2.10.1 Conductivity
When a water sample for off-line conductivity testing is collected, container cleanliness and atmospheric CO2 are the two greatest risks to preserving the original conductivity of the sample. If single use, disposable containers are not used, then re-used container cleanliness must be controlled and assured by routine procedures. Trace Conductive residues can leach from glass container surfaces. The solubility of the leaching materials is relatively poor, so the leaching process could be relatively slow, but it is nevertheless a factor, particularly if glass containers are used and if the conductivity of ultra-pure water is being assessed against tight specifications. Sample containers should be filled as much as practical to minimize air entrapment in the headspace which may allow additional atmospheric CO2 to impact the sample.