Frequent Questions

Low recovery of styrene and several other compounds in soil volatile organic analyte samples, likely caused by the bisulfate preservative.

We have observed low recovery of styrene and several other compounds in some soil VOA samples. After conducting some research, we found that the sodium bisulfate preservative is likely to be responsible for the low recoveries.


Chapter 4 – Table 4‐1 of SW‐846 recommends that a second set of samples without acid preservatives be collected and analyzed as soon as possible if the compounds (e.g., vinyl chloride, styrene, and 2-chloroethyl vinyl ether) are analytes of interest.  EPA 5035 does not provide another preservation option, aside from sodium bisulfate, for low concentration soil method unless the sample is effervescent.

An updated Method 5035A (Draft Revision 1, July 2002) is available and posted on the “Validated Methods” page:  The information provided in Appendix A of Method 5035A was based on EPA’s evaluation of currently available data and technology as applied to the most appropriate sample handling and preservation procedures in order to minimize the loss of volatile organic compounds (VOCs) during the collection and analysis of aqueous and solid materials. The intended users of this Appendix guidance are those individuals and organizations involved in the collection and preparation of samples for VOC analyses during the characterization of solid materials under the Resource Conservation and Recovery Act (RCRA).  See Appendix A for guidance on selecting an appropriate sample collection and preservation technique that are suitable for VOC analyses to meet the data quality requirements or objectives for the intended use of the results.

Table A-1 in Appendix A of 5035A recommends VOC Sample Preservation Techniques and Holding Times with a variety options using physical and chemical preservations and compound applicability.

Ultimately, holding times and preservation requirements are typically set by the regulator or data user in a project-specific QAPP.

Other Category: 8000 series



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