Recovery Of Hydrogen Peroxide Research Articles

Method for determination of hydrogen peroxide in adulterated milk using high performance liquid chromatography

Hydrogen peroxide is widely used for disinfection purposes by food industry enterprises. Apart from other purposes it is also used to sterilize the packaging of dairy products. In some countries hydrogen peroxide is added to milk as an adulterant for shelf life extension. However, in most countries the concentration of hydrogen peroxide in milk is limited or it is even prohibited to add this substance to the product. This study is the first one to describe the method of determination of hydrogen peroxide in milk using high performance liquid chromatography. Indirect quantitative evaluation of hydrogen peroxide is carried out according to the amount of triphenyl oxide produced after the reaction between hydrogen peroxide with triphenylphosphine. It has been shown that interaction of triphenylphosphine and hydrogen peroxide required about 40 min. The detection limit of this method is 0.28 mg/L. The recovery of hydrogen peroxide was from 97.8% to 103.8%.

Analysis of Hydrogen Peroxide in an Aqueous Extract of Cigarette Smoke and Effect of pH on the Yield

An analysis of hydrogen peroxide in an aqueous extract of cigarette smoke, which contains many redox-active compounds, requires a method with high selectivity. An aqueous extract of the particulate phase of cigarette smoke was analyzed by HPLC with an electrochemical detector (ECD). Samples were prepared by collecting the particulate phase of the cigarette smoke on a glass fiber filter and extracting it with a phosphate buffer. The obtained solution was purified by using a Waters Oasis MCX cation-exchange cartridge, and then analyzed by an HPLC-ECD system with a Shodex KS-801 mixed-mode resin column. Pre-injecting hydrogen peroxide at a high concentration into the HPLC instrument stabilized the analytical results. The recovery of hydrogen peroxide by using an extract of the particulate phase of the cigarette smoke was more than 80%. An increase in the amount of hydrogen peroxide was observed during extraction with the phosphate buffer at higher pH values. In contrast, extraction with phosphoric acid did not increase the amount of hydrogen peroxide during extraction.

A peroxidase-tetrathiafulvalene biosensor based on self-assembled monolayer modified Au electrodes for the flow-injection determination of hydrogen peroxide

The construction and performance under flow-injection conditions of an integrated amperometric biosensor for hydrogen peroxide is reported. The design of the bioelectrode is based on a mercaptopropionic acid (MPA) self-assembled monolayer (SAM) modified gold disk electrode on which horseradish peroxidase (HRP, 24.3U) was immobilized by cross-linking with glutaraldehyde together with the mediator tetrathiafulvalene (TTF, 1mumol), which was entrapped in the three-dimensional aggregate formed. The amperometric biosensor allows the obtention of reproducible flow injection amperometric responses at an applied potential of 0.00V in 0.05molL(-1) phosphate buffer, pH 7.0 (flow rate: 1.40mLmin(-1), injection volume: 150muL), with a range of linearity for hydrogen peroxide within the 2.0x10(-7)-1.0x10(-4)molL(-1) concentration range (slope: (2.33+/-0.02)x10(-2)Amol(-1)L, r=0.999). A detection limit of 6.9x10(-8)molL(-1) was obtained together with a R.S.D. (n=50) of 2.7% for a hydrogen peroxide concentration level of 5.0x10(-5)molL(-1). The immobilization method showed a good reproducibility with a R.S.D. of 5.3% for five different electrodes. Moreover, the useful lifetime of one single biosensor was estimated in 13 days. The SAM-based biosensor was applied for the determination of hydrogen peroxide in rainwater and in a hair dye. The results obtained were validated by comparison with those obtained with a spectrophotometric reference method. In addition, the recovery of hydrogen peroxide in sterilised milk was tested.

Flow injection spectrophotometric determination of hydrogen peroxide using a crude extract of zucchini (Cucurbita pepo) as a source of peroxidase

A flow injection (FI) spectrophotometric procedure is presented for determining hydrogen peroxide for pharmaceutical use and in swimming pool water samples. Crude extracts of several vegetables such as peach, yam, manioc, artichoke, sweet potato, turnip, horseradish and zucchini were investigated as the source of peroxidase (donor: hydrogen peroxide oxidoreductase, POD; EC 1.11.1.7). Of these, a zucchini crude extract was found to give highest specific activity and was used directly as the carrier solution. This enzyme catalyses the oxidation of guaiacol in the presence of hydrogen peroxide to tetraguaiacol, which shows strong absorbance at 470 nm. For the optimum extraction conditions found, the peroxidase activity in the crude extract did not vary for at least 5 months when stored at 4 °C and decreased by only 2–3% during an 8 h working period at 25 °C. The recovery of hydrogen peroxide from two samples ranged from 97.8 to 103.0% and a rectilinear calibration curve for hydrogen peroxide concentration from 1.6 × 10–5 to 6.6 × 10–4 mol l–1 was obtained. A detection limit of 2.1 × 10–6 mol l–1 and a sample throughput of 32 h–1 were attained. The relative standard deviations were <0.2% for hydrogen peroxide solutions containing 2.0 × 10–4 and 4.0 × 10–4 mol l–1 (n = 10) and a paired t-test showed that all results obtained for water samples using this FI procedure and permanganate titration agreed at the 95% confidence level.

Captopril scavenges hydrogen peroxide and reduces, but does not eliminate, oxidant-induced cell injury.

We investigated whether captopril, an angiotensin-converting enzyme (ACE) inhibitor with a sulfhydryl group, enalaprilat, an ACE inhibitor without a sulfhydryl group, and cysteine, an amino acid with a sulfhydryl group but no ACE-inhibiting properties, could scavenge hydrogen peroxide and prevent oxidant-induced cell injury. When 0.1-2.5 mM concentrations of captopril, cysteine, or enalaprilat were incubated with xanthine oxidase and hypoxanthine for 0-120 min, the recovery of hydrogen peroxide was significantly (P < 0.001) reduced in the presence of captopril or cysteine, whereas enalaprilat had no effect on the recovery of hydrogen peroxide. Captopril and cysteine could not scavenge hydrogen peroxide when the sulfhydryl group was blocked with N-ethylmaleimide. When human renal tubular epithelial cells and human umbilical vein endothelial cells were exposed to hydrogen peroxide, oxidant-induced depletion of ATP and efflux of [3H]adenine metabolites was mildly reduced in the presence of captopril or cysteine but was not altered by enalaprilat. Cysteine was more effective in preventing oxidant-induced cell injury than captopril. We conclude that because of its sulfhydryl group, captopril at millimolar concentrations can scavenge hydrogen peroxide and can slightly reduce, but does not eliminate, oxidant-induced cell injury.

Photosynthesis of hydrogen peroxide by crystal phosphors

The photosynthesis of hydrogen peroxide in the presence of zinc oxide, cadmium sulphide or basic zinc carbonate, as a means of storing solar energy, is re-examined. It is shown that with due allowance for losses of incident energy by the processes of reflection and luminescence, a maximum quantum yield of 0.5 can be obtained when no nonluminous transitions are incurred. Of the two quanta required to produce one equivalent of hydrogen peroxide, one is consumed to excite an electron whilst the other is, most likely, used to release a negatively charged oxygen or water molecule from the surface of the solid catalyst. The central problem in the recovery of hydrogen peroxide from these systems lies in the efficient removal of hydroxyl free radicals which are produced in concentrations equivalent to ·OOH or H·, the precursors of hydrogen peroxide. As the expenditure of chemical potential required to take care of ·OH is greater than the gain in free energy due to the generation of H2O2, these processes, and others based on the same electronic processes, must be considered thermodynamically unsound.