Organic compounds analysis methods

Accuracy, organic compound analysis, methods needed, 288-289 Acetylperoxy radicals, conversion to H02, 311... 

Many semiempirical methods have been created for modeling organic compounds. These methods correctly predict many aspects of electronic structure, such as aromaticity. Furthermore, these orbital-based methods give additional information about the compounds, such as population analysis. There are also good techniques for including solvation elfects in some semiempirical calculations. Semiempirical methods are discussed further in Chapter 4. 

The EPA Contract Laboratory Program (CLP) has responsibility for managing the analysis programs required under the U.S. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The approved analytical methods are designed to analyze water, soil, and sediment from potentially hazardous waste sites to determine the presence or absence of certain environmentally harmful organic compounds. The methods described here all require the use of GC/MS. 

Series—Sample preparation and cleanup methods for metal and organic compound analysis... 

Surrogate standard recovery measures analytical accuracy for each individual sample. Approved methods for organic compound analysis usually recommend the surrogate standard selection. Similar to target analytes, multipoint calibration curves are prepared for surrogate standards. 

Add 0.008% of sodium thiosulfate (Na2S203) to all samples collected for organic compound analysis with the exception of SW-846 Methods 8081, 8082, and 8141, if residual chlorine is present. 

The emphasis of this work is on the analysis of plastic additives through gas chromatography/mass spectrometry (GC/MS). GC/MS systems are a common analytical tool in quality control and analytical service laboratories and electron impact (El) mass spectra are recognized as reliable data for the identification of organic compounds. Traditional methods have employed a flame ionization detector (FID) with identifications based solely on GC retention time data. These methods lack the specificity necessary to distinguish between components attributable to the sample matrix or the additive(s). 

The rapid evolution of microcomputers has led to the derivative transformation of spectral data, which offer a powerful tool for both qualitative and quantitative analysis of mixtures of organic compounds. The method has found increasing application in UV-visible spectrophotometric analysis of organics for background correction and for resolution enhancement. The ability to eliminate matrix interferences such as irrelevant absorption and light scattering has been of particular value. 

The method of superposition lies at the basis of any scheme of identification, but because of the multiplicity of organic compounds this method in itself would prove of little value a scheme of analysis dependent upon it alone would lead to an immense amount of unnecessary work without the equivalent return in development of logical thinking and without the accumulation of a systematic knowledge of organic chemistry which may be best developed in the qualitative field. In order to be of value, the method of superposition must be preceded by a systematic method of elimination. 

The comparatively wide prevalence of micro-methods of quantitative organic analysis, applied more particularly to the estimation of the constituent elements in an organic compound, may cause the advisability of including the macro-methods in Part IV to be questioned. Quite apart, however, from the fact that the micro-methods still find no place in many laboratories, we consider that thorough practice in the macro-methods of quantitative analysis to be not only an excellent introduction to the micro-methods themselves, but also a valuable training in exact manipulation generally. 

In order to detect these elements in organic compounds, it is necessary to convert them into ionlsable inorganie substanees so that the ionic tests of inoiganio qualitative analysis may be applied. This conversion may be accomplished by several methods, but the best procedure is to fuse the organic compound with metallio sodium (Lassalgne s test). In this way sodium cyanide, sodium sulphide and sodium halides are formed, which are readily identified. Thus ... 

The general method to be adopted for the analysis of mixtures of organic compounds is to separate them into their components and to... 

Although many quantitative applications of acid-base titrimetry have been replaced by other analytical methods, there are several important applications that continue to be listed as standard methods. In this section we review the general application of acid-base titrimetry to the analysis of inorganic and organic compounds, with an emphasis on selected applications in environmental and clinical analysis. First, however, we discuss the selection and standardization of acidic and basic titrants. 

Coulometry may be used for the quantitative analysis of both inorganic and organic compounds. Examples of controlled-potential and controlled-current coulometric methods are discussed in the following sections. 

Kjeldahl analysis an acid-base titrimetric method for determining the amount of nitrogen in organic compounds, (p. 302)... 

The Clean Water Act (1972) requires discharge limits to be set on industrial and municipal wastewater, and these analyses are outlined in the National Pollution Discharge Elimination System for the 600 Series Methods. Method 624 covers the analysis of purgeable organic compounds Method 625 covers the analysis of 81 bases, neutrals, and acids Method 613 describes the analysis of dioxins and furans. 

To satisfy the Resource Conservation and Recovery Act (1977) and its amendment for hazardous and solid waste (1984), the 80(K) Series Methods have been designed to analyze solid waste, soUs, and groundwater. In particular, methods 8240/8260 require the use of a purge-and-trap device in conjunction with packed or capillary GC/MS, respectively, for the analysis of purgeable organic compounds. Methods 8250/8270 concern analyses for the less-volatile bases, neutrals, and acids by GC/MS after extraction from the matrix by an organic solvent. 

Comprehensive accounts of the various gravimetric, polarographic, spectrophotometric, and neutron activation analytical methods have been pubHshed (1,2,5,17,19,65—67). Sampling and analysis of biological materials and organic compounds is treated in References 60 and 68. Many analytical methods depend on the conversion of selenium in the sample to selenous acid, H2Se02, and reduction to elemental selenium when a gravimetric deterrnination is desired. 

Infrared Spectrophotometry. The isotope effect on the vibrational spectmm of D2O makes infrared spectrophotometry the method of choice for deuterium analysis. It is as rapid as mass spectrometry, does not suffer from memory effects, and requites less expensive laboratory equipment. Measurement at either the O—H fundamental vibration at 2.94 p.m (O—H) or 3.82 p.m (O—D) can be used. This method is equally appticable to low concentrations of D2O in H2O, or the reverse (86,87). Absorption in the near infrared can also be used (88,89) and this procedure is particularly useful (see Infrared and raman spectroscopy Spectroscopy). The D/H ratio in the nonexchangeable positions in organic compounds can be determined by a combination of exchange and spectrophotometric methods (90). 

Method 25 applies to the measurement of volatile organic compounds (VOC) as nonmethane organics (TGNMO), reported as carbon. Organic particulate matter will interfere with the analysis, and, therefore, in some cases, an in-stack particulate filter will be required. The method requires an emission sample to be withdrawn at a con-... 

N. A. Tananaev, simultaneously with F. Feigl, developed the spot analysis. Known Tserevitinov method for determining labile hydrogen atoms in organic compounds (1902-1907 should be noted (the method was later improved by A.P Terent ev). In the USSR, there were powerful schools in liquid-liquid extraction and inverse voltammetry. 

DETERMINATION OF ORGANIC COMPOUNDS BY RADICAL INDICATOR REACTIONS IN KINETIC METHODS OF ANALYSIS... 

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