Measurement methods organics

Separation and detection methods Very interesting hyphenated techniques have been developed for the separation and measurement of organic and inorganic lead spe-... 

International Standard ISO 5725, Accuracy (Tmeness and Precision) of Measurement Methods and Results, first edition, 1994-12-15 Part 2, International Standards Organization, Geneva... 

For destructive measuring methods, a CRM would serve as a reference to check the recovery of a particular matrix removal procedure. This is especially important for open destructions at atmospheric pressure. Alternatively, isotope dilution methods may be used once isotopic equilibrium is established, loss of analyte does not affect the analysis result. Isotope dilution techniques are only available in a few specialised laboratories. Another type of problem is encountered in pressurised methods oxidising the matrix in a closed vessel or bomb. Due to the large amounts of gas (CO2, NO, SO2) evolving from samples with a high organic matrix content, an excessive pressure build-up occurs that prohibits the use... 

In order to focus on more of the basic research problems related to radon, a symposium was organized in conjunction with the 191th National Meeting of the American Chemical Society. This volume presents most of the reports given at that symposium. There are five major groups of reports occurrence, measurement methods, physical and chemical properties of radon and its decay products, health effects, and mitigation of radon levels. 

Most of the methods of analysis for mercury actually measure inorganic mercury to measure either organic or total mercury by such methods, it is necessary to decompose any organic mercury compounds present. This decomposition can be effected by ultraviolet irradiation of the samples. Systems of this sort have been described [46-48]. Since as much as 50% of the mercury maybe present in organic form [46] the differentiation between inorganic and organic mercury can be of considerable importance. 

The earlier methods for the measurement of organic phosphorus generally used fairly drastic measures to decompose the organic compounds present and free the phosphates. For example, Duursma [34] used the technique originally described by Harvey [35] which included autoclaving the seawater with sulfuric acid at 140 °C for 6 h, at a pressure of 3 atmospheres. These methods required... 

An example of an automated colorimetric method, oxidation by ultraviolet irradiation for the determination of dissolved organic carbon in the presence of potassium persulfate [ 87], is that of Schreurs [86 ]. The method uses a Technicon analyser to measure dissolved organic carbon, is fast and precise, and may be used to measure dissolved organic carbon in both seawater and fresh water over the range 0.1 -10 mg C per litre. 

Wangersky PJ (1975) Measurement of organic carbon in seawater. In Analytical Methods in Oceanography (ed Gibb TRP) American Chemical Society Washington DC, p 148-162... 

Accuracy (Trueness and Precision) of Measurement Methods and Results - Part 1. General Principles and Definitions , ISO 5725-1 1994, International Organization for Standardization (ISO), Geneva, Switzerland 1994. 

Rapid equivalent methods - Generally based on a principle different from that of the corresponding laboratory method, alternative or surrogate systems are used more and more often for on-line and off-line monitoring. For example, the spectrophotometric methods or biosensors proposed for the measurement of organic compounds or electrochemical techniques for metals must be considered as alternative methods. 

Y. Hong and J. Kanicki, Integrating sphere CCD-based measurement method for organic light-emitting devices, Rev. Sci. Instrum., 74, 3572-3575, 2003. 

Zielinska B, Sagebiel JC, Harshfield G, et al. 1996. Volatile organic compounds up to C20 emitted from motor vehicles Measurement methods. Atmos Environ 30(12) 2269-2286. 

A recent brief review showed the working principles of various automatic analyzers6. A modified account of N and O analysis will be presented here. Today there exist in the market instruments that perform organic elemental analyses in a few minutes. The ease and speed of such analyses enable the use of such instruments for routine analysis. Although some operational details vary from model to model and between one manufacturer and another, all these instruments can be considered as exalted versions of the classical Pregl determination of C and H by conversion to CO2 and H2O, together with Dumas method for N by conversion to N2, the calorimetric bomb method for S by conversion to SO2 and SO3 and Schultzes method for O by conversion to CO. This is combined with modern electronic control, effective catalysts and instrumental measuring methods such as IR detectors and GC analyzers. 

International Organization for Standardization (ISO), Statistical methods for quality control, Vol. 2, 4th Edition, Accuracy (trueness and precision) of measurement methods and results - Part 2 Basic method for the determination of repeatability and reproducibility of a standard measurement method, ISO 1994(E), 5725-2. 

A number of significant oxygenated organic particulate compounds and gas-phase free radicals are formed by the reactions of gas-phase hydrocarbons (see Table 6-1 and (Chapter 2). The measurement methods for these substances are complicated and in the research stage. Their description is beyond the scope of this chapter. It is of major importance to develop methods for measuring hydroxyl and peroxyhydroxyl radicals, as well as the various oxygen species formed with ozone (see Chapter 12). 

ASTM. 1988. Standard practice for measuring volatile organic matter in water by aqueous-injection gas chromatography - method D 2908-87. In 1988 annual book of ASTM standards. Vol. 11.02. Water II. Philadelphia, PA American Society for Testing and Materials, 46-51. 

The COD method is preferable to the BOD method in determining the presence of oxygen-depleting substances in water because it produces faster results, usually in a matter of hours rather than days. The one disadvantage of the COD method is that it measures some organic substances in water that are not metabolized by aerobic bacteria. For this reason, the BOD and COD values obtained for the same sample of water may differ slightly. 

Experimental methods to measure the organic solute activity in surfactant solutions over a wide range of activities (not just at saturation) include vapor... 

International organization for Standardization, Accuracy (trueness and precision) of measurement methods and results, ISO/DIS 5725-1 to 5725-3, Draft versions 1990/91. 

However, Fraser et al. (1998) noted that this canister sampling technique may underestimate the methyl-naphthalenes. Thus, their methylnaphthalenes/naph-thalene ratios were lower than those obtained by Arey et al. (1989a) using Tenax-GC solid adsorbent. This may be due to significant adsorption of the methyl isomers to the canister (Arey, personal communication). Zielinska and co-workers (1996) evaluated measurement methods for VOCs up to C2() emitted from motor vehicles and reported that C8-Cl2 hydrocarbons were more stable on the Tenax cartridge than in canisters. Similar problems with canister sampling for organics are discussed in Chapter ll.A.4e. 

Zielinska, B., J. C. Sagebiel, G. Harshfield, A. W. Gertler, and W. R. Pierson, Volatile Organic Compounds up to C20 Emitted from Motor Vehicles Measurement Methods, Atmos. Environ., 30, 2269-2286 (1996). 

---