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Note 54: Identification of Volatile Organic Compounds in Office Products

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By Santford V. Overton & John J. Manura

INTRODUCTION

The quality of indoor air has become a major concern to the entire population. Numerous reports have been previously reported describing the "sick building syndrome" which has been associated with the quality of indoor air in public buildings. Health risks due to these "sick buildings" have caused concern in government and industry due to both time lost by sick employees and the costs involved with remediation. Buildings related health problems may be due to contamination of indoor air by emissions of volatile organic compounds (VOC's) from a variety of sources including construction materials, fabrics, furnishings, maintenance supplies, adhesives, paints, caulks, paper and cleaning products. Because many of the volatile emissions and by-products from these products are toxic, additional knowledge of the levels of these organic chemicals in the indoor air environment is required in order to determine human health impact. Not only will new methods be required to accurately determine the identity and to accurately quantify the levels of these volatile organics in indoor air samples, but additional studies will be needed to determine the sources of the air contamination. If manufacturing processes are contributing to poor air quality, then these manufacturing processes will need to be improved to limit the emission of VOC's. For this study, samples from several different office products were analyzed by a new technique entitled "Direct Thermal Extraction" which uses a thermal desorption system connected to the injection port of a GC/MS system to determine the VOC's present which may contribute to this "sick building syndrome". This technique can be easily incorporated into a troubleshooting technique to detect potential problems as well as implementation into a quality control program.

Instrumentation

Figure 1

A new technique called "Direct Thermal Extraction" which utilizes a thermal desorption apparatus attached to the injection port of a GC/MS system (Fig. 1) permits the direct thermal extraction of volatile and semi-volatile organics directly from small sample sizes (mg) without the need for solvent extraction or other sample preparation. The sample is placed inside a preconditioned glass-lined stainless steel desorption tube between two glass wool plugs which simply hold the sample in place. The desorption tube containing the sample is attached to the Short Path Thermal Desorption System and a syringe needle attached. The desorption tube with sample is injected into the GC injection port, ballistically heated and together with the carrier gas flow through the sample the volatiles are outgassed into the injection port and onto the front of the GC column for subsequent analysis.

All experiments were conducted using a Scientific Instrument Services model TD3 Short Path Thermal Desorption System accessory connected to the injection port of an HP 5890 Series II GC interfaced to an HP 5971 Mass Selective Detector. The mass spectrometer was operated in the electron impact mode (EI) AT 70 Ev and scanned from 35 to 550 daltons during the GC run for the total ion chromatogram.

A short 0.5 meter by 0.53 mm diameter fused silica precolumn was attached to the injection port end of a 30 meter x 0.25 mm i.d. DB-5MS capillary column containing a 0.25 um film thickness. The GC injection port was set to 260 degrees C and a 10:1 split was used. The head of the column was maintained at -70 degrees C using a GC Cryotrap model 961 (Scientific Instrument Services, Ringoes, NJ) during the desorption and extraction process and then ballistically heated to 200 degrees C after which the GC oven was temperature programmed from 35 degres C (hold for 5 minutes) to 80 degrees C at 10 degrees C/min, then to 200 degrees C at 4 degrees C/min and finally to 260 degrees C at a rate of 10 degrees C/min.

Experimental

Nine different office products were analyzed by "Direct Thermal Extraction" to determine the VOC's present which may have an influence on "sick building syndrome". Samples sizes measuring from < 1 to 25 mg were placed into an inert thermal desorption tube on top of a glass wool plug. The desorption tube with sample was then attached to the Short Path Thermal Desorption System and a syringe needle attached. The desorption tube was injected into the GC injection port at a desorption block temperature of 150 degrees C for 5 minutes each. The extracted organics were subsequently cryo-trapped at the front of the GC injection port using the GC Cryotrap at a temperature of -70 degrees C. After the 5 minute desorption period, the Cryotrap was heated to 200*C to elute the volatiles and begin the GC analysis and identification via the mass spectrometer.

Results and Discussion

Figure 2

Figure 3

Nine different office products including white out correction fluid, black magic markers, rubber bands, scotch tape, adhesives from envelopes, notepads and labels as well as white and yellow carbon copies were analyzed by "Direct Thermal Extraction" to identify and compare the volatile organics present. These office products were found to contain a wide variety of compounds ranging from the aromatic compound benzene to aldehydes, siloxanes and phthalates (Figs. 3, 5, 7-9). Numerous substituted benzenes and hydrocarbons were also identified (Figs. 2, 4, 6, 8-10). Although several of the same volatiles are present in some of these office products, there is significant variation in the quantities as well as the variety of volatile organics present.

Figure 4

Figure 5

The white out correction fluid, black magic markers and rubber bands exhibited a large number of volatile emissions. The white out correction fluid and rubber bands contained large quantities of straight and branched chain hydrocarbons (Fig. 2&4). In addition to several siloxanes and naphthalene, a number of substituted benzenes were found in the black magic markers (Fig. 3). Scotch tape was found to contain a very high concentration of the compound diethyl phthalate (Fig. 5) which is used as a solvent and plasticizer for cellulose and cellulose acetate-butyrate compositions.

Figure 6

Figure 7

Another common source of volatile organic compounds are adhesives. Envelope adhesives contained the compounds 2-[2-[2-methoxyethoxy] ethoxy-ethanol, 1, 1' [methylenebis (oxy)] bis-ethane and a higher molecular weight compound 11-hydroxy-7,8,9,10-tetrahydrobenz as well as the pleasant smelling 2-hydroxy-methyl benzoate (Fig. 6). A series of aldehydes ranging from butanal to nonanal and a number of higher molecular hydrocarbons were detected in the adhesives from white labels (Fig. 7). Additionally, N-butyl-n-butylamine, an intermediate for emulsifying agents and N, N- dibutyl-formamide, a softener for paper, were identified. The notepad adhesives exhibited the aromatic compound benzene and a series of higher molecular weight hydrocarbons ranging from pentadecane to nonadecane (Fig. 8).

Figure 8

Figure 9

Paper and paper products also are a major source of volatile emissions into the indoor air environment. Both white and yellow carbon copies contained numerous straight chained hydrocarbons (Figs. 9&10). Although samples from these carbon copies possessed many of the same compounds, each had its own distinct fingerprint chromatograph.

Figure 10

Conclusion

Many products which are used in the office workplace are responsible for contributing to the levels of volatiles in the indoor air environment. A large number of aromatics, hydrocarbons, halogenated hydrocarbons, phenols, terpenes and phthalates are emitted from these products. Individually, the contribution from any one product may not be significant. However, the cumulative levels of emissions from these products are increasingly becoming a concern. This is particularly noteworthy in the new energy efficient contruction which minimizes air exchange due to the tight construction of these buildings. In the future, the levels and extent of the volatile organics in indoor air will come under closer scrutiny by both the public and scientific communities. The technique of "Direct Thermal Extraction" and the subsequent analysis using the Short Path Thermal Desorption System has proven to be a useful technique for the analysis of office products which are the sources of indoor air contamination.