Anal. Chem. 1985, 57,238 R-254 R
(8SS)Tamaki, M., Hiraki, T., Watanabe, H., "Fundamental studies on Sampiing method of particulate nitrite in the air," Teiki Osen Gakkaishi, 17, 252-7 (1982). (9SS) Tamaki, M., T. Hiraki, H. Watanabe, "Reactions of particulate nitrite with molecular oxygen-water and ozone," Hyogo-ken Kogal Kenkyusho Kenkyu Hokoku, 15, 1-5 (1983). (1OSS) Burgess, D. D., "Evaluation of membrane filters for instrumental neutron activation analysis of alrborne particulates," J . Radioanal. Chem ., 74, 253-6 (1982). Aerosol Generatlon (1TT) John, W., Wail, S. M., "Aerosol testing techniques for size-seiectlve samplers," J . Aerosol Sci., 14, 713-27 (1983). (2TT) Mitchell, J. P., "The production of aerosols from aqueous solutions using the spinning top generator," J . Aerosol Scl., 15, 35-45 (1984). (3TT) Mitchell, J. P., Ramsey, C. A., Rowe, N. A., "The generation of caiibratlon aerosols of known particle number concentrafions," J . Aerosol Sci., 14, 257-60 (1983).
(4TT) Betz, L. R., Grob, R. L., "Generation of a lead metal aerosol test atmosphere," J . Environ. Sci. Health, Pert A , A19, 469-5013 (1984).
Other (1UU) Hikade, D. A,, Stedman, D. H., Walega, J. G., "Portable chemiluminescence detector for nickel carbonyl," Anal. Chem ., 58, 1629-32 (1984). (2UU) Cahill, T. A., Matsuda, Y., Shadoan, D.,Eidred, R. A,, Kusko, B. H., "Forward alpha scattering techniques (FAST) for elements hydrogen through fluorine," Nucl. Instrum. Methods f h y s . Res ., Sect. B , 231, 263-7 (1984). (3UU) Farmer, M. E., Linton, R. W., "Correlative surface analysis studies of environmental particles," Environ. Scl. Techno/. 18, 319-26 (1984). (4UU) Jach, T., Powell, C. J., "X-ray photoemission spectroscopy of environmental particles," Envlron. Sci. Technol., 18, 58-61 (1984). (5UU) Fukasawa, T., Iwatsuki, M., Tiiiekeratne, S. P., "X-ray diffraction analysis of airborne particulates collected by an Andersen sampler. Compound distrlbution vs. particle size," Environ. Sci. Technol., 17, 598-602 (1983).
Industrial Hygiene Richard G . Melcher* and Marsha L. Langhorst The Dow Chemical Company, Michigan Applied Science and Technology Laboratories, Analytical Laboratory, 574 Building, Midland, Michigan 48640
A. INTRODUCTION This review covers a period including 1983 and 1984 for those sections which were initially covered in the 1983 Analytical Reviews (AI). Many of the basic concepts of the most widely used techniques for personal monitoring were discussed in that review and only a 2-year update will be included at this time. Several new sections-F. Biomonitoring, G. Gas Monitoring Instruments And Sensors, H. Particulates, and I. Formaldehyde-are covered in greater detail and include references for a period of approximately 5 years. The section on Chemical Dosimeters has been expanded to include a discussion on validation and evaluation of methods. The emphasis of this review relates mainly to analytical technology used for the detection and determination of chemicals to assess exposure or potential exposure of personnel in the workplace. Discussions on toxicology and hazard assessment are not included. A number of reviews dealing with various phases of atmospheric analysis have been recently published (A2-AI 7), and although some deal mainly in ambient air analysis, the technology may be appropriate for industrial hygiene monitoring. Volumes 1 and 2 are now available for a NIOSH revision of their manual of analytical methods (AI8). Obsolete methods from their previous editions have been eliminated, and similar methods were combined. A new numbering system organizes methods for air samples, biological samples, and bulk samples into separate groups, and subgrouping further organizes similar sample types and collection techniques.
B. SOLID SORBENTS-SOLVENT DESORPTION Solid sorbents are being used extensively to sample contaminants in air. A small tube containing a solid sorbent is convenient to use, can concentrate trace contaminants, and can be worn by a worker to determine breathing zone concentrations. Because solid sorbents are so convenient to use and transport, methods using solid sorbents are generally preferred over whole air and impinger methods for many compounds. There are two basic techniques for collection of substances in air using solid sorbents. The most widely used technique utilizes a small pump to draw the air sample through a bed of solid sorbent. The second technique, which is discussed in Section E, utilizes diffusion of compounds into a chamber containing a solid sorbent. The compounds are
recovered from the sorbents by desorption with a suitable solvent or by thermal desorption, Solid sorbent tube pump sampling followed by solvent desorption of collecte compounds from solid sorbents is the most commonly used technique. The procedure is relatively simple; once the compound is desorbed, the extract can be analyzed by gas chromatography or other standard analytical techniques. Parts-per-million concentrations in air are usudy determined, although parts-per-billion sensitivity can be obtained for some compounds by using large sample volumes and high-sensitivity detectors. Charcoal is the most widely used sorbent while silica gel, alumina, porous polymers, and various gas chromatographic packings are used for specialized applications. The collection of organic vapors on charcoal followed by solvent desorption/gas chromatographic analysis has become a "standard" technique, and very often, this type of method is no longer reported in the literature. Using this technique for a multicomponent mixture becomes more complex because of the separations problem and the unknown effect of compound mixtures on collection. Whitehead et al. (BI),presented the data for the collection and analysis of 22 volatile solvents in various mixtures associated with spraying of paints and glues. Samples were collected by adsorption on 150-mg charcoal tubes and analyzed by gas chromatography after desorption with CSz. If acetone or methylene chloride were present, samples had to be limited to 90 min (50 mL/min) to minimize breakthrough. Otson et al. (B2) studied the simultaneous determination of nine organics in air, using 150-mg charcoal tubes. l,l,l-Trichloroethane, dichloromethane, n-hexane, toluene, 0- and p-xylenes, acetone, and Stoddard solvent were chosen for the study because of their frequent resence in consumer products. Benzene was also included Eecause of its potential presence in small amounts. Precision was better than 5% RSD when triplicate 2-L samples a t 22 "C and 95% relative humidity were taken. Only dichloromethane shows some breakthrough and migration on storage. In selection of a sorbent for high collection efficiency, the recovery of the compound must also be considered. Often, a mutual compromise may be necessary to obtain an acceptable system. Prior treatment and activation of the sorbent will affect efficiencies. Some work has been done to better understand the effect of water (B3-B5), coadsorbed compounds (B6), and reactions on the solid sorbent (B7, B8). Andersson (B3) studied the influence of air humidity on
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0 1985 American Chemical Society
I N W S T R I A L HYQIENE
Nonane was used as a control compound to verify that loss from the charcoal surface or from the vials during desorption. 4-Methylpentan-2-one was completely mvered &r 23 days while MEK and cyclohexanone recoveries were reduced. Folke proposed that the loss is due to a reaction between the analyte and some reactive sites on the charcoal samplin bed which leads to a modified surface and an analyte p r d u c t that is irreversibly bound to the charcoal. Because of the lack of stor e stability of butanone on charcoal, investigators examine7 other adsorbents for collection. Alumina, Tenax, Porapack P, and Chromosorb 101 sorbents were all found to have extremely poor collection capacity in a study by Elskamp and Schultz (BZO). Although the hreakthrough time for butanone was shorter for silica gel than for charcoal, this study showed that 3-L samples could be taken on silica gel and stored up to 15 days refrigerated or a t ambient temperature with no loss in recovery. Desorption efficiencies of 98% were obtained using dimethyl sulfoxide desorption solvent. Even though many of the parameters affecting collection and recovery can be teated in the laboratory. field validation may be necesenry to detect problems which are specific to the actual work site to be sampled. Borders and Melcher (BIZ) describe a statistical procedure to evaluate field validation experiments and recommend equipment and methodology necessary to perform these experiments. Much of the present research is going into developing methods for compounds which are difficult to desorb from cbarcoal with the existing standard teehniquea. JAW mol& weight aliphatic amines have always been difficult to collect and analyze at trace levels bemuse of their adsorption on solid surfaces and because of the resence of interfering organic substances. A method for Jetermining C, to C, aliphatic amines has been developed by Kuwata et al. (812) using collection on Sep-PAK CIS cartridges impregnated with phosphoric acid. The samples were desorbed with methanol-water (11) at a pH of 10 and analyzed on a SEPABEAD GHP-1 as chromatographic column modified with 10% potasaiumiydmxide. Because of the deactivation of the column, the amines at lees than 1-ng levels were accurately determined using a nitrogen selective and sensitive NP-FID detector. Detection limits in the low parts-per-billion range (v/v) in air were reported. In a different approach, Bouyoucos and Melcher (813)collected methylamines on silica gel, desorbed with 0.2 N HaO, in methanol-water (W10)and analyzed by ion chromatography. Fitzpatrick et al. ( 8 1 4 ) used Tenax adsorbent treated with hydrochloric acid followed by desorption with sodium hydroxide and tetrahydrofuran for the determination of NJf-dimethylcyclohexylamine. The desorbed samples were analyzed on a gas chromatograph/mass spectrometer using selected ion monitoring a t 84 and 127. Samples collected this way were found to be stable for at least 50 days. In another study, Kaahihira (815) evaluated five porous polymer beads: Tenax. Porapack T, Chromosorb 103, and alkalized Poraail A as collection adsorbents for trace levels of trimethylamine, acetonitrile, and acrylonitrile in air. From the results of the breakthrough curves, alkalized Poraail A was found efficient even at ambient temperatures. The detection limits for the nitrogen compounds, which combined the collection tube containing alkalized Poraail A with gaa chromatography, were parts-per-billion levels with a 20L air sampling. Fuselli et al. (816)reported that concentrations 89 low aa 0.005 ppm (v/v) of mono-, di-, and trimethylamine could be determined by collection on charcoal and desorption with 0.1 N HCI followed by gaa chromatography. Other techniques for obtaining g o d collection and recovery involve using a different solvent system or hy using different or modified sorbents. Dietz and Hoffman (BI7) developed and investigated both the charcoal tube and air bag method for the determination of chlorotrifluoroethylene monomer in air. The air bag waa analyzed directly by gaa chromatography, and the charcoal tube waa desorbed with toluene with desorption efficiencies greater than 90%. The Tedlar film bag waa able to store the sample for 5 days for recoveries greater than 90%. Pa& and Weight (BI8) have developed a method for low levels of acetic acid in air. The previously available methods use gas chromatography which presents a number of problem. In this work, charcoal tubes are used to collect acetic acid and desorbed with 0.1 N sodium hydroxide. The extract is injected directly into a liquid chromatograph emWBB not due to evaporation
-ply efficiencyofAmberlite XAD polymers and aetivated charco by detarmining the recovery of various organics a t 20% and 85% relative humidity. The sampling efticiency of XAD-'I was found to decrease with increasing relative humidity, while the sampling efficiencies of XAD-2 and charcoal were relatively d e c t e d for the 12 compounds hkd. Kalab ( 8 4 ) . however, found that recovery of ethanol, butanol, and acetone WBB greatly affected when collected at high humidities while benzene and tetrahydrofuran were not affected. In this study, carbon disulfide alone was listed as the desorption solvent. Langhorst (85)developed a unique technique for reducing the amount of water collected a t high humidities. A hollow fiber device was developed which uses Nafion perfluorinated membrane to separate water vapor from organic vapors rior to collection on an adsorbent tube. This device is capa&e of reducing humidity from 94% to
