Detection of Hydrogen Peroxide in Liquid and Vapors Using Titanium(IV)-Based Test Strips and Low-Cost Hardware

Titanium(IV) solutions are known to detect hydrogen peroxide in solutions by a colorimetric method. Xplosafe’s XploSens PS commercial titanium(IV)-based peroxide detection test strips are used to detect hydrogen peroxide in liquids. The use of these test strips as gas-phase detectors for peroxides was tested using low-cost hardware. The exposure of these strips to hydrogen peroxide liquid or gas leads to the development of an intense yellow color. For liquids, a digital single-lens reflex camera was used to quantify the color change using standardized solutions containing between 50 and 500 ppm peroxide by mass. Analysis of the images with color separation can provide a more quantitative determination than visual comparison to a color chart. For hydrogen peroxide gas, an inexpensive web camera and a tungsten lamp were used to measure the reflected light intensity as a function of exposure from a test strip held in a custom cell. First-order behavior in the color change with time was observed during the exposure to peroxide vapor over a range of peroxide concentrations from 2 and 30 ppm by volume. For a 1-min measurement, the gas-phase detection limit is estimated to be 1 ppm. A 0.01 ppm detection limit can be obtained with a 1-h exposure time. Titanium(IV)-based peroxide detection test strips are sensitive enough to work as a gas-phase hydrogen peroxide detector

A Simple Construction of Electrochemical Liver Microsomal Bioreactor for Rapid Drug Metabolism and Inhibition Assays

In order to design a green microsomal bioreactor on suitably identified carbon electrodes, it is important to understand the direct electrochemical properties at the interfaces between various carbon electrode materials and human liver microsomes (HLM). The novelty of this work is on the investigation of directly adsorbed HLM on different carbon electrodes with the goal to develop a simple, rapid, and new bioanalytical platform of HLM useful for drug metabolism and inhibition assays. These novel biointerfaces are designed in this study by a one step adsorption of HLM directly onto polished basal plane pyrolytic graphite (BPG), edge plane pyrolytic graphite (EPG), glassy carbon (GC), or high-purity graphite (HPG) electrodes. The estimated direct electron transfer (ET) rate constant of HLM on the smooth GC surface was significantly greater than that of the other electrodes. On the other hand, the electroactive surface coverage and stability of microsomal films were greater on highly surface defective, rough EPG and HPG electrodes compared to the smooth GC and less defective hydrophobic BPG surfaces. The presence of significantly higher oxygen functionalities and flatness of the GC surface is attributed to favoring faster ET rates of the coated layer of thin HLM film compared to other electrodes. The cytochrome P450 (CYP)-specific bioactivity of the liver microsomal film on the catalytically superior, stable HPG surface was confirmed by monitoring the electrocatalytic conversion of testosterone to 6β-hydroxytestosterone and its inhibition by the CYP-specific ketoconazole inhibitor. The identification of optimal HPG and EPG electrodes to design biologically active interfaces with liver microsomes is suggested to have immense significance in the design of one-step, green bioreactors for stereoselective drug metabolite synthesis and drug metabolism and inhibition assays

Synthetic, Structural, and Physical Investigations of the Large Linear and Branched Oligogermanes Ph₃GeGePh₂GePh₂GePh₂H, Ge₅Ph₁₂, and (Ph₃Ge)₄Ge

The syntheses of two linear oligogermanes, Ph₃GeGePh₂GePh₂GePh₂H and Ge₅Ph₁₂, were achieved using a hydrogermolysis reaction starting with HPh₂GeGePh₂GePh₂H. The preparation of the hydride-terminated tetragermane indicates that selectivity is possible using the hydrogermolysis reaction, which had not been observed previously. The structures of both of these compounds were determined, and they were also characterized by UV/visible spectroscopy and electrochemical methods (CV and DPV). The pentagermane Ge₅Ph₁₂ exhibits four irreversible oxidation waves in both its CV and DPV, as was observed for other aryl-substituted oligogermanes. The successful synthesis of the neopentane analogue (Ph₃Ge)₄Ge was also achieved by starting from GeH₄ and Ph₃GeCH₂CN. This material was structurally characterized; the structure of (Ph₃Ge)₄Ge is highly sterically congested and contains long Ge–Ge single-bond distances that average 2.497(6) Å and exhibits an nearly idealized tetrahedral geometry at the central germanium atom with an average Ge–Ge–Ge bond angle of 109.49(2)°. The UV/visible spectrum of (Ph₃Ge)₄Ge exhibits a broad absorbance maximum centered at 250 nm, and DFT calculations indicate that this compound has a stabilized HOMO at −6.223 eV and a large HOMO–LUMO gap relative to those in other branched oligogermanes

Synthetic, Structural, and Physical Investigations of the Large Linear and Branched Oligogermanes Ph₃GeGePh₂GePh₂GePh₂H, Ge₅Ph₁₂, and (Ph₃Ge)₄Ge

The syntheses of two linear oligogermanes, Ph₃GeGePh₂GePh₂GePh₂H and Ge₅Ph₁₂, were achieved using a hydrogermolysis reaction starting with HPh₂GeGePh₂GePh₂H. The preparation of the hydride-terminated tetragermane indicates that selectivity is possible using the hydrogermolysis reaction, which had not been observed previously. The structures of both of these compounds were determined, and they were also characterized by UV/visible spectroscopy and electrochemical methods (CV and DPV). The pentagermane Ge₅Ph₁₂ exhibits four irreversible oxidation waves in both its CV and DPV, as was observed for other aryl-substituted oligogermanes. The successful synthesis of the neopentane analogue (Ph₃Ge)₄Ge was also achieved by starting from GeH₄ and Ph₃GeCH₂CN. This material was structurally characterized; the structure of (Ph₃Ge)₄Ge is highly sterically congested and contains long Ge–Ge single-bond distances that average 2.497(6) Å and exhibits an nearly idealized tetrahedral geometry at the central germanium atom with an average Ge–Ge–Ge bond angle of 109.49(2)°. The UV/visible spectrum of (Ph₃Ge)₄Ge exhibits a broad absorbance maximum centered at 250 nm, and DFT calculations indicate that this compound has a stabilized HOMO at −6.223 eV and a large HOMO–LUMO gap relative to those in other branched oligogermanes

Synthetic, Structural, and Physical Investigations of the Large Linear and Branched Oligogermanes Ph₃GeGePh₂GePh₂GePh₂H, Ge₅Ph₁₂, and (Ph₃Ge)₄Ge

The syntheses of two linear oligogermanes, Ph₃GeGePh₂GePh₂GePh₂H and Ge₅Ph₁₂, were achieved using a hydrogermolysis reaction starting with HPh₂GeGePh₂GePh₂H. The preparation of the hydride-terminated tetragermane indicates that selectivity is possible using the hydrogermolysis reaction, which had not been observed previously. The structures of both of these compounds were determined, and they were also characterized by UV/visible spectroscopy and electrochemical methods (CV and DPV). The pentagermane Ge₅Ph₁₂ exhibits four irreversible oxidation waves in both its CV and DPV, as was observed for other aryl-substituted oligogermanes. The successful synthesis of the neopentane analogue (Ph₃Ge)₄Ge was also achieved by starting from GeH₄ and Ph₃GeCH₂CN. This material was structurally characterized; the structure of (Ph₃Ge)₄Ge is highly sterically congested and contains long Ge–Ge single-bond distances that average 2.497(6) Å and exhibits an nearly idealized tetrahedral geometry at the central germanium atom with an average Ge–Ge–Ge bond angle of 109.49(2)°. The UV/visible spectrum of (Ph₃Ge)₄Ge exhibits a broad absorbance maximum centered at 250 nm, and DFT calculations indicate that this compound has a stabilized HOMO at −6.223 eV and a large HOMO–LUMO gap relative to those in other branched oligogermanes