6. LABORATORY SAMPLE PROCESSING AND ANALYSIS

6.1 Introduction

This section presents current practices and options available to process and subsequently analyze field samples obtained via ISM. Multiple options are available depending on the contaminants (i.e., explosives, metals, SVOCs, perchlorate, etc.). It is important to note that sample processing for various analytical suites is currently in early developmental stages and/or has experienced limited usage such that in many instances little to no performance information or specific standardized and published procedures are available. Future development of laboratory equipment and/or sample processing techniques should be evaluated based on their applicability to ISM and their ability to meet project-specific objectives.

Incremental sampling has been successfully implemented at numerous sites for several contaminants other than explosives and metals, such as perchlorate and white phosphorus (Walsh et al. 1997; 75th CEG/CEV 2007; USACE 2009) and other analytical fractions (HDOH 2009, ADEC 2009). However, experience in applying ISM techniques to analytes other than explosives and, to a more limited extent, metals is limited and/or in early developmental stages. Therefore, not all of the possible sample processing and/or analysis approaches discussed in this section may be applicable to all ISM projects and contaminants.

As discussed in Section 2 and Section 3, it is paramount that the project planning team consider the various field-sampling approaches and options during the initial project planning stages when applying ISM (or any other sampling technique) at a site. Equally important during these early planning stages is a dialogue about, and resolution of, the field sample processing and subsequent analytical approaches/options and considerations that must be evaluated and agreed on by stake holders prior to finalizing an ISM field program. For example, will any sample processing such as sieving, drying, subsampling, or other processing occur in the field which is problematic and more likely to increase fundamental error, or will all processing occur at the analytical laboratory? It is recommended that all ISM sample processing occur in a controlled setting to minimize errors. Likewise, what will laboratory processing entail? Within the laboratory, how will bulk sample mass splitting or sample conditioning (if performed) be conducted? What sample conditioning steps, such as drying, disaggregation or hydration, will be performed? Will particle size reduction (if warranted) via grinding, milling, crushing or other means or particle size selection using sieving to focus on a particle size fraction of interest be required? Finally, what analytical subsampling techniques and/or determinative analytical methods will be performed? All have varying degrees of potential ramifications on data quality and usability, and each must be addressed in the project planning stages and DQO decision process along with close coordination with the analytical laboratory to ensure that appropriately defined and agreed on procedures are employed. Specifically, reference Sections 5.2 and 5.3, as well as Sections 2 and 3 of this document, as applicable, for ISM considerations that should be evaluated as part of the DQO decision process.

DQOs and Laboratory Coordination

Project planning DQOs guide the choices of sample processing and analytical options.

As outlined in USEPA DQO guidance (USEPA 2006b), the DQO process is used to establish performance and acceptance criteria, which serve as the basis for designing a plan for collecting data of sufficient quality and quantity to support the goals of the study. As discussed above, the project delivery team must decide during the initial project planning phase which of the sample processing and analytical options currently available and applicable to ISM are most appropriate to achieve the ISM project DQOs.

During this decision process, close coordination with the analytical laboratory is particularly important. Additionally, any deviations in the field that may affect laboratory processing and/or analysis must be communicated immediately to the lab and project delivery team. The project delivery team must know, through close interaction of the team or the project chemist with the laboratory, precisely how sample processing and analysis will proceed within the laboratory. Specifically, what processing/preparatory/analytical methods/procedures are used, what QA/QC is employed and at what frequency, and what acceptance criteria will be applied? All of these greatly impact the specified project DQOs by affecting the project-specific data quality indicators (DQIs) and method quality indicators (MQIs) determined during the DQO process.

The subsections that follow discuss various options regarding sample processing and analysis for ISM. Figure 6-1 presents a flow diagram of these options and where decision points typically occur for an ISM sample. As ISM sample processing and analysis techniques advance, modifications and/or additions to this generalized schematic are expected to occur. Hence, it is imperative that close communication and coordination with the analytical laboratory take place from the initial project planning phase and DQO formulation through ISM sample collection and subsequent sample processing and analysis to ensure defined data of known quality and usability are obtained for the project.

Sample processing and analysis flow chart.

Figure 6-1. Sample processing and analysis flow chart.



Figure 6-1. Sample processing and analysis flow chart (continued).