2-butanone Peroxide Research Articles

Characterization of 2-Butanone Peroxide Oligomeric Profiles and Their Associated Gas-Phase and Solution-Phase Rearrangement Products by Electrospray Ionization Mass Spectrometry for Forensic Applications.

2-Butanone peroxide (also known as methyl ethyl ketone peroxide, MEKP) has applications as a cross-linker in the chemical industry and is also encountered as a homemade primary high explosive; therefore, it is of interest to both process chemists and forensic examiners. Specifically for forensic applications, we demonstrate that when traditional synthetic procedures, available to any hobbyist, are utilized to generate MEKP, oligomeric peroxide units (n ≤ 12), along with several other oligomeric byproduct distributions, are readily observed by liquid chromatography-mass spectrometry (LC-MS). These oligomeric byproducts correspond to the formation of methyl/ethyl ketone end group(s) at the oligomer end group (i.e., loss of ethanol(s) and/or methanol(s) from the oligomer termini). Based on the interpretation of the MS and MS/MS behavior along with the characterization of newly generated terminal alkyl ketone products, we propose that these byproducts are consistent with a Hock-like rearrangement of the primary MEKP distribution in the acidified reaction medium. Following a procedure for homemade preparation, triplicate lots were synthesized. Unique oligomeric and byproduct distributions provided discriminatory power between the synthetic lots. Furthermore, the distributions of MEKP oligomers and the various byproducts in the initiated MEKP match the intensity distributions observed in the intact material with remarkable accuracy. This observation suggests that the postinitiation residue of MEKP could be associated or dissociated from a separately collected intact material obtained during an investigation by examining these oligomeric and byproduct profiles.

Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation

There is growing evidence that the interactions between sulfur dioxide (SO2) and organic peroxides (POs) in aerosol and clouds play an important role in atmospheric sulfate formation and aerosol aging, yet the reactivity of POs arising from anthropogenic precursors toward SO2 remains unknown. In this study, we investigate the multiphase reactions of SO2 with secondary organic aerosol (SOA) formed from the photooxidation of toluene, a major type of anthropogenic SOA in the atmosphere. The reactive uptake coefficient of SO2 on toluene SOA was determined to be on the order of 10−4, depending strikingly on aerosol water content. POs contribute significantly to the multiphase reactivity of toluene SOA, but they can only explain a portion of the measured SO2 uptake, suggesting the presence of other reactive species in SOA that also contribute to the particle reactivity toward SO2. The second-order reaction rate constant (kII) between S(IV) and toluene-derived POs was estimated to be in the range of the kII values previously reported for commercially available POs (e.g., 2-butanone peroxide and 2-tert-butyl hydroperoxide) and the smallest (C1-C2) and biogenic POs. In addition, unlike commercial POs that can efficiently convert S(IV) into both inorganic sulfate and organosulfates, toluene-derived POs appear to mainly oxidize S(IV) to inorganic sulfate. Our study reveals the multiphase reactivity of typical anthropogenic SOA and POs toward SO2 and will help to develop a better understanding of the formation and evolution of atmospheric secondary aerosol.

Identification of organic hydroperoxides and peroxy acids using atmospheric pressure chemical ionization–tandem mass spectrometry (APCI-MS/MS): application to secondary organic aerosol

Abstract. Molecules with hydroperoxide functional groups are of extreme importance to both the atmospheric and biological chemistry fields. In this work, an analytical method is presented for the identification of organic hydroperoxides and peroxy acids (ROOH) by direct infusion of liquid samples into a positive-ion atmospheric pressure chemical ionization–tandem mass spectrometer ((+)-APCI-MS/MS). Under collisional dissociation conditions, a characteristic neutral loss of 51 Da (arising from loss of H2O2+NH3) from ammonium adducts of the molecular ions ([M + NH4]+) is observed for ROOH standards (i.e. cumene hydroperoxide, isoprene-4-hydroxy-3-hydroperoxide (ISOPOOH), tert-butyl hydroperoxide, 2-butanone peroxide and peracetic acid), as well as the ROOH formed from the reactions of H2O2 with aldehydes (i.e. acetaldehyde, hexanal, glyoxal and methylglyoxal). This new ROOH detection method was applied to methanol extracts of secondary organic aerosol (SOA) material generated from ozonolysis of α-pinene, indicating a number of ROOH molecules in the SOA material. While the full-scan mass spectrum of SOA demonstrates the presence of monomers (m∕z = 80–250), dimers (m∕z = 250–450) and trimers (m∕z = 450–600), the neutral loss scan shows that the ROOH products all have masses less than 300 Da, indicating that ROOH molecules may not contribute significantly to the SOA oligomeric content. We anticipate this method could also be applied to biological systems with considerable value.

Determination of hydrogen peroxide and organic peroxides in micellar and aqueous–organic media using a spectrophotometric biosensor based on horseradish peroxidase

The expedience of the target-specific control of the properties of a medium (using micellar and aqueous–organic media), in which an indicator process providing the background for the operation of a spectrophotometric sensor based on a polyelectrolyte complex (horseradish peroxidase–chitosan) is conducted, is shown experimentally and proved by calculations of kinetic parameters of the enzymatic reaction. The application of the sensor ensures an increase in the sensitivity of the determination of peroxides of different nature and structures (e.g., hydrogen and urea peroxides, benzoyl peroxide, 2-butanone peroxide and tertbutyl hydroperoxide) in complex matrixes. The proposed approach allows the analyst not only to regulate the performance characteristics of the developed procedures for the determination of peroxides depending on the analytical task, but also to extend the range of test samples (including those insoluble in water) analyzed with no sample preparation.

Properties and analytical applications of the self-assembled complex {peroxidase–chitosan}

A novel promising approach to the improvement of analytical properties of horseradish peroxidase based on its inclusion into self-assembled structures of chitosan is discussed. It is shown that the reasonable choice of a polyelectrolyte, a detailed investigation of its interaction with the enzyme and the conditions of the {peroxidase–polyelectrolyte} complex formation allow for stabilizing the biocatalyst in aqueous and aqueous-organic media without a substantial loss in its activity and developing corresponding analytical procedures and biosensors. The latter provides highly selective determination of a number of organic compounds and sensitive determination of heavy metal ions that becomes possible due to the specific interactions of the analytes with the polymer matrix. Besides, the application of the proposed analytical systems and biosensors provides the expansion of the range of the compounds, and poorly water soluble and slowly oxidized substrates of peroxidase as well, which could be determined and real samples which could be analyzed by enzymatic methods. Analytical performance of the developed spectrophotometric indicator procedures and biosensors based on the self-assembled complex {peroxidase–chitosan} is demonstrated in the determination of metal ions (Hg(II), Cd(II), and Pb(II)), phenothiazines (promazine, chloropromazine, and trifluoroperazine), phenolic compounds (phenol, hydroquinone, catechol, pyrogallol, quercetin, rutin, and esculetin), organic peroxides (tert-butyl peroxide, 2-butanone peroxide, and benzoyl peroxide) in various samples, including water-insoluble matrices.

Antimicrobial efficacy in vivo of a new formulation of 2-butanone peroxide in n-propanol: comparison with commercial products in a cross-over trial

The use of hand rub to obtain maximum decrease in bacterial load is important because the reduction needed to avoid transmission is unknown. The monomer of 2-butanone peroxide is a peroxygen derivative with potential biocidal use in hospitals. The aim of this study was to compare the efficacy of hand rub with an alcoholic solution of peroxide 2-butanone versus five antiseptic products, against E. coli K12 (CECT 433) transient flora acquired by hand immersion in a broth culture following the UNE-EN-1500 standard. Isopropanol 60% (control) obtained 99.99% reductions, driving down the bacterial load from 10(6) cfu/mL in the initial inocula to <100 cfu/mL. Products A, B and C (different alcoholic solutions ranging from 65% to 75% with low amounts of biguanidines and/or quaternary ammonium compounds) resulted in significantly lower amounts, reducing initial inocula to approximately 500 cfu/mL. Products D and E (70-75% alcohol solutions containing higher amounts of different quaternary ammonium compounds and triclosan in the case of product E) produced reductions similar to that of isopropanol, with significantly larger reductions than products A, B and C. The product with the solution of 2-butanone peroxide produced the same effect as products D and E with mean reductions of approximately 4log(10) (99.99%), driving the initial inocula down to < or = 100 cfu/mL, despite the low concentration (35%) of propanol in the solution. This novel peroxygen biocide offers high in-vivo cidal activity against acquired E. coli transient flora, offering an alternative to products with higher alcohol concentrations.

Evaluation of the in-vitro cidal activity and toxicity of a novel peroxygen biocide: 2-butanone peroxide

The monomer of 2-butanone peroxide is a novel peroxygen derivative with potential use as biocide in the hospital environment. The aim of this study was to test the biocidal activity of different concentrations of the compound against American Tissue Culture Collection strains from 11 different micro-organisms, including bacteria, mycobacteria, spores, fungi and virus, following the European Standard guidelines. Toxicity tests were also carried out following United States Environmental Protection Agency Standards. 2-Butanone peroxide exhibited biocidal activity at 0.12% against Legionella pneumophila, at 0.5% against Escherichia coli, Pseudomonas aeruginosa and Enterococcus hirae, and at 1% against Staphylococcus aureus after 5 min contact at room temperature. Mycobactericidal activity was obtained at 0.5% after 60 min contact at 20 degrees C, and sporicidal activity was obtained at 4% after 60 min at 40 degrees C. Good fungicidal (against yeasts and moulds) and virucidal (adenovirus and poliovirus) activities were obtained at 0.5% after 60 min contact. Toxicity assessment showed negative results in the acute dermal irritation test, acute eye irritation test and acute oral toxicity test. The skin sensitisation test was negative. The safety profile in the toxicity tests and the basic cidal activity against the strains tested suggest that 2-butanone peroxide in the control of hospital infections.

A Direct Electrode-Driven Immobilized Catalase for Biocatalysis of Peroxides

The direct electrochemistry of catalase (Cat) immobilized in agarose hydrogel film on glassy carbon (GC) electrode was investigated. A pair of well-defined and quasi-reversible redox peaks both in aqueous buffer and ethanol-aqueous mixture was obtained. The formal potential (E°') indicates the reactions origin from the direct electron transfer between the CatFe(III)/(II) couple and the electrode surface. The E°' is linearly dependent on solution pH (redox Bohr effect), indicating the electron transfer of the CatFe(III)/(II) redox couple accompanied with the transfer of a proton. The electron transfer can be facilitated in ethanol-aqueous mixture for the reason of partial dehydration of the distal heme pocket. The water pools in agarose hydrogel play an important role in preventing either the change of conformation or the inactivity of Cat from polar organic solvent. Cat retains its original conformation in the agarose film that was confirmed by UV-Vis spectra and electrochemical behaviors in comparison to the controlled experiments using free hemin. The catalytic reactions to peroxides (hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 2-butanone peroxide) using Cat-agarose modified electrode were also explored both in aqueous buffer and ethanol-aqueous mixture. The method could be application to the preparation of the hydrogel based third generation biosensors or bioreactors in organic media.

Redox reactions and enzyme-like activities of immobilized myoglobin in aqueous/organic mixtures

Abstract Myoglobin (Mb) was immobilized on a glassy carbon electrode (GCE) surface by konjac glucomannan (KGM). The KGM hydrogel films on GCE are characteristic of relatively high stability in the mixture solutions of aqueous–organic. The entrapped Mb undergoes fast direct transfer-electron reactions in aqueous–organic solvents mixtures. The formal potential ( E 0 ′ = −0.434 V) indicate the redox of MbFe(III)/(II) couple. The E 0 ′ is linearly dependent on solution pH (redox Bohr effect), indicating the electron transfer of MbFe(III)/(II) redox couple accompanied with the transfer of a proton. The electrochemical properties of the Mb remain almost unchanged in aqueous–ethanol solution comparing with pure aqueous buffer, suggesting that the water pools in KGM hydrogel play an important role in preventing the change of conformation and inactivity of proteins from polar organic solvents. UV–vis absorption spectra show that KGM hydrogel can keep the environment hydrated for immobilized proteins in organic-water mixture. The enzyme-like properties of immobilized Mb were also explored. Peroxides (hydrogen peroxide, Cumene hydroperoxide, t -butyl hydroperoxide, 2-butanone peroxide), haloethanes (hexachloroethane, pentachloroethane, tetrachloroethane) and nitric oxide can be catalytically reduced using a Mb modified electrode. Stability and reproducibility of the modified electrode make it possible to determine these substances.

Direct electrochemistry and electrochemical catalysis of immobilized hemoglobin in an ethanol–water mixture

Hemoglobin (Hb) was immobilized on a glassy carbon electrode (GCE) surface by konjac glucomannan (KGM). KGM hydrogel films on GCE have relatively high stabilities in aqueous-ethanol mixtures. The entrapped hemoglobin undergoes fast direct electron transfer reactions in aqueous-organic solvent mixtures. The peak current is bigger, the peak-to-peak separation smaller and the formal potential observed in the cyclic voltammogram is more negative for Hb-KGM/GCE in ethanol-PBS compared to Hb-KGM/GCE in PBS. The electrochemical properties of the Hb in aqueous-organic solution are almost unchanged from with those observed for the purely aqueous solution, suggesting that water pools in the KGM hydrogel play an important role in preventing changes in conformation and making proteins unreactive with polar organic solvents. The immobilized Hb was able to catalyze the reduction of nitric oxide, peroxides (hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 2-butanone peroxide), and the dehalogenation of haloethanes (hexachloroethane, pentachloroethane, tetrachloroethane, etc.). The stability and reproducibility of the modified electrode meant that it could be used to determine these substances.

Development of Biobased Unsaturated Polyester Containing Functionalized Linseed Oil

Biobased neat unsaturated polyester materials containing epoxidized methyl linseedate (EML) were processed with cobalt naphthenate as a promoter and 2-butanone peroxide as an initiator. Up to 25 wt % of the unsaturated polyester resin (UPE) was replaced by EML to process biobased UPE. The combination of UPE and EML resulted in an excellent combination for a new biobased thermoset polymer with a relatively high elastic modulus and a high glass transition temperature with the replacement of UPE with EML. Izod impact strength increased with increasing amount of EML. The Izod impact strength of the biobased UPE was correlated with failure surface morphologies observed by scanning electron microscopy.

Amperometric enzyme electrode for organic peroxides determination prepared from horseradish peroxidase immobilized in poly(vinylferrocenium) film

Organic peroxides, t-butyl hydroperoxide, 2-butanone peroxide, cumene hydroperoxide and t-butyl peracetate, were determined by an amperometric enzyme electrode. The enzyme electrode was prepared through electrostatic immobilization of horseradish peroxidase (HRP) in a polyvinylferrocenium (PVF) film. A PVF+ClO4− film was coated on a Pt foil at +0.70 V by electrooxidation of polyvinylferrocene in methylene chloride with 0.1 M tetrabutylammonium perchlorate (TBAP). The enzyme modified electrode PVF+HRP− was prepared by anion-exchange in a solution of HRP− in 0.05 M phosphate buffer at pH 8.5. FTIR spectroscopy was used to identify PVF, PVF+ClO4−, and PVF+HRP−. The immobilized amount of the enzyme in the film was determined by UV spectroscopy. The effects of the polymeric film thickness, bulk enzyme concentration used in the immobilization treatment and the temperature on the performance of enzyme electrode were investigated. The inhibitory effect of oxygen was also examined. Linearities, lower detection limits, active life times and sensitivities of the electrode were determined for each peroxide.

Determination of organic peroxides in reversed micelles with a poly- N-methylpyrrole horseradish peroxidase amperometric biosensor

The preparation of a peroxidase biosensor by immobilization of the enzyme during the electropolymerization of N-methylpyrrole and its use in the determination of organic peroxides in a predominantly nonaqueous medium, such as reversed micelles, is reported. Reversed micelles were formed with ethyl acetate as the continuous phase, 4% of 0.05 mol l −1 phosphate buffer solution of pH 7.4 as the dispersed phase, and 0.1 mol l −1 AOT as the emulsifying agent. Working variables affecting the polymer biosensor preparation, such as the polymerization potential, the constant accumulated charge to stop the polymerization process, the concentration of monomer and enzyme in the polymerization solution and the pH and concentration of the phosphate buffer solution, were optimized and discussed. Concerning the variables regarding the amperometric measurements in the reversed micellar medium, the potential value applied, the pH of the phosphate buffer solution, and the temperature were also optimized. Under the optimized conditions, the steady-state current for 2-butanone peroxide is reached in only 4 s. Linear calibration plots over the ranges 5–85 μmol l −1, and 2–48 mmol l −1 were obtained for 2-butanone peroxide and tert-butylhydroperoxide, respectively. The limits of detection obtained were 0.086 μmol l −1, and 0.03 mmol l −1, respectively. The poly- N-methylpyrrole-HRP amperometric biosensor was used for the determination of the organic peroxide content in body lotion samples, by employing 2-butanone peroxide as a standard. Optimization of the peroxide extraction step from the sample was carried out, and recoveries approximating 100% were obtained.

Toward an Ideal Synthesis of Oligonucleotides: Development of a Novel Phosphoramidite Method with High Capability

Abstract Several novel methods for reliably carrying out the oligonucleotide synthesis via the phosphoramidite strategy have been developed. The first is the method using allyloxycarbonyl and allyl groups for the protection of nucleoside bases and internucleotide linkages, respectively. These protectors can be cleanly removed under almost neutral conditions with a mixture of an organic Pd(0) complex such as Pd[P(C6H5)3]4 or Pd2[(C6H5CH=CH)2CO]3·CHCl3, and P(C6H5)3 in the presence of a nucleophile such as butylammonium formate, diethylammonium hydrogencarbonate, diethylammonium carbonate, or dimedone. A method for the facile oxidation of nucleoside phosphites to phosphates has been developed; this is performed under non-aqueous and non-basic conditions using 2-butanone peroxide in dichloromethane, t-butyl hydroperoxide in toluene, or bis(trimethylsilyl) peroxide in dichloromethane. The combined use of the N-allyloxycarbonyl/P–O-allyl-protected method and anhydrous/non-basic oxidation is extremely useful for the synthesis of nucleotide derivatives sensitive to moisture and/or bases, producing them in higher yield and at a greater level of purity than the existing methods using acyl or aroyl and cyanoethyl groups for the protection of nucleoside bases and internucleotide linkages, respectively, and iodine in aqueous pyridine for the oxidation. Further, acid/azole complexes serving as highly useful activators of phosphoramidites have been invented. The reagents include imidazolium triflate, N-(phenyl)imidazolium triflate, benzimidazolium triflate, and N-(methyl)benzimidazolium triflate, which allow higher-yield synthesis of oligonucleotides than conventionally employed 1H-tetrazole and related reagents. For example, synthesis of oligoribonucleotides via the allyloxycarbonyl/allyl-protected strategy has been carried out more efficiently using N-(phenyl)imidazolium triflate as a promoter than 5-(ethylthio)-1H-tetrazole, which has been found to be the most effective promoter among those currently available for oligoribonucleotide synthesis. Further, imidazolium triflate has opened the door to the extremely convenient and efficient synthesis of oligodeoxyribonucleotides without nucleoside-base protection. This method is obviously advantageous over N-protected methods because it eliminates tedious operations and the use of superfluous reagents required for the introduction and removal of the N-protecting group; risks of decomposition and loss of product by protection and deprotection are also avoided. Facile liquid-phase preparation of short oligomers has also been developed; this is successfully accomplished using stoichiometric amounts of building blocks by the aid of an equimolar amount of azolium reagent or a catalytic amount of 5-(p-nitrophenyl)-1H-tetrazole. These two methods are beneficial from an economical point of view, particularly in large-scale synthesis.

Reticulated Vitreous Carbon-Based Composite Enzyme Electrodes as Suitable Biosensors in Both Aqueous and Predominantly Nonaqueous Media

The construction and performance of reticulated vitreous carbon (RVC)-based composite enzyme electrodes in different aqueous and predominantly nonaqueous working media is reported. Both the mediator (ferrocene or ferrocyanide) and the enzyme peroxidase were immobilized by direct adsorption on chemically pretreated RVC cylinders. Pores of RVC were filled up with epoxy resin. The working media considered were: an aqueous phosphate solution of pH 7.4, a predominantly nonaqueous medium constituted by acetonitrile:Tris buffer (pH 7.4) mixtures, and organized media such as micellar solutions and oil-in-water emulsions. Hydrogen peroxide and 2-butanone peroxide were used as the substrates. The composite biosensors showed a good stability in all these media. Polishing of the electrode surface everyday before working was necessary, the useful lifetime of each single electrode being of approximately 20 days. Furthermore, reproducible responses were obtained with different electrodes constructed in the same manner. Kinetic parameters Vm, Km,app and k′cat were calculated in all cases, as well as the analytical characteristics from the corresponding calibration plots. The detection limits obtained with the RVC-epoxy resin composite enzyme electrodes are, in general, considerably better than those found in the literature for bioelectrodes constructed with epoxy resin as the binder. Finally, this composite electrode also performed well in the flow injection mode.

Amperometric biosensors sensitive to organic peroxides based on immobilization of redox organic dyes and horseradish peroxidase in polyester ionomer film

Simple and effective organic biosensors sensitive to organic peroxides such as 2-butanone per-oxide and tertbutyl hydroperoxide are constructed by immobilizing a series of redox organic dyes and horseradish peroxidase in Eastman-AQ polymer film. The organic dyes are methylene blue, methylene green, meldola blue, new methylene blue N and N-methyl phenazine methosulphate. The biosensors display high sensitivity and fast response to tertbubtyl hydroperoxide and 2-butanone peroxide because of high efficiency of electron transfer between immobilized horseradish peroxidase and the electrode via the redox organic dyes. The comparison of the biosensors employing different organic dyes is made in formal potential, linear range and response time.

Graphite−Poly(tetrafluoroethylene) Composite Enzyme Electrodes as Suitable Biosensors in Predominantly Nonaqueous Media

The performance of a graphite-poly(tetrafluoroethylene) Teflon composite amperometric ferrocyanide-mediated peroxidase electrode in a predominantly nonaqueous medium such as reversed micelles is discussed and compared with the behavior in a medium formed by acetonitrile/water. The composite electrode was constructed by purely physical entrapment of both the enzyme and the mediator into the bulk of the graphite-Teflon matrix with no need of covalent attachments. This biosensor responded rapidly to the changes in the concentration of both hydrogen peroxide and 2-butanone peroxide in reversed micelles formed with ethyl acetate, 0.1 mol L(-)(1) dioctyl sulfosuccinate as the surfactant, and a 4% phosphate buffer (pH 7.4) as the dispersed phase. The electrode showed a long-term operation due to the renewability of its surface. Moreover, reproducible responses were obtained with different electrodes fabricated from different composite matrixes. No significant loss of the enzyme activity was observed after four months of dry storage at 4 °C of the composite electrode. Limits of detection of 2.1 × 10(-)(7) and 3.5 × 10(-)(7) mol L(-)(1) were obtained for H(2)O(2) and 2-butanone peroxide, respectively. The possibility of using this biocomposite electrode in flowing systems, using the reversed micelles as the carrier, has been demonstrated. The kinetic of the enzymatic reaction was faster in a 90:10 acetonitrile/phosphate buffer medium than in reversed micelles, which can be attributed to the higher water content present in the former medium. A similar stability of the biosensor and a slightly better sensitivity for peroxides was observed in the acetonitrile/water mixture when compared with reversed micelles. Finally, the electrode also performed well in the flow injection mode.

Ferrocene-Conjugated Polyaniline-Modified Enzyme Electrodes for Determination of Peroxides in Organic Media

The development and characteristics of a reagentless amperometric organic phase enzyme electrode (OPEE) employing covalently attached horseradish peroxidase and an electrochemically deposited ferrocene-modified polyaniline film on a glassy carbon electrode is reported. The covalent attachment of ferrocene to an electrochemically deposited insoluble polymer film provided a mechanism of preventing the leaching of ferrocene into the predominantly organic solvents, required for construction of reagentless OPEE. Hydrodynamic voltammetry studies showed that the response of the OPEE to hydrogen peroxides increased at higher cathodic potentials; however, interference due to molecular oxygen also increased. Interference of molecular oxygen was minimized when the OPEE was operated at an applied potential of -50 mV (or less negative) vs Ag/AgCl. The cathodic response of the OPEE was found to increase steeply when the aqueous buffer content of the acetonitrile was increased from 0% to 5 and then plateau with no further increase when the buffer content was increased to 30%. The dynamic properties of this enzyme electrode were exploited for the detection of micromolar concentrations of different peroxides in flow injection analysis were the sensitivity trend was lauroyl peroxide>hydrogen peroxide>2-butanone peroxide>cumene hydroperoxide>tert-butyl hydroperoxide. Applicability of the enzyme electrode for measurement of peroxide in real sample was demonstrated

Amperometric biosensors in reversed micelles

The behaviour of a horseradish peroxidase (HRP) amperometric biosensor in different reversed micellar systems has been studied in order to extract overall conclusions about the possibility of using such media for developing enzyme amperometric biosensors. The enzymatic reaction employed involves the catalytic reduction of 2-butanone peroxide using ferrocene as mediator. The characteristics of the organic solvent used to form the reversed micelles, which affect the enzyme activity and stability, have been explored regarding the biosensor performance. The dependence of the electrode response on the amount of water in the micelle, the applied potential and the mediator concentration has been evaluated using n-hexane, chloroform and ethyl acetate as organic solvents. Ethyl acetate has been demonstrated to be the most suitable solvent for biosensor performance for analytical purposes. A systematic study of the different variables affecting biosensor behaviour when the nature of the surfactant used as the emulsifying agent is varied has also been carried out. Triton X-405, Tween 40, Hyamine 3500 and dioctyl sulphosuccinate (AOT) have been considered. The best reproducibility of the HRP electrode measurements was obtained for emulsions formed with AOT; these reversed micelles were the most appropriate for developing a method for the determination of 2-butanone peroxide. A detection limit of 0.4 μM was obtained.