Activated charcoal tubes

The primary method of analyzing 1,2-dibromoethane in air is by adsorption on a solid phase (i.e., activated charcoal tube or Tenax adsorbent) followed by thermal or solvent elution for subsequent quantification. GC/ECD and GC/MS are the most commonly used analytical techniques for... 

ASTM. 1987a. Standard practice for sampling atmospheres to collect organic compound vapors (activated charcoal tube adsorption method) - method D 3686-84. In 1987 annual book of ASTM standards. Vol. 11.03. Atmospheric analysis occupational health and safety. Philadelphia, PA American Society for Testing and Materials, 326-336. 

U.S. Dept, of Health, Education and Welfare, PHS, NIOSH Collaborative Testing of Activated Charcoal Tubes for Seven Organic Solvents, NIOSH Publication No. 75-184 (1975). 

The primary method of analyzing carbon disulfide in air is by adsorption on an activated charcoal tube followed by solvent elution for subsequent quantification. GC equipped with either an electron capture detector (ECD), photo-ionization detector (PID), or FPD has been used for measuring carbon disulfide after elution from the solid phase. Detection limits of low ppm levels of carbon disulfide in the air sample were achieved with these techniques (McCammon et al. 1975 Peltonen 1989 Smith and Krause 1978 UK/HSE 1983). NIOSH has recommended GC/FPD (method 1600) for determining carbon disulfide in air. The range of quantification is 3-64 ppm for a 5-L air sample (NIOSH 1984b). 

Figure 4 Diagram showing a closed-loop headspace collection device. 1, Conical flask 2, flower 3, battery-powered suction pressure pump 4, headspace collection trap 5, activated charcoal tube (purification of the air stream) 6, direction of airflow.

Health and Safety. Petroleum and oxygenate formulas are either flammable or combustible. Flammables must be used in facUities that meet requirements for ha2ardous locations. Soak tanks and other equipment used in the removing process must meet Occupational Safety and Health Administration (OSHA) standards for use with flammable Hquids. Adequate ventilation that meets the exposure level for the major ingredient must be attained. The work environment can be monitored by active air sampling and analysis of charcoal tubes. 

Various types of detector tubes have been devised. The NIOSH standard number S-311 employs a tube filled with 420—840 p.m (20/40 mesh) activated charcoal. A known volume of air is passed through the tube by either a handheld or vacuum pump. Carbon disulfide is used as the desorbing solvent and the solution is then analyzed by gc using a flame-ionization detector (88). Other adsorbents such as siUca gel and desorbents such as acetone have been employed. Passive (diffuse samplers) have also been developed. Passive samplers are useful for determining the time-weighted average (TWA) concentration of benzene vapor (89). Passive dosimeters allow permeation or diffusion-controlled mass transport across a membrane or adsorbent bed, ie, activated charcoal. The activated charcoal is removed, extracted with solvent, and analyzed by gc. Passive dosimeters with instant readout capabiUty have also been devised (85). 

Charcoal Tubes Reference has been made earlier to adsorption, which is the property of some solid materials, such as activated charcoal, to physically retain solvent vapors on their surfaces. In environmental health testing, the adsorbed vapors are removed, generally with a solvent, in a laboratory. The solvent is then analyzed by physical methods (gas chromatography, etc.) to determine the individual compounds whose vapors, such as benzene, were present in the sampled air. Industrial atmospheric samples can be collected in small glass tubes (4 mm ID) packed with two sections of activated charcoal, separated and retained with fiberglass plugs. To obtain an air sample, the sealed ends of the tube are broken off, and air is drawn through the charcoal at the rate of 1 liter per minute by means... 

Sorbent tubes Small glass tubes that contain sampling media such as silica gel or activated charcoal. 

A common approach for personal dosimetry is collection of pollutant on, e.g., silica gel, organic resins or activated charcoal in small tubes worn on the operator s lapel (Table 9.2). Silica gel is useful for polar chemicals charcoal finds wide use for non-polar substances. The pollutant is then solvent-extracted or thermally desorbed for subsequent analysis by, e.g., chromatography. 

Figure 6. Schematic of apparatus measuring Os uptake. Ozone was generated by the flow of the carrier gasses over UV lamps, as in (10). The scrubs (1 and 2) are bypass tubes filled with activated charcoal used to decompose O3. Valves A, B, and C provide different paths for the gas flow. The bubble tube contained 50 ml of solution and has been previously described (24).

Supportive care is important, especially in unconscious patients. If the airway is protected (gag reflex or cuffed endotracheal tube present), then activated charcoal can be given. Repeated doses of oral activated charcoal increase the rate of elimination of several tricyclic antidepressants, but may not influence outcome. 

Repeated dose of activated charcoal administered by oral route have been shown to enhance the non-renal elimination of carbamazepine, salicylates, phenobarbitone, phenytoin, digoxin, theophylline and meprobamate. In severe cases activated charcoal is to be administered via a nasogastric tube. 

Carbonized Resins. A special sorbent made by controlled thermal pyrolysis of polyvinylidene chloride (Dow developmental Adsorbent XF-4175L) (34) was shown to be three to five times more effective for the collection of highly volatile compounds, such as vinyl chloride (Figure 5) and methyl chloride, than the best available activated charcoal (31,36,37). Although this sorbent is not commercially available, Carbosive and Carbosive S show similar collection properties and they are available from gas chromatographic supply houses or may be obtained already packed in small collection tubes (SKC Inc., Eighty Four, PA). 

Surface Area and Mesh Size. 20/40 mesh sorbent is generally used to minimize the pressure drop across a sorbent tube. Some sorbents, such as Tenax-GC, are not available in these mesh sizes, but can still be used by increasing the cross-sectional area of the sampling tube to lower the overall pressure drop for these smaller sorbent particles. Surface areas vary from very low in Tenax-GC to over 1000 m2/g in activated charcoal. In some cases, the greater surface area may increase the capacity of the sorbent. 

Charcoal. Activated coconut charcoal has gained the status as the almost universal solid sorbent. Petroleum-based charcoal is less active, but is also widely used. Charcoal is a very effective sorbent and is generally used for collection of nonpolar organic solvent vapors. It also collects polar organics, but they frequently cannot be recovered. However, many organic substances that are reactive, polar, or oxygenated (e.g., chloroprene, acetic acid, and acetone) have been successfully collected and recovered from charcoal. Substances for which charcoal tube methods have been validated are listed in Table II. 

The evaluation of diffusion samplers reported in this paper was initiated as an internal project at Arthur D. Little, Inc., to develop for ourselves a base of data which would help us to judge the utility of diffusion samplers in our work. Diffusion samplers were purchased from the two firms active in the marketplace when the field study began (early 1979), Abcor and 3M. A program was devised wherein, during each of approximately 50 surveys being undertaken in plastic fabrication plants, four to six diffusion samplers would be exposed, each adjacent to a charcoal tube personal sample. At the conclusion of the field sampling, a data base of over 100 pairs of samples (each pair including a diffusion sample and a charcoal tube sample) had been compiled for each of the two diffusion samplers. 

The activated charcoal (Columbia JXC) was selected for collection of the analytes. This adsorbent has been reported to give good results for ethylene oxide (9). The sampling tubes consisted of borosilicate glass tubes (15 cm x 4 mm i.d.) packed with 400 mg of the charcoal (300 mg in front section and 100 mg... 

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