High salt concentrations in aqueous samples decrease the solubility of polar organic volatiles in the sample matrix and promote their transfer into the headspace, resulting in lower K values. The magnitude of the salting-out effect on K, however, is not the same for all compounds.

Compounds with K values that are already relatively low will experience very little change in the partition coefficient after adding a salt to an aqueous sample matrix.

Generally, volatile polar compounds in polar matrices (aqueous samples) will experience the largest shifts in K and have higher responses after the addition of salt to the sample matrix.

Common salts used to decrease matrix effects:

• Ammonium chloride
• Ammonium sulphate
• Sodium chloride
• Sodium citrate
• Sodium sulphate
• Potassium carbonate

The value of K is also dependent on the Phase Ratio. This is discussed in the next section.