What is a primary concern when analyzing petroleum in groundwater samples?

When analyzing petroleum in groundwater samples, preventing VOC (Volatile Organic Compound) loss is a primary concern because VOCs are key indicators of contamination and their concentrations can significantly impact the assessment of environmental conditions. VOCs can easily evaporate when exposed to air, which can lead to underestimations of their presence in groundwater samples. This loss can skew data, resulting in an inaccurate picture of the contamination extent and potentially compromising remediation efforts.

Other factors like maintaining pH levels and avoiding microbial contamination are relevant in certain contexts, but they do not address the direct challenge posed by the volatility of organic compounds in petroleum. Counting bacteria accurately is also important but is not inherently tied to the assessment of petroleum contaminants in groundwater as VOCs would be. Thus, the preservation of VOC integrity is crucial for accurate analysis and understanding of petroleum impacts in groundwater.