When should samples be preserved at the time of collection versus at the laboratory?

There are very few parameters that require immediate preservation of samples at the time of collection. In most cases, we preserve samples upon receipt, as long as they are received by our laboratory within 24 hours of collection. Torrent prefers to send unpreserved containers whenever possible for the following reasons:
–Injuries or accidents may result in the field if untrained personnel are asked to preserve samples using acids and/or caustic materials.
–Fewer sample volumes need to be taken field, which reduces possible contamination.
–By preserving samples in the laboratory, we can ensure samples are preserved to the correct pH.