We have determined that the thermal sampling approach gives more accurate results of analyte levels on concrete surfaces when compared to the standard wipe test methods. The use of a quick-look detector eliminates the need to analyze ``clean`` environmental samples. The sorption tubes have been shown to provide a reliable quantitative means for transfer of analyte to an automated thermal desorption interface to a GC. We will be extending our work to include sampling of steel surfaces in Phase II of this program. Models of the extraction process for porous surfaces such as concrete will be developed in the next phase of this program

Barren, E.

Berdahl, D.R.

Dorn, S.B.

Feldman, S.F.

Ortiz, A.L. Jr.

Penny, C.M.

Staver, P.R.

UNT Digital Library

DOEMCI3O 174-95ICO446 Thermal Sampling Head and System for Concrete Walls Authors: E. Barren D. R. Berdahl S. B. Dorn S. F. Feldman A. L. Ortiz, Jr. C. M. Penny P. R. Staver Contractor: General Electric Company Research and Development Center P. 0. Box 8 Schenectady, N Y  123 0 1 Contract Number: DE-AC21-93MC30174 Conference Title: 4th International Conference on Field Screening Methods for Hazardous Wastes and Toxic Chemicals ~ Conference Location: I Las Vegas, Nevada , Conference Dates: I I February 22-24, 1995 MA Conference Sponsor: O\SPRtBl.JTlON OF THIS DOCUMENT IS ~~~i~~~~~ dv Air and Waste Management Association and U.S. EPA-Las Vegas DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. This report has been reproduced directly from the best available copy. Available to DOE and DOE contractors from the Office of Scientific and Technical Information, 175 Oak Ridge Turnpike, Oak Ridge, TN 37831; prices available at (6 15) 576-840 1 .  Available to the public fiom the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22 16 1 ; phone orders accepted at (703) 487-4650. DISCLAIMER Portions of this document may be illegible in electronic image products. images are produced from the best available original document. c * Thermal Sampling Head and System for Concrete Walls E Barren, DR Berdahl, SB Dorn, SF Feldman, AL Ortiz, Jr., CM Penney, PR Staver GE Corporate Research and Development Center Introduction and Background A number of contamination sites exist in this country where the area and volume of material to be remediated is very large, approaching or exceeding 106 m2 and 106 m3- Typically, only a small fraction of this material is actually contaminated. In such cases there is a strong economic motivation to test the material with a sufficient density of measurements to identify which portions are uncontaminated, so extensively they be left in place or be disposed of as uncontaminated waste. Unfortunately, since contamination often varies rapidly from position to position, this procedure can involve upwards of one million measurements per site. The situation is complicated further in many cases by the difficulties of sampling porous surfaces, such as concrete. For example, on concrete the standard wipe test provides results that are strongly operator- and surface condition-dependent. The results are not usually available real time, because the wipe samples are sent to a remote laboratory for analysis, entailing a delay of days to weeks between sampling and results. Further, the cost of analysis of a clean sample is usually the same as that of a contaminated sample; analysis of clean samples thereby increases the total analysis costs considerably. Another method for surface/subsurface characterization is to obtain a boring or a drilling. This method also involves the off-site analysis of the drilled material, incorporating the time and economic penalties described above. Other disadvantages of drilling techniques are disfiguration of the surface and distribution of contamination through byproduct dust. It is for the above reasons that we have chosen to develop thermal sampling methods for characterization of concrete, transite, and metal surfaces. The sampling system we describe has been designed to greatly reduce the economic penalty posed by these difficulties. Experimental Configuration Previous work in remediation technology has demonstrated that thermal methods are very effective at extracting semi-volatile organics from porous solid matrices. Therefore, we have developed a thermal sampling head for contamination measurements on concrete surfaces. The overall experimental configuration is illustrated in Figure 1. The concrete sampling head is connected to a “quick-look detector” whose purpose is to provide an immediate distinction between contaminated and uncontaminated surfaces. From the quick-look detector the contaminant-laden air is pulled through a sorption tube which provides long term storage of contaminants for detailed analysis. In operation the quick-look indication will be passed along with the sorption tube to indicate which tubes required detailed analysis and to permit avoidance of analysis of uncontaminated samples. It is intended that the sorption tubes will be held in a cassette capable of holding enough tubes for several hours of measurement at a rate on the order of ten measurements per hour. Sample acquisition and analysis will be automated. Test Methods The concrete sampler head was tested on concrete “cakes” that had been prepared with contaminated sand. In total, seven concrete cakes were prepared 30 cm in diameter and 3.3 cm thick. One of the concrete cakes was prepared with clean sand and was instrumented with thermocouples to enable us to determine the settings necessary to bring the surface of the concrete to 25OOC. The remaining six cakes were prepared using sand that had been contaminated with anthracene, 2,4,5- trichlorobiphenyl, and phenyldodecane. These three compounds represent three typical kinds of environmental pollutants. The contaminated sand was mixed with clean sand, portland cement, water, 1 and poured.into cake molds. The concrete cakes were aged in 100% humidity for 7 days, then at 45% humidity for 6 months. The concentrations of the analytes in the resulting cakes are shown in Table 1. Table 1. Mixtures of contaminated sand used to prepare concrete cakes. Sample A used to prepare cakes 1 and 2 Ingredients Contaminant Concentration Clean sand 2700g Anthracene 426 Portland cement lo00 g 2,4,5-Trichlorobiphenyl 380 (PPm) Contaminated sand 300 g Phenyldodecane 373 Water 590 g Sample B used to prepare cakes 3 and 4 Ingredients Contaminant concentration Clean sand 2920g Anthracene 114 Portland cement lo00 g 2,4,5-Trichlorobiphenyl 101 Water 590 g (PP@ Contaminated sand 80 g Phenyldodecane 99 Sample C used to prepare cakes 5 and 6 Ingredients Contaminant Concentration Clean sand 2980g Anthracene 28 Contaminated sand 20 g Phenyldodecane 25 Portland cement lo00 g 2,4,5-Trichlorobiphenyl 25 Water 590 g (PPW Table 2. Average temperature reading from three thermocouples buried 2 mm deep in concrete cake. Time Avg. thermocouple (min) reading (“c) 0 33 0.5 106 1 138 1.5 166 2 184 2.5 204 3 221 3.5 236 4 250 2 Results and Discussion Over a heating period of 4-5 minutes, the concrete sampling head extracts contaminants primarily from the first two millimeter surface layer of concrete. Table 2 shows the average heating rate we achieved over a 100 cm2 surface over this period. The quick-look detector provided a real time indication of contamination. A typical quick-look indication, corresponding to a total contaminant collection of 10 pg, is shown in Figure 2. Solvent traps were used to trap analyte vapor and water that evolved from the heated cake surface. In Figure 3 are shown the theoretical amounts of anthracene, 2,4,5-trichlorobiphenyl, and phenyldodecane that were found in the top 1 mm of the concrete cakes. Also shown are the micrograms of anthracene, 2,4,5-trichlorobiphenyl, and phenyldodecane that were found in our solvent traps. For the most part, the 5 minute collection time correlates within a factor of two with the assumed uniform distribution of analytes in the first lmm depth. Only anthracene exhibits anomalously low recovery. Loss of anthracene from the concrete surface by evaporation processes are believed to account for the low recovery. We have also designed and built a bulk sampling oven (see Figure 4) useful for the analysis of dust, sample drillings, and for the initial calibration measurements of equipment. The bulk sampling oven has a removable tray designed to hold loose material. The bulk sampling oven was used to volatilize known amounts of analyte (anthracene, 2,4,5-trichlorobiphenyl, or phenyldodecane). A methylene chloride solution of the analytes was placed in an aluminum pan and allowed to evaporate. The analyte vapors were trapped with almost 100 % efficiency on carbon-filled sorbent tubes. A photoionization detector connected to the exit side of the bulk sampling oven was adequately sensitive to 10 micrograms of analyte. Figure 2 shows the reponse of the quick-look photoionization detector (PID) to 10.3 pg of 2,4,5-trichlorobiphenyl vapor. The PID response to analyte vapor occurred within a matter of 1 minute of inserting the aluminum pan into the oven assembly. Conclusion We have determined that the thermal sampling approach gives more accurate results of analyte levels on concrete surfaces when compared to the standard wipe test methods. The use of a quick-look detector eliminates the need to analyze “clean” environmental samples. The sorption tubes have been shown to provide a reliable quantitative means for transfer of analyte to an automated thermal desorption interface to a GC. We will be extending our work to include sampling of steel surfaces in phase II of this program. Models of the extraction process for porous surfaces such as concrete will be developed in the next phase of this program. Acknowledgments Technology Center, Contract No. DEAC21-93MC30174, Morgantown, West Virginia. This study has been supported in part by the U.S. Department of Energy Morgantown Energy 3 Sampling Head I I Heated transfer line Module Multisample trap cassette Analysis Equipment (GC-MS, GC-ECD, Etc.) /- Figure 1. Experimental Configuration of the Concrete Sampling Head Figwe 2. Photoionization gauge reponse for 10.3 pg of Trichlmbiphenyl evaporated from a microsample pan into a 2.5 SCFH air flow by the bulk sampler head 4 Tost 12 f TW 1.1 / i T i loo00 Boo0 8Qoo 4am 0 I i- j - approx. origk\al amount in 1 mm t I + t I0 2 4 6 8 10 Minub. 0 2 4 6 8 10 YInUbr / T a t  31 8.00 10.00 200 4.00 6.00 yhrrdw 0 2 4 6 8 10 muk 0.00 800.00 700.00 600.00 500.00 400.00 300.00 200.00 100.00 0.00 t 700.00 Tost 6.1 J bt62 400.00 f 300.00 Y 200.00 ibo.00 0.00 0.00 2.00 4.00 6.00 8.00 10.00 Mindrr 8.00 10.00 0.00 2.00 4.00 6.00 Mlnutu Figure 3. Total extraction amounts versus timedetcnnined from GC analysis of solvent traps.The first test nurnber refers to the cake number and the second to the specific experiment; two experiments wefe run on each cake. '--+--Phenyldodec Figure 4. Picture of the bulk sampler head prior to heater design and insulation application. 6 

Thermal sampling head and system for concrete walls

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Thermal sampling head and system for concrete walls

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