To help ensure accurate measurements, Region 9 recommends that these guidelines be followed whenever VOCs in soil or other solid matrices are sampled and analyzed. These guidelines address methods for: (1) handling of samples as intact soil cores; (2) preserving samples; (3) storing samples in hermetically sealed containers; and (4) minimizing analyte losses due to direct volatilization (both in the field and the laboratory) and biodegradation. Region 9 believes that following these guidelines is a scientifically important part of ensuring that accurate concentrations of VOCs are measured. Therefore, the procedures by which data are generated for or.