Why is filtering groundwater samples for petroleum hydrocarbon analysis discouraged?

Filtering groundwater samples for petroleum hydrocarbon analysis is discouraged primarily because it can lead to the loss of constituents of interest. During the filtering process, some larger and more complex hydrocarbons may be removed along with particulate matter. This loss can skew the analytical results, making it difficult to accurately assess the concentration and composition of the hydrocarbons present in the groundwater. Since the goal is to obtain a comprehensive analysis of all relevant petroleum hydrocarbons, ensuring that none are inadvertently discarded during sample preparation is crucial for accurate environmental assessments and remediation planning.

In contrast, the factors that relate to slowing down the analysis process, contamination of the samples, or the need for specialized equipment are less central to the primary concern of preserving all relevant compounds for analysis. While these may be considerations in the overall sampling procedure, they do not directly address the critical issue of data integrity that comes with the potential loss of analytes.