12790 Seabreeze F.D. San Diego CA, 92130
Phone (858) 259-2252, FAX (858) 259-2384)
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Introduction
The purpose of this study was to present SoilCore™ (Figure 1) as an equivalent or better soil sampling device than the competitor for use in US EPA Method 5035. The study will present data to show BTEX /MTBE recovery at 94% after 48 hour storage in the SoilCore™. The analyses were performed by Synergic Analytics, Inc. in Grand Rapids, MI, an A2LA Accredited, Michigan DEQ drinking water certified, and DOD approved Laboratory.
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Analytical Procedure/Data
Fifteen SoilCore™ devices were filled (SOP:SC0010C) with uncontaminated but environmentally exposed sand at 10% moisture for 6-hour, 24-hour, and 48-hour testing. Five 2-oz jars were filled with the same sand for 0-hour testing purposes. All the devices were spiked with stock standard. All devices were capped within 1 minute of spiking and refrigerated. All devices and the 0-hour jars went through the sample prep SOP (SC0010C) before analysis. All samples were analyzed by method 8260 within 14 days from their sampling. According to the data obtained SoilCore™ (Table 1) has been able to maintain contamination within its device to levels above 87% in comparison to 0-hour methanol extraction procedure.
Discussion
Sample extraction and analyses were performed using EPA SW-846 Methods 5035, 8260b respectively. The study focused its attention on comparing the SoilCore™ recoveries to methanol extraction, which at this time is the most conservative approved sampling protocol. The BTEX and MTBE compounds were used for initial study because they are by far the majority of tests requested for volatile testing. The next study will include many other volatile compounds listed in method 8260b.
The study started with five samples for each group. 0-hour had one set of data which was statistically at the 95% Confd. Level, had an outlayer and was dropped out. The 48-hour group had a duplicate analysis performed which had 1% relative percent difference and was included in the calculations.
The study shows acceptable accuracy according to SW-846 8020 and 8260 between 87% to 112%, and precision between 6% to 16%.
Conclusion
According to the above data SoilCore™ can be used for BTEX/MTBE soil sampling procedures. The device shows acceptable precision and accuracy per SW-846, methods 8260 and 8020.
Ref 1) SW-846 methods 5035, 8020, 8260
Table 1, Percent Recovery
| Accuracy | Precision | |||
| Total BTEX/MTBE in ug/L of methanol in extraction jar | Percent recovery in comparison to methanol extraction method | RSD | No. of Data Points | |
| 0-hour,Methanol Extract | 3,480 | 7% | 4 | |
| 6-hour | 3,029 | 87% | 16% | 5 |
| 24-hour | 3,903 | 112% | 6% | 5 |
| 48-hour | 3,259 | 94% | 6% | 6 |
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SOP #Sc0010C
SOP detailing the proper use of the SoilCore™ Sampler and methanol preservation.
1.0 Principle Reference(s) EPA SW-846, Method 5035 State of Michigan Modified Method 5035, DEQ ORGLAB11
2.0 Scope and Application This method is for the methanol preservation of soils to be analyzed for the presence of volatile compounds.
3.0 Summary of Test Method A soil sample(s) is removed from the SoilCore™ Soil Sampler, placed in Methanol and/or Sodium Bisulfate, sonicated and held at 4o C for volatile analysis.
4.0 Interference's and Corrective Procedures Not Applicable
5.0 Safety Precautions General safety procedures should be observed at all times. Protective gloves and safety glasses should be worn at all times while sampling and preserving. The toxicity or carcinogenity of all analytes and reagents used in this method has not been precisely defined. Therefore each chemical compound should be treated as a potential health hazard.
6.0 Sample Size, and Handling Procedures Sample collection can be done using two different sizes. The 25g sample is used when there are high levels (>200 ug/Kg) of analytes present. The 5g sample is to be used when the analytes are expected to be present at low levels (<200 ug/Kg). So it stands to reason that if you are sampling an area with no previous analytical history, you are going to need both types of samples because you won't know what the VOC concentration is. The 5g sample must be preserved with sodium bisulfate and the 25g sample with methanol.
Additionally, all soil analyses must be reported out on a dry weight basis. This means that the person doing the sampling must take an extra soil-sampling jar into the field so that the lab can use the soil collected in it to determine the moisture content of the sample. However, once you have determined that you have a high level or low level site, you will only need to use the 25g portion of the sampler or the 5g portion of the sampler. You can then use the empty chamber to collect soil for the dry weight determination and will not have to bring that extra jar into the field. In the State of Michigan the 25g portion will be used for the methanol preservation and analysis and the 5g portion will be used for the dry weight determination.
7.0 Apparatus/Instrumentation Graduated Cylinder Purge and Trap Grade of Methanol Balance Jars with Teflon Lined Lids Sonicator (300 Watt)
8.0 Routine Preventative Maintenance
Not Applicable
9.0 Chemicals and Reagents
Purge and Trap Grade of Methanol
10.0 Sample Preparation, Collection, and Preservation
As with any sampling procedure for volatiles, care must be taken to minimize the disturbance of the sample in order to minimize the loss of the volatile components. The sample should be collected as soon as possible after the surface of the soil or other solid material has been exposed to the atmosphere; generally in less than a few minutes at most.
Each SoilCore™ Soil Sampler comes packaged in a sterile aluminized Mylar™ double sealed pouch. The pouch is to be opened by tearing the top of the pouch where the two indicator notches are located. You then open the "zipper" seal to gain access to the inside of the pouch. Inside the pouch will be the body of the SoilCore™, two end caps and a nylon security strap.
Remove the SoilCore™ body and insert the 25g or 5g cavity into the soil sampling location that you have just exposed to the atmosphere. Carefully wipe the exterior of the sampler with a clean cloth or towel to remove any excess soil still attached to the outside of the soil sampler. Quickly attach the appropriate end cap with a twisting, pushing motion. Make sure the cap is fully aligned with the cap closure line on the sampler body. Repeat this for the second cavity. The USEPA recommends that a second sampler be filled in the same manner to be available for QC etc.
It is now time to label your sample. On the back of the sampler pouch is a place for sample identification. At the bottom of the form is a removable sample ID tag. Write the same ID on this tag, remove it from the back of the pouch and place it on the SoilCore™ Sampler. Please verify that the labeled sampler is put into the pouch with the corresponding sample ID.
After the exterior of the sampler has been cleaned and capped, it is time to put the nylon security strap in place. This is done by placing the strap in the two notched wings on each cap. The security strap is then tightened. A security strap gun is available which will tighten the strap to the appropriate tension and automatically cut off the excess strapping. The SoilCore™ sampler is then placed back into the Mylar™ pouch and resealed. After resealing make sure that the sample is then stored on ice or at 4o C.
The preservation step must take place in an area free of fugitive vapors. To begin the preservation process tare the sample jar with the Teflon lid. Remove the lid in preparation to add the methanol and soil sample. Measure out 25ml of methanol. Cut the security strap on the SoilCore™ Sampler. Hold the soil sampler with the cap on top. Remove the cap and immediately discharge the soil into the jar. Immediately add the measured methanol to the jar and cap. Then reweigh the jar with the soil and methanol in it. Subtract the weight of the 25 mls of methanol (19.79g) and you will have the weight of the soil sample. Determine if the soil:methanol ratio is 1:1. Add MeOH if needed. Determine the appropriate amount of surrogate concentration based on the volume of MeOH in the jar and add to the sample jar.
Shake the sample for two minutes and then sonicate for twenty minutes. After allowing the soil to settle your sample is now ready to proceed with the analysis as outlined in USEPA Method 5035
11.0 Calibration Procedures (Instrumental Analyses)
12.0 Procedure
See 10.0 Above
13.0 Calculations/Data Handling
See 10.0 Above
14.0 Quality Assurance
Each SoilCore™ lot is tested with Ottawa sand to verify the inertness of the SoilCoreä Sampler. The lot is tested using USEPA SW-846, Method 8260.
15.0 Method Validation/Analyst Certification
A complete description of the materials used in the manufacturing of the SoilCore™ Sampler is available upon request to SoilCore customers and appropriate governing entities. Analytical data is available for both the raw material as well as the finished product.
16.0 Appendices As referenced
Not Applicable