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Analytical Reports >> Study to document SoilCore™ discrete sampling device as an equivalent and an alternative to En Core™ in EPA method 5035.

Introduction

The purpose of this study is to document the performance of the SoilCore™ Sampler as a discrete soil sampling and storage device verses methanol extraction on Volatile Organic Compounds (VOCs) impacted sites, based on EPA method 5035. The study will present acceptable accuracy and precision data for use of the SoilCore™ Sampler. It will be also compared verses En Core™ to show that it is an equivalent and an alternative as described in EPA SW-846 method 5035, section 4.5.2.

Procedure

Sampling devices were filled with soil and spiked with 2 ml of solution that contains 55 compounds at 40 mg/L ( Table1). This will bring the concentration in the device about 3.2 mg/kg (assuming 25 gram soil). Devices were then stored at 4 degree C for 65 hours. Devices were opened at 65 hours and the soil was placed in the methanol. EPA Method 5035 was followed for extraction and all samples were analyzed within three days of extraction. EPA method 8260B a GC/MS procedure was used for the analyses. The same procedure was used for the control samples which were spiked in soil and extracted in methanol at 0-hour along with sampling devices.

100 ul of methanol extract were introduced into 10 ml of purge and trap water and analyzed per stated methods. Five control samples, five SoilCore™ Sampler and three En Core™ samples were analyzed. Controls were all analyzed once, SoilCore™ Samplers were analyzed three times each, and two En Core™s were analyzed three times and one twice. The numerous replicate analyses were performed to reduce any possibility of method 8260B inaccuracy. In total, there are 15, 8, and 5 data points for SoilCore™ ,En Core™ , and immediate methanol extracts respectively. All analyses were done by Synergic Analytics, Inc., Grand Rapids, MI an A2LA (American Association for Laboratory Accreditation) accredited, and Drinking water certified laboratory.

Results

Based on data generated (table 1), SoilCore™ and En core™ have shown similar accuracy and precision for soil samples stored at 4° Celsius for 65 hours.

SoilCore™ recoveries range from 72% 24 for Bromoethane to 121% 39 for Vinylchloride, with total average recovery at 90% + 8. En core™ recoveries range from 21% 103 for Dichlorodiflouromethane to 115% 20 for 1112-Tetrachloroethane, with total average recovery at 87% 18.

Surrogates are VOC's that EPA method 8260B/5035 requires Labs to add to methanol extract at the time of soil and methanol extraction before sonication to monitor the stated methods performance. Surrogate recoveries of SoilCore™ and En Core™ were both within method requirements.

Discussion

The SoilCore™ Sampler has shown that it can be used as a discrete soil sampling and storage device based on its performance in this study. According to results presented in Table1 and Graph1, both SoilCore™ and En Core™ perform with in a similar level of accuracy and precision

Both SoilCore™ and En Core™ showed 91% recovery for compounds other than gases (Comp 7 to 55). However for gases (Comp 1 to 6) SoilCore™ had 83% 23 and En Core™ 58% 66. Gases are difficult compounds to collect and store due to their physical nature.

Conclusion

Accuracy and precision with in control limits are considered the cornerstone of any quality system. The accuracy and precision presented in this study is with in the EPA SW-846 guidelines. This device meets EPA method 5035 Section 4.5.2 requirement for SoilCore™ to be considered equivalent to En Core™. Therefore, it is the conclusion of this study, that based on the above data SoilCore™ Sampler could be used for collection and storage of soil samples up to 65 hours at 4° C.

References (General)

1) Wisconsin Department of Natural Resources, Validation Study for Sampling Devices Used to Collect Volatile Organic Compounds and Gasoline Range Organics in Soil. Bureau of Integrated Science Services, 1998.

2) U.S. EPA, Test Methods for Evaluating Solid Waste, SW846-Method 5035, Third Edition Update III, Office of Solid Waste and Emergency Response, Washington D.C.

3) U.S. EPA, Test Methods for Evaluating Solid Waste, SW846-Method 8260B, Third Edition Update III, Office of Solid Waste and Emergency Response, Washington D.C.

4) Hewitt, Allen ., Studies with SoilCore™ sampler and sample holders. US Army Corps of Engineers Cold Regions Research and Engineering Laboratory, Hanover, NH, 12/98.

5) SoilCore, Inc. Standard Operating Procedure SI0005A, "Detailing the proper use of the SoilCore™ Sampler", 12/98

6) SoilCore, Inc. Standard Operating Procedure SI0010C, " Detailing the proper use of the SoilCore™ Sampler and methanol preservation".12/98

7) Hewitt, Alan. D., "Storage and Preservation of Soil Samples for Volatile Organic Compound Analysis" Draft, US Army Corps of Engineers Cold Regions Research and Engineering Laboratory, Hanover, NH, 11/98.

Table 1a
SoilCore™ and En Core™ Accuracy and Precision comparison

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Table 1b
SoilCore™ and En Core™ Accuracy and Precision comparison

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