Sorbent solids

The volume of sample that can be passed through a solid sorbent before the analytes are no longer retained. 

D. W. HoWid.2cy, A Eiterature Survey Methodsfor the Removal of Iodine Spedafrom Off-Gas andEiquid Waste Streams of Nuclear Power and Nuclear Fuel Reprocessing Plants, with Emphasis on Solid Sorbents, ORNL/TM-6350, Oak Ridge National Laboratory, Oak Ridge, Term., 1979. 

The opportunity of application of filters, solid sorbents and absorbing solutions has been investigated for synthetic pyrethroids concentrating from air. Silicagel KSK and polysorb are provided quantitative sorbption and desorbption pyrethroids. In case of aerosol formulations application of paper filters is possible. 

Influence of speed and duration of aspiration on concentrating from air of pesticides as aerosol and vapors are investigated. Optimum conditions of concentrating on solid sorbents and paper filters are speed of 5 1/min during 20 minutes. 

One example is sampling for S02- Liquid sorbents for SO2 depend on the solubility of SO2 in the liquid collection medium. Certain liquids at the correct pH are capable of removing ambient concentrations of SO2 with 100% efficiency until the characteristics of the solution are altered so that no more SO2 may be dissolved in the volume of liquid provided. Under these circumstances, sampling is 100% efficient for a limited total mass of SO2 transferred to the solution, and the technique is acceptable as long as sampling does not continue beyond the time that the sampling solution is saturated (1). A second example is the use of solid sorbents such as Tenax... 

The collection medium for gases can be liquid or solid sorbents, an evacuated flask, or a cryogenic trap. Liquid collection systems take the form of bubblers which are designed to maximize the gas-liquid interface. Each design is an attempt to optimize gas flow rate and collection efficiency. Higher flow rates permit shorter sampling times. However, excessive flow rates cause the collection efficiency to drop below 100%. 

Fig. 13.2 Solid sorbent collection tube, (a) The tube is packed with a granular medium, (b) As the hydrocarbon-containing air is passed through the collection tube at f, f, and f, the collection medium becomes saturated at increasing lengths along the tube.

A solid sorbent Tenax cartridge has a capacity of 100 fig of toluene. If samples were collected at a rate of 5 liters/min, calculate the maximum ambient concentration which can be determined by an hourly sample and a 15-min sample. 

Lab method using diffusive solid sorbent tubes, thermal desorption and gas chromatography 80... 

Lab method using pumped solid sorbent tubes, solvent desorption and gas chromatography 96... 

Desorption The removal of adsorbed materials from a solid sorbent by the use of a solvent or the application of heat. Desulfurization The removal of sulfur from flue or other sulfur-containing gases. 

Gas chromatograph (GC) An analytical instrument with an internal tube or column that contains a solid sorbent, which allows some components of an injected sample to pass more quickly than others, separating the substances in the sample. 

Passive sampling Sampling that depends on the diffusion of the contaminant into a solid sorbent. 

Sample badge A small clip-on device that contains solid sorbent and is used for... 

Air Collect on solid sorbent extract with diethyl ether in hexane GC/FPD No data 72-105 EPA1980d... 

Analysis of environmental samples is similar to that of biological samples. The most common methods of analyses are GC coupled to MS, ECD, a Hall s electrolytic conductivity detector (HECD), or a flame-ionization detector (FID). Preconcentration of samples is usually done by sorption on a solid sorbent for air and by the purge-and-trap method for liquid and solid matrices. Alternatively, headspace above liquid and... 

Impingers and bubblers. Figure 8.5, containing liquids have been used extensively for collecting high boiling, reactive or polar substances that cannot be quantitatively recovered from solid sorbents [8,72]. They are most frequently used as personal sampling systems and in combination with filters and various... 

In off-line extraction the extracted analytes are collected and isolated independently from any subsequent analytical technique, which is to be employed next. For example, the extracted analyte can be collected in a solvent or on a solid sorbent. The choice of the collection method affects the possibilities for further analysis. The extracts may be used for final direct measurements (i.e. without further separation), e.g. UV and IR analysis. More usually, however, extraction is a pre-separation technique for chromatography, either off-line (the most common mode of SEE) or on-line (e.g. SFE-GC, SFE-LC-FTTR, etc.). The solvents used in extraction may affect subsequent chromatography. 

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