Direct Analysis of Oxidizing Agents in Aqueous Solution with Attenuated Total Reflectance Mid-Infrared Spectroscopy and Diamond-like Carbon Protected Waveguides

Abstract

A novel approach for the direct detection of oxidizing agents in aqueous solution is presented using diamond-like carbon (DLC) protected waveguides in combination with attenuated total reflectance (ATR) mid-infrared spectroscopy. Pulsed laser deposition was applied to produce high-quality DLC thin films on ZnSe ATR crystals with thicknesses of a few 100 nm. Scanning electron microscopy and X-ray photoelectron spectroscopy has been used to investigate the surface properties of the DLC films including the sp(3)/sp(2) hybridization ratio of the carbon bonds. Beside excellent adhesion of the DLC coatings to ZnSe crystals, these films show high chemical stability against strongly oxidizing agents. IR microscopy was utilized to compare differences in the chemical surface modification of bare and protected ATR waveguides when exposed to hydrogen peroxide, peracetic acid, and peroxydisulfuric acid. The feasibility of DLC protected waveguides for real-time concentration monitoring of these oxidizing agents was demonstrated by measuring calibration sets in a concentration range of 0.2-10%. Additionally, principal component regression has been applied to analyze multicomponent mixtures of hydrogen peroxide, acetic acid, and peracetic acid in aqueous solution. Due to high chemical stability and accurate monitoring capabilities, DLC protected waveguides represent a novel approach for directly detecting oxidizing agents in aqueous solution with promising potential for industrial process analysis.

A Simple Layer‐by‐Layer Assembly Strategy for a Reagentless Biosensor Based on a Nanocomposite of Methylene Blue‐Multiwalled Carbon Nanotubes

“…Compared with conventional detection methods, such as UV/Vis spectrophotometry [1] and chemiluminescence [2], an amperometric biosensor is particularly suited for the analysis of H 2 O 2 due to its simplicity and high sensitivity [3,4]. The construction of sensitive amperometric biosensors is an attractive goal.…”

ATR-FTIR spectroscopic analysis of sorption of aqueous analytes into polymer coatings used with guided SH-SAW sensors

“…Parameters that are determined for specific analytes are R, the polarizability contribution from n and  electrons;  H , the dipolarity;  H , the hydrogen bond acidity; β H , the hydrogen bond basicity; and L 16 , the gas-liquid partition coefficient of nhexadecane at 298 K. The above modeling has been used extensively in the analysis of gas-phase sensors [2]. Partitioning of an analyte from water into a polymer coating can be estimated by determining the air/polymer partition coefficient, Kap, and the partition coefficient from air to water (i.e., the Henry's Law coefficient) Kaw, using accessed by following the link in the citation at the bottom of the page.…”

“…Attenuated total internal reflectance Fourier transform infrared spectroscopy (ATR-FTIR) has been shown to be a useful technique for analysis of aqueous solutions where the strong infrared absorbance of water precludes transmittance measurements [10] and has been utilized to analyze polymer films [11], water diffusion into polymer films [12], and analyte sorption into polymers [13][14][15]. A number of chemical sensors have been implemented for direct detection of analytes in both air and water based on ATR-FTIR strategies [16][17][18]. Infrared reflection methods have also been applied to provide insight into the interaction between gas-phase analytes and sensor coatings [19,20].…”

Portable Infrared Laser Spectroscopy for On-site Mycotoxin Analysis

“…Recently emerging analytical measurement strategies have demonstrated the utility of quantum cascade lasers (QCLs) in combination with thin-film waveguides as a promising alternative to commonly used Fourier transform infrared (FTIR) spectroscopy techniques222324. Due to their exceedingly compact dimensions, high output power, operational stability, and broad tunability (>400 cm −1 per device), QCLs are unambiguously accepted as the most advanced light source facilitating compact and portable MIR spectroscopy and sensing schemes1325.…”