QA Approaches for Water Passive Sampling Methods

Field Sampling, Measurement and Sensor Technology
Oral Presentation

Prepared by H. Lord
Maxxam Analytics, 6740 Campobello Road, Mississauga, Ontario, L5N 2L8, Canada


Contact Information: hlord@maxxam.ca; 905-817-5711


ABSTRACT

Several passive sampling technologies for determining water contaminant concentrations are gaining acceptance for selected applications in water and sediment analysis, as either alternative or companion approaches to standard testing methods. As methods for these newer technologies are developed it is important to incorporate data quality assurance strategies that allow for a comparison of method performance between the newer and standard testing methods. However, the quality assurance procedures that are routinely applied in the standard methods are not always directly applicable to passive sampling technologies. The same can be said for some aspects of method validation. In addition, where the objective is to report water concentrations, as opposed to reporting contaminant concentrations or masses in the passive sampling media itself, some aspects of sampling uncertainty and quality assurance must also be considered whereas sampling data quality is typically not considered in standard analytical test methods.

This presentation will describe how our standard method quality assurance practices have been applied to sample processing and instrumental methods for polyethylene and diffusive gradients in thin-films (DGT) passive sampler media. It will also review the results of a full method validation for polyethylene, including determination of method detection limits, limits of quantification and precision and accuracy. Particular emphasis will be placed on the aspects of each where notable deviations from standard approaches were required. Finally, aspects of uncertainty in water concentration estimates that are dependent on field deployment and data manipulation procedures external to lab processing and instrumental analysis will be discussed, along with recommendations for quality assurance procedures for these stages as well.