Formaldehyde hydrogen peroxide determination

Dasgupta, P. K., S. Dong, H. Hwang, H.-C. Yang, and Z. Genfa, Continuous Liquid-Phase Fluorometry Coupled to a Diffusion Scrubber for the Real-Time Determination of Atmospheric Formaldehyde, Hydrogen Peroxide, and Sulfur Dioxide, Atmos. Environ., 22, 949-964 (1988). 

If sampling is not followed immediately by analysis, the sample must be treated with a preservative, but not such as to falsify the analytical results use is made of 10% potassium dichromate solution, formaldehyde, hydrogen peroxide, alcoholic solution of phenol, mercuric chloride (about 5% solution), etc., a few drops being added. The last of these preserves milk very well for several days without altering its composition or disturbing the determinations, but its poisonous character necessitates precautions. 

The explosion limits have been determined for liquid systems containing hydrogen peroxide, water and acetaldehyde, acetic acid, acetone, ethanol, formaldehyde, formic acid, methanol, 2-propanol or propionaldehyde, under various types of initiation [1], In general, explosive behaviour is noted where the ratio of hydrogen peroxide to water is >1, and if the overall fuel-peroxide composition is stoicheiometric, the explosive power and sensitivity may be equivalent to those of glyceryl nitrate [2],... 

Determination of the Formaldehyde Content of the Solution obtained.—With a pipette 5 c.c. of the solution are run into a measuring flask and diluted to 50 c.c. with water. Of the diluted solution 20 c.c. are placed in a conical flask (capacity 250 c.c.), 30 c.c. of about 3 per cent hydrogen peroxide solution, previously made... 

ALTERNATE PROTOCOL 2 ENZYMATIC MEASUREMENT OF CHOLESTEROL Test combination kits for enzymatic determination of cholesterol in food are now commercially available. For the determination of total cholesterol, esterified cholesterol is hydrolyzed to free cholesterol and fatty acid under mild alkaline conditions. Cholesterol oxidase oxidizes free cholesterol to cholest-4-en-3-one to generate hydrogen peroxide, which further oxidizes methanol to formaldehyde. Formaldehyde then reacts with acetyl acetone in the presence of NH4+ ions to form yellow lutidine dye, which is subsequently determined spectrophotometric al 1 y. 

Its most common adulterations consist of dilution and removal oj cream. It may also be mixed with various extraneous substances (occasionally flour, starch, dextrin, albumin, etc.) or treated with antiseptics (boric acid, borax, salicylic acid, formaldehyde, benzoic add, fluorides, hydrogen peroxide, etc.) to make it keep, or with alkaline salts (sodium carbonate or bicarbonate) to hinder or correct for fermentation. Analysis of milk includes, therefore, the following determinations ... 

Experiments determining temperature dependence of methanol oxidation with hydrogen peroxide were carried out under the same conditions. Figure 4.13 shows methanol conversion and formaldehyde yield (10%) maxima at 590 °C. A further increase of temperature decreases formaldehyde content in the reaction mixture. This testifies to the process proceeding by the consecutive scheme with further transformation of formaldehyde, CO and C02 concentration increasing simultaneously. 

Chapter 4 presents experimental data on methane oxidation to formaldehyde with hydrogen peroxide. We shall not discuss them here again, but use them only for determinant D calculation. The calculated D value is 0.2 which, according to currently developed ideas, indicates the conjugated type of CH4 oxidation with hydrogen peroxide. 

The activation energy of free radical recombination approached zero. As a result of these investigations, the conditions for selective conjugated oxidation of methane to formaldehyde with hydrogen peroxide were determined and the process mechanism was suggested. The example is notable, because two types of free radicals (CH and H02) are reactive particles in it. 

In dilute alkaline solution formaldehyde is oxidized quantitatively to a formate by hydrogen peroxide. The percentage of formaldehyde in commercial formalin can be determined... 

Water, formaldehyde, acetaldehyde, acetone, methanol, hydrogen peroxide, CO, CO2, and H2 were detected among the volatile products. The aldehydes and hydrogen peroxide were determined by a polarograph-ic method. Gas and gas-liquid chromatography were used to analyze the other products. Coal and fine white sand with dipropionitrile ester as the stationary phase were used as the adsorbants. The gas carrier was helium. 

For the determination of hydrogen peroxide, formaldehyde and acetaldehyde in mixtures formed during the low-temperature oxidation of hydrocarbons, the hydrogen peroxide wave is recorded in an acidic buffer solution (in which the aldehydes do not interfere). The formaldehyde wave is measured in a solution to which titanium tetrachloride is added to eliminate the interference of hydrogen peroxide in acidic media, and which is brought to pH 12-2. The acetaldehyde wave is recorded in a similar solution to which dimedone is added before making alkaline, to remove the excess of formaldehyde. The application of dimedone,... 

Other chemiluminescence FIA methodologies for AA determination are based on AA acidic reduction of potassium dichromate to generate Cr(III) and subsequent luminol-hydrogen peroxide-Cr(III) chemiluminescence reaction [87,88], and on chemiluminescence reaction of AA with potassium permanganate in the presence of formaldehyde [89,90], formic acid [91], or CdTe nanocrystals [92] as sensitivity enhancers. Quinine is also used as an enhancer of chemiluminescence produced by reaction between AA and Ce(IV) in acid media [93]. Perez-Ruiz et al. [94] proposed a chemiluminescent reaction, in alkaline solution, of lucigenin with the products from the photooxidation of AA sensitized by toluidine blue. 

The temperature and density structure of the troposphere, along with the concentrations of major constituents, are well documented and altitude profiles have been measured over a wide range of seasons and latitudes for the minor species water, carbon dioxide, and ozone. A few profiles are available for carbon monoxide, nitrous oxide, methane, and molecular hydrogen, while only surface or low-altitude measurements have been made for nitric oxide, nitrogen dioxide, ammonia, sulfur dioxide, hydrogen sulfide, and nonmethane hydrocarbons. No direct measurements of nitric acid and formaldehyde are available, though indirect information does exist. The concentrations of a number of other important species, such as peroxides and oxy and peroxy radicals, have never been determined. Therefore, while considerable information concerning trace constituent concentrations is available, the picture is far from complete. 

The hydrogen evolved in the alkaline peroxide oxidation of formaldehyde has been used as a basis for a gas volumetric method of formaldehyde determination by Frankforter and West. ... 

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