Vapor organic, sampling

Figure 3.2 Signal patterns from 80% organic vapor samples at 120°C. Responses are normalized to the surface loading of ionic liquids and the concentrations of vapors in the carrier gas. (Reprinted from Jin, X., Yu, L., Garcia, D., Ren, R.X., and Zeng, X., Anal. Chem., 78,6980-6989,2006. Copyright 2006 American Chemical Society. With permission.)...

TABLE II ORGANIC VAPOR SAMPLING AND ANALYTICAL RESULTS... 

The collection of air samples using air tubes and/or filters is of value during the course of the field research when performing SDDBM studies. The air tube/air filter data can be used to estimate the portion of the total body burden, which originates from respiratory exposure to the active ingredient. Of course, if an organic vapor respirator is used by the worker as a matter of course, the respiratory exposure component should be backed out of the final exposure calculation. 

Similar to the previous section, we discuss only selected works to highlight the development of SPMDs. Also, we include some discussion of several unpublished pilot smdies (Huckins, 1989) that influenced our early development of SPMDs. These pilot studies were directed solely toward sampling the aqueous phase. The flrst application of SPMDs for sampling organic vapors did not occur until several years later (Petty et al., 1993). To our knowledge, only SPMDs, PESs and SPMEs are being applied in both air and water, because the use of many passive samplers is limited to a specific medium and exposure scenario. 

Fig. 9.4.10 Apparatus for the gas flow-arc plasma method. The apparatus is composed of two components. The upper part is a glass Dewar, which accumulates small particles in a cryogenic matrix on the trim cooled with liquid nitrogen (LN). Sorv, inlet of organic vapor Syr, syringe for transferring produced colloids under anaerobic conditions RP, rotary pump S, target sample. Lower part is for plasma discharge. A BN furnace has gas inlets (G) and is specially designed for Ar gas to flow in screwed stream hence the plasma is emitted in a jet flame due to a plasma pinch effect. The black parts are copper electrodes cooled by water. In order to maintain a constant spacing between the surface of sample and tbe upper electrode, the sample position can move vertically so that the current through the sample to the upper electrode is precisely controlled and constant. This is very important to produce powders with a narrow size distribution.

Many of the charcoal tube methods are based on NIOSH Method P CAM 127 (4) for organic solvents. In this method, a known volume of air is drawn through a charcoal tube to trap organic vapors, the charcoal is transferred to a vial, and the sample is desorbed with carbon disulfide. The sample is analyzed by gas chromatography (GC) with flame ionization detection (FID). Most methods use CS2 as the desorption solvent because it yields good recoveries from charcoal and produces a very low flame response. 

Recent years have seen advances in collection and analytical methods to determine contaminant concentrations in the air. One of these innovations involves the sampling of Organic Vapors without the use of mechanical air pumps in particular the monitoring of personal exposures. 

The diffusional monitoring system is a much simpler, easier method to present a sample of organic vapor to a charcoal collector. It eliminates mechanical problems of pumps and in the case of the 3M system, provides for elution inside the monitor body, rather than forcing transfer of the sorbent. It has a wide dynamic range, a quick response to... 

The badge sampling rate is a direct function of the diffusion coefficient (D) of the organic vapor(s) being sampled and the total cross-sectional area (A) of the badge cavities. The rate is an inverse function of the diffusion path or length (L) of the cavities. 

To date, laboratory sampling tests for acetone, methyl-chloroform, trichloroethylene and toluene have confirmed the Pro- G-BB Organic Vapor Air Monitoring Badge s ability to ... 

As with any laboratory method, there are precautions and limitations of lyophilization that must be understood. Only aqueous solutions should be lyophilized. Organic solvents lower the melting point of aqueous solutions and increase the chances that the sample will melt and become denatured during freeze-drying. There is also the possibility that organic vapors will pass through the cold trap into the vacuum pump, where they may cause damage. 

As the temperature dependence of the CTL spectrum has information about the type of vapor, the present authors and coworkers [17] reported a method to recognize organic vapors by means of spectrum-temperature imaging. For this purpose, a system to simultaneously measure the CTL spectra at various temperatures was developed (Fig. 27). The sintered layer of the CTL catalyst is laid on a ceramic heater substrate of 5 x 60 mm2, which has a temperature distribution ranging from 440 to 530 °C along the stream of a sample gas in a quartz tube. A mask with an optical slit of 0.3 mm width is placed on a quartz tube. The CTL emission passing through the slit is focused on... 

The purpose of trip blanks is to assess the collected sample representativeness by determining whether contaminants have been introduced into the samples while they were handled in the field and in transit, i.e. in coolers with ice transported from the site to the analytical laboratory. A possible mechanism of such contamination is the ability of some volatile compounds, such as methylene chloride or chlorofluor-ocarbons (Freons), to penetrate the PTFE-lined septum and dissolve in water. Potential sources of this type of contamination are either ambient volatile contaminants or the VOCs that could be emanating from the samples themselves, causing sample cross-contamination. To eliminate ambient contamination, samples must not be exposed to atmospheres containing organic vapors. Cross-contamination is best controlled by such QA measures as sample segregation and proper packaging. 

Ambient blanks are intended to detect airborne contamination that may be affecting samples collected in atmospheres with high contents of organic vapor. This type of ambient contamination may be present at airport runways, refineries, gasoline... 

Before a well is sampled, as a health and safety measure, we may record organic vapor contents in the wellhead with a field photoionization detector (PID). Chemical odors emanating from the well may overpower the sampler and warrant the use of appropriate PPE. 

Open the well cap and measure organic vapor at the wellhead with a PID. Record the reading in the Groundwater Sampling Form. 

Semiquantitative field screening for organic vapor in soil headspace, at wellheads, at sampling... 

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