Determination in air

J. Greyson, Carbon, Nitrogen and SulfurPollutants andPheir Determination in Air and Water, Marcel Dekker, Inc., New York, 1990. 

For carrying out of given researches method of synthetic pyrethroids determination in air has been developed. Chromatographic behaviour is investigated and optimum conditions of the synthetic pyrethroids analysis with application of capillary column with stationary phase DB-5 and electron-capture detector are selected. 

Polytetrafluoroethylene decomposition products thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentration should be minimal. (Trade names Algoflon, Fluon, Teflon, Tetran.)... 

In this reaction, iodine is liberated from a solution of potassium iodide. This reaction can be used to assess the amount of ozone in either air or water. For determination in air or oxygen, a measured volume of gas is drawn through a wash bottle containing potassium iodide solution. Upon lowering the pH with acid, titration is effected with sodium thiosulfate, using a starch solution as an indicator. There is a similar procedure for determining ozone in water. 

For the enantiomeric pair, (2R, 3R) 19a and (2,S , 35) 19b, the odor thresholds are very much higher (> 12 to > 30 pg L 1 in H20, not determined in air). These two materials both were contaminated with small amounts of the highly potent (2R, 35) enantiomer so these values are not too reliable. The (2R, 35) enantiomer is one of the most powerful flavor components to be discovered. 

Nitro-PAH were determined in air particulate matter by RP-HPLC with reductive electrochemical detection sensitivity of 3-0.3 ng injected483. 

Clear, colorless, watery-liquid with a chloroform-like odor. Odor threshold concentrations determined in air were 21.4 ppmv (Leonardos et al., 1969) and 3.9 ppmv (Nagata and Takeuchi, 1990). The average least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 10 and 2.6 mg/L, respectively (Alexander et al., 1982). 

V-Nitrosodiethanolamine can be determined in air and bulk process samples. Air samples are collected on glass fibre filters, extracted with 2-propanol and analysed by gas chromatography with thermal energy analyser detection. The limit of detection is 200 ng per sample (0.42 pg/m ). Bulk samples can be screened for 7V-nitrosodiethanol-amine by high-performance liquid chromatography (HPLC) with ultraviolet detection (Occupational Safety and Health Administration, 1990). 

Ellwood PA, Hardy HL, Walker RF. 1981. Aliphatic and aromatic isocyanates and their oligomers were determined in air by high-performance thin-layer chromatography. Analyst(London) 106(1258) 85-93. 

Tsitouridou R, Samara C (1993) First results of acidic and alkaline constituents determination in air particulates of Thessaloniki, Greece. Atmos Environ Part B 27 313-319... 

In studies of toxaphene in Lakes Superior [46] and Ontario [51,67], two persistent congeners, B8-1413 and B9-1979, were determined in air and six other congeners in water. B8-1413 and B9-1979 were of particular interest because they were among the most prominent chlorobornanes in Great Lakes fish [74,81,82], It should be noted that although peaks matching the retention... 

The TOC content can also be determined in air. However, the parameter used in this case is called total hydrocarbons (TH) rather than TOC. One significant difference between the OC in air and in other matrices is that the atmosphere contains a nearly constant background concentration of methane ( 1.7 u.g g 1 v/v),14 derived mostly from natural sources. Thus, any TH measurement will... 

Formaldehyde, which is difficult to detect at trace levels without deri-vatization, was determined in air to about 200 ppb with the HID. Reviews of the performance characteristics and applications of the HID have been published [113,114]. 

Atomic fluorescence spectroscopy (AFS) has also been used as a means of detection in gas chromatography. Alkylmercury compounds have been determined in air by cold-vapor GC-AFS with limits of detection of about 0.3-2.0 pg [129]. 

We have already seen in Chapter 2 that choice of atomizer system to be used may have a dramatic effect upon sensitivity, and thus upon signal-to-noise ratio. It is necessary to choose not only between flames, electrothermal atomization (ETA), and cold vapour and hydride generation techniques (which are discussed in Chapter 6), but sometimes also between different flames. Those elements which tend to form thermally stable oxides, such as Al, Ti, Si, Zr, may only be determined in a hotter, reducing nitrous oxide-acetylene flame. They cannot be determined with useful sensitivity in the air-acetylene flame. Some elements, Ba and Cr for example, may be determined in air-acetylene, but are more efficiently atomized in nitrous oxide-acetylene. 

Studies carried out with the aim of developing models to estimate migration include a study by Aurela and Ketoja (2002). They estimated the diffusion rate of model compounds (butanol, ethanol, butyl acetate and tetrahydrofuran) in air at room temperature. They then measured the diffusion of these substances through papers with different grammages (and hence, porosities) produced from birch Kraft pulp. The model compounds were not in contact with the test papers and hence transferred via the gas phase. They concluded that the diffusion constants determined in air could be used in random walk simulation to predict migration in a fibre network. Random walk simulations are a mathematical means of modelling processes based on probability distribution and are often applied to investigate diffusion processes. 

The surface tension of thin Sn foils was also determined in air. No attempt was made to prevent the samples from oxidizing. The surface tension of the Sn samples was determined to be 452 dynes/cm at 88 % T j. This value is lower than the values reported in the literature of 500 dynes/cm(26,27). This lower value is consistent with a sample that was partialy oxidized as evidenced by XRD. No attempt was made to calculate the surface free energy of the Sn due to the presence of the bulk oxide. 

Of the various methods suggested, the two described here enable very small quantities of carbon monoxide to be determined in air. Other methods (gas-volumetric, gravimetric, by combustion, etc.) may be found in the usual books on chemical analysis. 

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