ASTM D6345 – 98 R03

Designation: D 6345 – 98 (Reapproved 2003) Standard Guide for Selection of Methods for Active, Integrative Sampling of Volatile Organic Compounds in Air1 This standard is issued under the fixed designation D 6345; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This guide provides assistance in the selection of active integrative sampling methods, in which the volatile organic analytes are collected from air over a period of time by drawing the air into the sampling device, with subsequent recovery for analysis. Where available, specific ASTM test methods and practices are referenced. 1.2 Guidance is provided for the selection of active sam- pling methods based either on collection of an untreated air sample (whole air samples) or selective sampling using sorbent concentration techniques that selectively concentrate compo- nents in air. Advantages and disadvantages of specific collec- tion vehicles are presented. 1.3 This guide does not cover the use of cryogenically cooled field sampling devices used in some automated analysis systems. Detailed instructions for cryogenic recovery of com- pounds captured as whole air samples or thermally desorbed from sorbents are typically covered in standard methods for sample analysis and are beyond the scope of this guide. 1.4 Both thermal and solvent desorption techniques for sample recovery are discussed. 1.5 Organic compounds are classified on the basis of vapor pressure as very volatile, volatile, semivolatile and nonvolatile. Physical characteristics of many volatile organic compounds (VOCs) are provided to aid in selection of sampling techniques for VOC measurement. Semivolatile and nonvolatile organic compounds are defined in the guide to help guide users avoid misidentifying compounds that are not covered in this guide. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety and health practices and determine the applica- bility of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 D 1356 Terminology Relating to Sampling and Analysis of Atmospheres D 1357 Practice for Planning the Sampling of the Ambient Atmosphere D 3686 Practice for Sampling Atmospheres to Collect Or- ganic Compound Vapors (Activated Charcoal Tube Ad- sorption Method) D 3687 Practice for Analysis of Organic Compound Vapors Collected by the Activated Charcoal Tube Adsorption Method D 5197 Test Method for Determination of Formaldehyde and Other Carbonyl Compounds in Air (Active Sampler Methodology) D 5466 Test Method for Determination of Volatile Organic Chemicals in Atmospheres (Canister Sampling Methodol- ogy) D 5953M Test Method for Determination of Non-Methane Organic Compounds (NMOC) in Ambient Air Using Cryogenic Preconcentration and Direct Flame Ionization Detection Method (Metric) D 6196 Practice for Selection of Sorbents, Sampling, and Thermal Desorption Analysis Procedures for Volatile Or- ganic Compounds in Air 3. Terminology 3.1 Definitions—For definitions of terms used in this guide refer to Terminology D 1356. 3.2 Definitions of Terms Specific to This Standard: 3.2.1 cryofocus—the process of concentrating compounds from an air sample for subsequent analysis by collection on a trap cooled with a cryogen to very low temperatures (for example, -186°C). 1 This guide is under the jurisdiction of ASTM Committee D22 on Sampling and Analysis of Atmospheres and is the direct responsibility of Subcommittee D22.05 on Indoor Air. Current edition approved October 1, 2003. Published November 2003. Originally approved in 1998. Last previous edition approved in 1998 as D 6345 - 98.. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. 3.2.1.1 Discussion—Cryogenic traps used for cryofocusing are typically U-shaped stainless steel tubes filled with glass beads or other inert material. An example of such a cryofocus- ing trap is given in Test Method D 5933M. Compounds are typically released from cryogenic traps into the analytical system by rapid heating to elevated temperatures. Sorbent- filled tubes cooled to sub-ambient temperatures (for example, -30°C) have also been used for this purpose. 3.2.2 very volatile organic compounds (VVOCs)—Low mo- lecular weight organic compounds that possess vapor pressures greater than 15 kPa at 25°C and boiling points typically below 30°C. 4. Significance and Use 4.1 This guide provides a broad perspective on techniques that can be used by environmental managers for selecting VOC air monitoring methods. It summarizes various methods for measurement of VOC in air derived from a variety of sources and experiences and incorporates them into condensed guide- lines. This guide provides a common basis for selecting methods for VOC measurement as well a discussion of the limitations of typical methods. 4.2 This guide should be used during the planning stages of an air monitoring program along with other applicable guides and practices (for example, D 1357) to select ASTM or other appropriate methods. 5. Characteristics of Organic Compounds 5.1 Physical and chemical characteristics of VOCs are available from numerous references (1, 2, 3, 4).3 The properties of the VOCs listed under the Clean Air Act of 1990 (5) are presented in Table 1 and Table 2. TABLE 1 Properties of Clean Air Act Very Volatile Organic HAPsA,B Vapor Boiling Water Pressure Point Solubility (g/L Customary Reactivity in Compound CAS No. (kPa at 25°C) (°C) at °C) Classification Air Acetaldehyde 75-07-0 127 21 33.0 / 25 Polar Acrolein 107-02-8 29 53 >100 /21 Polar Reactive Allyl chloride 107-05-1 45 45 19.5 / 20 Non-Polar 1.3-Butadiene 106-99-0 267 -5 Insoluble Non-Polar Reactive (?) Carbon disulfide 75-15-0 35 47 <1 / 20 Non-polar Carbonyl sulfide 463-58-1 493 -50 >100 / 20 Polar Chloroform 67-66-3 21 61 0.85 / 20-24 Non-Polar Chloromethly methyl ether 107-30-2 30 59 Reacts Polar Reactive Chloroprene 126-99-8 30 59 Slightly soluble Non-Polar Diazomethane 334-88-3 373 -23 Reacts Polar Highly reactive 1,1-Dimethylhydrazine 57-14-7 21 63 Reacts Non-Polar Reactive (?) 1,2-Epoxybutane 106-88-7 22 63 >100 / 17 Polar Reactive Ethyl chloride 75-00-3 133 13 >100 / 20 Non-Polar Ethyleneimine 151-56-4 21 56 Miscible Polar Reactive (?) Ethylene oxide 75-21-8 147 11 Miscible Polar Reactive Ethylidene dichloride 75-34-3 31 57 <1 / 20 Non-Polar Formaldehyde 50-00-0 360 -20 >100 / 20.5 Polar Hexane 110-54-3 16 69 <1 / 16.5 Non-Polar Methyl bromide 74-83-9 240 4 Slightly soluble Non-Polar Pesticide Methyl chloride 74-87-3 507 -24 Slightly soluble Non-Polar Methyl iodide 74-88-4 53 42 10-50 / 18 Non-Polar Methyl isocyanate 624-83-9 46 60 Reacts Polar Highly reactive Methyl tert-butyl ether 1634-04-4 33 55 Soluble Polar Methylene chloride 75-09-2 47 40 10-50 / 21 Non-Polar Phosgene 75-44-5 160 8 Slightly soluble Polar Reactive (?) Propionaldehyde 123-38-6 31 49 50-100 / 18 Polar Reactive Propylene oxide 75-56-9 59 34 400 / 20 Polar Reactive 1,2-Propyleneimine 75-55-8 15 66 >100 / 19 Polar Highly reactive (?) Vinyl bromide 593-60-2 147 16 Insoluble Non-Polar Vinyl chloride 75-01-4 427 -14 Slightly soluble Non-Polar Vinylidene chloride 75-35-4 67 32 5-10 / 21 Non-Polar ACompounds with vapor pressures > 15 kPa. BData taken from Ref. (3). TABLE 2 Properties of Clean Air Act Volatile Organic HAPA,B Vapor Pressure Water (kPa at Boiling Point Solubility Customary Reactivity Compound CAS No. 25°C) (°C) (g/L at °C) Classification in Air Acetonitrile 75-05-8 9.86 82 >100 / 22 Polar 3 The boldface numbers in parentheses refer to the list of references at the end of this standard. D 6345 – 98 (2003) 2 TABLE 2 Continued Vapor Pressure Water (kPa at Boiling Point Solubility Customary Reactivity Compound CAS No. 25°C) (°C) (g/L at °C) Classification in Air Acetophenone 98-86-2 0.13 202 6.3 / 25 Polar Acrylamide 79-06-1 0.07 125/25 mm >100 / 22 Polar Reactive Acrylic acid 79-10-7 0.43 141 >100 / 17 Polar Acrylonitrile 107-13-1 13.33 77 716.0 / 254 Polar Aniline 62-53-3 0.09 184 1.0 / 254 Polar o-Anisidine 90-04-0 0.01 224.0 <0.1 / 19 Polar Reactive Benzene 71-43-2 10.13 80 1-5 / 18 Non-Polar Benzyl chloride 100-44-7 0.13 179 Reacts Non-polar Reactive(?) Bis (chloromethyl) ether 542-88-1 4.00 104 Reacts Polar Reactive Bromoform 75-25-2 0.75 149 <0.1 / 22.5 Non-Polar Carbon tetrachloride 56-23-5 12.00 77 <1 / 21 Non-Polar Catechol 120-80-9 0.03 240 >100 / 21.5 Polar Chloroacetic acid 79-11-8 0.09 189 >100 / 20 Polar Chlorobenzene 108-90-7 1.17 132 <1 / 20 Non-Polar o-Cresol 95-48-7 0.03 191 25.9 / 25 Polar Cumene 98-82-8 0.43 153 Insoluble Non-Polar 1,2-Dibromo-3- chloropropane 96-12-8 0.11 196 <0.1 / 18 Non-Polar 1,4-Dichlorobenzene 106-46-7 0.08 173 <1 / 23 Non-Polar Dichloroethyl ether 111-44-4 0.09 178 Reacts Polar Reactive(?) 1,3-Dichloropropene 542-75-6 3.71 112 <0.1 / 16.5 Non-Polar Diethyl sulfate 64-67-5 0.04 208 Reacts Polar Reactive(?) N,N-Dimethylaniline 121-69-7 0.07 192 <1 / 21 Polar Dimethylcarbamyl chloride 79-44-7 0.65 166 Reacts Polar Highly reactive N,N- Dimethyformamide 68-12-2 0.36 153 >100 / 22 Polar Dimethyl sulfate 77-78-1 0.13 188 >100 / 20 Polar Reactive(?) 1,4-Dioxane 123-91-1 4.93 101 >100 / 20 Polar Epichlorohydrin 106-89-8 1.60 117 50-100- / 22 Polar Highly reactive Ethyl acrylate 140-88-5 3.91 100 4.2 / 204 Polar Ethylbenzene 100-41-4 0.93 136 <1 / 23 Non-Polar Ethyl carbamate 51-79-6 0.07 183 >100 / 22 Polar Ethyl dibromide 106-93-4 1.47 132 <1 / 21 Non-Polar Pesticide Ethylene dichloride 107-06-2 8.20 84 5-10 / 19 Non-Polar Pesticide Hexachlorobutadiene 87-68-3 0.05 215 <0.1 / 22 Non-Polar Hexachloroethane 67-72-1 0.05 Sublimes at 186 <1 / 21 Non-Polar Hexamethylphosphoramide 680-31-9 0.01 233 >100 / 18 Polar Isophorone 78-59-1 0.05 215 0.1-1 / 18 Polar Methanol 67-56-1 12.26 65 >100 / 21 Polar Methyl chloroform 71-55-6 13.33 74 <1 / 20 Non-Polar Methyl ethyl ketone 78-93-3 10.33 80 >100 / 19 Polar Methylhydrazine 60-34-3 6.61 88 <1 / 24 Non-Polar Highly reactive Methyl isobutyl ketone 108-10-1 0.80 117 1-5 / 21 Polar Methyl methacrylate 80-62-6 3.73 101 15.9 / 20 Polar Nitrobenzene 98-95-3 0.02 211 1.9 / 25 Polar 2-Nitropropane 79-46-9 1.33 120 1.7 / 20 Polar N-Nitroso-N- methylurea 684-93-5 1.33 124 <1 / 18 Polar Reactive N-Nitrosodimethylamine 62-75-9 0.49 152 >100 / 19 Polar Reactive N-Nitrosomorpholine 59-89-2 0.04 225 >100 / 19 Polar Phenol 108-95-2 0.03 182 50-100- / 19 Polar 1,3-Propane sultone 1120-71-4 0.27 180/30 mm 0.1 Polar Reactive(?) Beta-Propiolactone 57-57-8 0.45 Decomposes at 162 37.0 / 20 Polar Propylene dichloride 78-87-5 5.60 97 <0.1 / 21.5 Non-Polar Pesticide Quinoline 91-25-5 0.01 238 <0.1 / 22.5 Polar Styrene 100-42-5 0.88 145 <1 / 19 Non-Polar Styrene oxide 96-09-3 0.04 194 <1 / 19.5 Polar Highly reactive 1,1,2,2- Tetrachloroethane 79-34-5 0.67 146 <0.1 / 22 Non-Polar Tetrachloroethylene 127-18-4 1.87 121 <0.1 / 17 Non-Polar Toluene 108-88-3 2.93 111 <1 / 18 Non-Polar o-Toluidine 95-53-4 0.01 200 5-10 / 15 Polar 1,2,4-Trichlorobenzene 120-82-1 0.02 213 <1 / 21 Non-Polar 1,1,2-Trichloroethane 79-00-5 2.53 114 1-5 / 20 Non-Polar Trichloroethylene 79-01-6 2.67 87 <1 / 21 Non-Polar Triethylamine 121-44-8 7.20 90 Soluble Polar Reactive (?); strong base 2,2,4-Trimethyl pentane 540-84-1 5.41 99 Insoluble Non-polar Vinyl acetate 108-05-4 11.06 72 Insoluble Polar D 6345 – 98 (2003) 3 TABLE 2 Continued Vapor Pressure Water (kPa at Boiling Point Solubility Customary Reactivity Compound CAS No. 25°C) (°C) (g/L at °C) Classification in Air o-Xylene 95-47-6 0.67 144 Insoluble Non-Polar m-Xylene 108-38-3 0.80 139 Insoluble Non-Polar p-Xylene 106-42-3 0.87 138 Insoluble Non-Polar ACompounds with vapor pressures between 102 and 15 kPa. BData taken from Ref. (4). 5.2 Organic compounds can be divided into four groups based on volatility (1). 5.2.1 VOCs with vapor pressures above 15 kPa at 25°C (boiling points typically below 30°C) are sometimes referred to as very volatile organic compounds (VVOCs). At room tem- perature and atmospheric pressure, VVOCs are present in the gas phase in air. Due to their high vapor pressures, VVOCs are generally more difficult to collect and retain on sorbents than other VOCs. 5.2.2 Volatile organic compounds typically have vapor pres- sures above 10-2 kPa at 25°C (typical boiling points from about 30 to 180°C). VOCs with boiling points at the upper end of the range still have a significant vapor pressure at room tempera- ture and atmospheric pressure. At room temperature and atmospheric pressure VOCs are present in the gas phase in air. 5.2.3 Semivolatile organic compounds (SVOCs) typically have vapor pressures between 10-2 and 10-8 kPa at 25°C (typical boiling points from 180 to 350°C). SVOCs may be present in both the vapor and particulate phases (1). 5.2.4 Nonvolatile organic compounds have vapor pressures below 10-8 kPa at 25°C (boiling points typically above 300°C). Nonvolatile organic compounds occur primarily in the particu- late phase. NOTE 1—Boiling points are not reliable predictors of volatility. Some compounds that boil above 300°C are volatile at room temperature. 5.3 The polarity, water solubility, and reactivity of a VOC are critical in the choice of the sampling and analytical methods. 5.3.1 VOCs range in polarity from nonpolar (for example, propane) to very polar (for example, acetic acid). Polar organic compounds typically contain oxygen, nitrogen, sulfur, or other heteroatoms and may be categorized as either ionizable or polarizable. The former category includes alcohols, phenols, amines, and carboxylic acids; the latter includes ketones, ethers, nitro-compounds, nitriles, and isocyanates. 5.3.2 VOCs also range in reactivity from stable (for ex- ample, benzene) to highly reactive (for example, diaz- omethane). Polar compounds are often also reactive com- pounds and are generally more difficult to recover from sampling devices and present special analytical problems because of their chemical reactivities, affinities for metal and other surfaces, and water solubilities. These problems are more severe with ionizable compounds. 5.4 The sampling location and concentration of VOCs are also important in selecting a monitoring method. VOCs are typically found in indoor air in residences, offices, and public access buildings at concentrations ranging from 0.1 to 100 µg/m3. VOC data may also be reported in parts per billion by volume (ppbv). The conversion between these reporting units is shown in Eq 1 and requires the molecular weight and the standard molar volume at standard temperature (273.15 K, 0°C) and pressure (101.3 kPa, 760 mm Hg): C~ppbv! 5 C~µg/m3! 3 22.4/molecular weight (1) NOTE 2—Indoor sampling is usually performed at temperature near 293 K (20°C). The standard molar volume at this temperature is 24.1 L/mol. 6. Selection of Sampling Methods for VOCs 6.1 The first criteria for selection of an appropriate method for sampling are the physical and chemical characteristics of the compounds to be monitored. Once the analyte has been characterized as a volatile compound, the appropriate measure- ment method (sampling and analysis) is chosen. Sampling methods can be active or passive. 6.1.1 Active methods employ some means of setting and controlling the air sampling rate (for example pump, syringe, or other vacuum source with a flow-controller). 6.1.2 Passive/diffusive sampling methods have sampling rates that depend on the molecular diffusion rate, sampling temperature, length and area of the diffusive path, and other conditions. 6.1.3 Active sampling methods can be divided into three broad types: whole air methods which use canisters, bags, or syringes; sorbent collection methods; and specialized sampling methods for reactive compounds. 6.1.4 Sampling can also be integrative (accumulative) or continuous (real-time). 6.2 Whole Air Sampling: 6.2.1 If the VOC of interest is relatively stable, and volatile enough to be recovered from an inert container, then whole air sampling may be a valid choice. The major advantage of whole air sampling is the ability to trap the most volatile compounds, since the entire air sample is collected and retained for subsequent analysis. A fraction of this sample is then concen- trated under controlled conditions in the laboratory immedi- ately prior to analysis. 6.2.2 Bags made from polyfluorinated polymer, polyester, or polyvinylidene plastics have been used for whole air sampling, but have the disadvantage of limited (24 to 48 h) useful sample holding times and should be used only when analyses can be performed within that time limit (6, 7). Shipping of bags is usually restricted to ground transport since changing pressures in aircraft shipping cause sample loss or contamination. Bags also have the disadvantage of being bulky and are inconvenient for personal monitoring. 6.2.3 Passivated stainless steel canisters are superior to bags for collection of whole air samples. Two ASTM test methods D 6345 – 98 (2003) 4 are available for use of this technique–Test Methods D 5466 and D 5953M. The canisters are treated with a proprietary electropolishing process to remove or cover reactive metal sites on the interior surface of the vessel (8). Another type of passivated stainless steel canister has the interior walls deac- tivated by a proprietary fused silica coating process (9). 6.2.3.1 Canister sampling is carried out by allowing the air to enter a pre-evacuated container either by way of a critical orifice or mass flow controller, or by using a pump to fill the canister to a pressure of a few atmospheres (8). For analysis, an aliquot (100 to 500 mL) of air is withdrawn from the canister and cryofocused into a GC attached to a mass selective detector, ion trap detector, or flame ionization detector. Detec- tion limits are generally below 1 µg/m3. 6.2.3.2 Various sizes are available from a number of com- mercial vendors that can be used to collect air volumes ranging from fractions of a litre to hundreds of litres. 6.2.3.3 Canisters have advantages over plastic bags for whole-air sampling. They display relatively good stabilities for VOCs (including some polar compounds) with vapor pressures above 10-2 kPa, greatly reduced problems due to contamination and artifact formation, the absence of breakthrough effects, and the ability to permit multiple analyses (8, 10, 11). Typical sample holding time before significant wall losses occurs is on the order of 35 days for most nonpolar VOCs of interest. Recovery of many polar VOCs from canisters is poor, however. 6.2.3.4 Whole air samples can be collected in canisters over a short period of time (grab samples) or integrated over a preselected period to time-weighted average concentrations. 6.2.3.5 Major disadvantages associated with the use of canisters include their high cost and bulkiness, the limited air volumes that can be sampled, difficulties experienced in recovering less volatile and more polar VOCs, and the co- collection of water. 6.2.3.6 Water is present in relatively large amounts in air samples and cause serious problems, such as ice formation that can clog the cryogenic trap. In the analysis of nonpolar compounds, the sample aliquot is normally passed through a dryer membrane tubing to remove the water (see Test Method D 5466). This process