Flow Injection Analysis of H₂O₂ in Natural Waters Using Acridinium Ester Chemiluminescence:  Method Development and Optimization Using a Kinetic Model

Abstract

Chemiluminescence (CL) of acridinium esters (AE) has found widespread use in analytical chemistry. Using the mechanism of the reaction of H2O2 with 10-methyl-9-(p-formylphenyl)acridinium carboxylate trifluoromethanesulfonate and a modified flow injection system, the reaction rates of each step in the mechanism were evaluated and used in a kinetic model to optimize the analysis of H2O2. Operational parameters for a flow injection analysis system (reagent pH, flow rate, sample volume, PMT settings) were optimized using the kinetic model. The system is most sensitive to reaction pH due to competition between AE hydrolysis and CL. The optimized system was used to determine H2O2 concentrations in natural waters, including rain, freshwater, and seawater. The lower limit of detection varied in natural waters, from 352 pM in open ocean seawater (mean, 779 pM +/- 15.0%, RSD) to 58.1 nM in rain (mean, 6,340 nM +/- 0.92%, RSD). The analysis is specific for H2O2 and is therefore of potential interest for atmospheric chemistry applications where organoperoxides have been reported in the presence of H2O2.

Hydrogen Peroxide Cycling in High-Temperature Acidic Geothermal Springs and Potential Implications for Oxidative Stress Response

“…The similar concentrations of H 2 O 2 was likely due to similar geochemistry across the three sites [e.g., Fe(II) ∼30-40 µM, pH ∼3-3.5, T ∼68-80 • C]. The observed range in H 2 O 2 values in acidic geothermal systems is higher than previously observed in a limited set of thermal systems supporting phototrophic activity (<300 nM; Wilson et al, 2000a), and fall within values observed in rainwater (∼6 µM; King et al, 2007), freshwater (∼300 nM; King et al, 2007) or coastal waters (50-150 nM; Miller et al, 2005), but are considerably higher than values in the open ocean (∼0.7 nM; King et al, 2007). The Fe-oxide mat systems sampled in the current study do not contain phototrophic organisms, although small increases in DO during peak photon flux may in part, be due to inputs from adjacent phototrophic systems.…”

“…A flow-injection analysis instrument [FeLume(II)] with chemiluminescence (CL) detection (Waterville Analytical, Waterville, ME) was used in the field for the determination of H 2 O 2 concentrations in geothermal waters as described in prior reports (Miller et al, 2005;King et al, 2007). The CL detector was a Hamamatsu HC-135 photon counting PMT (Hamamatsu Corp., Bridgewater NJ) operated at the manufacturer's recommended voltage (700 V) for optimal signal/noise ratio for µM concentrations of hydrogen peroxide to avoid PMT saturation.…”

Possibilities and Challenges for Quantitative Optical Sensing of Hydrogen Peroxide

“…Additionally, many probes show a lack of selectivity, which means they react readily (and sometimes even much faster than with H 2 O 2 ) with another analyte. Another quite problematic issue becomes apparent when looking at the published values of H 2 O 2 concentration in different samples (summarized in the Supplementary Materials [24,25,110,128,[135][136][137] is a highly important analyte and it will be important for future research to be able to quantify this analyte in real time. We think there is still room for new creative sensing schemes and solutions, but also improvements of current methods are needed.…”

“…FIA analysis of H2O2 relies on a few chemiluminescent reactions, where the two most frequently used reactions in the literature are (1) acridinium ester (10-methyl-9-(p-formylphenyl)-acridinium carboxylate trifluoromethanesulfonate) [127][128][129][130][131] and (2) luminol and a Co(II) catalyst [132][133][134][135][136]. Less frequently used reactions involve (3) TCPO (bis-(2,4,6-trichlorophenyl)oxalate) [110] or (4) the oxidation of phenol [137].…”

“…With more complicated systems a multivalve for sample injection can be used. For more information see for example King et al [128].…”