Eastern Analytical Symposium

The 1995 Eastern Analytical Symposium will be held at the Garden State Convention Center in Somerset, NJ the week of November 12-17, 1995. 

Scientific Instrument Services will be presenting the following lectures and posters at this years meeting. 

Selection and Use of Adsorbent Resins for Purge and Trap Thermal Desorption Applications

Poster Presentation #165 by John J. Manura

Tuesday, November 14, 1995 at 10:00

Adsorbent resins including Tenax® TA, Tenax GR and a wide variety of activated charcoals are widely used to trap volatile and semi-volatile organics form air samples or when utilizing purge and trap techniques for the trapping and subsequent analysis of volatiles from liquid or solid samples. Adsorbent resins are specified in several EPA methods for air and water testing. Manufacturers of these resins report the breakthrough volumes for organics at room temperature. This data is required in order to determine the gas volume which can be sampled in order to efficiently trap the organics on the resin bed. However little data is available on the breakthrough volumes at elevated temperature. This data is required in order to determine the desorption temperature, gas volumes and desorption times to remove all the organics off the resin bed for subsequent analysis.

This paper describes the parameters which must be considered when selecting an adsorbent resin for a particular application. Small tubes (0.25 in. O.D. x 4 in. long) were packed with seven different adsorbent resins which were used as mini GC columns to determine the breakthrough volumes for more than 200 organic compounds as a function of temperature. From this data a series of Temperature Breakthrough Volume charts were developed. These charts can then be used to permit the proper selection of both adsorption as well as desorption parameters for the use of these adsorbent resins for purge and trap thermal desorption applications. Other parameters such as backpressures created by the adsorbent resins were also studied in order to aid in the selection of the adsorbent resin or combination of resins which will permit the accurate and quantitative analysis under optimum experimental conditions. 

Detection and Identification of Volatiles in Latex Paints by Headspace GC with On Column Cryo-Trapping

Poster Presentation # 167 by John J. Manura

Tuesday, November 14, 1995 at 10:00

Large gas volumes from GC introduction techniques such as headspace and thermal desorption can be introduced into a capillary GC column for subsequent analysis. This is accomplished with the use of a GC Cryo-Trap which permits the concentration and focusing of volatiles at the head of the GC capillary column from sample gas volumes ranging in size from 0.1 to more than 100 ml. The resulting GC chromatogram produces sharp well resolved peaks.

One to 5.0 gram sample sizes of latex (water base) paints were weighed into 10 ml headspace sample vials and sealed. The vials were then heated to 900 deg C and agitated for 10 minutes. Headspace volumes from 0.1 to 8.0 ml were injected in the GC injection port slowly (1.5 ml/min) utilizing the LEAP Headspace autosampler and cryo focused at the front of the GC capillary column using a GC Cryo-Trap. Liquid nitrogen is used to trap volatiles at temperatures down to -180 deg. C. After the injection was complete and the injection port flushed of all volatiles, the cryo-trap was heated to 200 deg C to release the trapped organics and the GC oven was temperature programmed to chromatograph the volatile organics. A DB5-MS capillary column (0.25 mm x 0.25u film thickness x 60 meters) was used for the analysis. A HP MSD (Model 5971) detector was used in the El mode to detect and identify the compounds eluted off the capillary column. The mass spec was scanned from 25 to 350 daltons throughout the entire GC run. For each of the latex paints analyzed, 50 to 100 organic compounds were detected and identified by the mass spectrometer. Depending on the manufacturer there were significant variations in the composition of the latex paints. The technique has proven to be a useful technique for the identification of the volatiles present in latex paints, for use as a quality control technique and for the comparison of paints from different manufacturers. 

Identification of Volatile Organic Compounds in a New Automobile

Poster Presentation # by Santford V. Overton

Wednesday, November 15, 1995 at 10:00

The quality of indoor air has become a major concern to the entire population. In addition to industry and other businesses, the identification and quantification of volatile organic compounds (VOC) in newly manufactured automobiles are extremely important to the automobile industry The condition of indoor air is caused by emissions of volatile organic compounds (VOC's) from a variety of sources including fabrics, upholstery, carpets, adhesives, paints, cleaning materials as well as from exhaust fumes outside the vehicle. Potential health risks exist due to the to the nature of many of these components. Individually, the contribution from any one product may not be significant, but the cumulative levels of emissions from these products are increasingly becoming a major concern. Because many of the volatile emissions and by-products from these products are toxic, additional knowledge of the levels of these organic compounds in the car's interior is required in order to determine human health impacts. Analytical techniques are needed to identify and quantitate VOC's present in these areas to help identify potential health risks. Further studies will also be required to determine the sources of the air contamination. If manufacturing processes are contributing to poor air quality, then the manufacturing processes will need to be improved to limit the emission of VOC'S. For this study, air samples were collected over a period of time from a new automobile to determine the presence and changes of VOC's over time. Samples were collected by pumping 1.0 liter of air through a desorption sampling tube and trapping the volatiles on an adsorbent resin inside this sample tube. The volatile organics present in the automobile's interior were quantified using matrix spiked deuterated standards. The samples were then analyzed by thermally desorbing the trapped volatiles into a gas chromatograph using a thermal desorption system and subsequently analyzing the eluted organics via gas chromatography-mass spectrometry (GC-MS). 

Volatile Organic Emissions from Automobile Tires

Poster Presentation # by Santford V. Overton & John J. Manura

Wednesday, November 15, 1995 at 10:00

Numerous reports have appeared describing the 'sick building syndrome' which has been associated with the quality of indoor air in public buildings. Building related health problems may be due to contamination of indoor air by emissions of volatile organic compounds (VOCS) from a variety of sources including construction materials, fabrics, furnishings, maintenance supplies, combustion byproducts, adhesives, paints, caulks, paper and cleaning products. Recently new allegations have appeared suggesting increased danger to the population due to emissions from automobile tires. Because many of the volatile emissions and by-products from these products are toxic, additional knowledge of the levels of these organic chemicals is required in order to determine the human health impacts. This is particularly important in highly populated cities where these compounds can not escape the maze of high rise office buildings and gradually affect the quality of indoor air in public buildings. In the next few years it is expected that the quality of indoor air will come under closer scrutiny by the public in both the domestic home and industrial workplace environments. New methods will be required to accurately determine the identity and to accurately quantify the levels of these volatile organics to help identify potential health risks. If manufacturing processes are contributing to poor air quality, then the manufacturing processes will need to be improved to limit the emission of VOC'S. For this study, samples of automobile tires were analyzed by 'Direct Thermal Extraction". This new technique using a thermal desorption apparatus attached to the injection port of a GC/MS system 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 samples are balistically. heated and together with the carrier gas flow through the samples the volatiles are outgassed into the injection port and onto the front of the GC column for subsequent analysis via the GC and/or GC/MS. The volatile organics present in the tires were quantified using matrix spiked deuterated internal standards. 

Volatile Organic Composition in Cranberry

Poster Presentation # by Santford V. Overton & John J. Manura

Wednesday, November 15, 1995 at 10:00

Volatile and semi-volatile organic compounds present both in the sample matrix and in the headspace aroma exhibit a great influence on the flavor/fragrance qualities of cranberries. There is a concern in the cranberry industry as to what constitutes the optimum conditions for harvesting berries so as to provide a consistent quality and flavor of cranberry to the consumer. An additional concern also exists as to the level of pesticide residue that may be present in the fruit. Several investigations have reported that the concentrations of volatile constituents increased with the maturation of cranberries. The major volatiles of cranberries appear to be useful indices for determining maturity, and recently, the determination of flavor precursors and intermediates have become the target of flavor studies. To date headspace GC analysis, cryofocusing techniques, and high-resolution GC have been used for the analysis of cranberry volatiles from promising cultivars under development However, static headspace techniques are limited in their detection and identification of many organic volatiles and especially the semi-volatiles organics. Other analytical techniques are needed to profile a wider range of volatile and semi-volatile organics in cranberries and to identify the flavors, fragrances, off-flavors, off-odors and potential contaminants that may be present The purpose of this investigation was to develop an analytical technique that could detect and identify a wide range of volatile and semi-volatile organic compounds m cranberry. For this study, volatile organic compounds were purged from cranberry samples followed by trapping on Tenax TA adsorbent resin using a dynamic purge and trap technique (P&T). The adsorbent traps were subsequently analyzed by thermal desorption-gas chromatography-mass spectrometry CID-GCMS). The P&T technique permits the analysis of a wider range of both volatile and semi-volatile organic compounds and is more sensitive as compared to the static headspace technique. 

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