Organic determination under acidic conditions

In each class the problem may be resolved into two essential parts (i) the breakdown of the organic compound under appropriate conditions to give a quantitative yield of fluoride ions in aqueous solution, and (ii) the determination of the concentration of these fluoride ions. Methods of breaking down the organic compounds were examined and the procedure adopted for the phosphorofluoridate was different from that used for the fluoroacetate series. From both, however, sodium fluoride was obtained as the breakdown product containing all the fluorine present. After numerous preliminary experiments we came to the conclusion that on the macro-scale a very convenient method of determining the quantity of fluoride ions in the products was by precipitation as lead chlorofluoride,2 PbCIF, which was then dissolved in dilute nitric acid and the chloride was determined by the Volhard method and calculated to the equivalent amount of fluorine. We determined carefully the conditions for the quantitative precipitation of lead chlorofluoride. 

The heavy metal contaminants are strongly adsorbed by soil constituents such as organic matter, clays and metal hydroxides. Mobility and bioavailability in turn being determined by soil pH, organic matter content and redox conditions. Most metals are more mobile under acid conditions. 

Alternatively, direct analysis of nonfluorescent organic ligands by adding an excess of metal ion to form florescent compounds is also possible. Although this derivatization strategy has attractive analytical potential for the analysis of nonfluorescent aromatic compounds, it has received little attention. A typical example includes the fluorimetric determination of anthracyclines and tetracyclines as metal chelates with Mg " ", Ca " ", and Eu + under neutral or alkaline solutions, and with Al + or Zr", under acidic conditions. 

Ions that are most commonly determined in food samples are inorganic anions, carboxylic acids, metal ions, and organic cations. Some anion-exchange stationary phases do not always allow a baseline-resolved separation of all inorganic and organic ions under isocratic conditions. 

ISO 2870 1986 (E) Surface active agents—Detergents—Determination of anionic-active matter hydrolyzable and non-hydrolyzable under acid conditions. International Organization for Standardization, Geneva. 

Highly hydrophilic compounds belonging to biogenic amines were analyzed in a reversed phase system, modified with the addition of ionic liquids l-Ethyl-3-methylimidazolium hexafluoro-phosphate and the chaotropic salt NaPp6 on a Discovery HS CIS column under acidic conditions. The effect of the additives concentration and the presence of organic solvent on the analytes chromatographic parameters, such as retention factor, tailing factor and theoretical plate numbers, were determined (24). 

Most solvent products, especially organic solvents and some additives, emitted from paints and varnishes are VOCs. The largest components of VOCs are solvents, e.g., aliphatic and aromatic hydrocarbons, alcohols, amines, acids, aldehydes, esters, ketones, ter-penes. The defrnition of the term VOC varies, a standard definition is published by CEN (European Committee for Standardization) VOCs are any organic liquids and/or sohds that evaporate spontaneously at the prevailing temperature and pressure of the atmosphere. VOCC (volatile organic compound content) is defined as follows Mass of the volatile organic compounds in a coating material, as determined under specified conditions. 

Description of Method. Creatine is an organic acid found in muscle tissue that supplies energy for muscle contractions. One of its metabolic products is creatinine, which is excreted in urine. Because the concentration of creatinine in urine and serum is an important indication of renal function, rapid methods for its analysis are clinically important. In this method the rate of reaction between creatinine and picrate in an alkaline medium is used to determine the concentration of creatinine in urine. Under the conditions of the analysis, the reaction is first-order in picrate, creatinine, and hydroxide. 

The dehydrohalogenated product reacts with 85% sulfuric acid to produce a red complex of unknown composition with an absorption maximum at 555 mfi (Figure 1). No other organic insecticide now in use produces any color under similar conditions. Therefore, the method is specific for methoxychlor. Fats and waxes, however, yield strong brown colors which will completely mask the methoxychlor reaction. In the method described this interference has been reduced to a point where it introduces an error of less than 1% when the methoxychlor concentration is between 5 and 50 micrograms. Quantities of methoxychlor of less than 1 microgram may be determined by this method. 

Earlier studies showed that reactions of sugars with ammonia lead to small molecules such as amines or organic acids. A. L. Weber has reported important autocatalytic processes occurring when trioses are allowed to react with ammonia under anaerobic conditions, such reactions provide products which are autocatalyt-ically active. Their autocatalytic activity was determined directly by investigating their effect on an identical triose-ammonia reaction. Both an increase in the triose degradation rate and an increased rate of synthesis of pyruvate, the dehydration product of the triose, were observed. Such processes may have been of importance for prebiotic chemistry occurring on the primeval Earth (Weber, 2007). 

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