Round-Robin Light Gas Study - Marcellus Shale Coalition - Phase 3 Study Completed
Environment Standards, Inc. was commissioned by the Marcellus Shale Coalition to design, execute, and report results of round-robin, inter-laboratory studies for the analysis of dissolved methane. Phases 1 and 2 were completed in March 2015 and October 2016 respectively. Both prior studies identified significant variance and bias across the laboratory community with dissolved methane analysis.
To identify the specific steps and techniques associated with the method that was causing the bias, Phase 3 entailed preparing replicate vials of a reference standard. The replicate standard was sent to 11 participating laboratories, three of which were identified as reference laboratories. The eight non-reference laboratories were provided the study design concentration and the concentration of the values reported by the reference standard provider. They were instructed to analyze each vial at a pace that allowed them to review their value against the design and self-diagnose issues impacting bias. This approach proved successful, and all non-reference laboratories were able to report concentrations within 70-130% of the average value (7130 µg/L) from the reference laboratories.
In some cases, this was achieved with the first vial and included all six analyses. In other cases, laboratories made adjustments to their procedure, ultimately removing significant bias. Specific and critical techniques, as well as corrective actions, were identified using this study design. Based upon this phase, the Marcellus Shale Coalition intends to prepare a detailed standard operating procedure (SOP) that will serve as the procedure for a future inter-laboratory study. The SOP will detail three calibration approaches that the commercial environmental laboratory communities use, thus differentiating this procedure from current published methods and available procedures.