, 2005;Tengberg et al, 2006;Takeshita et al, 2013), while similar technology for pH and pCO 2 has proven more challenging but recent developments show promise in field deployments (Atamanchuk et al, 2014;Clarke et al, 2015;Fritzsche et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Autonomous Optofluidic Chemical Analyzers for Marine Applications: Insights from the Submersible Autonomous Moored Instruments (SAMI) for pH and pCO2

2018

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The commercial availability of inexpensive fiber optics and small volume pumps in the early 1990's provided the components necessary for the successful development of low power, low reagent consumption, autonomous optofluidic analyzers for marine applications. It was evident that to achieve calibration-free performance, reagent-based sensors would require frequent renewal of the reagent by pumping the reagent from an impermeable, inert reservoir to the sensing interface. Pumping also enabled measurement of a spectral blank further enhancing accuracy and stability. The first instrument that was developed based on this strategy, the Submersible Autonomous Moored Instrument for CO 2 (SAMI-CO 2 ), uses a pH indicator for measurement of the partial pressure of CO 2 (pCO 2 ). Because the pH indicator gives an optical response, the instrument requires an optofluidic design where the indicator is pumped into a gas permeable membrane and then to an optical cell for analysis. The pH indicator is periodically flushed from the optical cell by using a valve to switch from the pH indicator to a blank solution. Because of the small volume and low power light source, over 8,500 measurements can be obtained with a ∼500 mL reagent bag and 8 alkaline D-cell battery pack. The primary drawback is that the design is more complex compared to the single-ended electrode or optode that is envisioned as the ideal sensor. The SAMI technology has subsequently been used for the successful development of autonomous pH and total alkalinity analyzers. In this manuscript, we will discuss the pros and cons of the SAMI pCO 2 and pH optofluidic technology and highlight some past data sets and applications for studying the carbon cycle in aquatic ecosystems.

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“…However, this evaluation becomes ambiguous in the presence of DOM and H 2 S because both contribute to A T (Kuliński et al ; Yang et al ) and this contribution is not accounted for in the available software for CO 2 ‐system calculations, e.g., CO 2 sys (Pierrot et al ). In addition, analytical techniques to determine the pCO 2 of discrete samples are not well developed and optical pCO 2 sensors are prone to poisoning by H 2 S (Atamanchuk et al ; Fritzsche et al ). Consequently, A T and pCO 2 are often not accessible for an overdetermination of the CO 2 system.…”

mentioning

confidence: 99%

Spectrophotometric pH measurements in the presence of dissolved organic matter and hydrogen sulfide

Müller

Schneider

Aßmann³

et al. 2017

Limnology & Ocean Methods

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Spectrophotometric pH measurements were first introduced for oceanic environments and they facilitated the determination of the marine CO2 system, including the direct observation of Ocean Acidification. Extended characterizations of the indicator dye m‐Cresol purple over the past two decades enabled the application of this method to natural waters ranging from brines to freshwaters. However, the required determination of the dye's dissociation constants and absorbance properties were exclusively performed in buffer solutions prepared with artificial seawater. Potential perturbations by substances that occur in natural waters, but are not included in the buffer solutions, have never been tested. Therefore, we studied the impact of elevated amounts of dissolved organic matter (DOM) and hydrogen sulfide (H2S) on spectrophotometric pH measurements. We did not observe an impact on spectrophotometric pH measurements by H2S concentrations up to 400 μmol kg−1, which reflect high levels such as those reported from the Black Sea. Likewise, natural DOM did not interfere with the spectrophotometric measurements at concentrations typical for oceanic environments and large estuarine systems. However, strongly colored river waters can cause spectral disturbances resulting in calculated pH values that are up to tenths of pH units too low. To circumvent such disturbances, we recommend using intense light sources, a shorter cuvette length or spectrophotometrically calibrated glass electrodes when performing spectrophotometric measurements under critical conditions.

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Highly sensitive poisoning-resistant optical carbon dioxide sensors for environmental monitoring

Abstract: Resistivity of optical carbon dioxide chemosensors towards poisoning by acidic gases is significantly improved by using an additional perfluorinated polymer coating making the sensors suitable for long-term measurements.

Cited by 25 publications

References 71 publications

Characterization of a Time-Domain Dual Lifetime Referencing pCO2 Optode and Deployment as a High-Resolution Underway Sensor across the High Latitude North Atlantic Ocean

Characterization of a Time-Domain Dual Lifetime Referencing pCO2 Optode and Deployment as a High-Resolution Underway Sensor across the High Latitude North Atlantic Ocean

Autonomous Optofluidic Chemical Analyzers for Marine Applications: Insights from the Submersible Autonomous Moored Instruments (SAMI) for pH and pCO2

Spectrophotometric pH measurements in the presence of dissolved organic matter and hydrogen sulfide

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